dnv ship rules pt.3 ch.3 - hull equipment and safety

RULES FORCLASSIFICATION OF

SHIPS

NEWBUILDINGS

HULL AND EQUIPMENTMAIN CLASS

PART 3 CHAPTER 3

HULL EQUIPMENT AND SAFETYJANUARY 2006This booklet includes the relevant amendments and corrections shown in the January 2007 version of Pt.0 Ch.1 Sec.3.

CONTENTS PAGE

Sec. 1 General Requirements ................................................................................................................ 7Sec. 2 Sternframes, Rudders and Steering ........................................................................................... 8Sec. 3 Anchoring and Mooring Equipment ........................................................................................ 23Sec. 4 Masts and Rigging.................................................................................................................... 37Sec. 5 Foundations for Deck Machinery, Towing Equipment and Lifting Appliances ...................... 40Sec. 6 Openings and Closing Appliances ........................................................................................... 46Sec. 7 Corrosion Prevention................................................................................................................ 69Sec. 8 Protection of the Crew.............................................................................................................. 72Sec. 9 Stability .................................................................................................................................... 74Sec. 10 Internal Communication........................................................................................................... 81

DET NORSKE VERITASVeritasveien 1, NO-1322 Høvik, Norway Tel.: +47 67 57 99 00 Fax: +47 67 57 99 11

CHANGES IN THE RULES

General

This booklet is a reprint of the previous edition and apart from clari-fications of text and the inclusion of amendments and corrections,published in the July 2005 edition of Pt.0 Ch.1 Sec.3, no other chang-es have been made. The booklet supersedes the January 2005 editionof the same chapter.This chapter is valid until superseded by a revised chapter. Supple-ments will not be issued except for an updated list of minor amend-ments and corrections presented in Pt.0 Ch.1 Sec.3. Pt.0 Ch.1 isnormally revised in January and July each year.Revised chapters will be forwarded to all subscribers to the rules.Buyers of reprints are advised to check the updated list of rule chap-ters printed in Pt.0 Ch.1 Sec.1 to ensure that the chapter is current.

Comments to the rules may be sent by e-mail to [email protected] subscription orders or information about subscription terms, please use [email protected] information about DNV and the Society's services is found at the Web site http://www.dnv.com

© Det Norske VeritasComputer Typesetting (FM+SGML) by Det Norske Veritas Printed in Norway

If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of Det Norske Veritas, then Det Norske Veritas shall pay compensation to such personfor his proved direct loss or damage. However, the compensation shall not exceed an amount equal to ten times the fee charged for the service in question, provided that the maximum compen-sation shall never exceed USD 2 million.In this provision "Det Norske Veritas" shall mean the Foundation Det Norske Veritas as well as all its subsidiaries, directors, officers, employees, agents and any other acting on behalf of DetNorske Veritas.

Amended, Rules for Ships, January 2006see Pt.0 Ch.1 Sec.3, January 2007 Pt.3 Ch.3 Contents –

CONTENTS

SEC. 1 GENERAL REQUIREMENTS .......................... 7

A. Classification..........................................................................7A 100 Application........................................................................7

B. Definitions ..............................................................................7B 100 Symbols.............................................................................7

C. Documentation ......................................................................7C 100 General ..............................................................................7

SEC. 2 STERNFRAMES, RUDDERS AND STEERING ........................................................... 8

A. General...................................................................................8A 100 Introduction.......................................................................8A 200 Definitions.........................................................................8A 300 Documentation .................................................................9

B. Materials ................................................................................9B 100 Plates and sections ............................................................9B 200 Forgings and castings........................................................9B 300 Bearing materials ..............................................................9B 400 Material certificates.........................................................10B 500 Heat treatment .................................................................10

C. Arrangement and Details ...................................................10C 100 Sternframes and rudders..................................................10

D. Design Loads and Stress Analysis......................................11D 100 Rudder force and rudder torque, general .......................11D 200 Rudders with stepped contours .......................................12D 300 Stress analysis .................................................................12

E. Sternframes and Rudder Horns ........................................12E 100 General ............................................................................12E 200 Propeller posts.................................................................13E 300 Sole pieces ......................................................................13E 400 Rudder horns ...................................................................13

F. Rudders ................................................................................15F 100 General arrangement and details.....................................15F 200 Rudder plating.................................................................16F 300 Rudder bending ...............................................................16F 400 Web plates.......................................................................16F 500 Single plate rudders.........................................................16F 600 Mounting of rudder .........................................................17

G. Rudder Stocks and Shafts ..................................................17G 100 General ............................................................................17G 200 Rudder stock with couplings...........................................17G 300 Rudder shaft ....................................................................19G 400 Bearings and pintles .......................................................20

H. Propeller Nozzles.................................................................21H 100 General ............................................................................21H 200 Plating .............................................................................21H 300 Nozzle ring stiffness........................................................21H 400 Welding...........................................................................21H 500 Supports ..........................................................................22

I. Propeller Shaft Brackets ....................................................22I 100 General ............................................................................22I 200 Arrangement....................................................................22I 300 Struts ...............................................................................22I 400 Welding...........................................................................22I 500 Material ...........................................................................22I 600 Testing.............................................................................22

J. Testing ..................................................................................22J 100 Sternframes .....................................................................22J 200 Rudders and rudder stock connections............................22

SEC. 3 ANCHORING AND

MOORING EQUIPMENT ............................... 23

A. General ................................................................................ 23A 100 Introduction.....................................................................23A 200 Documentation................................................................23A 300 Assumptions....................................................................23

B. Structural Arrangement for Anchoring Equipment ...... 23B 100 General ...........................................................................23

C. Equipment Specification.................................................... 24C 100 Equipment number..........................................................24C 200 Equipment tables.............................................................25

D. Anchors ............................................................................... 26D 100 General ............................................................................26D 200 Materials .........................................................................26D 300 Anchor shackle................................................................27D 400 Testing.............................................................................27D 500 Additional requirements for H.H.P. and

S.H.H.P. anchors .............................................................27D 600 Identification ...................................................................28

E. Anchor Chain Cables ........................................................ 28E 100 General ............................................................................28E 200 Materials .........................................................................28E 300 Heat treatment and material testing ...............................30E 400 Breaking test ...................................................................30E 500 Proof test .........................................................................30E 600 Tolerances .......................................................................30E 700 Identification ...................................................................31E 800 Repair of defects .............................................................31

F. Windlass and Chain Stoppers .......................................... 33F 100 General design ................................................................33F 200 Materials .........................................................................33F 300 Testing.............................................................................34

G. Towlines and Mooring Lines ............................................ 34G 100 General ............................................................................34G 200 Materials .........................................................................34G 300 Testing of steel wire ropes ..............................................34G 400 Testing of natural fibre ropes..........................................35G 500 Mooring Winches............................................................36

SEC. 4 MASTS AND RIGGING................................... 37

A. General ................................................................................ 37A 100 Introduction.....................................................................37A 200 Assumptions....................................................................37A 300 Definitions.......................................................................37A 400 Documentation................................................................37

B. Materials and Welding ...................................................... 37B 100 Materials .........................................................................37

C. Arrangement and Support ................................................ 38C 100 Masts and posts ...............................................................38C 200 Standing rigging..............................................................38

D. Design and Scantlings ........................................................ 38D 100 General ............................................................................38D 200 Unstayed masts and posts with derricks .........................38D 300 Stayed masts or posts with derricks with a

lifting capacity not exceeding 10 t ..................................38D 400 Stayed masts of posts with derricks with a

lifting capacity of 10 t or more, but not exceeding 40 t ..38D 500 Stayed masts without derricks ........................................39D 600 Shrouds ...........................................................................39

SEC. 5 FOUNDATIONS FOR DECK MACHINERY, TOWING EQUIPMENT AND LIFTING APPLIANCES..................................................... 40

A. Crane and Lifting Appliances ........................................... 40A 100 Introduction ....................................................................40

DET NORSKE VERITAS

Rules for Ships, January 2006 Amended,Pt.3 Ch.3 Contents – see Pt.0 Ch.1 Sec.3, January 2007

A 200 Documentation ................................................................40A 300 Materials..........................................................................40A 400 Arrangement....................................................................40A 500 Design loads ....................................................................41A 600 Allowable stresses...........................................................41A 700 Testing.............................................................................41

B. Foundations for Winches, Windlasses and other Pulling Accessories........................................................................... 41

B 100 Introduction.....................................................................41B 200 Documentation ................................................................41B 300 Design loads and allowable stresses ...............................41B 400 Securing requirements for fore deck windlasses.............42B 500 Materials..........................................................................43

C. Shipboard Fittings and Supporting Hull Structures Associated with Towing and Mooring on Conventional Vessels .................................................................................. 44

C 100 Towing ............................................................................44C 200 Mooring...........................................................................44C 300 Materials..........................................................................45

SEC. 6 OPENINGS AND CLOSING APPLIANCES . 46

A. General ................................................................................ 46A 100 Application......................................................................46A 200 Definitions.......................................................................46A 300 Documentation for approval ...........................................46A 400 Testing.............................................................................47A 500 Certification of control and monitoring system ..............47

B. Access Openings in Superstructures and Freeboard Deck................................................................... 47

B 100 Doors ...............................................................................47B 200 Sill heights.......................................................................48B 300 Access openings in freeboard and superstructure decks .48B 400 Strength and securing of small hatches on the

exposed fore deck...........................................................48

C. Side and Stern Doors.......................................................... 50C 100 General. ...........................................................................50C 200 Structural arrangement ....................................................50C 300 Design loads ....................................................................50C 400 Plating .............................................................................50C 500 Stiffeners .........................................................................51C 600 Girders.............................................................................51C 700 Closing arrangement, general .........................................51C 800 Closing arrangement, strength ........................................51C 900 Closing arrangement, system for operation and

indication/monitoring......................................................52

D. Hatchway Coamings........................................................... 53D 100 General ............................................................................53D 200 Coaming heights .............................................................53D 300 Scantlings ........................................................................53

E. Hatch Covers....................................................................... 53E 100 General ............................................................................53E 200 Design loads ....................................................................54E 300 Plating .............................................................................55E 400 Stiffeners .........................................................................55E 500 Girders.............................................................................56E 600 Stiffness of cover edges ..................................................56E 700 Structural analysis ...........................................................56

F. Hatchway Tightness Arrangement and Closing Devices 57F 100 General ............................................................................57F 200 Design and tightness requirements .................................57F 300 Securing devices in general.............................................57F 400 Securing arrangement for weathertight hatch covers......58F 500 Securing arrangement for deep tank or cargo oil tank

hatch covers.....................................................................58F 600 Securing arrangement for hatch covers

carrying deck cargo.........................................................58F 700 Drainage arrangement .....................................................59

G. Internal Doors and Hatches for Watertight Integrity..... 59G 100 General ............................................................................59G 200 Operation.........................................................................60G 300 Strength ...........................................................................60

H. Ventilators ...........................................................................60H 100 Coamings and closing arrangements...............................60H 200 Thickness of coamings....................................................60H 300 Arrangement and support................................................60H 400 Strength requirements for fore deck ventilators..............61

I. Tank Access, Ullage and Ventilation Openings ...............61I 100 General ............................................................................61I 200 Hatchways.......................................................................61I 300 Air Pipes..........................................................................61I 400 Strength requirements for fore deck air pipes.................62

J. Machinery Space Openings ...............................................63J 100 Openings .........................................................................63

K. Scuppers, Inlets and Discharges........................................63K 100 Inlets and discharges .......................................................63K 200 Pipe thickness..................................................................65K 300 Scuppers ..........................................................................65K 400 Periodically unmanned machinery space........................65

L. Side Scuttles, Windows and Skylights ..............................65L 100 Side Scuttles, Windows and Skylights............................65L 200 Glass dimensions, side scuttles and windows.................66

M. Freeing Ports .......................................................................67M 100 Definitions.......................................................................67M 200 Freeing port area .............................................................67M 300 Location and protection of openings...............................67M 400 Multiple wells .................................................................67M 500 Free flow area..................................................................67M 600 Type «A», «B-100» and «B-60» ships............................68

N. Special Requirements for Type A Ships ...........................68N 100 Machinery casings...........................................................68N 200 Gangway and access .......................................................68N 300 Hatchways.......................................................................68N 400 Freeing arrangements......................................................68

SEC. 7 CORROSION PREVENTION ......................... 69

A. General.................................................................................69A 100 Definitions.......................................................................69A 200 Documentation ................................................................69

B. Corrosion prevention systems ...........................................70B 100 General ............................................................................70B 200 Coatings ..........................................................................70B 300 Cathodic protection .........................................................71

SEC. 8 PROTECTION OF THE CREW ..................... 72

A. Protection of the Crew........................................................72A 100 Guard rails.......................................................................72A 200 Gangways, walkways and passageways .........................72

SEC. 9 STABILITY........................................................ 74

A. Application, Definitions and Document Requirements...74A 100 Application......................................................................74A 200 Terms ..............................................................................74A 300 Documentation for approval ...........................................75

B. Surveys and Tests ..............................................................75B 100 General ............................................................................75

C. General Requirements........................................................75C 100 Stability book ..................................................................75C 200 Fixed Ballast ...................................................................75C 300 Draught Marks ................................................................75C 400 Loading Computer System..............................................75

D. Intact Stability Criteria .....................................................75D 100 General stability criteria..................................................75D 200 Weather criterion.............................................................77D 300 Assumptions concerning intact stability criteria and

calculations......................................................................79

E. Damage Stability.................................................................79E 100 Damage stability .............................................................79

DET NORSKE VERITAS

Amended, Rules for Ships, January 2006see Pt.0 Ch.1 Sec.3, January 2007 Pt.3 Ch.3 Contents –

F. Determination of Lightweight Data...................................79F 100 Application......................................................................79F 200 Procedure ........................................................................79F 300 Lightweight Survey.........................................................80

SEC. 10 INTERNAL COMMUNICATION................... 81

A. General Requirements........................................................81A 100 Application......................................................................81A 200 Classification...................................................................81A 300 Design documentation ....................................................81A 400 Onboard survey or functional testing..............................81A 500 Terms, definitions and abbreviations ..............................81

B. Ship Requirements - Main Class Cargo Ship and Passenger Vessels ............................................................... 81

B 100 Two way voice communication ......................................81B 200 Public address system/General alarm, applicable to

all vessels ........................................................................82B 300 Public address system, applicable to passenger vessels..83B 400 Electrical requirements ...................................................83

C. Ship Requirements - Additional Class ............................. 84C 100 Fishing vessels ................................................................84C 200 Oil production and storage vessels .................................84C 300 Periodically unattended machinery space.......................84C 400 Dynamic positioning systems .........................................84C 500 Nautical safety ................................................................84

DET NORSKE VERITAS

Rules for Ships, January 2006 Amended,Pt.3 Ch.3 Contents – see Pt.0 Ch.1 Sec.3, January 2007

DET NORSKE VERITAS

Amended, Rules for Ships, January 2006see Pt.0 Ch.1 Sec.3, January 2007 Pt.3 Ch.3 Sec.1 –

SECTION 1 GENERAL REQUIREMENTS

A. ClassificationA 100 Application101 The Rules in this chapter apply to steering arrangementand anchoring, mooring and load handling equipment.102 Necessary strengthening of the hull structure due toloads imposed by the equipment and installations are givenwhere appropriate.

B. DefinitionsB 100 Symbols101

L = Rule length in m 1)B = Rule breadth in m 1)

D = Rule depth in m 1)

T = Rule draught in m 1)

∆ = Rule displacement in t 1)

CB = Rule block coefficient 1)

V = maximum service speed in knots on draught T

1) For details see Ch.1 Sec.1 B

C. Documentation

C 100 General101 Plans and particulars to be submitted for approval or in-formation are specified in the respective sections of this chap-ter.

DET NORSKE VERITAS

Rules for Ships, January 2006 Amended,Pt.3 Ch.3 Sec.2 – see Pt.0 Ch.1 Sec.3, January 2007

SECTION 2 STERNFRAMES, RUDDERS AND STEERING

A. GeneralA 100 Introduction101 Vessels shall be provided with means for steering (direc-tional control) of adequate strength and suitable design. Themeans for steering shall be capable of steering the ship at max-imum ahead service speed, which shall be demonstrated.102 Steering may be achieved by means of rudders, foils,flaps, steerable propellers or jets, yaw control ports or sidethrusters, differential propulsive thrust, variable geometry ofthe vessel or its lift system components, or by any combinationof these devices.103 Requirements in this section are related to rudder andrudder design. For requirement to steering gear operating therudder, reference is made to Pt.4 Ch.14 Sec.1.

If steering is achieved by means of waterjet or thrusters refer-ence is made to Pt.4 Ch.5 Sec.2 and Sec.3 respectively. Othermeans of steering is subject to special consideration.

A 200 Definitions201 Maximum ahead service speed is the maximum speedcorresponding to maximum nominal shaft RPM and corre-sponding engine MCR in service at sea on summer load water-line.202 Maximum astern speed is the speed which it is estimatedthe ship can attain at the designed maximum astern power atthe deepest seagoing draught.203 Some terms used for rudder, rudder stock and supportingstructure are shown in Fig.1.

Fig. 1Rudders

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204 Symbols:

f1 = material factor, see Bpm = maximum bearing surface pressure, see BFR = design rudder force, see DMTR= design rudder torque, see DA = total area in m2 of rudder bladeH = mean rudder height in m.

A 300 Documentation 301 Plans etc. as specified below shall be submitted for ap-proval:

— sternframe, horn and propeller brackets— rudder including details of bearings, shaft, pintles and rud-

der lock arrangement— rudder stock including details of couplings, bolts and keys— rudder carrier including fastening arrangement (bolts,

chocking and side stoppers)— steering gear and/or rudder carrier foundation— lubrication arrangement for rudder bearings— rudder stoppers external to steering gear.

The plans shall give full details of scantlings and arrangementas well as data necessary for verifying scantling calculationstogether with proposed rated torque. Material specificationsand particulars about heat treatment are also required.302 For important components of welded construction (e.g.rudder, rudder stock), full details of the joints, welding proce-dure, filler metal and heat treatment after welding shall bespecified on the plans.303 Procedure for stress relieving of cast steel parts shall bespecified on the plans.304 Plans of the following items shall be submitted for infor-mation:

— outline of the propeller— instruction manual for mounting, dismounting and mainte-

nance. In addition to information considered relevant bythe manufacturer, such a manual shall contain at least thefollowing:

— mounting and dismounting procedures for rudder (in-cluding flaps as a detached component), rudder stockand pintles

— securing arrangement for rudderstock and pintles— measuring procedure of bearing clearances— for flap rudders, the allowable bearing clearances for

pins (hinges and link system)— bearing lubrication system (if relevant)

a copy of the manual shall be made available onboard.— for flap rudders and others of non-conventional design:

torque characteristics (torque versus rudder angle).Guidance note:For the last item it is sufficient to have hydrodynamic torque ver-sus rudder angle documented in homogeneous water stream.

---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---

305 For rudders included under DP-control documentationof expected life time of bearings subjected to extra ordinarywear rate due to DP shall be submitted for approval, see Pt.6Ch.7.

B. MaterialsB 100 Plates and sections101 Selection of material grades for plates and sections forsternframes, rudders, rudder horns and shaft brackets are in

general not to be of lower grades as given in Table B1.

For rudder and rudder body plates subjected to stress concen-trations (e.g. in way of lower support of semi-spade rudders orat upper part of spade rudders) Class IV as given in Pt.3 Ch.1Sec.2 Table B1 shall be applied.(IACS UR S6 Rev.4)102 The material factor f1 included in the various formulaefor structures may be taken as:f1 = 1.0 for NV-NS steelf1 = 1.08 for NV-27 steelf1 = 1.28 for NV-32 steelf1 = 1.39 for NV-36 steelf1 = 1.47 for NV-40 steel

B 200 Forgings and castings201 Rudder stocks, pintles, coupling bolts, keys and castparts of rudders shall be made of rolled, forged or cast carbonmanganese steel in accordance with Pt.2.

Guidance note:Rudder stocks and pintles should be of weldable quality in orderto obtain satisfactory weldability for any future repairs by weld-ing in service.


For rudder stocks, pintles, keys and bolts the minimum yieldstress shall not be less than 200 N/mm2.202 Nodular cast iron may be accepted in certain parts afterspecial considerations. Materials with minimum specified ten-sile strength lower than 400 N/mm2 or higher than 900 N/mm2

will normally not be accepted in rudder stocks, shafts or pint-les, keys and bolts.203 The material factor f1 for forgings (including rolledround bars) and castings may be taken as:

σf = minimum upper yield stress in N/mm2, not to be takengreater than 70% of the ultimate tensile strength. If notspecified on the drawings, σf is taken as 50% of the ul-timate tensile strength.

a = 0.75 for σ f > 235 = 1.0 for σ f < 235

204 Before significant reductions in rudder stock diameterdue to the application of steels with yield stresses exceeding235 N/mm2 are granted, the Society may require the evaluationof the rudder stock deformations. Large deformations shouldbe avoided in order to avoid excessive edge pressures in wayof bearings. The slope of the stock should be related to thebearing clearance, see G405.

B 300 Bearing materials301 Bearing materials for bushings shall be stainless steel,bronze, white metal, synthetic material or lignum vitae. Stain-less steel or bronze bushings shall be used in an approved com-bination with steel or bronze liners on the axle, pintle or stock.The difference in hardness of bushing and liners shall not be

Table B1 Plate material gradesThickness in mm Normal strength

structural steelHigh strength

structural steelt ≤ 20 A A

20 < t ≤ 25 B A25 < t ≤ 40 D D40 < t ≤ 150 E E

f1σ f

235---------⎝ ⎠

⎛ ⎞a

=

DET NORSKE VERITAS


less than 65 Brinell. 13% Chromium steel shall be avoided.302 Synthetic bearing bushing materials shall be of an ap-proved type. For this type of bushing, adequate supply of lubri-cation to the bearing for cooling/lubrication purposes shall beprovided.

303 The maximum surface pressure pm for the various bear-ing combinations shall be taken as given in Table B2. Highervalues than given in Table B2 may be taken in accordance withthe maker's specification if they are verified by tests. (IACS UR S10)

B 400 Material certificates401 «Det Norske Veritas Product Certificate» (NV) will berequired for:

— sternframe structural parts— rudder structural parts— rudder shaft or pintles— rudder stock— rudder carrier.

402 “Works certificate” (W) will be accepted for:

— bolts— stoppers.

B 500 Heat treatment501 Nodular cast iron and cast steel parts for transmission ofrudder torque by means of conical connections shall be stressrelieved.

C. Arrangement and DetailsC 100 Sternframes and rudders101 Relevant types of rudder arrangements are shown inFig.1. Other combinations of couplings and bearings may beapplied.102 Suitable arrangement to prevent the rudder from liftingand accidental unshipping shall be provided. The arrangementshall effectively limit vertical movement of rudder in case ofextreme (accidental) vertical load on rudder.103 Effective means shall be provided for supporting theweight of the rudder without excessive bearing pressure, e.g.by a rudder carrier attached to the upper part of the rudderstock. The hull structure in way of the rudder carrier shall besuitably strengthened.104 If the rudder trunk is open to the sea, a seal or stuffingbox shall be fitted above the deepest load waterline, to preventwater from entering the steering gear compartment and the lu-bricant from being washed away from the rudder carrier.An additional seal of approved type is required when the rud-der carrier is below the summer load waterline.

105 Guidance note:The after body should be so shaped as to ensure a proper flow ofwater to the propeller, and so as to prevent uneven formation ofeddies as far as possible. The apex of the waterlines in front ofthe propeller should have the least possible radius, together witha relatively small angle φ. Plane or approximately plane partsabove the propeller tip should be avoided.The strength of pressure impulses from propeller to hull will nor-mally decrease with increasing clearances. However, even withlarge clearances to the propeller, a hull may be exposed to strongimpulses if the propeller is subject to heavy cavitation.For a moderately cavitating propeller, the following minimumclearances are proposed (see Table C1 and Fig.2):

R = propeller radius in mZP = number of propeller blades.


Fig. 2Propeller clearances

106 Guidance note:Rudders (one or more) working directly behind a propellershould preferably have a total area not less than:

For ships which frequently manoeuvre in harbours, canals or oth-er narrow waters, the rudder area determined by the formulashould be increased. For ships with a streamlined rudder post,half of the lateral area of the post may be included in the rudderarea. For ships with a rudder horn, the whole area of the horn lay-ing below a horizontal line from the top of the rudder may be in-cluded.Rudders not working directly behind a propeller should have thearea as given above, increased by at least 30%.Rudders with special profiles or special configurations (e.g. flapsor nozzles) giving increased efficiency may have smaller total ar-eas.For ships with large freeboard and/or high continuous super-structures an increase of the rudder area ought to be considered.Larger rudder area may result in excessive heeling angle whenusing the rudder in extreme position at full speed ahead. This is

Table B2 Bearing surface pressuresBearing material pm (kN/m2)Lignum vitae 2500White metal, oil lubricated 4500Synthetic material with hardness between 60 and 70 Shore D 1) 5500

Steel 2) and bronze and hot-pressed bronze-graphite materials 7000

1) Indentation hardness test at 23°C and with 50% moisture, according to a recognized standard

2) Stainless and wear-resistant steel in an approved combination with stock liner

Table C1 Minimum clearancesFor single screw ships: For twin screw ships:a ≥ 0.2 R (m)b ≥ (0.7 – 0.04 ZP) R (m)c ≥ (0.48 – 0.02 ZP) R (m) c ≥ (0.6 – 0.02 ZP) R (m)e ≥ 0.07 R (m)

A TL100--------- 1 50CB

2 BL----⎝ ⎠

⎛ ⎞ 2+ (m2 )=

DET NORSKE VERITAS


particularly relevant for passenger vessels, ferries, vehicle ro/rocarriers and other vessels where the combination of speed,draught, vertical centre of gravity and metacentric height may re-sult in excessive heeling angle in case of smaller turning circles.For estimating the result angle of heel, reference is made to Pt.5Ch.2 Sec.2 F300.In cases where the resulting angle of heel may exceed 10 degrees,the Master should be provided with warning about this in the sta-bility manual.


107 Guidance note:In order to minimise vibrations, the balancing and design of therudders should be carried out as follows:- the balanced portion should not be greater than 23% of the to-

tal area of the rudder- the length of the balanced part at any horizontal section

should nowhere be greater than 35% of the total length of therudder

- the widest part of the rudder section should preferably be atleast 30% aft of the leading edge of the rudder section consid-ered.


108 Over-balanced rudders are subject to special considera-tion with respect to type of steering gear and risk of an unex-pected and uncontrolled sudden large movement of ruddercausing severe change of ship's pre-set course. See Pt.4 Ch.14Sec.1 B900.

Guidance note:A rudder shall be considered over-balanced, when balanced por-tion exceed 30% in any actual load condition. Special ruddertypes, such as flap rudders, are subject to special consideration.


D. Design Loads and Stress AnalysisD 100 Rudder force and rudder torque, general 101 The rudder force upon which the rudder scantlings shallbe based shall be determined from the following formula:

FR = 0.044 k1 k2 k3 A V2 (kN)

A = area of rudder blade in m2, including area of flap. = vertical projected area of nozzle rudderk1 = coefficient depending on rudder profile type (see

Fig.3):

k2 = coefficient depending on rudder/nozzle arrangement = 1.0 in general = 0.8 for rudders which at no angle of helm work in the

propeller slip stream = 1.15 for rudders behind a fixed propeller nozzle

k3 = not to be taken greater than 4

H = mean height in m of the rudder area. Mean height andmean breadth B of rudder area to be calculated asshown in Fig.4

At = total area of rudder blade in m2 including area of flapand area of rudder post or rudder horn, if any, withinthe height H.

V = maximum service speed (knots) with the ship on sum-mer load waterline. When the speed is less than 10knots, V shall be replaced by the expression:

For the astern condition the maximum astern speed shall beused, however, in no case less than:

Vastern = 0.5 VThe maximum service speed corresponds to the maximumcontinuous rating (MCR) of the engine. In special ship types(such as tugs) the maximum output of the propelling machin-ery may exceed MCR by more than 15%. In such cases V shallbe increased by the following percentage:

102 The rule rudder torque shall be calculated for both theahead and astern condition according to the formula:

MTR = FR xe (kNm) = minimum 0.1 FR B

FR = as given in 101 for ahead and astern conditionsxe = B (α − k) (m)B = mean breadth of rudder area, see Fig.4α = 0.33 for ahead condition = 0.66 for astern condition

k =

AF = area in m2 of the portion of the rudder blade area situ-ated ahead of the center line of the rudder stock

A = rudder blade area as given in 101.

For special rudder designs (such as flap rudders) direct calcu-lations of rudder torque, supported by measurements on simi-lar rudders, may be considered as basis for rudder torqueestimation.

Fig. 3Rudder profiles

Table D1 Rudder profile type - coefficientProfile type Ahead AsternNACA - Göttingen 1.1 0.8Hollow profile 1) 1.35 0.9Flatsided 1.1 0.9Profile with «fish tail» 1.4 0.8Rudder with flap 1.65 1.3Nozzle rudder 1.9 1.51) Profile where the width somewhere along the length is 75% or less of

the width of a flat side profile with same nose radius and a straight line tangent to after end

H2

At------ 2+

Table D2 Percentage increase in MCR vs VMaximum engine output above normal (%) 15 20 25 30 35 40

V increase (%) 3 5 7 9 11 12

VminV 20+

3----------------=

AFA-------

DET NORSKE VERITAS


D 200 Rudders with stepped contours201 The total rudder force FR shall be calculated accordingto 101, with height and area taken for the whole rudder.202 The pressure distribution over the rudder area may bedetermined by dividing the rudder into relevant rectangular ortrapezoidal areas, see e.g. Fig.5. The rule rudder torque may bedetermined by:

= minimum 0.1 FR xem

n = number of partsi = integer

F Ri =

x ei = Bi (α - ki)

x em =

Ai = partial area in m2

Bi = mean breadth of part area, see Fig.4α = as given in 102

For parts of a rudder behind a fixed structure such as arudder horn:

α = 0.25 for ahead condition = 0.55 for astern condition

ki =

A iF = rudder part area forward of rudder stock centre line,see Fig.5

FR and A as given in 101.

Fig. 4Rudder dimensions

Fig. 5Rudder area distribution

D 300 Stress analysis301 The rudder force and resulting rudder torque as given in100 and 200, causes bending moments and shear forces in therudder body, bending moments and torques in the rudder stock,supporting forces in pintle bearings and rudder stock bearingsand bending moments, shear forces and torques in rudderhorns and heel pieces.The bending moments, shear forces and torques as well as thereaction forces shall be determined by a direct calculation or byapproximate simplified formulae as given in the following.For rudders supported by sole pieces or rudder horns thesestructures shall be included in the calculation model in order toaccount for the elastic support of the rudder body.Acceptable direct calculation methods are given in Classifica-tion Note No. 32.1 “Strength Analysis of Rudder Arrange-ments”. For rudder horns, see also E404.302 Allowable stresses for the various strength members aregiven in subsections E to J.For evaluation of angular deflections, see B204 and G405.

E. Sternframes and Rudder HornsE 100 General101 Sternframes and rudder horns shall be effectively at-tached to the surrounding hull structures. In particular the sternbearing or vertical coupling flange for rudder axle shall be ap-propriately attached to the transom floor adjacent to the rudderstock.For semi-spade and spade rudder arrangements structural con-tinuity in the transverse as well as the longitudinal directionshall be specially observed.102 Cast steel sternframes and welded sternframes shall bestrengthened by transverse webs.Castings shall be of simple design, and sudden changes of sec-tion shall be avoided. Where shell plating, floors or other struc-tural parts are welded to the sternframe, there shall be a gradualthickness reduction towards the joint.Steel forgings and castings for sternframes, rudder horns andrudders shall be in accordance with the requirements in Pt.2Ch.2 Sec.5 and Sec.7 for general applications.

MTR FRixei( ) (kNm)

i 1=

n

∑=

AiA-----FR

AiBi( )A

----------------

i 1=

n

∑

AiFAi

--------

DET NORSKE VERITAS


103 Depending on casting facilities, larger cast steel propel-ler posts shall be made in two or more pieces. Sufficientstrength shall be maintained at connections. The plates ofwelded propeller posts may be welded to a suitable steel bar atthe after end of the propeller post.104 Stresses determined by direct calculations as indicatedin D300 are normally not to exceed the following values:

— Normal stress : σ = 80 f1 (N/mm2)— Shear stress : τ = 50 f1 (N/mm2)— Equivalent stress : σ e = 120 f1 (N/mm2)

E 200 Propeller posts201 The boss thickness at the bore for the stern tube shall notbe less than:

dp = rule diameter of propeller shaft in mm.

202 The scantlings of fabricated propeller posts shall not beless than:

l, b and t are as shown in Fig.6 Alt. I.Where the section adopted differs from the above, the sectionmodulus about the longitudinal axis shall not be less than:

203 The scantlings of cast steel propeller posts shall not beless than:

l, b, t1 and t2 are as shown in Fig.6 Alt. II.Where the section adopted differs from the above, the sectionmodulus about the longitudinal axis shall not be less than:

When calculating the section modulus, adjoining shell plateswithin a width equal to 53 from the after end of the postmay be included.

Fig. 6Propeller posts

E 300 Sole pieces301 The sole piece shall be sloped in order to avoid pressurefrom keel blocks when docking. The sole piece shall extend atleast two frame spaces forward of forward edge of the propel-ler boss. The cross section of this extended part may be gradu-ally reduced to the cross section necessary for an efficientconnection to the plate keel.302 The section modulus requirement of the sole piece abouta vertical axis abaft the forward edge of the propeller post isgiven by:

ls = distance in m from the centre line of the rudder stockto the section in question. ls shall not be taken less thanhalf the free length of the sole piece.

303 If direct stress analysis are carried out, the nominalbending stress in the sole piece shall not exceed:σ = 120 f1 304 The section modulus of the sole piece about a horizontalaxis abaft the forward edge of the propeller post is in no placeto be less than:

305 The sectional area of the sole piece shall not be less than:

E 400 Rudder horns401 The section modulus requirement of the rudder hornabout a longitudinal axis is given by:

σe σ12 σ2

2 σ1σ2– 3τ2+ +=

t 5 dp 60– (mm)=

l 53 L (mm)=

b 37 L (mm)=

t 2.4 Lf1

---------------- (mm)=

ZW1.35L L

f1----------------------- (cm3 )=

l 40 L (mm)=

b 30 L (mm)=

t13 L

f1----------- (mm)=

t23.7 L

f1---------------- (mm)=

ZC1.3L L

f1-------------------- (cm3 )=

L

Z16.25FRls

f1---------------------- (cm3 )=

Z2Z13

------ (cm3 )=

AS0.1FR

f1--------------- (cm2 )=

Z15MVlh

yhf1-------------------- (cm3 )=

DET NORSKE VERITAS


lh = vertical distance in m from the middle of the horn pin-tle bearing to the section in question

yh = vertical distance in m from the middle of the rule pintlebearing to the middle of the neck bearing

F Ri = part of rudder force acting on the i-th part of the rudderarea, see D202

y ei = vertical distance in m from the centroid of the i-th partof the rudder area to the middle of the neck bearing

n = number of rudder parts

For the straight part of the rudder horn the section modulusmay be taken for the total sectional area of the horn.When the connection between the rudder horn and the hullstructure is designed as a curved transition into the hull platingthe section modulus requirement as given above shall be satis-fied by the transverse web plates as follows:

n = number of transverse websbi = effective breadth in mm of web no. i. (including the

flange thickness)ti = thickness in mm of web no. ibmax = largest bi.

Z, bi and bmax shall be taken at a horizontal section 0.7 r abovethe point where the curved transition starts (r = radius ofcurved part, see Fig.7).The formula for ZW is based on the material in web plates andshell plate being of the same strength.For a cast rudder horn any vertical extension of the side plating(see Fig.8) may be included in the section modulus.

Fig. 7Curved plate transition rudder horn/shell plating

Fig. 8Curved cast transition rudder horn/shell plating

402 The rudder horn thickness requirement is given by:

k =

MV FRiyei

i 1=

n

∑=

ZW

bi3ti

i 1=

n

∑6000bmax------------------------ 0.45Z≥=

t110kFReh

f1AS------------------------- (mm)=

50

4000 1500 Z ZA⁄( )2–---------------------------------------------------------

DET NORSKE VERITAS


eh = horizontal projected distance in m from the centre lineof the horn pintle to the centroid of AS

AS = area in cm2 in horizontal section enclosed by the horn.

For a curved transition between horn plating and shell platingthe thickness of the transition zone plate shall not be less than:

s = spacing between transverse webs in mmr = radius of curved transition in mmZA = section modulus at section immediately below the

transition zoneZ = section modulus requirement in same section, as given

in 401.

403 The vertical parts of the rudder horn participating in thestrength against transverse shear shall have a total area in hor-izontal section given by:

C =

= 1.0 at lower endAH = area of horn in m2. At intermediate sections AH should

be taken for part of horn below sectionA = total area of rudder in m2.

In a curved transition zone the thickness of the transverse webplates shall not be less than:

tr = 0.8 tc (mm)

tc = thickness of curved plate

In the transition zone the curved shell plate shall be welded tothe web plates by full penetration weld or by a fillet weld withthroat thickness not less than:

t = 0.55 f1 tr (mm) 404 A direct stress analysis of the rudder horn, if carried out,shall be based on a finite element method.For a curved transition to the hull structure the maximum al-lowable normal and equivalent stresses as given in 104, may inthe curved plate be increased to:

σ = 120 f1 N/mm2

σ e = 180 f1 N/mm2

A fine-mesh finite element calculation will be considered as anacceptable method.In the web plates the normal stresses should not exceed σ = 130 f1 N/mm2.405 For a curved transition between the horn side plating andthe shell plating, the side plate thicknesses given in 401 to 404shall be extended to the upper tangent line of the curved part.The transverse web thicknesses shall be kept to the same leveland shall be welded to the floors above. No notches, scallopsor other openings shall be taken in the transition area.The alternative design shall carry the side plating of the rudderhorn through the shell plate and connect it to longitudinal gird-ers (see Fig.9), or weld it to the shell plate in line with longitu-dinal girders. In the latter case the welds below and above theshell plate shall be full penetration welds, and the shell plateshall be specially checked for lamellar tearing. The transversegirders shall be connected to/supported by transverse floors.Floor plating welded to rudder horn web plates shall have a

thickness not less than 75% of the web plate thickness.406 The lower end of the rudder horn shall be covered by ahorizontal plate with thickness not less than the side plating.

Fig. 9Shell plating connected to longitudinal girders in line with rudderhorn sides

F. RuddersF 100 General arrangement and details101 Rudders shall be double plate type with internal verticaland horizontal web plates.The rudder body shall be stiffened by horizontal and verticalwebs enabling it to act as a girder in bending.Single plate rudders may be applied to smaller vessels of spe-cial design and with service restrictions, see 500.102 All rudder bearings shall be accessible for measuring ofwear without lifting or unshipping the rudder.

Guidance note:In case cover plates are permanently welded to the side plating,it is recommended to arrange peep holes for inspection of secur-ing of nuts and pintles.


103 Great care shall be taken in highly stressed connectionssuch as:

— welds between rudder side plating and upper heavy part ofrudder at stock coupling

— welds around cut-outs in semi-spade rudders and openingsfor demounting of cone coupling and pintles.

104 Welds between plates and heavy pieces (cast or verythick plating) shall be made as full penetration welds, prefera-bly to cast or welded on ribs. Where back welding is impossi-ble welding shall be performed against backing bar orequivalent.105 Webs shall be connected to the side plates in accordancewith Ch.1 Sec.11.Slot-welding shall be limited as far as possible. Horizontalslots in side plating in areas with large bending stresses shallbe completely filled by welding.

tc0.15 s 40–( )2

r--------------------------------- Z

ZA------- (mm)=

AW C0.3FR

f1--------------- (cm2 )=

1A AH+( )AH

A2--------------------------------+

⎝ ⎠⎜ ⎟⎛ ⎞

at upper end of horn

DET NORSKE VERITAS


Normally, slots of length 75 mm and a breadth of 2 t (where t= rudder plate thickness), with a distance of 125 mm betweenends of slots, will be accepted. In areas where slots are requiredto be completely filled by welding, more narrow slots with in-clined sides (minimum 15° to the vertical) and a minimumopening of 6 mm at bottom may be used. A continuous slotweld may, however, in such cases be more practical.106 Plate edges at corners in cut-outs and openings in rudderside plating shall be ground smooth in those parts of the rudderwhere high stresses will occur.107 Means for draining the rudder completely after pressuretesting or possible leakages shall be provided. Drain plugsshall be fitted with efficient packing.108 Internal surfaces shall be covered by a corrosion-resist-ant coating after pressure-testing and possible stress-relieving.109 For testing of rudder, see J.

F 200 Rudder plating201 The thickness requirement of side, top and bottom plat-ing is given by:

ka =

maximum 1.0

s = the smaller of the distances between the horizontal orthe vertical web plates in m

b = the larger of the distances between the horizontal or thevertical web plates in m.

In no case the thickness shall be less than the minimum sideplate thickness as given in Ch.1 Sec.7 C101 or Ch.2 Sec.6C102.

F 300 Rudder bending301 Bending moments in the rudder shall be determined bydirect calculations as indicated in D300.For some common rudder types the following approximateformulae may be applied:

— For balanced rudders with heel support:Mmax = 0.125 FR H (kNm)

— For semi-spade rudders at the horn pintle:

— For spade rudders:

A1 = area in m2 of the rudder part below the cross-section inquestion

hs = vertical distance in m from the centroid of the rudderarea A1 to the section in question.

302 The nominal bending stress distribution in the ruddermay normally be determined on the basis of an effective sec-tion modulus to be estimated for side plating and web plateswithin 40% of the net length (cut-outs or openings deducted)of the rudder profile. At the top of the rudder, the effectivelength shall not be taken greater than 2.5 ds (ds = rudder stock

diameter at neck bearing) or the length of the flange coupling.Special attention to be paid to open flange couplings on therudder. The external transverse brackets will normally have tobe supplied with heavy flanges to obtain the necessary sectionmodulus of the rudder immediately below the flange.As an alternative the bending stress distribution in the ruddermay be determined by a finite element calculation.303 Nominal bending stresses calculated as given in 301 and302 shall not exceed:

σ = 110 f1 N/mm2 in general = 75 f1 N/mm2 at sections in way of cut-outs (e.g. semi-

spade rudders) in the rudder.

In case of openings in side plate for access to cone coupling orpintle nut, σ = 90 f1 to be applied when the corner radius isgreater than 0.15 l ( l = length of opening), σ = 60 f1 when theradius is smaller.

F 400 Web plates401 The thickness of vertical and horizontal webs shall notbe less than 70% of the thickness requirement given in 200, inno case less than 8 mm.402 The total web area requirement for the vertical webs isgiven by:

P =

with heel support

= for spade rudder or lower part of

semi-spade rudderh1 = height in m of the smaller of rudder parts below or

above the cross-section in questionh2 = height in m of the rudder part below the cross section

in question.

Shear stresses in web plates determined by direct stress calcu-lations shall not exceed:

τ = 50 f1 (N/mm2)Equivalent stress shall not exceed:

σe =

= 120 f1 N/mm2 in rudder-blades without cut-outs = 100 f1 N/mm2 in rudder-blades with cut-outs.

F 500 Single plate rudders501 Mainpiece diameterThe mainpiece diameter is calculated according to G201. Forspade rudders the lower third may taper down to 0.75 timesstock diameter.When calculating the rudder force FR as given in D101 the fac-tor k1 may be taken equal to 1.0 in ahead condition.502 Blade thicknessThe blade thickness shall not be less than:

tb = 1.5 s V + 2.5 (mm)

s = spacing of stiffening arms in metres, not to exceed 1 mV = speed in knots, see D101.

t 5.5f1

--------kas T0.1FR

A---------------+ 2.5 (mm)+=

1.1 0– .5 sb---⎝ ⎠

⎛ ⎞ 2

MFRA1hs

A------------------- (kNm)=

MmaxFRA1hs

A------------------- (kNm)=

AWP

5f1------- (cm2 )=

0.6h1H-----–⎝ ⎠

⎛ ⎞ FR for balanced rudder

h2H-----FR

σb2 3τ2+

DET NORSKE VERITAS


503 ArmsThe thickness of the arms shall not be less than the blade thick-ness:

ta = tbThe section modulus shall not be less than:

Za = 0.5 s C12 V2 (cm3)

C1 = horizontal distance from the aft edge of the rudder tothe centre line of the rudder stock in metres.

For higher tensile steels the material factor according to B100shall be used correspondingly.

F 600 Mounting of rudder601 For rudder with continuous shaft it shall be checked thatthe rudder shaft has the right position in relation to the uppercoupling, both longitudinally and transversely, when the lowertapered part of the rudder axle bears hard at the heel. The rud-der shaft shall be securely fastened at the heel before the cou-pling bolts at the upper end are fitted.602 Before final mounting of rudder pintles, the contact be-tween conical surfaces of pintles and their housings shall bechecked by marking with Prussian blue or by similar method.When mounting the pintles, care shall be taken to ensure thatpackings will not obstruct the contact between mating surfac-es. The pintle and its nut shall be so secured that they cannotmove relatively to each other.

G. Rudder Stocks and ShaftsG 100 General101 Stresses determined by direct calculations as indicatedin D300 are normally to give equivalent stress σe not exceed-ing 118 f1 N/mm2 and shear stress τ not exceeding 68 f1 N/mm2. The equivalent stress for axles in combined bending andtorsion may be taken as:

σ = bending stress in N/mm2

τ = torsional stress in N/mm2.

102 The requirements to diameters are applicable regardlessof liner. Both ahead and astern conditions shall be considered.103 A rudder stock cone coupling connection without hy-draulic arrangement for mounting and dismounting shall notbe applied for spade rudders.104 An effective sealing shall be provided at each end of thecone coupling.

G 200 Rudder stock with couplings201 The diameter requirement is given by:

kb = 1 above the rudder carrier, except where the rudderstock is subjected to bending moment induced by therudder actuator (bearing arrangement versus rudderstock bending deflections, or actuator forces acting ontiller)

=

MB = calculated bending moment in kNm at the section inquestion.

If direct calculations of bending moment distribution are notcarried out, MB at the neck bearing or the rudder coupling maybe taken as follows:

— for balanced rudder with heel support:

— for semi-spade rudder:

— for spade rudder:MB = FR hs (kNm)

hs = vertical distance in m from the centroid of the rudderarea to the middle of the neck bearing or the coupling.

At the bearing above neck bearing MB = 0, except as follows:

— for rotary vane type actuators with two rotor bearings,which allow only small free deflections, calculation ofbending moment influence may be required if bending de-flection in way of upper bearing exceeds two times dia-metrical bearing clearances at full rudder force FR

— for actuator force induced bending moment the greater ofthe following:

M BU = Fdes hA (kNm) or

M BU = FMTR hA (kNm)

hA = vertical distance between force and bearing cen-tre

FMTR = according to Pt.4 Ch.14 Sec.1 B1121M BU = bending moment at bearing above neck bearingFdes = radial force induced by actuator at design pres-

sure.Minimum diameter of the rudder stock between the neck andthe bearing above shall not be less than if tapered with kb=1.0at the second bearing.In steering systems with more than one rudder where thetorque from one actuator can be transferred to another, for in-stance by means of a connecting rod, the rudders stock shallnot be permanently damaged when exposed to the sum of ac-tuating loads (see Pt.4 Ch.14 Sec.1 B1108).202 Tapered cone connections between rudder stock andrudder shall have strength equivalent to that required for rud-der stock with respect to transmission of torque and bendingmoments as relevant and shall comply with the following (seeFig.10):

a) Length/diameter ratio:lt/ds ≥ 1.5

b) Hub/shaft diameter ratio D/ds:

c) Taper of cone:

σe σ2 3τ2+ (N/mm2 )=

ds 42kbMTR

f1------------⎝ ⎠

⎛ ⎞

13---

(mm)=

1 43---

MBMTR------------⎝ ⎠

⎛ ⎞2

+

16---

at arbitrary cross-section

Type With key Keyless D/ds ≥ 1.5 ≥ 1.25

Type With key Keylesstaper 1:10 − 1:15 1: ≥ 15

MBFRH

7----------- (kNm)=

MBFRH17

----------- (kNm)=

DET NORSKE VERITAS


d) Contact surface roughness in micron:

— contact area minimum 70% evenly distributed (seeK200 for control and testing)

— if oil is used for fitting, the design must enable escapeof the oil from between the mating surfaces

— the connection shall be secured by a nut which is prop-erly locked to the shaft.

203 Connection between rudder stock and steering gear to beaccording to Pt.4 Ch.14 Sec.1 B1200. The length/diameter ratio for conical connections to steeringgear shall be not less than lt/ds ≥ 0.75.

Fig. 10Cone coupling

204 Where the tapered end of the rudder stock is shrink fittedto the rudder, with hydraulic arrangement for mounting anddismounting (with oil injection and hydraulic nut), the neces-sary push-up length and push-up force shall be based on thefollowing:

a) Pull-up length, minimum:

δmin = K ( ∆min + 2 (RAi + RAe) 10-3 ) (mm)

δmin ≥ 2 mm for all keyless rudder - rudder stock connec-tions.

b) Pull-up length, maximum:

δmax = K ( ∆max + 2 (RAi + RAe) 10-3 ) (mm)

δ = pull-up length (mm)K = taper of the cone = lt/(ds – dt)∆min = calculated minimum shrinkage allowance∆max = calculated maximum shrinkage allowanceRAi = surface roughness RA of shaft (micron)RAe = surface roughness RA of hub (micron).

c) Shrinkage allowance ∆ (mm):

E = module of elasticity: 2.06 ⋅105 (N/mm2)ce = diameter ratio d/D at considered sectiond = mean shaft diameter (mm)

p = surface pressureD = outer diameter of the hub at considered section

(mm).Minimum shrinkage allowance (∆min) shall be calculatedbased on average diameters and the minimum requiredsurface pressure (pmin).Maximum shrinkage allowance (∆max) shall be calculatedbased on average diameters and maximum permissiblesurface pressure (pmax).In case hub wall thickness have large variation the meanouter diameter of the hub will have to be specially consid-ered.

d) The surface pressure used for calculation of pull-up length(δmax or δmin) shall not be taken less than:

pr ≤ pmin ≥ 1.25 pb (N/mm2)and shall not exceed:

k = 0.95 for steel forging and cast steel = 0.90 for nodular cast iron = 0.50 for keyed connections.Variation due to different hub wall thickness shall be con-sidered.Pressure at the bigger end due to bending moment, Mb,may be taken as:

which may be reduced to zero at a distance lx = 0.5 d or 0.5 l (smaller applies) as follows:

p bx = pressure due to bending moment at position xlx = distance from top of cone, see Fig.10 (mm)dx = ditto shaft diameter at distance lx (mm)Mb = bending moment (kNm).

e) Average surface pressure (pr) due to shrinkage for trans-mission of torque by means of friction shall be:

Tfr = required torque to be transmitted by means offriction in following coupling = 3 MTR

dm = mean diameter = 0.5 (ds + dt) (mm)l = effective cone length, which may normally be

taken as boss length lt, see Fig.10, (mm)µ = maximum 0.14 for oil injection fitting = maximum 0.17 for dry fittingMTR = rule rudder torque (kNm), see D102 and D202.

f) Necessary force for pull-up may be estimated as follows:

µ pu = average friction coefficient for pull-up (for oil in-jection usually in the range 0.01 to 0.03).

205 Tapered key-fitted (keyed) connections shall be de-signed to transmit rudder torque in all normal operating condi-

Type of fitting Dry fitted Oil injectionroughness (RA) maximum 3.5 maximum 1.6

∆ 2dpE

--------- 1

1 ce2–

----------------⎝ ⎠⎜ ⎟⎛ ⎞

=

pmax kσf1 ce

2–

3 ce4+

--------------------- pb (N/mm2 )–≤

pb3.5Mb

dml2----------------106 (N/mm2 )=

pbx pb 1lx

0.5dx--------------–

⎝ ⎠⎜ ⎟⎛ ⎞

(N/mm2 )=

pr2Tfr106

π dm2l µ

------------------- (N/mm2 )≥

F π dml pr1

2K------- µpu+⎝ ⎠

⎛ ⎞ 10 3– (kN)≥

DET NORSKE VERITAS


tions by means of friction in order to avoid mutual movementsbetween rudder stock and hub. The key shall be regarded as asecuring device.For calculation of required pull-up length (δ ), see 204 a), b)and e) where pr is given with Tfr = 1.5 MTR.Where it is not possible or practicable to obtain the requiredpull-up length (δ ), special attention shall be given to fitting ofthe key in order to ensure tight fit (no free sideways play be-tween key and key-way). In this case Tfr may be taken as Tfr = 0.5 MTR.Tapered key-fitted connections shall in addition comply withthe following:

a) Key-ways shall not be placed in areas with high bendingstresses in the rudder stock and shall be provided with suf-ficient fillet radii (r):

r ≥ 0.01 dsb) The abutting surface area between the key and key-way in

the rudder stock and hub respectively, shall not be lessthan:

where the torque Tkey is (kNm):Tkey ≥ 2 M TR – Tfr

based on verification of pull-up force, andTkey ≥ 2 MTR – 0.7 Tfr

based on verification of pull-up distance, but not less than:Tkey = M TR (kNm).

Yield strength used for calculation of fk shall not exceedthe lowest of:

σ f,key

and1.5 σ f, hub (for calculation of hub) or1.5 σ f, stock (for calculation of stock).

A ab = effective abutting area of the key-way in stockand hub respectively (cm2)

fk = material factor (see B204)σ f,hub = yield strength of hub material (N/mm2)σ f,key = yield strength of key material (N/mm2)σ f,stock= yield strength of stock material (N/mm2).

c) The height/width ratio of the key shall be:

h = height (thickness) of the keyb = width of the key.

Where necessary tapered connections shall be provided withsuitable means (e.g. oil grooves and bores to connect hydraulicinjection oil pump) to facilitate dismantling of the hub.The dimensions at the slugging nut shall not be less than (seeFig.10):

— external thread diameter:dg = 0.65 ds

— height of nut:hn = 0.6 dg

— outer diameter of nut:dn = 1.2 dt or dn = 1.5 dg whichever is the greater.

206 Where the rudder stock is connected to the rudder byhorizontal flange coupling the following requirements shall becomplied with:

a) At least 6 tight fitted coupling bolts shall be used.b) The shear diameter of coupling bolts shall not be less than:

ds = rule diameter of rudder stock at coupling flange inmm as given in 201 based on the calculated bend-ing moment at the coupling flange

n = number of coupling boltse = mean distance in mm from the centre of bolts to the

centre of the bolt systemf ms = material factor (f1) for rudder stockf mb = material factor (f1) for bolts.

c) Nuts shall be securely fastened by split pins or other effi-cient means.

d) If the coupling is subjected to bending stresses, the meandistance a from the centre of the bolts to the longitudinalcentre line of the coupling shall not be less than 0.6 ds.Further, bolt prestress in shear part of bolt shall normallybe in the range of 60 fmb to 120 fmb. In the minimum sec-tion of the bolt, prestress shall not exceed 165 fmb.

e) The width of material outside the bolt holes shall not beless than 0.67 db.

f) The thickness of coupling flanges shall not be less than thegreater of:

db = bolt diameter, calculated for a number of bolts notexceeding 8

f mf = material factor (f1) for flange,

or

MB = bending moment in kNm at couplinga = mean distance from centre of bolts to the longitudi-

nal centre line of the coupling, in mmd = diameter as built of rudder stock for stock flange,

breadth of rudder for rudder flange, both in mmβ = factor to be taken from the following table:

Ample fillet radius shall be in accordance with recognisedstandards.

G 300 Rudder shaft301 At the lower bearing, the rudder shaft diameter shall notbe less than:

c =

l, a and b are given in Fig.11 in m.The diameter df below the coupling flange shall be 10% greaterthan dl. If, however, the rudder shaft is protected by a corro-sion-resistant composition above the upper bearing, df may beequal to dl.

Aab65Tkeydmfk

----------------- (cm2 )≥

hb--- 0.6≤ d/a 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6

β 1.8 1.5 1.25 1.0 0.8 0.6 0.45 0.35 0.25

db 0.62ds

3 fmsn e fmb---------------- (mm)=

t dbfmbfmf-------- , minimum 0,9db (mm)=

t 70βMBafmf------------ (mm)=

dl 39FRc l c–( )

lf1-------------------------⎝ ⎠

⎛ ⎞

13---

(mm)=

a b+2

------------

DET NORSKE VERITAS


302 The taper, nut, etc. at lower end of rudder shafts, shall betaken as for rudder stock given in 202.303 The scantlings of the vertical coupling at the upper endof the rudder shaft shall be as required for horizontal ruddercouplings in 206, inserting the shaft dl instead of the stock di-ameter ds in the formula for bolt diameter.

Fig. 11Rudder shaft

G 400 Bearings and pintles 401 The height of bearing surfaces shall not be greater than:

hb = 1.2 dsl (mm)

dsl = diameter in mm of rudder shaft or pintle measured onthe outside of liners.

Bearing arrangements with a height of the bearinggreater than above, may be accepted based on directcalculations provided by the designer showing accept-able clearances at the upper and lower edges of thebearing.

402 The bearing surface area shall not be less than:

AB = hb dslhb and dsl = as given in 401P = calculated reaction force in kN at the bearing in

questionpm = maximum surface pressure as given in B303.If direct calculations of reaction forces are not carried out, P atvarious bearings may be taken as given in the following (notethat values given for stern pintle or neck bearing in semi-spaderudders are minimum values):

a) For balanced rudder with heel support:P = 0.6 FR (kN) at heel pintle bearingP = 0.7 FR (kN) at stern pintle or neck bearingP = 0.1 FR (kN) at upper bearing.

b) For semi-spade rudder (The horn pintle bearing is assumedto be situated not more than 0.1 H above or below the cen-tre of the rudder area):

P = 1.1 FR (kN) at horn pintle bearingPmin = 0.4 FR (kN) at stern pintle or 0.3 FR (kN) at neck

bearingP = 0.1 FR (kN) at upper bearing.

c) For spade rudder:

(kN) at neck bearing

(kN) at upper bearing

h1 = vertical distance from the centroid of rudder area tothe middle of the neck bearing

h2 = vertical distance from the middle of the neck bear-ing to the middle of the upper bearing.

403 The diameter of pintles shall not be less than:

P = as given in 402.

404 The thickness of any bushings in rudder bearings shallnot be less than:

minimum 8 mm for steel and bronze,maker's specification for synthetic materials,minimum 22 mm for Lignum Vitae,other materials shall be especially considered.P = as given in 402.The bushing shall be effectively secured to the bearing. Thethickness of bearing material outside of the bushing shall notbe less than:

P = as given in 402.

ABP

pm------ 106 (mm2 )=

Ph1 h2+

h2-----------------FR=

Ph1h2-----FR=

dp 10 Pf1---- (mm)=

tv 0.32 P (mm)=

t 2.0 Pf1---- (mm)=

DET NORSKE VERITAS


405 With metal bearings the clearance on the diameter isnormally not to be less than:

0.001 db + 1.0 (mm) db = inner diameter in mm of the bushing.If non-metallic bearing material is applied, the bearing clear-ance shall be specially determined considering the materials'swelling and thermal expansion properties. This clearanceshall not be taken less than 1.5 mm on the bearing diameter.For spade rudders with large bending moment and inducedslope at the neck bearing the clearance should be related to thecalculated angular deflection over the bearing length.Due attention should, however, be given to the manufacturer'srecommended clearance. For pressure lubricated bearings theclearance will be especially considered.406 Pintles shall have a conical attachment to the gudgeons.The various dimensions (taper, nut, key) shall be as requiredfor rudder stock in 202, 204 and 205, inserting the pintle diam-eter dp instead of the stock diameter ds in the various formulaewith the following exemptions:

— the length of pintle housing shall not be less than the pintlediameter: lt/dp ≥ 1.0

— the thickness of material outside the bushing shall not beless than 0.25 db: D/dp ≥ 1.5

— the taper of keyless cone not to be greater than 1:12.

The bending moment, MB to be taken as pintle force P multi-plied by the height from 1/3 of height of bearing to 1/2 of thelength of cone and Tfr to be taken as 0.00025 dbP.

db = inner diameter of bushing (mm).An effective sealing against sea water shall be provided at bothends of the cone.

H. Propeller NozzlesH 100 General101 The following requirements are applicable to fixed andsteering nozzles of inner diameter 4 metres or less.

Guidance note:The requirements may also be applied for the initial design ofnozzles with diameter exceeding 4 metres. In that case the scantlings and arrangement should be speciallyconsidered with respect to exciting frequencies from the propel-ler.


H 200 Plating201 The thickness of the nozzle shell plating in the propellerzone shall not be less than:

where:

N = 0.01 PS D, need not be taken greater than 100PS = maximum continuous output (kW) delivered to the

propellerD = inner diameter (m) of nozzles = distance in m between ring webs, shall not be taken

less than 0.35 metres in the formulaka = aspect ratio correction as given in F201, to be applied

when longitudinal stiffeners.

The thickness in zone I and II shall not be less than 0.7 t and in

zone III not less than 0.6 t, corrected for spacing s.The propeller zone shall be taken minimum 0.25 b (where b =length of nozzle). For steering nozzles the propeller zone shallcover the variations in propeller position.On the outer side of the nozzle, zone II shall extend beyond theaftermost ring web.202 The thickness of ring webs and fore and aft webs shallnot be taken less than 0.6 t. They shall be increased in thicknessin way of nozzle supports.203 If the ship is reinforced according to an ice class nota-tion, the part of the outer shell of the nozzle which is situatedwithin the ice belt shall have a plate thickness not less than cor-responding to the ice class requirement for the after part of theship.

Guidance note:In order to prevent corrosion and erosion of the inner surface ofthe nozzle, application of a corrosion resistant material in thepropeller zone is recommended. All but welds should be groundsmooth. When a corrosion resistant material is used, the plate thicknessmay be reduced by 15%.


H 300 Nozzle ring stiffness301 In order to obtain a satisfactory stiffness of the nozzlering the following requirement shall be fulfilled:

I = 2.8 k b D3 V2 (cm4)

I = moment of inertia of nozzle section about the neutralaxis parallel to centre line

k =

tm = mean thickness of nozzle inner and outer shell plating(mm), in propeller plane

b = length of nozzle, see Fig.12, in mD = as given in 201V = maximum service speed (knots)n = number of ring webs.

Fig. 12Section through nozzle ring

302 If the ship is reinforced according to an ice class notationthe parameter V for the requirement in 301 shall not be takenless than:

V = 14, 15, 16 and 17 knots for ice class 1C, 1B, 1A and1A*, respectively.

H 400 Welding401 The inner shell plate shall be welded to the ring webswith double continuous fillet welding.402 The outer shell plate is as far as possible to be weldedcontinuously to the ring webs. Slot welding may be accepted

t 10 3kas Nf1---- (mm)+=

28bDtm n 1+( )

--------------------------------

DET NORSKE VERITAS


on the following conditions:If the web spacing s ≤ 350 mm all welds to outer plating maybe slot welds. If the web spacing s > 350 mm at least two ringwebs shall be welded continuously to the outer shell. A contin-uous weld according to Fig.13 may be accepted.403 Slot welds shall have a slot length l not less than 75 mmand a breadth equal to 2 t (t = nozzle shell plate thickness),maximum 30 mm. More narrow slots may be applied whereslots are completely filled by welding. The distance betweenslots (from centre to centre) shall not exceed 2 l, maximum 250 mm. The slot weld throat thickness is normal-ly to be 0.7 t.

H 500 Supports501 The nozzle shall be supported by at least two supports.The web plates and shell plates of the support structure shall bein line with web plates in the nozzle.

Fig. 13Connection nozzle shell plate/ring web

I. Propeller Shaft BracketsI 100 General101 The following requirements are applicable to propellershaft brackets having two struts to support the propeller tailshaft boss. The struts may be of solid or welded type.102 The angle between the struts shall not be less than 50 de-grees.

I 200 Arrangement201 Solid struts shall be carried continuously through theshell plating and shall be given satisfactory support by the in-ternal ship structure.202 Welded struts may be welded to the shell plating. Theshell plating shall be reinforced, and internal brackets in linewith strut plating shall be fitted. If the struts are built with alongitudinal centre plate, this plate shall be carried continuous-ly through the shell plating. The struts shall be well rounded atfore and aft end at the transition to the hull.203 The propeller shaft boss shall have well rounded foreand aft brackets at the connection to the struts.204 The strut structure inside the shell shall terminate withina compartment of limited volume to reduce the effect of flood-ing in case of damage.

I 300 Struts301 Solid or built-up struts of propeller shaft brackets shallcomply with the following requirements:

h = 0.4 d (mm) A = 0.4 d2 (mm2)

W = 0.12 d3 (mm3)

A = area of strut sectionW = section modulus of section. W shall be calculated with

reference to the neutral axis Y-Y as indicated on Fig.14h = the greatest thickness of the sectiond = Propeller shaft diameter in mm.

The diameter refers to shaft made of steel with a minimumspecified tensile strength of 430 N/mm2.

Fig. 14Strut section

I 400 Welding401 Welding between struts and hull and propeller shaft bossshall be made as full penetration welds.402 For welded construction full details of the joints, weld-ing procedure, filler metal and heat treatment after weldingshall be specified on the plans.

I 500 Material501 Regarding material of brackets reference is made to sub-section B.

I 600 Testing601 Ultrasonic and magnetic particle examination of thewelds shall be carried out on the brackets and at the shell pen-etrations.

J. Testing

J 100 Sternframes101 Built sternframes with closed sections shall be pressuretested on completion.

J 200 Rudders and rudder stock connections201 Contact area of conical connections shall be (minimum70%) verified by means of paint test (e.g. tool-maker blue) inpresence of the surveyor.202 Test pull-up followed by control of contact area may berequired before final assembly for conical keyless connectionsintended for injection fitting, if calculations are considered in-accurate due to a non-symmetric design or other relevant rea-sons. Pull-up length during test pull-up shall not be less thanfinal pull-up length.

DET NORSKE VERITAS


SECTION 3 ANCHORING AND MOORING EQUIPMENT

A. GeneralA 100 Introduction101 The requirements in this section apply to equipment andinstallation for anchoring and mooring.102 Towlines and mooring lines are not subject to classifica-tion. Lengths and breaking strength are, however, given in theequipment tables as guidance. If certification of materials isneeded voluntarily, it shall be done in accordance with 204.

A 200 Documentation201 The following plans and particulars shall be submittedfor approval:

— equipment number calculations— equipment (list) including type of anchor, grade of anchor

chain, type and breaking load of steel and fibre ropes— anchor design if different from standard or previously ap-

proved anchor types. Material specification— windlass design. Material specifications for cable lifters,

shafts, couplings and brakes— chain stopper design. Material specification.

202 The following plans and particulars shall be submittedfor information:

— arrangement of deck equipment.

203 For barges the towline fastening arrangement and de-tails, stating towing force shall be submitted for approval.204 Det Norske Veritas Product Certificate (NV) (for mate-rials, ISO 10474: Type 3.1 C) will be required for the follow-ing items:

— anchor and anchor shackle— anchor chain cable and accessories (shackles, swivels,

etc.)— windlass cable lifter— winch drum and drum flanges— shafts for cable lifter and/or drum— pawl wheel, stopper and couplings— gear shafts and wheels (W)— windlass/winch frame work (W)— brake components— chain stopper— steel wire ropes (W)— fibre ropes (W).

For items above marked with (W), work's certificate (for ma-terials, ISO 10474: Type 3.1 B) from approved manufacturerwill normally be accepted.

A 300 Assumptions301 The anchoring equipment required is the minimum con-sidered necessary for temporary mooring of a vessel in moder-ate sea conditions when the vessel is awaiting berth, tide, etc.The equipment is therefore not designed to hold a vessel offfully exposed coasts in rough weather or for frequent anchor-ing operations in open sea. In such conditions the loads on theanchoring equipment will increase to such a degree that itscomponents may be damaged or lost owing to the high energyforces generated.

Guidance note:If the intended service of the vessel is such that frequent anchor-ing in open sea is expected, it is advised that the size of anchorsand chains is increased above the rule requirements, taking into

account the dynamic forces imposed by the vessel moving inheavy seas. The Equipment Numeral (EN) formula for requiredanchoring equipment is based on an assumed current speed of 2.5m/s, wind speed of 25 m/s and a scope of chain cable between 6and 10, the scope being the ratio between length of chain paid outand water depth.


302 The anchoring equipment required by the Rules is de-signed to hold a vessel in good holding ground in conditionssuch as to avoid dragging of the anchor. In poor holdingground the holding power of the anchors will be significantlyreduced.303 It is assumed that under normal circumstances the vesselwill use only one bower anchor and chain cable at a time.

B. Structural Arrangement for Anchoring Equipment

B 100 General 101 The anchors are normally to be housed in hawse pipes ofsuitable size and form to prevent movement of anchor andchain due to wave action.The arrangements shall provide an easy lead of the chain cablefrom the windlass to the anchors. Upon release of the brake,the anchor is immediately to start falling by its own weight. Atthe upper and lower ends of hawse pipes, there shall be chafinglips. The radius of curvature shall be such that at least 3 linksof chain will bear simultaneously on the rounded parts at theupper and lower ends of the hawse pipes in those areas wherethe chain cable is supported during paying out and hoisting andwhen the vessel is laying at anchor. Alternatively, roller fair-leads of suitable design may be fitted.Where hawse pipes are not fitted alternative arrangements willbe specially considered.102 The shell plating in way of the hawse pipes shall be in-creased in thickness and the framing reinforced as necessary toensure a rigid fastening of the hawse pipes to the hull.103 Ships provided with a bulbous bow, and where it is notpossible to obtain ample clearance between shell plating andanchors during anchor handling, local reinforcements of bul-bous bow shall be provided as necessary.104 The chain locker shall have adequate capacity and a suit-able form to provide a proper stowage of the chain cable, andan easy direct lead for the cable into the spurling pipes, whenthe cable is fully stowed. Port and starboard cables shall haveseparate spaces. If 3 bower anchors and 3 hawse pipes areused, there shall be 3 separate spaces. Spurling pipes and chainlockers shall be watertight up to the weather deck.

Guidance note:Bulkheads separating adjacent chain lockers need not be water-tight.


Where means of access are provided, they shall be closed by asubstantial cover and secured by closely spaced bolts. Spurlingpipes through which anchor cables are led shall be providedwith permanently attached closing appliances to minimize wa-ter ingress. Adequate drainage facilities of the chain lockershall be adopted.Provisions shall be made for securing the inboard ends of chain

DET NORSKE VERITAS


to the structure. This attachment shall be able to withstand aforce of not less than 15% nor more than 30% of the minimumbreaking strength of the chain cable. The fastening of the chainto the ship shall be made in such a way that in case of emergen-cy when anchor and chain have to be sacrificed, the chain canbe readily made to slip from an accessible position outside thechain locker.

Guidance note:The spurling pipe is the pipe between the chain locker and theweather deck.


Guidance note:The emergency release of the chain dead end should consequent-ly be arranged watertight or above the weather deck.


Guidance note:Concerning permanently attached appliances. Examples of ac-ceptable arrangements are:

i) steel plates with cut-outs to accommodate chain links or

ii) canvas hoods with a lashing arrangement that maintains thecover in the secured position


(IACS UR L4)105 The windlass and chain stoppers shall be efficiently bed-ded to the deck. The deck plating in way of windlass and chain-stopper shall be increased in thickness and supported by pillarscarried down to rigid structures. See Sec.5 B.

C. Equipment SpecificationC 100 Equipment number101 The equipment number is given by the formula:

E N = ∆2/3 + 2 B H + 0.1 A

H = effective height in m from the summer load waterlineto the top of the uppermost deckhouse, to be measuredas follows:

H = a + Σ hi

a = distance in m from summer load waterline amidshipsto the upper deck at side

hi = height in m on the centre line of each tier of houseshaving a breadth greater than B/4. For the lowest tier,hi shall be measured at centre line from the upper deck,or from a notional deck line where there is local dis-continuity in the upper deck

A = area in m2 in profile view of the hull, superstructuresand houses above the summer load waterline, which iswithin L of the ship. Houses of breadth less than B/4shall be disregarded.

In the calculation of Σ hi and A sheer and trim shall be ignored.Windscreens or bulwarks more than 1.5 m in height shall be re-garded as parts of superstructures and of houses when deter-mining H and A. The total area of the mentioned itemsmeasured from the deck, shall be included.The area of hatch coamings more than 1.5 m in height abovedeck at side shall be included in A.102 For a barge rigidly connected to a push-tug the equip-ment number shall be calculated for the combination regardedas one unit.

Table C1 Equipment table, general

Equipment number

Equip-ment letter

Stockless bower anchors Stud-link chain cables Towline

(guidance)Mooring lines 1)

(guidance)

Number

Mass per

anchor

kg

Total length Diameter and steel grade Steel or fibre ropes Steel or fibre ropes

m

NV K1

mm

NV K2

mm

NV K3

mm

Mini-mum

length m

Minimum breaking strength

kNNumber

Length of each

m


kN30-4950-6970-8990-109

a0abc

2222

120180240300

192.5220220

247.5

12.51416

17.5

12.51416

170180180180

88.598.098.098.0

2333

8080100110

32343739

110-129130-149150-174

def

222

360420480

247.5275275

1920.522

17.517.519

180180180

989898

333

110120120

444954

175-204205-239240-279

ghi

222

570660780

302.5302.5330

242628

20.52224

20.522

180180180

112129150

344

120120120

596469

280-319320-359360-399

jkl

222

90010201140

357.557.5385

303234

262830

242426

180180180

174207224

444

140140140

747888

400-449450-499500-549

mno

222

129014401590

385412.5412.5

363840

323434

283030

180180190

250277306

444

140140160

98108123

550-599600-659660-719

pqr

222

174019202100

440440440

424446

363840

323436

190190190

338371406

444

160160160

132147157

720-779780-839840-909

stu

222

228024602640

467.5467.5467.5

485052

424446

363840

190190190

441480518

444

170170170

172186201

910-979980-1059

1060-1139

vwx

222

285030603300

495495495

545658

485050

424446

190200200

559603647

444

170180180

216230250

1140-12191220-12991300-1389

yzA

222

354037804050

522.5522.5522.5

606264

525456

464850

200200200

691738786

444

180180180

270284309

DET NORSKE VERITAS


C 200 Equipment tables201 The equipment is in general to be in accordance with therequirements given in Table C1.The two bower anchors and their cables shall be connected andstowed in position ready for use. The total length of chain cablerequired shall be equally divided between the two anchors. Thetowline and the mooring lines are given as guidance only, rep-resenting a minimum standard, and shall not be considered asconditions of class.

Guidance note:If anchor chain total length is an uneven number of shackles, nomore than one standard shackle (27.5 m) difference in length isallowed between the two anchors.


202 For fishing vessels the equipment shall be in accordancewith the requirements given in Table C2. When the equipment

number is larger than 720, table C1 should be applied.203 Unmanned barges are only to have equipment consistingof 2 mooring lines with length as required by Table C1.204 For ships and manned barges with restricted service theequipment specified in Table C1 and C2 may be reduced in ac-cordance with Table C3. No reductions are given for class no-tations R0 and R1.205 For ships and manned barges with equipment numberEN less than 205 and fishing vessels with EN less than 500 theanchor and chain equipment specified in Table C1 and C2 maybe reduced, on application from the Owners, based upon a spe-cial consideration of the intended service area of the vessel.The reduction shall not be more than given for the service no-tation R4 in Table C3. In such cases a minus sign will be givenin brackets after the equipment letter for the vessel in the “Reg-ister of vessels classed with DNV”, e.g. f(–).

1390-14791480-15691570-1669

BCD

222

432045904890

550550550

666870

586062

505254

200220220

836888941

455

180190190

324324333

1670-17891790-19291930-2079

EFG

222

525056106000

577.5577.5577.5

737678

646668

565860

220220220

102411091168

555

190190190

353378402

2080-22292230-23792380-2529

HIJ

222

645069007350

605605605

818487

707376

626466

240240240

125913561453

555

200200200

422451480

2530-26992700-28692870-3039

KLM

222

780083008700

632.5632.5632.5

909295

788184

687073

260260260

147114711471

666

200200200

480490500

3040-32093210-33993400-3599

NOP

222

93009900

10500

660660660

97100102

848790

767878

280280280

147114711471

666

200200200

520554588

3600-37993800-39994000-4199

QRS

222

111001170012300

687.5687.5687.5

105107111

929597

818487

300300300

147114711471

667

200200200

618647647

4200-43994400-45994600-4799

TUV

222

129001350014100

715715715

114117120

100102105

879092

300300300

147114711471

777

200200200

657667677

4800-49995000-51995200-5499

WXY

222

147001540016100

742.5742.5742.5

122124127

107111111

959797

300300300

147114711471

788

200200200

686686696

5500-57995800-60996100-6499

ZA*B*

222

169001780018800

742.5742.5742.5

130132137

114117120

100102107

300300300

147114711471

889

200200200

706706716

6500-68996900-73997400-7899

C*D*E*

222

200002150023000

770770770

124127132

111114117

300300300

147114711471

91011

200200200

726726726

7900-83998400-88998900-93999400-9999

F*G*H*I*

2222

24500260002750029000

770770770770

137142147152

122127132132

300300300300

1471147114711471

11121314

200200200200

735735735735

10000-1069910700-1149911500-12399

J*K*L*

222

310003300035500

770770770

137142147

151617

200200200

735735735

12400-1339913400-1459914600-16000

M*N*O*

222

385004200046000

770770770

152157162

181921

200200200

735735735

1) For individual mooring lines with breaking force above 490 kN according to the table, the strength may be reduced by the corresponding increase of the number of mooring lines and vice versa. The total breaking force of all mooring lines on board should not be less than according to the table. However, the number of mooring should not be less than 6, and no line should have a breaking force less than 490 kN.

Table C1 Equipment table, general (Continued)

Equipment number

Equip-ment letter


(guidance)Mooring lines 1)

(guidance)

Number

Mass per

anchor

kg

Total length Diameter and steel grade Steel or fibre ropes Steel or fibre ropes

m

NV K1

mm

NV K2

mm

NV K3

mm

Mini-mum

length m


kNNumber

Length of each

m


kN

DET NORSKE VERITAS


D. AnchorsD 100 General101 Anchor types dealt with are:

— ordinary stockless bower anchor— ordinary stocked bower anchor— H.H.P. (“High Holding Power”) anchor— S.H.H.P. ("Super High Holding Power") anchor.

102 The mass of ordinary stockless bower anchors shall notbe less than given in C. The mass of individual anchors mayvary by 7% of the table value, provided that the total mass ofanchors is not less than would have been required for anchorsof equal mass.The mass of the head shall not be less than 60% of the tablevalue.

103 The mass of stocked bower anchor, the stock not includ-ed, shall not be less than 80% of the table-value for ordinarystockless bower anchors. The mass of the stock shall be 25%of the total mass of the anchor including the shackle, etc., butexcluding the stock.104 For anchors approved as H.H.P. anchors, the mass shallnot be less than 75% of the requirements given in C. In suchcases the letter r will follow the equipment letter entered in the“Register of vessels classed with DNV”.105 For anchors approved as S.H.H.P. anchors, the massshall not be less than 50% of the requirements given in C. Insuch cases the letter rs will follow the equipment letter enteredin the "Register of vessels classed with DNV".106 The use of S.H.H.P. anchors is limited to vessels withservice restriction notation R1 or stricter.107 The S.H.H.P. anchor mass shall not exceed 1500 kg.

D 200 Materials201 Anchor heads may be cast, forged or fabricated fromplate materials. Shanks and shackles may be cast or forged.202 The materials shall comply with relevant specificationgiven in Pt.2.Plate material in welded anchors shall be of the grades as givenin F200 Table F3.203 Anchors made of nodular cast iron may be accepted insmall dimensions subject to special approval of the manufac-turer.204 Fabricated anchors shall be manufactured in accordancewith approved welding procedures using approved weldingconsumables and carried out by qualified welders.

Table C2 Equipment table for fishing vessels and sealers

Equip-ment

number

Equip - ment letter


(guidance)Mooring lines

(guidance)

Number

Mass per anchor

kg

Total length

Diameter and steel grade Steel or fibre ropes Steel or fibre ropes

m

NV K1

mm

NV K2

mm

Minimum length

m


kN

Number

Length of

each

m

Mini-mum

breaking strength

kN30-3940-4950-5960-69

a0f1a0f2af1af2

2222

80100120140

165192.5192.5192.

1111

12.512.5

180180

9898

2233

50608080

29293434

70-7980-8990-99

100-109

bf1bf2cf1cf2

2222

160180210240

220220220220

14141616

12.512.51414

180180180180

98989898

3333

100100110110

37373939

110-119120-129130-139140-149

df1df2ef1ef2

2222

270300340390

247.5247.5275275

17.517.51919

1616

17.517.5

180180180180

98989898

3333

110110120120

44444949

150-174175-204205-239240-279

fghi

2222

480570660780

275302.5302.5330

22242628

1920.52224

180180180180

98112129150

3344

120120120120

54596469

280-319320-359360-399

jkl

222

90010201140

357.5357.5385

303234

262830

180180180

174207224

444

140140140

747888

400-449450-499500-549

mno

222

129014401590

385412.5412.5

363840

323434

180180190

250277306

444

140140160

98108123

550-599600-659660-720

pqr

222

174019202100

440440440

424446

363840

190190190

338371406

444

160160160

132147157

Table C3 Equipment reductions for service restriction notations. (See Table C1)

Class notation

Stockless bower anchors

Stud-link chain cables

Number Mass change per

anchor

Length reduction

Diameter

R2 R3 R4 RE

2222

- 10% - 20% - 30% - 40%

No red.No red. - 20% - 30%

No red.No red. - 10% - 20%

Alternatively:R3 R4 RE

111

+40%No change

- 20%

- 40% - 50% - 60%

No red.No red. - 10%

DET NORSKE VERITAS


D 300 Anchor shackle301 The diameter of the shackle leg is normally not to be lessthan:

ds = 1.4 dc

dc = required diameter of stud chain cable with tensilestrength equal to the shackle material, see Table C1 orC2. For shackle material different from the steel gradesNV K1, NV K2 and NV K3, linear interpolation be-tween table values of dc will normally be accepted.

302 The diameter of the shackle pin is normally not to be lessthan the greater of:

dp = 1.5 dcdp = 0.7 l p

dc = as given in 301 lp = free length of pin. It is assumed that materials of the

same tensile strength are used in shackle body and pin.For different materials dp will be specially considered.

D 400 Testing401 Ordinary anchors with a mass more than 75 kg, orH.H.P. anchors with a mass more than 56 kg, or S.H.H.P. an-chors with a mass more than 38 kg, shall be subjected to prooftesting in a machine specially approved for this purpose.402 The proof test load shall be as given in Table D1, de-pendent on the mass of equivalent anchor, defined as follows:

— Total mass of ordinary stockless anchors.— Mass of ordinary stocked anchors excluding the stock.— 4/3 of the total mass of H.H.P. anchors— 2 times of the total mass of S.H.H.P. anchors.

For intermediate values of mass the test load shall be deter-mined by linear interpolation.403 The proof load shall be applied on the arm or on the palmat a distance from the extremity of the bill equal to 1/3 of thedistance between it and the centre of the crown. The anchorshackle may be tested with the anchor.404 For stockless anchors, both arms shall be tested simulta-neously, first on one side of the shank and then on the otherside.For stocked anchors, each arm shall be tested individually.405 The anchors shall withstand the specified proof loadwithout showing signs of injurious defects.This shall be confirmed by visual inspection after proof loadtesting. S.H.H.P. anchors and the welds of fabricated anchors,regardless of anchor type, are in addition subject to magneticparticle testing. 406 In every test the difference between the gauge lengths(as shown in figures) where one-tenth of the required load wasapplied first and where the load has been reduced to one-tenthof the required load from the full load may be permitted not toexceed one percent (1%).

Fig. 1Gauge length

D 500 Additional requirements for H.H.P. and S.H.H.P. anchors501 H.H.P. and S.H.H.P. anchors shall be designed for effec-tive hold of the sea bed irrespective of the angle or position atwhich they first settle on the sea bed after dropping from a nor-mal type of hawse pipe. In case of doubt a demonstration ofthese abilities may be required.502 The design approval of H.H.P. and S.H.H.P. anchors arenormally given as a type approval, and the anchors are listed inthe Register of Type Approved Products No.3 "StructuralEquipment, Containers, Cargo Handling and Securing Equip-ment".The design approval of H.H.P. anchors is normally given as atype approval, and the anchors are listed in the "Register ofType Approved Products No.3: Containers, Cargo Handling,Lifting Appliances and Miscellaneous Equipment."503 H.H.P. anchors for which approval is sought shall betested on sea bed to show that they have a holding power perunit of mass at least twice that of an ordinary stockless boweranchor.504 S.H.H.P. anchors for which approval is sought shall betested on sea bed to show that they have a holding power perunit of mass at least 4 times that of an ordinary stockless bower

anchor.505 If approval is sought for a range of H.H.P. anchor sizes,at least two sizes shall be tested. The mass of the larger anchorto be tested shall not be less than 1/10 of that of the largest an-chor for which approval is sought. The smaller of the two an-chors to be tested shall have a mass not less than 1/10 of thatof the larger.506 If approval is sought for a range of S.H.H.P. anchor siz-es, at least three sizes shall be tested, indicative of the bottom,middle and top of the mass range.507 Each test shall comprise a comparison between at leasttwo anchors, one ordinary stockless bower anchor and oneH.H.P. or S.H.H.P. anchor. The mass of the anchors shall be asequal as possible.508 The tests shall be conducted on at least 3 different typesof bottom, which normally shall be: soft mud or silt, sand orgravel, and hard clay or similar compacted material.509 The tests are normally to be carried out by means of atug. The pull shall be measured by dynamometer or deter-mined from recently verified curves of the tug's bollard pull asfunction of propeller r.p.m.The diameter of the chain cables connected to the anchors shallbe as required for the equipment letter in question. During the

DET NORSKE VERITAS


test the length of the chain cable on each anchor shall be suffi-cient to obtain an approximately horizontal pull on the anchor.Normally, a horizontal distance between anchor and tug equalto 10 times the water depth will be sufficient.

D 600 Identification601 The following marks shall be stamped on one side of theanchor:

— Mass of anchor (excluding possible stock)— H.H.P., when approved as high holding power anchor— S.H.H.P., when approved as super high holding power an-

chor— Certificate No.— Date of test— Det Norske Veritas' stamp.

E. Anchor Chain Cables

E 100 General101 Chain cables shall be made by makers approved by theSociety for the pertinent type of chain cable, size and methodof manufacture.102 The form and proportion of chain cable links and shack-les are normally to be in accordance with Fig.2. Deviation inaccordance with International Standard ISO/1704-1991, willbe generally accepted.Other design solutions, e.g. short link chain cable or steel wirerope may be accepted after special consideration.103 The diameter of stud link chain cable shall not be lessthan given in C.104 If ordinary short link chain cable is accepted instead ofstud link chain cable at least the same proof load will normallybe required.For fishing vessels with equipment number EN ≤ 110 the di-ameter shall be at least 20% in excess of the table value for thesteel grade used.105 Steel wire rope instead of stud link chain cable may beaccepted for vessels of special design or operation, for vesselswith restricted services and for fishing vessels. The acceptancewill be based on a case-by-case evaluation, including consid-eration of operational and safety aspects. If steel wire rope isaccepted, the following to be fulfilled:

— the steel wire rope shall have at least the same breakingstrength as the stud link chain cable

— a length of chain cable shall be fitted between the anchorand the steel wire rope. The length shall be taken as thesmaller of 12.5 m and the distance between the anchor instowed position and the winch

— the anchor weight shall be increased by 25%— the length of the steel wire rope shall be at least 50% above

the table value for the chain cable— a corresponding “Memo to Owner” (MO) shall be issued.

Arrangements applying the steel wire ropes of trawl winchesmay be accepted, provided the strength of the rope is sufficient.

E 200 Materials201 The chain cable links may be made by electric resistancebutt welding (melt welding), by casting or drop forging.Shackles and swivels may be cast or forged.The studs in stud link chain cables shall be made of cast orforged steel.Tapered locking pins for shackle bolts shall be made of stain-less or tinned steel with a lead stopper at the thick end.202 The materials shall be delivered with Det Norske Ver-itas' material certificates in compliance with the specificationsfor steel grades NV K1, K2 and K3.203 Steel grade NV K1 is normally not to be used in associ-ation with H.H.P. or S.H.H.P. anchors.204 Steel grade NV K3 shall not be used for chain diameterless than 20.5 mm.205 Ships equipped with chain cable of steel grade NV K2 orNV K3, will have the letters s or sh, respectively, added to theequipment letter.

Table D1 Proof test load for anchorsMass of anchor

kg

Proof test load

kN

Mass of anchor

kg

Proof test oad

kN

Mass of anchor

kg

Proof test load

kN

Mass of anchor

kg

Proof test load

kN

Mass of anchor

kg

Proof test load

kN

Mass of anchor

kg

Proof test load

kN5055606570758090100120140160180200225250275300325350375400425450475500

23.225.227.128.930.732.433.936.339.144.349.153.357.461.366.870.474.979.684.288.893.497.9103107112116

550600650700750800850900950

10001050110011501200125013001350140014501500160017001800190020002100

125132140149158166175182191199208216224231239247255262270278292307321335349362

22002300240025002600270028002900300031003200330034003500360037003800390040004100420043004400450046004700

376388401414427438450462474484495506517528537547557567577586595604613622631638

48004900500051005200530054005500560057005800590060006100620063006400650066006700680069007000720074007600

645653661669677685691699706713721728735740747754760767773779786795804818832845

78008000820084008600880090009200940096009800

100001050011000115001200012500130001350014000145001500015500160001650017000

861877892908922936949961975987999

101010401070109011101130116011801210123012601270130013301360

1750018000185001900019500200002100022000230002400025000260002700028000290003000031000320003400036000380004000042000440004600048000

13901410144014701490152015701620167017201770180018501900194019902030207021602250233024102490257026502730

DET NORSKE VERITAS


D = dc = Rule diameter of chain cables

Fig. 2Standard dimensions of stud link chain cable

DET NORSKE VERITAS


E 300 Heat treatment and material testing 301 All chain cables and accessories for chain cables, re-gardless of manufacturing process, shall be heat-treated asspecified in Table E1. When normalising, care shall be takento ensure that no links are lying on top of each other whilecooling, and thereby delaying the cooling. A description of theheat treatment shall be given on the certificate.302 When a manufacturer of chain cable buys material forthe links from the steel producer, he shall be instructed on theproper method of heat treatment.303 After the chain has been heat-treated, the efficiency ofthe heat treatment shall be controlled by testing of the materialin the finished links as stated in 304 to 306.304 From chain cables of grade NV K1 and NV K2, one setof 3 impact tests shall be taken from every four 27.5 m lengthof chain cable or from every 100 m.The material for the testing is obtained by supplying cablelengths with extra links. The tests shall satisfy the require-ments stated in Table E1.Subject to agreement with the Society, a reduction in thenumber of impact tests may be allowed, provided the manufac-turer by means of statistical tests data verifies that the impactrequirements in Table E1 are consistently met.305 From chain cables of grade NV K3, one set of tests (1tensile and 6 impact tests) shall be taken from every four 27.5m length of chain or from every 100 m.The material for the testing is obtained by supplying the cablelengths with extra links. The tensile test piece shall be takenfrom the base material opposite to the weldment. The tensiletests results shall satisfy the requirements stated in Table E1.306 For all steel grades, 3 impact test pieces shall be takenclear of the weld (position of the test pieces, see Fig.3). Forsteel grade K3, there shall be taken 3 additional impact testpieces from the welded zone, cut with the notch in the middleof the weld.Impact test values of specimens taken clear of the weld shallcomply with the requirements given in Table E1. Impact testvalues (KV) for steel grade K3 of specimens taken from theweld shall be at least 50 J as average value of 3 tests when thetests are carried out at 0°C. The surveyor may also require im-pact tests from more than one length in every four.

E 400 Breaking test401 A breaking test specimen consists of at least 3 links con-nected together, and they shall be manufactured at the sametime and in the same way as the chain cable and heat-treated asthis. During the heat treatment the test specimen shall be se-curely attached to the chain cable.402 At least one breaking test specimen shall be taken fromevery four 27.5 m lengths of chain cable or from every 100 m.For chain cables of grade NV K1 which is not heat-treated afterwelding, breaking test shall be carried out on one specimenfrom each 27.5 m length. For cast chain cables (grades NV K2and NV K3), one breaking test per heat treatment batch shallbe taken, with a minimum of one for every four 27.5 m lengths.The testing may be recognized as having been passed, if frac-ture has not occured at the minimum breaking strength givenin Tables E2 and E3.403 Other tests may replace the breaking test after agreement

with the Society.404 Should a breaking load test fail, a further test specimenmay be taken from the same length of chain cable and tested.The test shall be considered successful if the requirements arethen satisfied.If the retest fails, the length of chain cable concerned shall berejected. If the manufacturer so wishes, the remaining threelengths belonging to the batch may then be individually sub-jected to test at the breaking load. If one such test fails to meetthe requirements, the entire batch is rejected.405 From each manufacturing batch (same grade, size andheat treatment batch) of 25 units or less of shackles, swivels,swivel shackles, large links and end links, and from each man-ufacturing batch of 50 units or less of Kenter shackles, one unitshall be subjected to the breaking load test. Parts tested in thisway may not to be put to further use.The Society may waive the breaking load test if:

a) the breaking load has been demonstrated on the occasionof the approval testing of parts of the same design, and

b) the mechanical properties and the impact energy of eachmanufacturing batch are proved, and

c) the parts are subjected to suitable non-destructive testing.

E 500 Proof test501 Each length of the chain cable shall be proof tested in amachine specially approved for that purpose, and shall with-stand the load given in Tables E2 and E3 for the type, size andgrade of steel concerned, without showing any signs of defects.All joining shackles, end shackles and swivels shall be testedwith the proof load prescribed for the chain concerned. SeeD403 for specific relaxation for anchor shackle.502 Should a proof load test fail, the defective link(s) is (are)to be replaced, a local heat treatment according to 801 to becarried out on the new link(s) and the proof load test to be re-peated. In addition, an investigation shall be made to identifythe cause of the failure.

E 600 Tolerances601 All required measurements shall be taken after the prooftesting. The measurements shall be carried out to the satisfac-tion of the surveyor.602 The allowable manufacturing minus tolerance on the di-ameter dc of the common links is:

— for dc ≤ 40 mm : –1 mm— for 40 < dc ≤ 84 mm : – 2 mm— for 84 < dc ≤ 122 mm : – 3 mm— for dc > 122 mm: – 4 mm.

The allowable manufacturing plus tolerance is 5%. The cross-sectional area of the link is at least to be the theoretical area forthe nominal diameter.The calculation of the theoretical area shall be based on the av-erage of four measurements of the diameter equally spacedaround the circumference.Three links from every four 27.5 m length or every 100 mlength of chain cable shall be chosen for measurements of thediameter.

DET NORSKE VERITAS


603 The allowable manufacturing tolerance on length of 5links is + 2.5 %. The measurements shall be taken while thechain is loaded to about 10% of the proof load. Other methodsfor the measurements may be agreed upon.604 The allowable manufacturing tolerance on other dimen-sions that are described in 602 and 603, is ± 2.5%. For commonlinks, three links from every four 27.5 m length or every 100 mlength of chain cable shall be chosen for measurements of out-side length and width.

E 700 Identification701 Every 27.5 m length of chain cable and all accessoriesshall be stamped with:

— Chain grade, according to Table E1— Certificate No.— Det Norske Veritas' stamp.

E 800 Repair of defects801 Links seriously damaged shall be replaced with shacklesof approved type and grade of steel or with new links corre-sponding to the original ones as regards grade of steel andspecified properties. The use of other material and processes ofmanufacture is subject to approval in each case. Each substi-tute (new link) shall be subjected to a satisfactory method ofheat treatment (normalising, normalising and tempering orquenching and tempering) as required, without affecting adja-cent links, if the entire chain is not reheat-treated. Processes forindividual treatment of links shall be tested as to impact prop-erties (for NV K3 chain also the tensile strength) by testing ex-tra links which are manufactured and treated in the same wayas the new links in the chain.The repaired chain length is finally to be subjected to the re-quired proof testing.802 Defective accessories for chain cables (shackles andswivels) shall be replaced by new ones of the same grade as thechain cable, or better.

Table E1 Heat treatment and mechanical properties

Mechanical properties:

Grade Heat treatmentNV K1 Normalised 1) NV K2 Normalised 2) NV K3 Quenched and tem-

pered, normalised or nor-malised and tempered

Yield stress REH or proof stress RP0.2 N/mm2 Minimum 295 Minimum 410Tensile strength, RM N/mm2 370 - 490 490 - 690 Minimum 690Elongation (L0 = 5d) A5 % Minimum 25 Minimum 22 Minimum 17Reduction of area, Z % minimum 40 3)

Impact values (KV), as an average of 3 tests, J minimum 27; 20 °C minimum 27; 0 °C minimum 60; 0°C1) Chain cables with diameters up to 50 mm may be supplied without heat treatment after welding, provided that a breaking test is carried out on one spec-

imen from each length, see 402.2) Cast chain cable, grade NV K2, shall be normalised or may, at option of the manufacturer, be quenched and tempered.3) 35% for cast links and chain accessories.

DET NORSKE VERITAS


Table E2 Test loads and mass. Stud link chain cables

Diameter of chain mm

Chain of Steel grade NV K1

Chain of Steel grade NV K2

Chain of Steel grade NV K3 Guidance

Proof test load

kN


kN

Proof test load

kN


kN

Proof test load

kN


kN

Approximate mass per m

kg

1112.51416

17.519

20.52224262830323436384042444648505254565860626466687073767881848790929597100102105107111114117120122124127130132137142147152157162

3646587689

1051231401671942252572913283664064484925385856356867397948519099691030110011601230129013901500158016901810192020502130226023402470256027002790297031103260340035003600375039004000426045204790505053205590

516682

107127150175200237278321368417468523581640703769837908981106011401220129013801470156016601750184019902150226024102580275029203040323033503530366038603980425044404650486050005140535055705720608064506840722076007990

516682

107127150175200237278321368417468523581640703769837908981106011401220129013801470156016601750184019902150226024102580275029203040323033503530366038603980425044404650486050005140535055705720608064506840722076007990

7292

1161501792112442803323894495145836557328128969811080117012801370148015901710181019402060219023102450258027903010316033803610385040904260451046804940512053905570594062306510681070007200749078008000851090309560

101001064011170

7292116150179211244280332389449514583655732812896981

1080117012801370148015901710181019402060219023102450258027903010316033803610385040904260451046804940512053905570594062306510681070007200749078008000851090309560101001064011170

102132165216256301349401476556642735833937

105011601280140015401680181019602110227024302600277029403130330035003690399043004500482051605500584060806440669070607320770079608480889093009720999010280107101114011420121601291013660144301520015970

3.74.45.66.88.09.310.612.614.817.119.622.325.128.131.334.738.241.945.849.854.058.463.067.872.777.883.188.694.2100.0106.0115.2124.9131.6142.0152.9164.2176.0184.1196.6205.0218.5227241250269284299314326335351367378408437470500530570

DET NORSKE VERITAS


Fig. 3Position of test pieces

F. Windlass and Chain Stoppers F 100 General design101 The anchors are normally to be operated by a speciallydesigned windlass. For ships with length L < 50 m, one of thecargo winches may be accepted as windlass, provided the re-quirements to the arrangement and function are satisfied.102 The windlass shall have one cable lifter for each anchorstowed in hawse pipe.The cable lifter is normally to be connected to the driving shaftby release coupling and provided with brake.The number of pockets in the cable lifter shall not be less than5. The pockets, including the groove width etc. shall be de-signed for the joining shackles/kenter shackles with due atten-tion to dimensional tolerances.When the chain cable diameter is less than 26 mm, only one ofthe cable lifters need be fitted with release coupling and brake.103 For each chain cable there is normally to be a chain stop-per, arranged between windlass and hawse pipe. The chain ca-bles shall reach the hawse pipes through the cable lifter only.

104 Electrically driven windlasses shall have a torque limit-ing device.Electric motors shall comply with the requirements of Pt.4Ch.8.105 The windlass with prime mover shall be able to exert thepull specified by Table F1 directly on the cable lifter. For dou-ble windlasses the requirements apply to one side at a time.

Attention shall be paid to stress concentrations in keyways andother stress raisers and also to dynamic effects due to suddenstarting or stopping of the prime mover or anchor chain.106 The capacity of the windlass brake shall be sufficient forsafe stopping of anchor and chain cable when paying out.The windlass with brakes engaged and release coupling disen-gaged shall be able to withstand a static pull of 45% of thechain cable minimum breaking strength given in Table E2,without any permanent deformation of the stressed parts andwithout brake slip.If a chain stopper is not fitted, the windlass shall be able towithstand a static pull equal to 80% of the minimum breakingstrength of the chain cable, without any permanent deforma-tion of the stressed parts and without brake slip.107 Calculations indicating compliance with the require-ments in 105 and 106 may be dispensed with when completeshop test verification shall be carried out.108 The chain stoppers and their attachments shall be able towithstand 80% of the minimum breaking strength of the chaincable, without any permanent deformation of the stressedparts. The chain stoppers shall be so designed that additionalbending of the individual link does not occur and the links areevenly supported. Bar type chain stoppers stopping the chainlink from one side may be accepted after special considerationand provided that satisfactory strength is demonstrated by cal-culation or prototype test.

Guidance note:A chain stopper designed to a recognised national or internation-al standard may be accepted provided its service experience isconsidered satisfactory by the Society.


F 200 Materials201 Cable lifter shafts and cable lifters with couplings shallbe made from materials as stated in Table F2.

202 Windlass and chain stoppers may be cast components orfabricated from plate materials. The material in cast compo-nents shall be cast steel or nodular cast iron with elongation notless than 18%. Plate material in welded parts shall be of grade

Table E3 Test loads for short link chain cablesDiameter of chain

mmProof load

kNBreaking load

kN111213

22.426.631.3

47.753.262.5

141516

36.341.647.4

72.583.294.7

171819

53.559.866.7

107.0119.5133.5

202122

73.981.489.6

147.5163.0179.0

232425

97.9106.5116.0

195.5213231

262728

125.0135.0144.5

250270289

293031

155.5166.5177.5

311333355

32333435

190.0201214227

380402428453

Table F1 Lifting powerLifting force and speed

Grade of chainK1 K2 K3

Normal lifting force for 30 min in N 36.8 dc

2 41.7 dc2 46.6 dc

2

Mean hoisting speed 9 m/min.Maximum lifting force for 2 minutes (no speed requirement) 1.5 x normal lifting force

dc = diameter of chain in mm.

Table F2 Material requirementsChain cable diame-

ter ≤ 46 mmChain cable diame-

ter > 46 mmCable lifters and cou-plings

Nodular cast iron or special cast iron

Cast steel

Cable lifter shaft Forged or rolled steel, cast steel

DET NORSKE VERITAS


as given in Table F3.

F 300 Testing301 Before assembly the following parts shall be pressuretested:

— housings with covers for hydraulic motors and pumps— hydraulic pipes— valves and fittings— pressure vessels— steam cylinders.

The tests shall be carried out in accordance with Pt.4 Ch.6Sec.5 and Sec.7, and Pt.4 Ch.7. Test pressure for steam cylin-ders shall be 1.5 times the working steam pressure.302 After completion, at least one prime mover of the wind-lass shall be shop tested with respect to required lifting forcesand if relevant, braking forces.If calculations have not previously been accepted, shop testingof the complete windlass shall be carried out.303 After installation of the windlass on board, an anchoringtest shall be carried out to demonstrate that the windlass withbrakes etc. functions satisfactorily.The mean speed on the chain cable when hoisting the anchorand cable shall not be less than 9 m/min. and shall be measuredover two shots (55 m) of chain cable during the trial. The trialshould be commenced with 3 shots (82.5 m) of chain cable ful-ly submerged. Where the depth of water in trial areas is inade-quate, consideration will be given to acceptance of equivalentsimulated conditions.

G. Towlines and Mooring Lines G 100 General101 Steel wire ropes, shall be made by an approved manu-facturer.102 The number, length and breaking strength of towlinesand mooring lines are given in C. Note that towlines andmooring lines are given as guidance only.103 The strands of steel wire ropes shall be made in equal layconstruction (stranded in one operation), and are normally tobe divided in groups as follows:

— 6x19 Group consists of 6 strands with minimum 16 andmaximum 27 wires in each strand

— 6x36 Group consists of 6 strands with minimum 27 andmaximum 49 wires in each strand.

Fig.4 gives examples of rope constructions. Other rope con-structions may be accepted by the Society upon special consid-eration.

Fig. 4Constructions of steel wire ropes

104 The diameter of a fibre rope shall not be less than 20mm.105 Synthetic fibre ropes will be specially considered withrespect to size, type, material and testing.

G 200 Materials201 Towlines and mooring lines may be of steel, natural fi-bre or synthetic fibre construction.202 Wire for steel wire ropes shall be made by open hearth,electric furnace, LD process or by other processes specially ap-proved by the Society.Normally, the tensile strength of the wires shall be 1570 N/mm2 or 1770 N/mm2. The wire shall be galvanised or bright(uncoated). Galvanised wire shall comply with the specifica-tions in ISO Standard 2232.203 The steel core shall be an independent wire rope. Nor-mally, the wires in a steel core shall be of similar tensilestrength to that of the main strand, but shall not be less than1570 N/mm2.The fibre core shall be manufactured from a synthetic fibre.204 Unless otherwise stated in the approved specification,all wire ropes shall be lubricated. The lubrications shall haveno injurious effect on the steel wires or on the fibres in therope.

G 300 Testing of steel wire ropes301 Steel wire ropes shall be tested by pulling a portion ofthe rope to destruction. The test length which is dependent onthe rope diameter, is given in Table G1. The breaking load ofthe ropes shall not be less than given in Table G2 for the di-mension concerned.

Table F3 Plate material gradesThickness in mm Normal strength

structural steelHigh strength structural steel

t ≤ 20 A A20 < t ≤ 25 B A25 < t ≤ 40 D D40 < t ≤ 150 E E

DET NORSKE VERITAS


302 If facilities are not available for pulling the completecross section of the rope to destruction, the breaking load maybe determined by testing separately 10% of all wires from eachstrand. The breaking strength of the rope is then considered tobe:

P = f t k (kN)

f = average breaking strength of one wire in kNt = total number of wiresk = lay factor as given in Table G3.

303 The following individual wire tests shall be performed:

— torsion test— reverse bend test— weight and uniformity of zink coating.

These tests shall be made in accordance with and shall complywith ISO Standard 2232.

G 400 Testing of natural fibre ropes401 Natural fibre ropes are, if possible, to be tested by pull-ing a piece of the rope to destruction. For qualities 1 and 2, thebreaking load shall not be less than given in Table G4.

Table G1 Test lengthsRope diameter

in mmMinimum test length

in mmd ≤ 6 300

6 < d ≤ 20 600d < 20 30 x d

Table G2 Test load and mass. Steel wire ropesConstruction

groupsNom. dia. mm

Minimum required breaking strength in kN Approximate mass kg/100 m1570 N/mm2 1770 N/mm2

FC IWRC FC IWRC FC IWRC6 x 19 group 14

1618202224262830

102133168208251299351407468

110144182224272323379440505

115150190234283337396459527

124162205253306364428496569

72.794.9120148179214251291334

82.0107135167202241283328376

6 x 19 groupand

6 x 36 group

32364044485256606468

53067182910001190140016201860

5737258951080129015101750201022902590

59875793411301350158018302100

646817

10101220145017101980227025802920

380480593718854

100011601330

428542669810964

11301310151017101930

6 x 36 group 72768084889296

100104108112116120124128

290032303580395043304730516055906050652070207530806086009170

3270364040404450488053405810631068207360791084909080970010330

217024202680295032403540385041804520488052505630602064306850

C = fibre coreIWRC = independent wire rope core

Table G3 Lay factor kRope construction

groupRope with FC Rope with IWRD

6 x 196 x 36

0.860.84

0.800.78

DET NORSKE VERITAS


402 If facilities are not available for making the above test,

the Society may accept testing of a specified number of theyarns from the rope. The breaking strength of the rope will thenbe deduced from these tests.

G 500 Mooring Winches501

Guidance note:Each winch should be fitted with drum brakes the strength ofwhich is sufficient to prevent unreeling of the mooring line whenthe rope tension is equal to 80 per cent of the breaking strengthof the rope as fitted on the first layer.Where this is achieved by the winch being fitted with a pawl andratchet or other positive locking device, then the braking mecha-nism shall be such that the winch drum can be released in con-trolled manner while the mooring line is under tension.For powered winches the maximum hauling tension which canbe applied to the mooring line (the reeled first layer) should notbe less than 1/4.5 times the rope's breaking strength and not morethan 1/3 times the rope's breaking strength. For automatic winch-es these figures shall apply when the winch is set on the maxi-mum power with automatic control.The rendering tension which the winch can exert on the mooringline (reeled 1st layer) should not exceed 1.5 times, nor be lessthan 1.05 times the hauling tension for that particular power set-ting of the winch on automatic control. The winch shall bemarked with the range of rope strength for which it is designed.


Table G4 Breaking loads. - natural fibre ropesCircum- ference

mm

Breaking load (approximately) in kNThree-stranded (hawser-laid)

Four-stranded (hawser-laid)

Quality 1 Quality 2 Quality 1 Quality 2647076

31.637.644.8

28.233.439.8

28.233.439.8

24.929.635.3

838995

52.059.568.0

46.353.160.5

46.052.860.2

41.147.153.6

102108114

76.485.295.4

68.075.784.7

67.075.484.7

60.267.075.2

121127140

105.1116.1139.0

93.4103.1123.5

93.2103.1123.5

82.791.6

109.6152165178

163.9190.8219.7

145.5169.4195.3

144.5169.4195.3

128.5150.5173.3

203229254

282.5353.3433.0

251.1313.9384.7

250.2318.9383.7

222.2279.0340.7

279305

520.2617.0

462.1548.2

461.5547.2

410.2486.4

DET NORSKE VERITAS


SECTION 4 MASTS AND RIGGING

A. General

A 100 Introduction101 In this section the requirements to strength and supportof masts, derrick posts and standing rigging are given.102 The derricks and the cargo handling gear, are not subjectto approval.

A 200 Assumptions201 The cargo handling systems are assumed only to be op-erated in harbours or in sheltered waters.202 The formulae for determining the scantlings of stayedmasts, post and standing rigging are based on a symmetrical ar-rangement of stays and shrouds related to a vertical longitudi-nal plane through the mast or post.Steel wire ropes for shrouds are assumed with a modulus ofelasticity equal to 7.5 · 106 N/mm2.

A 300 Definitions301 Symbols:

P = load in t which may be lifted by the derrick ld = length of derrick in m. Where the working position of

the derrick is such that the angle between the centreline of the derrick and the horizontal always exceeds15°, ld is taken as the greatest horizontal projection ofthe derrick

ls = length of shrouds in m lm = length of mast in m from deck or top of mast house to

houndsH = height of derrick heel above deck or top of mast house

in ma = athwartship distance in m from the mast to the deck at-

tachment of shroud in question, see Fig.1c = longitudinal distance in m from the mast to the deck at-

tachment of shroud in question, see Fig.1With reference to a transverse plane through the mast,c shall be taken negative (–) for shrouds fitted on thesame side as the derricks in question and positive (+)for those fitted on the opposite side

e = horizontal distance in m from the mast to the deck at-tachment of shroud in question, see Fig.1.a0, c0 and e0 refer to the shrouds nearest the transverseplane through the mast. c0 shall not be taken greaterthan B/4.

Σ = summation of:

a) Load functions for derricks simultaneously serv-ing one hatch.

b) Support functions for effective shrouds whenloads are as indicated in a), i.e. all shrouds forwardor aft of the mast whichever is opposite to thehatch in question.

c) Load functions for derricks simultaneously work-ing outboard.

d) Support functions for effective shrouds whenloads are as indicated in c), i.e. all shrouds on oneside of the ship, however the attachment to thedeck shall not exceed 0.3 B forward or aft of themast.

Fig. 1Arrangement of shrouds.

A 400 Documentation401 The following plans and information shall be submitted:

— Arrangement plan showing location of mast or derrickpost, standing rigging and cargo handling gear. Informa-tion about the operation of the derrick booms, if provided,i.e. how the derricks are intended to be worked, for in-stance, if more than one derrick is intended to simultane-ously serve one hatch. Safe working load and workingposition for each provided derrick.

— Plan showing proposed scantlings of mast, derrick postand standing rigging.

— Plan showing supporting structures and strengthening ofhull in way of mast, post and standing rigging fastenings.

— Specification of the steel wire ropes intended to be usedfor standing rigging, indicating rope construction, scant-lings and minimum breaking strength.

B. Materials and Welding

B 100 Materials101 Selection of material grades for plates and sections shallbe based on material thickness. NV-steel grades as given in Ta-ble B1 will normally be accepted.

102 The tensile strength of wire ropes intended for shroudsand stays is normally to be minimum 1570 or 1770 N/mm2 (seeTable G2 of Sec.3) and should not exceed 2200 N/mm2.103 Material certificates for standing rigging shall be issuedby the manufacturer, confirming that the delivered productsare manufactured and tested according to the Rules (see Sec.3G) or another approved specification.

Table B1 Plate material gradesThickness

in mmNormal strength structural steel

High strength structural steel

t ≤ 20 A A20 < t ≤ 25 B A25 < t ≤ 40 D D

40 < t ≤ 150 E E

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C. Arrangement and Support

C 100 Masts and posts101 Masts and posts shall be efficiently supported and con-nected to at least two decks or to one deck and a mast house topabove. If the latter arrangement is adopted, the mast house topshall be of sufficient size and adequately stiffened. A winchhouse of usual size and scantlings is not considered to meet therequirements.

C 200 Standing rigging201 The mast or post shall have at least two shrouds on eachside of the centre line of the ship. The attachment of shrouds tomast shall be carefully made so as to reduce torsional strains asfar as possible.202 At fastenings for standing rigging and for guys and top-ping lifts, the deck shall be securely stiffened and reinforcedfor the additional loading.

D. Design and Scantlings

D 100 General101 The requirements to diameter d0 and plate thickness t0for masts and posts given in the following shall be maintainedfor a distance not less than 1 m above the derrick heel fitting.Above this level, the diameter and the plate thickness may begradually reduced to 0.75 d0 and 0.75 t0 at the hounds. Mini-mum thickness is 7.5 mm.102 Where masthead span blocks are attached to outriggers,the section modulus of the mast at the level of the outriggershall not be less than:

Z = 120 r Q (cm3)

r = horizontal distance in m from mast to masthead spanblocks on outrigger

Σ P = total load in t which may be lifted by the derrickson one side of the centre line of the ship

n = 1, 2, 3 etc. for single, double and triple blocks etc.,respectively.

103 Masts and posts shall be increased in thickness or rein-forced with doubling at the heel, deck and hounds.

D 200 Unstayed masts and posts with derricks201 The section modulus and moment of inertia of masts andposts with derricks are not, at decks, to be less than:

Z = 100 Σ (P l d) (cm3)

Minimum thickness of plating t = 7.5 mm.Masts with outriggers on unusual spread will be specially con-sidered.

D 300 Stayed masts or posts with derricks with a lifting capacity not exceeding 10 t301 The outer diameter of masts or posts shall not be lessthan:

302 The plate thickness of masts or posts shall not be lessthan:

t0 = 0.014 d0 mm, minimum 7.5 mm 303 The moment of inertia of masts or posts shall not be lessthan:

α = 0.5 for derricks with a lifting capacity of 5 t or less = 1.0 for derricks with a lifting capacity of 10 t. Between

5 and 10 t, α is determined by linear interpolation.

f =

V = breaking strength of shrouds in Nq = tensile strength of shrouds in N/mm2.

D 400 Stayed masts of posts with derricks with a lifting capacity of 10 t or more, but not exceeding 40 t401 The required outer diameter d0 in mm of masts or posts,measured at deck or top of mast house, is determined from theexpression:

t0 = plate thickness of mast in mm at diameter d0F = the greater of:

402 The plate thickness of masts or posts is in no place to beless than 7.5 mm.403 The moment of inertia of masts or posts shall not be lessthan:

G = the smaller of

404 Section modulus of masts is in general not to be lessthan:

G = as defined in 403.

405 Where derricks are fitted both forward and aft of themast, the section modulus is further not to be less than:

Q PP∑

n---------- 1

ldlm H–---------------⎝ ⎠

⎛ ⎞2

+ (t)+∑=

I 240lm

2

lm H–--------------- Pld( ) (cm4 )∑=

d0 140 Pld( )

13--- (mm)∑=

I 240lm

2

lm H–--------------- Pld( ) 1500lm

3 fc2

ls3

------α (cm4 )∑–∑=

V100q------------ (cm2 )

d0t0100---------- 1.5 P 10lm

2F +∑≥

fc

ls3

------ and 12--- f 1.7a c+( )

ls3

---------------------------∑∑

I 240lm

2

lm H–--------------- Pld 1500lm

3G (cm4 )–∑=

fc2

ls3

------ and 14--- f 1.7a c+( )2

ls3

------------------------------∑∑

Z80lm

lm H–--------------- Pld

30000lm3

d0-----------------------G (cm3 ) –∑=

DET NORSKE VERITAS


K =

Σ P1 l d1 and Σ P2 l d2 refer to derricks on either side of a trans-verse plane through the mast. Σ P1 l d1 shall be the smaller of these products.

D 500 Stayed masts without derricks501 The diameter of stayed masts without derricks shall notbe less than:

d1 = 0.75 d0 (mm) d0 and d1 are the diameter at deck and hounds respectively.

l m1 = length of mast in m measured from deck to hounds.

502 The plate thickness shall not be less than:t = 2.5 + 0.35 l m1 (mm)

D 600 Shrouds601 Shrouds for masts or posts with derricks shall havebreaking strength not less than:

Permanent centre line stays may be included in Σ e when rele-vant.602 Shrouds for masts without derricks shall have circumfer-ence of steel wire rope not less than 63 mm.

Z80lm

lm H–--------------- Pld

Klm3

d0------------

fa2

lm3

--------∑ (cm3 ) –∑=

24000 1 0.25P1ld1∑P2ld2∑

--------------------+⎝ ⎠⎜ ⎟⎜ ⎟⎛ ⎞

d0100lm1

3----------------- (mm)=

V10.8g0lm

Pld∑

lm H–( ) 1c0B-----+⎝ ⎠

⎛ ⎞ e∑---------------------------------------------------- ((kN)=

DET NORSKE VERITAS


SECTION 5 FOUNDATIONS FOR DECK MACHINERY, TOWING EQUIPMENT AND

LIFTING APPLIANCES

A. Crane and Lifting Appliances

A 100 Introduction 101 In this sub-section the requirements for strength andsupport of crane pedestals, support of davits, A-frames andother lifting equipments are given. The requirements are appli-cable to equipment specified for safe working load (SWL)> 30 kN or resulting bending moment at hull fixation> 100 kNm.102 The crane including pedestal flange and bolts or the lift-ing gear itself is not subject to approval, unless class notationCRANE, DSV or Crane Vessel is requested.

Guidance note:If ILO certification of lifting appliances is requested and DNVshall issue the certificate, approval of documentation will be re-quired. See Rules for Certification of Lifting Appliances.


103 For the requirements in this section, the following defi-nitions will apply:

— Shipboard cranes are lifting appliances onboard ships andsimilar units intended for use within harbours areas andwhen at sea within the cargo deck area.

— Offshore cranes are lifting appliances onboard ships andsimilar units intended for cargo handling outside the deckarea at open sea, e.g. loading and discharging of offshoresupport vessels, barges, etc. or from the seabed.

104 Design of foundations and supporting structure for lift-ing appliances in general, e.g. cranes and A-frames, intendedfor large loads, having a complex arrangement and or com-prised by irregular shaped plating, shall be supported by astrength analysis at an extent and content to be agreed beforehand with the Society. Calculations shall follow principles out-lined in Ch.1 Sec.12.

A 200 Documentation201 The following plans shall be submitted:For approval:

— pedestal/post with scantlings and grades of material— support for stowage of crane and derrick booms during

transit— hull strengthening

for cranes on rails, also:

— support of rails with scantlings, material grades and detailsof fixation bolts and /or pads

— end buffers and respective supports— arrangement and details of support for rack bar with scant-

lings, material grades and fixation bolts and/or pads— parking position with locking arrangement and hull rein-

forcements.

For information:

— arrangement of crane showing main dimensions, limitingpositions of its movable parts, location on board duringoperation and in parked position

— load data including the safe working load (SWL) and cor-responding arm, e.g. as a load chart

— dynamic coefficient "ψ"— crane self-weight and position of centre of gravity— resulting loads acting on the hull supporting structure dur-

ing operation in various lifting positions and in parked po-sition

for "offshore cranes", also:

— significant wave height (Hs) for operation— if available, dynamic load chart, i.e. chart showing crane

capacity at each given Hs.

A 300 Materials301 For pedestal/posts and supporting structures to be usedin harbour only, selection of material grade for plates and sec-tions shall be based on Table B1 of Sec.4.302 When intended for offshore use, the selection of materi-als for crane pedestal and respective foundation shall be basedon the Rules for Certification of Lifting Appliances.If not otherwise stated the design temperature TD, for determi-nation of the impact test temperature, shall be –20°C or lower.303 When a pedestal subjected to bending is not continuousthrough a deck plating, the following applies:

— either Z-quality material for t > 15 mm (Pt.2 Ch.2 Sec.1 E)shall be used in the deck plating

— or an ultrasonic lamination test after the welding has beencompleted, shall be carried out in tension exposed areas.

304 For welding procedures and details in general, see rele-vant requirements given in Pt.2 and Pt.3 Ch.1 and Ch.2.

A 400 Arrangement401 Support of heavily loaded crane pedestals shall prefera-bly be provided by at least 2 deck levels. The supporting struc-ture shall have continuity and allow safe access for survey ofits interior. Reference is made to Fig.1 and Fig.2.

Fig. 1Not recommended

DET NORSKE VERITAS


Fig. 2Recommended support

A 500 Design loads501 The structural strength of the supporting structure andpedestal shall be based on the safe working load (SWL) multi-plied by the design dynamic coefficient "ψ" (specified for thecrane designer) plus the self weight. However, the dynamic co-efficient shall not be taken less than the following:

For "shipboard cranes" :

— 1.3.

For "offshore cranes":

— with the operator placed above the slewing ring: - ψ increased by 30%, min. 2.0

— with the operator placed below the slewing ring:- 1.5.

Lifting appliances fitted with shock absorbers may be speciallyconsidered.502 Vertical and horizontal accelerations for the specifiedsea state. av, at and al to be taken as a safe fraction of the ex-treme values given in Ch.1 Sec.4 B. Accelerations to be com-bined as indicated for deck equipment in Ch.1 Sec.4 C500.

Guidance note:When the significant wave height HS is known,

may be inserted in the formulae of Ch.1 Sec.4 B.Cw = wave coefficient.- Wind forces for the specified wind velocity, according to the

Rules for Certification of Lifting Appliances.---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---

503 When the transit condition is considered critical, the de-sign loads shall normally be taken as given for idle deck equip-ment in Ch.1 Sec.4 C500.For vessels with length less than 100 metres, see also Ch.2Sec.3 B300.For non-compact units wind and icing shall be taken into ac-count as appropriate.Standard ice load for North Sea winter conditions may be takenas 5 cm ice deposit on wind and weather exposed surfaces.

Guidance note:For vessel with class notation Supply Vessel, the loads men-tioned above shall be determined as given in Pt.5 Ch.7 Sec.3E301.


504 Supporting structure for survival craft and work boatdavits shall be designed for a dynamic coefficient taken as 2.2.505 For man-overboard boat davits, the supporting structureshall also be designed to withstand a horizontal towing force.

A 600 Allowable stresses601 Allowable stresses in crane pedestals and respectivesupporting structure shall in principle be taken as follows:

Normal stresses: 160 f1 N/mm2Shear stresses: 90 f1 N/mm2

The above also applies to supporting structures for davits, A-frames and other similar lifting devices.In way of structures subject to longitudinal hull stresses, the al-lowable stresses will be especially considered.

A 700 Testing701 Upon completion of crane foundation, load test shall becarried out in the presence of a DNV surveyor.

B. Foundations for Winches, Windlasses and other Pulling Accessories

B 100 Introduction101 This sub-section gives requirements for foundations andrespective supporting structures for deck machinery in general,like winches, windlasses, chain stoppers, and other similaritems, including stern rollers and shark jaws for handlingchains of offshore rigs fitted onboard offshore support vessels.

Guidance note:Only windlasses, anchor chain stoppers and equipment related toadditional class notations, when specifically mentioned (e.g.towing equipment for vessels with class notation Tug ) are in-cluded in scope of classification, requiring plan approval and cer-tification of the equipment by DNV.


B 200 Documentation201 When the breaking load of the wire or chain is > 150 kN,or SWL > 30 kN, the following plans and information shall besubmitted:Documents for approval:

— foundations and respective supporting structure includingscantlings, material data, details of connections and weld-ing

— fixation of windlass (bolts, chocks and stoppers).

Documents for information:

— arrangement of the equipment showing main dimensions,design loads (SWL, brake rendering load and wire break-ing load, if relevant) and foot print loads.

B 300 Design loads and allowable stresses301 The strength of the foundations and supporting struc-tures shall fulfil the strictest of the following requirements asfound relevant:

a) Design load to be given by the respective SWL times dy-namic coefficient, "ψ", as specified by designer. "ψ" ishowever not to be taken less than 1.3.

CW23--- HS=

DET NORSKE VERITAS


b) Design load to be given by the force in the rope causingthe brake to render.

c) For winches with constant tension control, design load tobe taken as 1.1 times the maximum pulling force.

d) For transit condition, see A503.For the above load conditions the allowable stresses are the fol-lowing:


e) For winches (e.g. trawl winches) where the rope/equip-ment can get stuck on the sea bottom or otherwise, the de-sign load shall be equal to the breaking load of the rope.

f) For structure under windlasses and chain stoppers de-signed for loads as given in Sec.3 F106.

For the above load conditions e) and f) the allowable stressesare the following:


When such condition occurs, the breaking load of the rope willbe stated in the Appendix to Class Certificate.

B 400 Securing requirements for fore deck windlasses401 This subsection gives requirements for the securing ofwindlasses when fitted under the following three conditions:

— in ships of length 80 m or more— located on an exposed deck over the forward 0.25 L— the distance between their base and the summer load wa-

terline is less than 0.1 L or 22 m, whichever is the lesser.

402 These requirements are additional to those appertainingto the anchor and chain performance criteria.403 Where mooring winches are integral with the anchorwindlass, they shall be considered as part of the windlass.404 The following pressures and associated areas shall beapplied (see Fig.3):

200 kN/m2 normal to the shaft axis and away from the for-ward perpendicular, over the projected area inthis direction

150 kN/m2 parallel to the shaft axis and acting both inboardand outboard separately, over the multiple of ftimes the projected area in this direction,

where f is defined as: f = 1+ B/H, but not greater than 2.5

where:B = width of windlass measured parallel to the shaft axisH = overall height of windlass.405 Forces in the bolts, chocks and stoppers securing thewindlass to the deck shall be calculated. The windlass is sup-

ported by N bolt groups, each containing one or more bolts, seeFig.3.406 The axial force Ri in bolt group (or bolt) i, positive intension, may be calculated from:

Rxi = Px hxi Ai / IxRyi = Py hyiAi / Iy

andRi = Rxi + Ryi - Rsi

where:

Px = force (kN) acting normal to the shaft axis Py = force (kN) acting parallel to the shaft axis, either in-

board or outboard whichever gives the greater forcein bolt group i

h = shaft height above the windlass mounting (cm) xi , yi = x and y coordinates of bolt group i from the centroid

of all N bolt groups, positive in the direction oppo-site to that of the applied force (cm)

Ai = cross sectional area of all bolts in group i (cm2) Ix = ΣAi xi

2 for N bolt groups Iy = ΣAi yi

2 for N bolt groups Rsi = static reaction at bolt group i, due to weight of wind-

lass.407 Shear forces Fxi , Fyi applied to the bolt group i, and theresultant combined force Fi may be calculated from:

Fxi = (Px – α g M) / NFyi = (Py – α g M) / N

andFi = (Fxi

2 + Fyi2)0.5

where:

α = coefficient of friction (0.5) M = mass of windlass (tonnes) g = gravity (9.81 m/sec2) N = number of bolt groups.408 Axial tensile and compressive forces in 406 and lateralforces in 407 shall also be considered in the design of the sup-porting structure.409 Tensile axial stresses in the individual bolts in each boltgroup i shall be calculated. The horizontal forces Fxi and Fyishall normally be reacted by shear chocks. Where "fitted" boltsare designed to support these shear forces in one or both direc-tions, the von Mises' equivalent stresses in the individual boltsshall be calculated, and compared to the stress under proofload. Where pourable resins are incorporated in the holdingdown arrangements, due account shall be taken in the calcula-tions. The safety factor against bolt proof strength shall be not lessthan 2.0.(IACS UR S27)

DET NORSKE VERITAS


Fig. 3Direction of forces and weight

B 500 Materials501 Material of the foundation above the deck plating shallcomply with requirements given in Sec.4 Table B1. Deck dou-blers are generally not acceptable if tension perpendicular todeck occurs. When deck plating and/or foundation bedplate

are/is subjected to tension in the thickness direction, either Z-quality material (Pt.2 Ch.2 Sec.1 E) or a lamination test afterfinishing welding may be required. Full penetration weldsshall be considered.

DET NORSKE VERITAS


C. Shipboard Fittings and Supporting Hull Structures Associated with Towing and Mooring

on Conventional VesselsC 100 Towing101 These requirements apply to displacement-type vesselsof 500 GT and above, excluding high speed craft and specialpurpose vessels. The strength of shipboard fittings i.e. bollardand bitts, fairleads, stand rollers, chocks used for normal moor-ing and the similar components used for the towing and emer-gency towing of the vessel at bow, sides and stern and theirsupporting structures shall comply with the requirements givenbelow.102 The following plans shall be submitted:For approval:

— mooring fittings, towing devices (if provided) and respec-tive hull strengthening showing scantlings, material gradeand weld details.

For information:

— arrangement of mooring and towing fittings including di-mensions, information on the maximum breaking strengthof the tow and mooring lines and respective nominal SafeWorking Load (SWL).

103 Shipboard fittings for towing shall be located on longi-tudinals, beams and/or girders, which are part of the deck con-struction so as to facilitate efficient distribution of the towingload.104 The design load to be used is the greater of 1) and 2) asspecified below:

1) Twice the maximum breaking strength of the tow linespecified to be used throughout the service life of the ship.

2) Twice the breaking strength of the tow line according tovalues given in Sec.3 Table C1, for the ship's correspond-ing equipment number, under the heading of "guidance".

105 The selection of shipboard fittings shall be made in ac-cordance with a recognized industry standard (e.g. IS03913 -Shipbuilding Welded Steel Bollards). When the shipboard fit-ting is not selected from an accepted industry standard, the de-sign load to assess its strength and its attachment to the shipshall be in accordance with 104.106 Arrangement of the supporting structure members be-neath shall consider any variation of direction (laterally andvertically) of the towing forces (which shall be not less than thedesign load as per 104) acting through the arrangement of con-

nection to the towing fittings.The acting point of the towing force on deck fittings shall betaken at the attachment point of a towing line.

107 For a single post basis the following requirements applyto the (SWL):

1) The SWL shall not exceed one half of the design load giv-en in 104.

2) The SWL of each fitting shall be marked (by weld bead)on the deck fittings used for towing.

3) The SWL with its intended use (for normal and/or emer-gency conditions) for each fitting referred to in 2) above,shall be noted in the towing and mooring arrangement planor other information available on board for the guidance ofmaster.

4) The above requirements on SWL apply for a single postbasis (no more than one turn of one cable).

108 Arrangement of emergency towing when provided, or asrequired for tankers of 20 000 tonnes deadweight and above,including oil tankers, chemical tankers and gas carriers, shallalso comply with additional requirements in Pt.5 Ch.3 Sec.2C600.

C 200 Mooring201 Equipment that is used for both towing and mooringshall be in accordance with C100. However when equipment isonly used for mooring, C101 through C107 shall be appliedwith the understanding that "towing" shall read to mean"mooring" throughout.(IACS UR A2) (Feb. Corr.1 2004)

Guidance note:Load direction and height of load point should be evaluatedbased on arrangement drawings. For mooring equipment TableC1 below may be used as guideline.


Guidance note:(2005)IACS UR A2 is currently under review by IACS Hull Panel. Subsequent to the outcome of this review DNV shall use IMOMSC/Circ.1175 concerning rules for shipboard towing andmooring equipment.


Allowable bending stress: 210 f1 N/mm2

Allowable shear stress: 120 f1 N/mm2

DET NORSKE VERITAS


Table C1 Guidance on load direction and height of loadpoint for mooring equipment

© OCIMF (1997)

C 300 Materials301 Materials of deck fittings covered in this section, whennot specified in accordance with recognized standard, shall ful-fil requirements given in B501.

vertical: ± 15º

DET NORSKE VERITAS


SECTION 6 OPENINGS AND CLOSING APPLIANCES

A. GeneralA 100 Application101 In this section the requirements for the arrangement ofopenings and closing appliances have been collected. The clos-ing appliances are in general to have strength at least corre-sponding to the required strength of that part of the hull inwhich they are fitted.102 This section applies to all ships above 24 m in length,with the following exceptions:

— pleasure yachts not engaged in trade— fishing vessels, see Pt.5 Ch.6 Sec.6.

For ships less than 24 m in length this section applies as prac-ticable.

A 200 Definitions201 Symbols:

L = rule length in m 1)

B = rule breadth in m 1)

CB = rule block coefficient 1)

t = plate thickness in mm. 1)

Z = rule section modulus in cm3 of stiffeners and simplegirders

ka = correction factor for aspect ratio of plate field = (1.1 – 0.25 s/ l)2

= maximum 1.0 for s/ l = 0.4 = minimum 0.72 for s/ l = 1.0s = stiffener spacing in m, measured along the platingl = stiffener span in m, measured along the topflange of

the member. For definition of span point, see Ch.1Sec.3 C100. For curved stiffeners l may be taken as thecord length

S = girder span in m. For definition of span point, see Ch.1Sec.3 C100

f1 = material factor = 1.0 for NV-NS steel 2)

= 1.08 for NV-27 steel 2)




wk = section modulus correction factor in tanks, see Ch.1Sec.3 C1004.

σ = nominal allowable bending stress in N/mm2 due to lat-eral pressure

τ = nominal allowable shear stress in N/mm2 due to lateralloads

p = design pressure in kN/m2 as given for the variousstructures.

1) See Ch.1 Sec.1 B.2) For details see Ch.1 Sec.2 B and C.

202 TermsPositionFor the purpose of the Regulations, two positions of hatch-ways, doorways and ventilators are defined as follows:

Position 1 - Upon exposed freeboard and raised quarterdecks, and upon exposed superstructure deckssituated forward of a point located a quarter ofthe ship's length from the forward perpendicu-lar.

Position 2 - Upon exposed superstructure decks situated

abaft a quarter of the ship's length from the for-ward perpendicular.

(ICLL Reg.13)Freeboards greater than minimumWhere freeboards are required to be increased, because of suchconsideration as strength, location of shell or side scuttles orother reasons, then:

a) The height of doors sills, hatchway coamings, sills of ma-chinery space openings, miscellaneous openings, ventila-tors and air pipes

b) the scantlings of hatch coversc) freeing arrangements and means for protection of crewd) windows and side scuttles

on the actual freeboard deck may be as required for a super-structure deck, provided the summer freeboard is such that theresulting draught will not be greater than that corresponding tothe minimum freeboard calculated from an assumed freeboarddeck situated at a distance equal to a standard superstructureheight below the actual freeboard deck. Similar considerationsmay be given in cases of draught limitation on account of bowheight.Ship typesThe basic ship types are as follows:

Type "A" Ships designed solely for the carriage ofliquid cargo

Type "B" Cargo ship other than "A", with steelweathertight hatch covers

Type "B-100" "B-60"Cargo ship of type "B" with reducedfreeboard on account of their ability tosurvive damage

Type "B+" Cargo ship with increased freeboard onaccount of hatch cover arrangement

Weathertight means that in any sea condition water will notpenetrate into the vessel.Watertight means capable of preventing the passage of waterthrough the structure under a head of water for which the sur-rounding structure is designed.Ro-ro passenger ship is a passenger ship with ro-ro spaces orspecial category spaces.Ro-ro spaces are spaces not normally subdivided in any wayand normally extending to either a substantial length or the en-tire length of the ship in which motor vehicles with fuel in theirtanks for their own propulsion and/or goods (packaged or inbulk, in or on rail or road cars, vehicles (including road or railtankers), trailers, containers, pallets, demountable tanks or inor on similar stowage units or other receptacles) can be loadedand unloaded normally in a horizontal direction.Special category spaces are those enclosed spaces above or be-low the bulkhead deck, into and from which vehicles can bedriven and to which passengers have access. Special categoryspaces may be accommodated on more than one deck providedthat the total overall clear height for vehicles does not exceed10 m.Freeboard, freeboard deck and superstructure, see Ch.1 Sec.1B200.

A 300 Documentation for approval301 The following plans covering items treated in this sec-tion are normally to be submitted for approval:

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Arrangement and design of:

— small hatches and manholes— watertight hatches— watertight doors— weathertight doors— ventilators— side scuttles, windows— freeing ports— cargo hatchway with covers and securing appliances— horizontal stopper arrangement for hatch covers— doors in side shell, bow and stern with securing appliances— tank access, ullage and ventilation openings— scuppers and sanitary discharges— air pipes above deck with vent heads— engine room skylights and their closing appliances.

Each item should be easily identifiable in the drawing with re-spect to make, size, position and type (function). Several ofthese items are covered by the freeboard plan as required in302.302 Freeboard planA freeboard plan, covering the arrangement and design of thefollowing items treated in this section, shall be submitted forapproval:

— doors— side scuttles and windows— hatches— ventilators— air pipes— scuppers, sanitary discharges and garbage chutes— sea inlets and outlets in connection with unmanned ma-

chinery space— freeing arrangements— guard rails and bulwarks— gangway, passageway, under deck passage and life line— timber deck cargo fittings— doors in side shell, bow and stern.

303 Operating and maintenance manual An operating and maintenance manual for the side shell doors,bow doors and stern doors shall be submitted for approval forall ro-ro passenger ships and ro-ro cargo ships. This manualshall be approved with respect to the items given in Pt.5 Ch.2Sec.3 A301 c) being contained in the manual. In addition, theinclusion of the necessary information with regard to inspec-tions, trouble-shooting and acceptance/rejection criteria in themaintenance part shall be verified. The manual shall be provid-ed on board the ship.304 Documentation for the following indication, control andmonitoring systems shall be submitted for approval:

— watertight doors monitoring system— side and stern doors monitoring system— water leakage monitoring system.

For requirements to documentation types, see Pt.4 Ch.9.

A 400 Testing401 All weathertight/watertight doors and hatch covers shallbe function tested.402 For ships exclusively intended for the carriage of con-tainers in the cargo holds, for which an exemption to the ICLL,Reg.16 (see E and F) has been granted by the Flag Administra-tion, and which complies with the requirements given in Pt.5Ch.2 Sec.6 K, the required testing for weathertightness givenin Pt.2 Ch.3 Sec.8 may be dispensed with.403 If non weathertight hatch covers are fitted in accordancewith 402, this will be noted in the main letter of approval with

the implication that hose testing for weathertightness in ac-cordance with Pt.2 Ch.3 Sec.8 will not be carried out.

A 500 Certification of control and monitoring system501 The control and monitoring systems for :

— water tight doors — side and stern doors

shall be certified according to Pt.4 Ch.9

B. Access Openings in Superstructures and Freeboard Deck

B 100 Doors101

1) All access openings in bulkheads at ends of enclosed su-perstructures shall be fitted with doors of steel or otherequivalent material, permanently and strongly attached tothe bulkhead, and framed, stiffened and fitted so that thewhole structure is of equivalent strength to the unpiercedbulkhead and weathertight when closed. The means for se-curing these doors weathertight shall consist of gasketsand clamping devices or other equivalent means and shallbe permanently attached to the bulkhead or to the doorsthemselves, and the doors shall be so arranged that theycan be operated from both sides of the bulkhead.

2) Except as otherwise provided in these Regulations, theheight of the sills of access openings in bulkheads at endsof enclosed superstructures shall be at least 380 millime-tres above the deck.

(ICLL Reg.12)102

a) Doors should generally open outwards to provide addi-tional security against the impact of the sea. Doors whichopen inwards shall be especially approved.

b) Portable sills should be avoided. However, in order to fa-cilitate the loading/unloading of heavy spare parts or sim-ilar, portable sills may be fitted on the followingconditions:

i) They must be installed before the ship leaves port.ii) Sills shall be gasketed and fastened by closely spaced

through bolts.iii) Whenever the sills are replaced after removal, the

weathertightness of the sills and the related doorsmust be verified by hose testing. The dates of removal,replacing and hose testing shall be recorded in theship's log book.

(IACS LL5)103 Weathertight doors as specified above shall be fitted inall access openings in:

— bulkheads at ends of superstructures— bulkheads of deckhouses on freeboard deck protecting

openings in the freeboard deck— companionways on freeboard deck and superstructure

deck— bulkheads of deckhouses on superstructure deck protect-

ing openings in the superstructure deck— companionways and bulkheads of deckhouse upon anoth-

er deckhouse on freeboard deck protecting openings in thefreeboard deck.

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B 200 Sill heights201 Openings as mentioned in 100 are in general to have sillheights not less than 380 mm.The following openings in position 1 shall have sill heights notless than 600 mm:

— Companionways— where access is not provided from the deck above: Open-

ings in poop frontbulkhead, bulkheads at ends of midshipssuperstructures and bulkheads at ends and sides of deck-houses

— openings in forecastle end bulkhead covering entrance tospace below the deck

— openings in engine casings.

202 In ships which have their freeboard assignment basedupon a flooding calculation (type «A», «B-60» or «B-100»),the sill heights for the superstructure bulkhead openings mayrequire to be adjusted according to the calculated damage wa-terline. In such ships were engine casings are not protected byouter structures, two weathertight doors in series are required,the sill height of the inner door shall not be less than 230 mm.203 Openings which are used only when the ship is in har-bour (for handling of spare parts, etc.), may have a reduced sillheight.204 For vessels trading in domestic waters reduced sillheight may be accepted in accordance with Pt.1 Ch.1 Sec.2 B900.

B 300 Access openings in freeboard and superstructure decks301 Manholes and flush scuttles in position 1 or 2 or withinsuperstructures other than enclosed superstructures shall beclosed by substantial covers capable of being made watertight.Unless secured by closely spaced bolts, the covers shall be per-manently attached.302 Openings in freeboard decks other than hatchways, ma-chinery space openings, manholes and flush scuttles shall beprotected by an enclosed superstructure, or by a deckhouse orcompanionway of equivalent strength and weathertightness.Any such opening in an exposed superstructure deck or in thetop of a deckhouse on the freeboard deck which gives accessto a space below the freeboard deck or a space within an en-closed superstructure shall be protected by an efficient deck-house or companionway. Doorways in such deckhouses orcompanionways shall be fitted with doors complying with therequirements of 101.303 In position 1 the height above the deck of sills to thedoorways in companionways shall be at least 600 millimetres.In position 2 it shall be at least 380 millimetres.(ICLL Reg.18)304 Regarding the requirement to protect openings in super-structures (302) it is considered that openings in the top of adeckhouse on a raised quarterdeck having a height equal to orgreater than a standard height raised quarterdeck shall be pro-vided with an acceptable means of closing but need not be pro-tected by an efficient deckhouse or companionway as definedin the regulation provided the height of the deckhouse is atleast the height of a full superstructure. (IACS LL46)305 Only those doorways in deckhouses leading to or givingaccess to companionways leading below, need to be fitted withdoors in accordance with 101.Alternatively, if stairways within a deckhouse are enclosedwithin properly constructed companionways fitted with doorscomplying with 101, the external doors need not be weather-tight.

Where an opening in a superstructure deck or in the top of adeckhouse on the freeboard deck which gives access to a spacebelow the freeboard deck or to a space within an enclosed su-perstructure is protected by a deckhouse, then it is consideredthat only those side scuttles fitted in spaces which give directaccess to an open stairway need be fitted with deadlights in ac-cordance with L100. A cabin is considered to provide adequateprotection against the minimal amount of water which will en-ter through a broken side scuttle glass fitted on the second tier.In the application of 301 and 302 it is understood that:

i) Where access is provided from the deck above as an alter-native to access from the freeboard then the height of sillsinto a bridge or poop should be 380 mm. The same consid-eration should apply to deckhouses on the freeboard deck.

ii) Where access is not provided from above the height of thesills to doorways in a poop bridge or deckhouse on thefreeboard deck should be 600 mm.

iii) Where the closing appliances of access openings in super-structures and deckhouses are not in accordance with 101,interior deck openings shall be considered exposed, i.e.situated in the open deck.

(IACS LL8)

B 400 Strength and securing of small hatches on the exposed fore deck401 For vessels with L > 80 m:Small hatches (< 2.5 m2) on the exposed deck over the forward0.25 L, where the height of the exposed deck in way of thehatch is less than 0.1L or 22 m above the summer load water-line, whichever is the lesser, shall comply with 403 to 414.(IACS UR S 26)402 Hatches designed for use of emergency escape shallcomply with these requirements, excepting 407 (i) (ii), 411 and414.403 For small rectangular steel hatch covers, the plate thick-ness, stiffener arrangement and scantlings shall be in accord-ance with Table B1, and Fig 1. Stiffeners, where fitted, shall bealigned with the metal-to-metal contact points, required in 409,see Fig.1. Primary stiffeners shall be continuous. All stiffenersshall be welded to the inner edge stiffener, see Fig.2.

404 The upper edge of the hatchway coamings shall be suit-ably reinforced by a horizontal section, normally not more than170 to 190 mm from the upper edge of the coamings.405 For small hatch covers of circular or similar shape, thecover plate thickness and reinforcement shall be according tothe requirements of E.406 For small hatch covers constructed of materials otherthan steel, the required scantlings shall provide equivalentstrength.407 Small hatches located on exposed fore deck shall be fit-ted with primary securing devices such that their hatch coverscan be secured in place and weather tight by means of a mech-anism employing any one of the following methods:

Table B1 Scantling for small steel hatch covers on the fore deckNominal size(mm x mm)

Cover plate thickness

(mm)

Primary stiffeners

Secondary stiffeners

Flatbar (mm x mm); number630 x 630 8 – –630 x 830 8 100 x 8; 1 –830 x 630 8 100 x 8; 1 –830 x 830 8 100 x 10; 1 –

1030 x 1030 8 120 x 12; 1 80 x 8; 21330 x 1330 8 150 x 12; 2 100 x 10; 2

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i) butterfly nuts tightening onto forks (clamps)ii) quick acting cleats, or iii) central locking device.

408 Dogs (twist tightening handles) with wedges are not ac-ceptable.409 The hatch cover shall be fitted with a gasket of elasticmaterial. This shall be designed to allow a metal to metal con-

tact at a designed compression and to prevent over compres-sion of the gasket by green sea forces that may cause thesecuring devices to be loosened or dislodged. The metal-to-metal contacts shall be arranged close to each securing devicein accordance with Fig.1, and of sufficient capacity to with-stand the bearing force.410 The primary securing method shall be designed andmanufactured such that the designed compression pressure isachieved by one person without the need of any tools.

Fig. 1Arrangement of stiffeners

411 For a primary securing method using butterfly nuts, theforks (clamps) shall be of robust design. They shall be de-signed to minimize the risk of butterfly nuts being dislodgedwhile in use; by means of curving the forks upward, a raisedsurface on the free end, or a similar method. The plate thick-ness of unstiffened steel forks shall not be less than 16 mm. Anexample arrangement is shown in Fig.2.412 For small hatch covers located on the exposed deck for-ward of the fore-most cargo hatch, the hinges shall be fittedsuch that the predominant direction of green sea will cause thecover to close, which means that the hinges are normally to belocated on the fore edge.

413 On small hatches located between the main hatches, forexample between Nos. 1 and 2, the hinges shall be placed onthe fore edge or outboard edge, whichever is practicable forprotection from green water in beam sea and bow quarteringconditions.414 Small hatches on the fore deck shall be fitted with an in-dependent secondary securing device e.g. by means of a slid-ing bolt, a hasp or a backing bar of slack fit, which is capableof keeping the hatch cover in place, even in the event that theprimary securing device became loosened or dislodged. It shallbe fitted on the side opposite to the hatch cover hinges.(IACS UR S26)

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Fig. 2Example of primary securing method

C. Side and Stern DoorsC 100 General.101 These requirements cover cargo and service doors in theship side (abaft the collision bulkhead) and stern area, belowthe freeboard deck and in enclosed superstructures. For re-quirements for bow doors, see Pt.5 Ch.2 Sec.3.102 The side and stern doors shall be fitted as to ensure tight-ness and structural integrity commensurate with their locationand the surrounding structure.The number of such openings shall be the minimum compati-ble with the design and proper working of the ship.103 Where the sill of any cargo or service door is above theuppermost loadline, special consideration shall be given to pre-venting the spread of any leakage water over the deck. A flat-bar welded to the deck and provision of scuppers would be anacceptable arrangement.104 Where the sill of any cargo or service door is below theuppermost load line, the arrangements will require to be spe-cially considered to ascertain that the safety of the ship is in noway impaired. It is considered that the fitting of a second doorof equivalent strength and watertightness is one acceptable ar-rangement. In that case leakage detection device should beprovided in the compartment between the two doors. Further,drainage of this compartment to the bilges controlled by aneasily accessible screw down valve, should be arranged. Theouter door should preferably open outwards. (IACS LL21)105 Doors should preferably open outwards.106 Terms:Cleats: Devices for pre-compression of packings and steel tosteel contact.Supports: Load carrying devices designed for transfer of act-ing forces from door structures to hull structures.Locking arrangement: Preventive measures ensuring thatcleats and supports as applicable always remain in positionwhen engaged.

C 200 Structural arrangement201 Door openings in the shell shall have well rounded cor-ners and adequate compensation shall be arranged with web

frames at sides and stringers or equivalent above and below.202 Doors shall be adequately stiffened, and means shall beprovided to prevent movement of the doors when closed. Ad-equate strength shall be provided in the connections of the lift-ing/manoeuvring arms and hinges to the doors structures andto the ship structure.203 A ≥ 12 m2 Doors with light opening area shall be suchthat the sea pressure is transferred directly to the hull coam-ings.204 For doors with light opening area A < 12 m2 securingbolts or similar devices may be accepted as carriers of sea pres-sure to the coamings, if an arrangement as required in 203 isnot feasible.205 If a door is divided into separate sections, each sectionshall have full strength independent of the other sections.206 Where doors also serve as vehicle ramps, the design ofthe hinges should take into account the ship angle of trim andheel, which may result in uneven loading on the hinges.

C 300 Design loads301 The design sea pressure is given by:

p = ( pdp – (4 + 0.2 ks) h0 ) 1)

minimum 6.25 + 0.025 L (kN/m2)

pdp, ks = as given in Ch.1 Sec.4 C201h0 = vertical distance in m from the load point to the wa-

terline at draught T.

1) For ships with service restrictions p may be reduced with the percentagesgiven in Ch.1 Sec.4 B202. CW should not be reduced.

302 The design force for securing bolts and other closing de-vices, supporting members and surrounding structure is givenby:

F1 = A pe 103 + FP (N)or

F2 = F0 + 10 W + FP (N)F1 is applicable for ports opening inwards.F2 is applicable for ports opening outwards.

pe = external design pressure p according to 301, minimum25 kN/m2.

FP = total packing force in NF0 = the greater of FC and 5000 A (N)FC = accidental force (N) due to loose cargo etc., to be uni-

formly distributed over the area A and not to be takenless than 300 000 N.For small doors such as bunker doors and pilot doors,the value of FC may be appropriately reduced. Howev-er, the value of FC may be taken as zero, provided anadditional structure such as an inner rampway is fitted,which is capable of protecting the door from accidentalforces due to loose cargo etc.

A = area of door opening (m2) to be determined on the ba-sis of the loaded area taking account of the direction ofthe pressure

W = mass of door (kg).

pe is normally to be calculated at the midpoint of A.Packing force shall be decided depending on type and hardnessof packing. For calculation purpose, however, the packing linepressure should not be taken less than 5 N/mm. The packingline pressure shall be specified.

C 400 Plating401 The thickness requirement corresponding to lateral pres-sure is given by:

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p = as given in 300.

The thickness is in no case to be less than the minimum shellplate thickness.402 Where doors also serve as vehicle ramps, the platingshall not be less than required for vehicle decks.

C 500 Stiffeners501 The section modulus requirement is given by:

assuming simply supported ends.

p = as given in 300

502 The stiffener web plate at the ends shall have a net sec-tional area not less than:

A = 0.08 l s p (cm2)

p = as given in 300.

503 Edge stiffeners of doors shall have a moment of inertianot less than:

I = 8 pl d4 (cm4)for cover edges connected to a rigid ship structure member oradjacent door coaming.

d = distance between closing devices in mpl = packing line pressure along edges in N/mm, see 302.

504 For edge stiffeners supporting main door stiffeners be-tween securing devices, the moment of inertia shall be in-creased corresponding to the extra force.505 Where doors also serve as vehicle ramps, the stiffenerscantlings shall not be less than required for vehicle decks.

C 600 Girders601 The section modulus requirement for simple girders as-suming simply supported ends is given by:

S = girder span in mb = loading breadth in mp = design pressure according to 300.

602 The web area requirement (after deduction of cut-outs)at the girder ends is given by:

S, b and p as in 601.603 For large doors with a grillage girder system, a directstress analysis as outlined in Ch.1 Sec.12 may be necessary.Design loads shall be as given in 300, and the allowable stress-es are as follows:

— bending or normal stress:

s = 120 f1 N/mm2

— Shear stress:

τ = 80 f1 N/mm2

— Equivalent stress:

The material factor f1 shall not be taken greater than 1.39 un-less a direct stress analysis with regard to relevant modes offailures (e.g. fatigue) is carried out.604 The webs of girders and stringers shall be adequatelystiffened, preferably in a direction perpendidular to the shellplating.605 The girder system shall be given sufficient stiffness toensure integrity of the boundary support of the door. Edgegirders should be adequately stiffened against rotation andshall have a moment of inertia not less than:

I = 8 pl d4 (cm4)

d = distance between closing devices in mpl = packing line pressure in N/mm, see 302.

For edge girders supporting main door girders between secur-ing devices, the moment of inertia shall be increased in relationto the additional force.

C 700 Closing arrangement, general701 Closing devices shall be simple to operate and easily ac-cessible. Where hinges are used as closing devices they shouldbe well integrated into the door structure.702 Packing material shall be of a comparatively soft type,and the supporting forces shall be carried by the steel structureonly. Other types of packing will be specially considered.703 Flat bars or similar fastening devices for packings shallhave scantlings and welds determined with ample considera-tions to wear and tear.704 Devices shall be arranged for the doors to be secured inopen position.705 Documented operating procedures for closing and se-curing of side shell, bow and stern doors shall be kept on boardand posted at the appropriate places.

C 800 Closing arrangement, strength801 Side and stern doors shall be fitted with adequate meansof closing and securing, commensurate with the strength of thesurrounding structure.802 The closing and/or supporting devices shall be fitted notmore than 2.5 metres apart and as close to corners as possible.The number of devices is generally to be the minimum practi-cal whilst taking into account the requirement for redundantprovision given in 806 and the available space for adequatesupport in the surrounding hull structure which may limit thesize of each device.803 Only supports having an effective stiffness in a given di-rection shall be included in a calculation of the load carryingcapacity of the devices. The total external or internal force, asgiven in 302, may normally be considered as equally distribut-ed between the devices. However, the distribution of the totalforces acting on the supports may, for doors with a complexclosing arrangement, be required calculated by a direct calcu-lation taking into account the flexibility of the door and sur-rounding hull structure and the position of the supports.Maximum design clearance for effective supports should nor-mally not exceed 3 mm. Design clearances shall be included inthe Operating and Maintenance Manual as given in Pt.5 Ch.2Sec.3 A301 c). Allowable normal, shear and equivalent stress-es in closing and supporting elements are as given in 603.

t1.58ka s p

f1----------------------------- (mm)=

Z 0.8 l2 s pf1

--------------------- (cm3)=

Z 1.05 S2 b pf1

--------------------------- (cm3)=

A 0.08 S b pf1

------------------------- (cm2)=

σe σ2 3τ2+ 150 f1 N mm2⁄= =

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804 The nominal tensile stress in way of threads of boltsshall not exceed 105 f1 N/mm2. The arrangement of securingand supporting devices shall be such that threaded bolts do notcarry support forces.805 For steel to steel bearings in closing and supporting de-vices, the nominal bearing pressure calculated by dividing thedesign force by the projected area shall not exceed 0.8σf,where σf is the yield stress of the bearing material. For otherbearing materials, the permissible bearing pressure shall be de-termined according to the manufacturer's specification.806 For side and stern doors effective supports includingsurrounding door and hull structural members are, in the caseof failure of any single support, to have sufficient capacity towithstand the total design forces. In this case the allowablestresses as given in 603 may be increased by 20%.807 All load transmitting elements in the design load path,from the door through securing and supporting devices into theship structure, including welded connections, shall be to thesame strength standard as required for the securing and sup-porting devices.

C 900 Closing arrangement, system for operation and indication/monitoring901 Cleats and support devices shall be equipped with me-chanical locking arrangement (self locking or separate ar-rangement) or to be of the gravity type.902 Where hydraulic operating systems are applied, cleatsand support devices shall remain locked in closed position incase of failure in the hydraulic system.903 Systems for opening and closing of the door, operation ofcleats and support devices and, where applicable, for locking ar-rangement shall be interlocked in such a way that they can onlyoperate in the proper sequence. Hydraulic operating systemsshall be isolated from other circuits and to be blocked whendoors and closing arrangement are in closed/locked position.904 Signboards giving instructions to the effect that thedoors shall be closed and all the closing devices locked beforeleaving quay side (or terminal), shall be placed at the operatingpanel (or for small doors at the door when no operating panel)and on the bridge, and shall be supplemented by warning indi-cator lights on the panel and on the bridge.905 Doors with clear opening area greater than 6 m2 shall beprovided with an arrangement for remote control, from a con-venient position above the freeboard deck, of:

— the closing and opening of the doors— associated cleats, support and locking devices.

For doors which are required to be equipped with a remotecontrol arrangement, the open/closed position of the door andevery closing device (cleats, support and locking device) shallbe indicated at the remote control station.The operating panel for remote controlled doors shall be inac-cessible to unauthorised persons.906 The requirements given in 907 to 911 apply to doors inthe boundary of special category spaces or ro-ro spaces,through which such spaces may be flooded.For cargo ships, where no part of the door is below the upper-most waterline and the area of the door opening is not greaterthan 6 m2, then the requirements in 907 to 911 need not be ap-plied.907 Separate indicator lights shall be provided on each oper-ating panel to indicate that the doors are closed and that theircleats, support and locking devices as applicable are properlypositioned.Indication panels shall be provided with a lamp test function.908 Separate indicator lights and audible alarms shall be pro-

vided on the navigation bridge to show and monitor that eachof the doors is properly positioned and that cleats, support andlocking devices as applicable are properly positioned.The indicator system shall show by visual indication if any ofthe doors are not fully closed and not fully locked, and by au-dible alarms if securing devices become open or locking devic-es become unsecured.The indication panel on the navigation bridge shall beequipped with a mode selection function "harbour/sea voy-age", so arranged that audible alarm is given on the navigationbridge if the vessel leaves quay side (or terminal) with any sideshell or stern door not closed or with any of the cleats, supportand locking devices, as applicable, not in the correct position.When a mechanical lock is placed inside the hydraulic cylinderoperating a cleat or support, indication of the open or closedposition of the cleat or support shall be made on the lock insidethe cylinder.909 The indicator and alarm system on the navigation bridgeshall be designed on the fail-to-safe principle in compliancewith the following:

1) The indication panel shall be provided with:

— a power failure alarm, provided for both power sources

— an earth failure alarm— a lamp test device— for each door, separate indications for door closed /

not closed, door locked / not locked.— a dimmer (however, it shall not be possible to turn off

the indicator lights completely).

2) The electrical circuits used for indicating door positionshall be normally closed when the door is completelyclosed and completely open. When more limit switchesare provided for each door they may be connected in se-ries.

3) The electrical circuit used for indicating securing arrange-ments position shall be normally closed when the securingarrangements are completely locked and completely un-locked. When more limit switches are provided for eachdoor they may be connected in series.

4) Separate circuits shall be arranged for indication of doorposition (closed / not closed) and for securing arrange-ments position (locked / not locked). Multicore cable ispermitted.

5) In case of dislocation of limit switches, this shall be indi-cated by not closed / not locked / securing arrangement notin place - as appropriate.

910 The power supply for indicator and alarm systems shallbe independent of the power supply for the operating and clos-ing arrangements and shall be provided with a backup powersupply from the emergency source of power or secure powersupply, e.g. UPS (Uninterrupted Power Supply) with a mini-mum capacity of 30 minutes.Sensors for the indicator system shall be protected from water,ice formation and mechanical damage.911 For passenger ships, a water leakage detection systemwith audible alarm and television surveillance shall be ar-ranged to provide an indication to the navigation bridge and tothe engine control room of any leakage through the doors.For cargo ships, a water leakage detection system with audiblealarm shall be arranged to provide an indication to the naviga-tion bridge.912 For ro-ro passenger ships, the special category spacesand ro-ro spaces shall be continuously patrolled or monitoredby effective means, such as television surveillance, so that anymovement of vehicles in adverse weather conditions and unau-

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thorised access by passengers thereto can be detected whilstthe ship is underway.

D. Hatchway CoamingsD 100 General101 Side coamings of hatchways shall extend to lower edgeof deck beams. Side coamings not forming part of continuousgirders, are below deck to extend two frame spaces beyond thehatch ends.102 Hatch end coamings not in line with ordinary deck trans-verses are below deck to extend at least three longitudinalframe spaces beyond the side coamings.103 Continuous hatchway coamings on strength deck shallbe made from steel of the same strength group as the deck plat-ing. The same apply to non-continuous coamings effectivelysupported by longitudinal strength member or being an effec-tive part of the deck girder system.104 If the junction of hatch coamings forms a sharp corner,well rounded brackets shall be fitted towards the deck both lon-gitudinally and transversely. The longitudinal brackets shall bewelded by full penetration welding.The hatch end beam shall be given a smooth transition to thedeck transverse.If the hatch end beam is replaced by a stool tank, this shall bein line with structures outside the hatch.105 The web plate of low hatch side coamings shall be stiff-ened over the entire height at each frame or with a stiffenerspacing of about 60 x web thickness. Tripping brackets shall befitted on every 2nd frame.106 Cut-outs in the top of hatch coamings are normally to beavoided. Unavoidable cut-outs shall be circular or elliptical inshape. Local reinforcements should be given a soft transitionin the longitudinal direction.Unavoidable cutouts in longitudinal coaming end bracketsshall be as small as possible and with edge reinforcement.

D 200 Coaming heights201 The minimum height of coamings for hatches withweathertight covers is normally not to be less than:600 mm in position 1450 mm in position 2202 Manholes and small scuttles with coaming height lessthan given in 201, and flush scuttles may be allowed when theyare closed by substantial watertight covers. Unless secured byclosely spaced bolts, the covers shall be permanently attached.203 Coamings with heights less than given in 201 may be ac-cepted after special consideration of arrangement and integrityof the vessel. When such acceptance is given, the stiffness ofdeck girders supporting the covers is given by the following re-quirement to moment of inertia:

p = design pressure for deck girder in kN/m2 as given inE200

b = breadth in m of load area for deck girderl = total length in m of hatch coaming between supportsn = number of cover elements along length l of coaming.

204 Coamings with increased height may be required onships of «type B-100» and «B-60» if found necessary by thefloatability calculation.

D 300 Scantlings301 Hatchway coamings to holds also intended to carry wa-ter ballast or oil in bulk, shall satisfy the requirements for tankbulkheads given in Ch.1 Sec.9.302 The scantlings of coamings acting as deck girders shallsatisfy the requirements in Ch.1 Sec.8.303 For hatches with area larger than 12.0 m2, the platethickness of hatchway coamings on weather deck shall not beless than 11 mm. For hatches with area less or equal to 12.0 m2,the plate thickness of the hatchway coamings on weather deckshall not be less than 9.0 mm.304 Hatchway coamings of conventional design shall bestiffened by a horizontal section of substantial strength nor-mally not more than 0.25 m from the upper edge of the coam-ing. Coaming brackets spaced not more than 3 m apart, shall befitted. The brackets shall not end on unstiffened plating. Thecoamings shall be satisfactorily stiffened against buckling.

Guidance note:In Position 2, the horizontal stiffening of the upper end of thecoaming can normally be omitted for hatches with area less than1.0 m2.


305 Stiffeners, brackets and coamings shall be able to with-stand the local forces set up by the clamping devices and/or thehandling facilities necessary for securing and moving the hatchcovers as well as vertical and horizontal mass forces from car-go stowed on the hatch covers, e.g. containers, see E200.306 The strength of the stiffeners shall also comply with therequirements given in Ch.1 Sec.7 C. Maximum stiffener spac-ing shall not exceed 750 mm.

E. Hatch CoversE 100 General101 The requirements below are valid for steel hatch coversin holds intended for dry cargo, liquid cargo and ballast.102 Steel hatch covers shall be fitted to hatch openings onweather decks so as to ensure tightness consistent with opera-tional conditions and type of cover and to give effective pro-tection to the cargo in all sea conditions.103 Requirements for small cargo tank hatch covers used foraccess and ventilation only, are given in I.104 Materials for steel hatch covers shall satisfy the require-ments given for hull material.Other material than steel may be used, provided the strengthand stiffness of covers are equivalent to the strength and stiff-ness of steel covers.For aluminium alloys, see Ch.1 Sec.2 C.105 Tank hatch covers of closed box type construction shallbe provided with effective means for ventilation and gasfreeing.106 Hatch covers shall be mechanically lockable in open po-sition.107 Upon completion of installation of hatch covers, a chalktest shall be carried out. For tightness testing, see A400.

Guidance note:It is recommended that ships with steel hatch covers are suppliedwith an operation and maintenance manual including: - opening and closing instructions- maintenance requirements for packing, securing devices and

operating items- cleaning instructions for the drainage system

I 7 p b l4

n2E-----------------105 (cm4)=

DET NORSKE VERITAS


- corrosion prevention instructions- list of spare parts.


E 200 Design loads201 All generally applicable lateral loads on hatch covers aregiven in Table E1, based upon the general loads given in Ch.1Sec.4.

a = 1.0 for weather decks forward of 0.15 L from FP, orforward of deckhouse front, whichever is the fore-most position

= 0.8 for weather decks elsewherepdp, ks = as given in Ch.1 Sec.4 C201h0 = vertical distance in m from the waterline at draught

T to the cover topav = vertical acceleration as given in Ch.1 Sec.4 B600q = deck cargo load in t/m2, as specified. Weather decks

above cargo holds in dry cargo ships are normally tobe designed for a minimum cargo load:

qmin = 1.0 for ships with L = 100 m = 1.3 for ships with L > 150 m when superstructure

deck = 1.75 for ships with L > 150 m when freeboard deck.

For ships with length between 100 and 150 m the q-value may be varied linearly.When it is specially stated that no deck cargo shallbe carried, the qmin may be discarded

ρc = dry cargo density in t/m3, if not otherwise specifiedto be taken as 0.7, see also Ch.1 Sec.4 C401

ρ = density of ballast, bunker or liquid cargo in t/m3,normally not to be less than 1.025 (i.e. ρ g0 ≈ 10)

HC = stowage height in m of dry cargo. Normally the'tweendeck height or height to top of cargo hatch-way to be used.

hs = vertical distance in m from the load point to top oftank, excluding smaller hatchways

hp = vertical distance in m from the load point to the topof air pipe

hb = vertical distance in metres from the load point to thedeepest equilibrium waterline in damaged conditionobtained from applicable damage stability calcula-tions. The deepest equilibrium waterline in dam-aged condition should be indicated on the drawingof the deck in question

∆ pdyn = as given in Ch.1 Sec.4 C300p0 = 25 in general = 15 in ballast holds in dry cargo vessels = pv when exceeding the general valuepv = pressure valve opening pressureH = height in m of tankb = the largest athwartship distance in m from the load

point to the tank corner at the top of tank/ hold mostdistant from the load point

bt = breadth in m of top of tank/holdl = the largest longitudinal distance in m from the load

point to the tank corner at top of tank most distantfrom the load point

lt = length in m of top of tankφ = roll angle in radians as given in Ch.1 Sec.4 B400θ = pitch angle in radians as given in Ch.1 Sec.4 B500.202 Horizontal loads from cargo stored on hatch covers aregiven by:

— Total transverse force:

PT = C at q lh bh (kN)

— Total longitudinal force:

Table E1 Design loadsHatch cover at Load type p (kN/m2)

Weather decks 1)Sea pressure

Deck cargop2 = (g0 + 0.5 av) q

Cargo 'tweendecks p3 = ρc (g0 + 0.5 av) HC

Deck as tank top in general

Ballast or liquid cargo

p4 = ρ g0 hp + ∆ pdynp5 = ρ g0 hs + p0

Deck as tank top in tanks with breadth > 0.4 B

Deck as tank top towards ends of tanks with length > 0.15 L

Deck as tank top in tanks with unrestricted filling and with free breadth bt < 0.56B 4)

Watertight decks submerged in damaged condition 6) Sea pressure p9 = 10 hb

1) On weather decks combination of the design pressures p1 and p2 may be required for deck cargo with design stowage height less than 2.3 m.2) For ships with service restrictions p1 may be reduced with the percentages given in Ch.1 Sec.4 B202. CW should not be reduced.3) Distribution across hatch: Maximum value at one side linearly reduced to pv at other side.4) For tanks with free breadth above 0.56 B the design pressure will be specially considered, see Ch.1 Sec.4 C305.5) Distribution across hatch: Maximum value constant for 0.25 bt from one side, reduced to pv elsewhere.6) The strength may be calculated with allowable stresses for plating, stiffeners and girders increased by 60 f1.

p1 a pdp 4 0.2ks+( )h0–( )2 ) minimum 5,0=

p6 ρg0 0.67 hs φb+( ) 0.12 H φ bt–[ ] pV3 )+=

p7 ρg0 0.67 hs θl+( ) 0.12 Hθ lt–[ ] pV+=

p8 ρ 3 B100---------–⎝ ⎠

⎛ ⎞ bt pV5 )+=

DET NORSKE VERITAS


PL = C al q lh bh (kN)

at = transverse acceleration as given in Ch.1 Sec.4 B700

al = longitudinal acceleration as given in Ch.1 Sec.4B 800

q = deck cargo load in t/m2, see Table E1lh = length of hatch in mbh = breadth of hatch in mq lh bh = total cargo mass (M) on hatch cover in tC = 0.5 when horizontal forces are combined with

vertical forcesC = 0.67 when horizontal forces are considered

alone.If the cargo is secured (lashed etc.) to the deck outside thehatch cover, the horizontal load on covers may be reduced.203 In addition to the distributed design loads specified in201, forces acting on hatch covers from heavy cargo units shallbe taken into account as given in Ch.1 Sec.4 C500.Deflections and loads due to movements and thermal effectsare also to be considered, see F 203.204 Hatch covers subjected to wheel loading shall satisfy thestrength requirements given in Pt.5 Ch.2 Sec.4 C.

E 300 Plating301 The thickness corresponding to lateral pressure is givenby:

p = p1– p9, whichever is relevant, as given in Table E1σ = 0.58 σf N/mm2 for hatchways in position 1 or 2 when

p = p1 or p2 = 0.67 σf N/mm2 in all other casesσf = minimum upper yield stress in N/mm2. NV-NS-steel

may be taken as having σf = 235 N/mm2.

σf shall not be taken greater than 70% of the ultimatetensile strength.

302 The thickness of top plating shall not be less than:t = 10 s (mm) , min. 6 mm.

303 The thickness of bottom plating of closed box construc-tion shall not be less than 6 mm.304 Top or bottom plating acting as compression flanges inhatch cover main stiffening members (girders) shall be effec-tively stiffened against buckling.In the middle half part of simply supported span the criticalbuckling stress is normally not to be less than:

— for hatchways in position 1 or 2:

— for hatchways in position 3:

η = stability factor (usage factor) = 0.77 for sea loads and wave induced internal liquid

loads = 0.87 for other loadsZR = Z according to 401 or 0.7 Z according to 402 (position

1 or 2), whichever gives the highest stress valueZA = actual section modulus in plate flange.

The critical buckling stress may be taken as:

or

σel =

k = 4 for plating with local stiffeners parallel to main stiff-ening members

=

for plating with local stiffeners perpendicular to mainstiffening members

c = 1.21 when local stiffeners are angles or T-sections = 1.10 when local stiffeners are bulb flats = 1.05 when local stiffeners are flat bars.

E 400 Stiffeners401 The section modulus is given by:

p = p1– p9, whichever is relevant, as given in Table E1m = 8 for stiffeners simply supported at both ends, or sim-

ply supported at one end and fixed at the other end = 12 for stiffeners fixed at both endsσ = 0.58 σf N/mm2 for hatchways in position 1 or 2 when

p = p1 or p2 = 0.67 σf N/mm2 in all other cases.

Stiffeners subject to point loads from heavy cargo units (see203) shall be specially considered.402 The section modulus for stiffeners of normal strengthsteel in position 1 or 2 is in no case to be less than:

m = as defined in 401

ql =

=

For other materials the requirement will be specially consid-ered. The allowable nominal tensile stress is normally given byσb /4.25, where σb is the ultimate tensile strength of the mate-rial.403 The moment of inertia of steel members in position 1 or2, supported at side or end coamings only, shall not be lessthan:

I = 22 l 3 s ql (cm4)

ql = as defined in 402.

For other materials the requirement will be specially consid-ered. The requirement corresponds to a maximum allowabledeflection of 0.0028 l.404 The requirements for section modulus and moment ofinertia given above are valid for strength members with a con-stant cross section over the entire span. Covers with graduallyreduced Z and I towards the ends of the span shall be designedso that the maximum bending stresses and deflections are notincreased.

t15 8ka s p,

σ------------------------------ tk (mm)+=

σc0.58σf

η-----------------

ZRZA------- N/mm2( )=

σc0 67σf,

η-----------------

ZRZA------- N/mm2( )=

σc σel when σelσf2-----≤=

σc σf 1σf

4σel-----------–⎝ ⎠

⎛ ⎞ when σelσf2----->=

185000 kt tk–1000s--------------⎝ ⎠

⎛ ⎞2

N/mm2( )

c 1 sl--⎝ ⎠

⎛ ⎞ 2+

2

Z1000 l2 s p wk

mσ---------------------------------- (cm3)=

Z 103m

--------- l2 s ql wk (cm3)=

0.76 0 75,76

------------ L+⎝ ⎠⎛ ⎞ , maximum 1,75 t/m2 in position 1

0.58 0 55,76

------------ L+⎝ ⎠⎛ ⎞ , maximum 1,30 t/m2 in position 2

DET NORSKE VERITAS


With a Z-reduction towards ends, the rule section modulus atmiddle of span shall be multiplied by a factor:

α =

β =

l 1, l 0, Z1, and Z0 are given in Fig.1.C1 shall not be taken less than 1.0.With an I-reduction towards ends, the rule moment of inertiashall be multiplied by a factor:

δ =

I1 and I0 are given in Fig.1.405 The net web area shall not be less than:

Fig. 3Hatch cover with variable cross-section

x = distance in m from the end of span to section consid-ered, and shall not be taken greater than 0.25 l

h = web height in m.

(IACS LL20)406 The cover edges shall be adequately stiffened to with-stand the forces imposed upon them during opening and clos-ing of the hatches. For stiffness of cover edges, see also 600.407 Stiffeners shall be connected to supporting girders orcover edges by an area not less than:

a = 5 + 0.07 (l 1 + l 2) s p + ak (cm2)l 1 and l 2 are stiffener spans in m on each side of support.

ak = corrosion addition in tanks corresponding to tk.

408 Weld attachment other than given in 407, shall be in ac-cordance with Ch.1 Sec.11.For covers above cargo- and ballast tanks, chain or staggeredfillet welds on the tank side are not acceptable.409 The web and flange thickness shall not be less than:

t = 5.0 + tk (mm) tk as defined in Ch.1 Sec.2 Table D1, but assuming that thehatch cover is a part of the hold, or tank, as appropriate.

E 500 Girders501 When calculating the actual Z for strength members sup-porting other stiffeners, the effective flange shall be deter-mined in accordance with Ch.1 Sec.3 C400. When the hatchcover is of closed box girder construction, the flange may betaken as 100 % effective.502 The section modulus and moment of inertia shall not beless than according to the requirement given in 400, when s isreplaced by b.

b = half the sum in m of stiffener span on either side of thegirder.

503 The net web area at ends shall not be less than:A = 0.07 l b p + 10 h tk (cm2)

b = as defined in 502h = as defined in 405.

At each intersection with supported members, A may be re-duced by the value 0.14 s b p towards the middle of the span, sbeing the distance in m between supported members. A shallnot be taken less than 50% of the value at ends.Web plates shall be effectively stiffened against buckling.504 Double continuous fillet welds are normally to be usedwithin areas with shear stress greater than 75 N/mm2, and notless than 150 mm from each end of the girder. The throat thick-ness of the weld attachment between web plates and flanges inthese areas is normally not to be less than 0.4 t, where t = webplate thickness.

E 600 Stiffness of cover edges601 To ensure sufficient packing pressure for the whole dis-tance between the securing devices, the moment of inertia ofthe side elements of the covers shall be at least:

I = 6 pl a4 (cm4)for cover edges connected to a rigid hatch coaming and

I = 12 pl a4 (cm4)between cover edges of equal stiffness.

pl = packing line pressure along edges in N/mm, minimum5 N/mm

a = spacing in m of bolts or other securing devices.

602 When determining the moment of inertia of tank coverside elements supporting primary cover stiffening elements be-tween securing devices, the internal pressure in the tank shallbe taken into consideration.

E 700 Structural analysis701 For hatch covers of special construction or arrangement(e.g. covers constructed as a grillage, covers supported alongmore than two opposite edges, covers supporting other covers)a separate strength calculation may be required, in which thearrangement of girders and supports is taken into account. Thisis specially valid for hatch covers in open bulk carriers andcombination carriers where deflections are important to tight-ness, see F203.702 Load conditions shall be established in accordance withthe loads given in 200. For calculations according to beam the-ory the following stresses will be accepted:

a) Bending stress:

σ = 0.58 σf N/mm2 for hatchways in position 1 or 2when p = p1 or p2

= 0.67 σf N/mm2 in all other cases

C1 1 3.2α β– 0 8,–7β 0 4,+

------------------------------------+=

l1l0----

Z1Z0------

C2 1 8α3 1 δ–0 2, 3 δ+-------------------------+=

I1I0----

A 0.14 0 5, xl---–⎝ ⎠

⎛ ⎞ l s p 10 h tk (cm2)+=

l0

Z0

l1

Z1

I1I0

DET NORSKE VERITAS


b) Shear stress:

τ = 0.33 σf N/mm2 for hatchways in position 1 or 2when p = p1 or p2

= 0.37 σf N/mm2 in all other cases.σf as defined in 301The sum of girder bending stress and local bending stress instiffeners being part of the girder shall not exceed 0.8 σf N/mm2

c) critical buckling stress:

η = 0.77 for sea loads and wave induced internal liquidloads (weather deck hatch covers)

= 0.87 for other loadsσa = actual calculated stress.

σc to be calculated as shown in 304.703 For hatchway in position 1 or 2 additional conditionscorresponding to pressure 9.81 ql kN/m2 shall be checked (ql as defined in 402). For these conditions the following bend-ing stress for normal strength steel will be accepted:

σ = 95 N/mm2.

For other materials a bending stress of σb / 4.25 will normallybe accepted, σb being the ultimate tensile strength of the mate-rial.Maximum deflection at the middle of hatch cover:

δ = 0.0028 ll = the smaller of hatch breadth and hatch length.

704 In way of holds/tanks for cargo oil and/or water ballast,the calculated scantlings for the hatch covers shall be increasedby a corrosion addition tk as specified in Ch.1 Sec.1.

F. Hatchway Tightness Arrangement and Clos-ing Devices

F 100 General101 The requirements below are valid for steel hatch coverson weather decks and above tanks, with ordinary packing ar-rangement between hatch cover and coaming, and packing ar-ranged for vertical packing pressure in joints between coverelements. Other packing arrangements will be specially con-sidered.102 Closing of hatches by portable hatch beams, covers andtarpaulins will be specially considered.103 Packing and drainage arrangements of hatch covers forcargoes which are not sensitive to moisture from small leakag-es may be specially considered.

F 200 Design and tightness requirements201 The weight of covers and any cargo stowed thereon, to-gether with inertial forces generated by ship motions, shall betransmitted to the ship structure through steel to steel contact.This may be achieved by continuous steel to steel contact ofthe cover skirt plate with the ships structure or by means of de-fined bearing pads. A proper alignment between coaming andcover is very important in this respect.202 The sealing shall be obtained by a continuous gasket ofrelatively soft, elastic material compressed to achieve the nec-essary weathertightness. Similar sealing shall be arranged be-tween cross-joint elements. Where fitted, compression flat bars

or angles shall be well rounded where in contact with the gas-ket and shall be made of a corrosion-resistant material.203 Special consideration shall be given to the gasket and se-curing arrangements in ships with large relative movementsbetween cover and ship structure or between cover elements.For such ships, relative deflections both in the vertical and thehorizontal planes should be calculated and submitted with thehatch cover plans. Also vertical deflections due to thermal ef-fects and internal pressure loads shall be considered.For ships with large deck openings as defined in Ch.1 Sec.5,the torsional deformation of the hatch opening shall be calcu-lated based on a torsional moment

Mt = M ST + MWT

M ST , M WT = as given in Pt.5 Ch.2 Sec.6.

The necessary compression of the gasket to obtain sufficientsealing shall be estimated on the basis of the vertical deflec-tions calculated, including building/installation tolerances,seen in relation to results from compression/ leakage tests per-formed.204 It is assumed that the gasket material and any gluing ma-terial used in gasket junctions or to fasten the gasket to the cov-er are of a quality suitable for all environmental conditionslikely to be experienced by the ship, and are compatible withthe cargoes carried. The material and form of gasket selectedshall be considered in conjunction with the type of cover, thesecuring arrangement and the expected relative movement be-tween cover and ship structure. The gasket shall be effectivelysecured to the cover.205 There shall be a metallic contact between hatch coverand hull (earthing connection). If necessary, this shall beachieved by a special connection.

Guidance note:

1) As practical limits for the hatch opening horizontal defor-mations in ships with hatch openings less than given in Ch.1Sec.5 A106 (calculated with rule design loads) are indicat-ed:- single amplitude diagonal deformation: ld/1000- bending deflection of coamings: lc/1000

l d = length of hatch opening diagonall c = length of side or end coaming.

2) Deflections due to temperature differences should bechecked, especially for closed (double-skin) hatch coverpontoons. The deflections should be calculated both for hotcargo (80°C) and cold air (–5°C) resulting in upward bend-ing of pontoon corners, and for hot air (60°C) and cold cargo(0°C) resulting in upward bending of middle of pontoon andpontoon edges. Securing devices shall be given sufficientstrength and pre-tension to reduce deflections to acceptablefigures.Designing the pontoons as open panels (one continuousplate flange only) will normally reduce the temperature de-flections effectively.Combination of loads and deflections should be based on aconsideration of the probability of simultaneous occurrence.

3) Laboratory compression tests should be performed on testpanels arranged for observing leakage for various combina-tions of internal liquid pressure and compression of gasket.By this a minimum compression/internal pressure curve forno leakage may be obtained. Necessary compression of gas-kets may thus be estimated by adding minimum compres-sion to maximum vertical deflections calculated.


F 300 Securing devices in general301 Panel hatch covers on weather decks above dry cargo

σcσaη----- (N/mm2)≥

DET NORSKE VERITAS


holds or on top of deep tanks are in general to be secured byappropriate devices (bolts, wedges or similar) suitably spacedalongside the coamings and between cover elements. Arrange-ment and spacing shall be determined with due attention to theeffectiveness for tightness, depending upon the type and thesize of the hatch cover, as well as the stiffness of the cover edg-es between the securing devices, see E600. Scantlings of secur-ing devices are given in 400 to 600.302 Securing means of other material than mild steel or othermeans than bolts shall be of strength equivalent to the require-ments given in 400 and 600, and so arranged that the correctpressure on the packing between the covers and the coamings,and adjacent covers as well, is obtained.Bolts with nuts, wedges and other parts for securing the covers,shall be of reliable construction and securely attached to thehatchway coamings, decks or covers.The individual securing elements shall have approximately thesame deflection characteristics.Bolts and adjusting screws shall be secured in position by ap-propriate means.Where rod cleats are fitted, resilient washers or cushions shallbe incorporated.Where hydraulic cleating is applied, the system shall remainmechanically locked in closed position in the event of failureof the hydraulic system.303 Spare securing elements shall be kept on board, thenumber depending on the total number fitted, as well as type ofelement, special material used, etc.

F 400 Securing arrangement for weathertight hatch covers401 Ordinary packed hatch covers shall be secured to thecoaming by a net bolt area for each bolt not less than:

a = spacing of bolts in m

f1e =

σf = minimum upper yield stress in N/mm2, not to be takengreater than 70% of the ultimate tensile strength

e = 0.75 for σf > 235 = 1.0 for σf < 235.

402 Between cover and coaming and at cross-joints, a pack-ing line pressure sufficient to obtain weathertightness shall bemaintained by a bolt area as given in 401.403 For packing line pressures exceeding 5 N/mm, the areashall be increased accordingly. The packing line pressure shallbe specified.404 The net bolt diameter shall not be less than 19 mm forhatchways exceeding 5 m2 in area.405 Closing appliances of covers to hatches on exposeddecks (position 1 and 2) where reduced coaming heights areaccepted (see D 200) will be specially considered.In this case each cover element shall be equipped with at least2 securing devices along each side, and the maximum distanceshall not exceed amax = 2.5 metres.

F 500 Securing arrangement for deep tank or cargo oil tank hatch covers501 In addition to the requirements given in 400, deep tankor cargo oil tank hatch covers have to fulfil the following re-quirements.The net securing bolt area for each bolt shall not be less than:

a = spacing of bolts in ml = span in m of hatch cover girder or stiffener perpendic-

ular to coaming, if any — or distance from cover edgeto the first parallel stiffener

p = p4 – p9, whichever is relevant, as given in Table E1pl = packing line pressure in N/mm. For calculation pur-

pose, however, the packing pressure shall not be takenless than 5 N/mm

f1e = as given in 401.

502 Between cover elements the packing line pressure shallbe maintained by a net bolt area for each bolt not less than:

a = spacing of bolts in m.

Corrections to be applied as given in 403 and 404.503 Covers particularly calculated, as mentioned in E700,shall be fitted with closing devices corresponding to the reac-tion forces found by the calculation. The maximum tension inway of threads of bolts shall not exceed 125 f1e N/mm2. Themaximum stresses in closing devices of other types than boltsare:

— normal stress:

σ = 120 f1e N/mm2

— shear stress:

τ = 80 f1e N/mm2

— equivalent stress:

Guidance note:In order to satisfy the tightness requirements the following de-sign recommendations are given:

1) The horizontal distance between the gaskets and the secur-ing devices should be as small as possible.

2) Securing devices should be arranged as close to the panelcorners as possible.

3) Securing devices with a vertical clearance (passive cleating)should be avoided, i.e. active cleating with a certain pre- ten-sion should be used.


F 600 Securing arrangement for hatch covers carrying deck cargo601 In addition to the requirements given in 400 or 500, allhatch covers, especially those carrying deck cargo shall be ef-fectively secured against horizontal shifting due to the hori-zontal forces given in E202, which may be reduced by 10%due to friction.The maximum allowable stresses in stoppers are as given in503.602 To prevent damage to hatch covers and ship structure,the location of stoppers shall be compatible with the relativemovements between hatch covers and ship structure. Thenumber of stoppers shall be as small as possible, preferablyonly one stopper at each end of each cover element.

A 1.4af1e

----------- (cm2 )=

σf235---------⎝ ⎠

⎛ ⎞e

A 0.08af1e

-------------- 0.5lp pl+( ) (cm2 )=

A 3af1e------- (cm2 )=

σe σ2 3τ2+ 150 f1e N/mm2= =

DET NORSKE VERITAS


In case of twin hatches supported by a narrow box girder atcentre-line, two-way stopper at outboard coaming may be re-quired.603 Towards the ends of the ship vertical acceleration forcesmay exceed the gravity force. The resulting lifting forces mustbe considered when dimensioning the securing devices. Alsolifting forces from cargo secured on the hatch cover duringrolling shall be taken into account. The allowable stresses inbolts and other types of securing devices are as given in 503.604 Hatch coamings and supporting structure shall be ade-quately stiffened to accommodate the loading from hatch cov-ers.605 At cross-joints of multi-panel covers vertical guides(male/female) shall be fitted to prevent excessive relative ver-tical deflections between loaded/unloaded panels.

F 700 Drainage arrangement701 On weather deck hatch covers drainage shall be ar-ranged inside the line of gasket by means of a gutter bar or ver-tical extension of the hatch side and end coaming.702 Drain openings shall be arranged at the ends of drainchannels and shall be provided with effective means for pre-venting ingress of water from outside, such as non-returnvalves or equivalent.703 Cross-joints of multi-panel covers shall be arranged withdrainage of water from the space above the gasket and a drain-age channel below the gasket.704 If a continuous outer steel contact between cover andship structure is arranged, drainage from the space between thesteel contact and the gasket is also to be provided for.

G. Internal Doors and Hatches for Watertight Integrity

G 100 General101 General requirements for internal openings in connec-tion with watertight integrity are given in Ch.1 Sec.3 A600.For pipe tunnel openings, see also Ch.1 Sec.6 A407.102 Watertight doors or hatches may be of the followingtypes:

— hinged doors or hatches, dividing cargo spaces, shall be ofan approved type with mechanical securing devices andmay be fitted 'tween decks in approved positions. Suchdoors shall not be used where remote control is required.Hinged doors for passage shall be of quick acting or singleacting type. Tighteners shall be mounted also on thehinged side. Indication open/closed shall be fitted on thebridge.See Table G1.

— rolling doors, guided and supported by steel rollers, andwith mechanical or hydraulic securing devices

— sliding doors, moving along and supported by track-waygrooves and with mechanical locking due to taper and fric-tion. A positive force shall be required to re-open thedoors. These types of door may be only hand operated orboth power and hand operated. Sliding doors shall have anindication (i.e., a red light) placed locally on both sidesshowing that the door is in the remote control mode.(IACS UI SC156). Signboards and instructions shall beplaced in way of the door advising how to act when thedoor is in the “door closed” mode. In passenger areas andareas of high ambient noise , audible alarms shall be sup-plemented by visual signals on both sides of the door.

Table G1 Internal doors in watertight bulkheads in cargo ships and passenger shipsPosition relative to equilibrium or intermediate waterplane

1. Frequency of use whilst at sea

2. Type

3. Remote control 6

4. Indication locally and on bridge 6

5. Audible alarm 6

6. Notice

7. Comments

8. Regulation

I. Passenger ships

A. At or below Norm. closed POS Yes Yes Yes No

Certain doors may be left open, see SOLAS II-1/15.9.3

SOLAS II-1/ 15.9.1,2 & 3

Perm. closed S, H No No No Yes see Notes 1 + 4 SOLAS II-1/ 15.10.1 & 2

B. Above

Norm. open POS, POH Yes Yes Yes No SOLAS II-1/ 15.9.3

SOLAS II-1/20.1 MSC/Circ.541

Norm. closed S, H No Yes No Yes see Note 2

S, H No Yes No Yes Doors giving access to Ro-Ro Deck SOLAS II-1/20-2

I. Cargo ships

A. At or below

Used POS Yes Yes Yes No SOLAS II-1/ 25-9.2 Norm. closed S, H No Yes No Yes see Notes 2 + 3 + 5 SOLAS II-1/ 25-9.3

Perm. closed S, H No No No Yes see Notes 1 + 4 SOLAS II-1/ 25-9.4 SOLAS II-1/ 25-10

B. Above Used POS Yes Yes Yes No SOLAS II-1/ 25-9.2

Norm. closed S, H No Yes No Yes See Notes 2 + 5 SOLAS II-1/ 25-9.3SOLAS II-1/ 25-10

Notes:

1) Doors in watertight bulkheads subdividing cargo spaces. 2) If hinged, this door shall be of quick acting or single action type.3) "ICLL66+A.320" or "1988 Protocol to ICLL66", SOLAS, MARPOL, IGC and IBC- Codes require remotely operated watertight doors

to be sliding doors. 4) The time of opening such doors in port and closing them before the ship leaves port shall be entered in the logbook. 5) The use of such doors shall be authorised by the officer of the watch. 6) Cables for control and power systems to power operated watertight doors and their status indication should comply with the requirements

of UR E15.

DET NORSKE VERITAS


G 200 Operation201 All watertight doors and access hatches shall be opera-ble from both sides of the bulkhead or deck.202 Remotely controlled doors are also to be locally opera-ble. Indicators shall be provided at the control position to indi-cate whether the doors are open or closed.

G 300 Strength301 Watertight doors and hatches shall be designed with astrength equivalent to that of the structure in which they are po-sitioned. They shall withstand the design pressure from bothsides.302 The thickness corresponding to lateral pressure is givenby:

p = design pressure p, as given in Ch.1 Sec.9, Table B1c = 1.58 for collision bulkhead = 1.35 for all other bulkheads and decks.

The thickness is in no case to be less than the minimum bulk-head thickness.303 The stiffener section modulus requirement is given by:

p = as given in 302c1 = 0.8 for collision bulkhead = 0.6 for all other bulkheads and decks.

304 Edge stiffeners of doors shall have a moment of inertianot less than:

I = 8 pe d4 (cm4)

d = distance between closing devices in m, to be measuredalong door edge

pe = packing line pressure along edges, not to be taken lessthan 5 N/mm

= pb, whichever is the greaterp = design pressure p1 as given in Ch.1 Sec.9, Table B1b = load breadth, normally taken as h/3 or w/2, whichever

is the less.

h and w are height and width of door in m.305 The coaming of watertight doors (door frame) shall bedesigned with the necessary stiffness in order to avoid large de-flections resulting in leakage in the damaged condition. Thedoor frames shall have no groove at the bottom in which dirtmight lodge and prevent the door from closing properly.306 Securing devices shall be designed for the load actingalso on the opposite side of where they are positioned. Allow-able stresses in securing devices are as follows:

normal stress: σ = 165 f1 N/mm2

shear stress: τ = 110 f1 N/mm2

equivalent stress:

H. VentilatorsH 100 Coamings and closing arrangements101

1) Ventilators in position 1 or 2 to spaces below freeboarddeck or decks of enclosed superstructures shall havecoamings of steel or other equivalent material, substantial-ly constructed and efficiently connected to the deck.Where the coamings of any ventilators exceed 900 milli-metres in height it shall be specially supported.

2) Ventilators passing through superstructures other than en-closed superstructures shall have substantially constructedcoamings of steel or other equivalent material at the free-board deck.

3) Ventilators in position 1 the coamings of which extend tomore than 4.5 metres above the deck, and in position 2 thecoamings of which extend to more than 2.3 metres abovethe deck, need not be fitted with closing arrangements un-less specifically required by the Society.

4) Except as provided in (3) ventilator openings shall be pro-vided with efficient weathertight closing appliances. Inships of not more than 100 metres in length the closing ap-pliances shall be permanently attached; where not so pro-vided in other ships, they shall be conveniently stowednear the ventilators to which they shall be fitted. Ventila-tors in position 1 shall have coamings of a height of at least900 millimetres above the deck; in position 2 the coamingsshall be of a height of at least 760 millimetres above thedeck.

5) In exposed positions, the height of coamings may be re-quired to be increased to the satisfaction of the Society.

(ICLL Reg.19)102 Reduced coaming height may be accepted for vesselstrading in domestic waters only, in accordance with Pt.1 Ch.1Sec.2 B 900.

H 200 Thickness of coamings201 The thickness of ventilator coamings shall not be lessthan given in the following table:

For intermediate external diameter the wall thickness is ob-tained by linear interpolation.(IACS LL36)

H 300 Arrangement and support301 Where required by 101, weathertight closing appliancesfor all ventilators in positions 1 and 2 shall be of steel or otherequivalent materials.Wood plugs and canvas covers are not acceptable in these po-sitions. (IACS LL52)302 The deck plating in way of deck openings for ventilatorcoamings shall be of sufficient thickness, and efficiently stiff-ened between ordinary beams or longitudinals. Coamings withheights exceeding 900 mm shall be additionally supported.303 Where ventilators are proposed to be led overboard in anenclosed superstructure deck house or shipside the closing ar-rangement shall be submitted for approval. If such ventilatorsare lead overboard more than 4.5 m above the freeboard deck,closing appliances may be omitted, provided that satisfactorybaffles and drainage arrangements are provided.

tckas p

f1------------------ tk (mm)+=

Zc1 l2 s p wk

f1--------------------------- (cm3 )=

σe σ2 3τ2+ 200f1e N/mm2= =

External diameter in mm

Wall thickness in mm

≤ 80 6.0≥165 8.5

DET NORSKE VERITAS


304 To ensure satisfactory operation in all weather condi-tions, machinery spaces and emergency generator room venti-lation inlets and outlets shall be located in such positions thatclosing appliances will not be necessary.Alternatively, depending on vessel's size and arrangement,lesser coaming heights may be accepted if weathertight closingappliances are provided, in accordance with 101 and in combi-nation with suitable means arranged to ensure uninterruptedand adequate supply of air to these spaces.

Guidance note:The term suitable means is meant e.g. that direct and sufficientsupply of air is provided through open skylights, hatches or doorsat a higher level than the heights required by 101.


H 400 Strength requirements for fore deck ventilators401 For vessels with L > 80 m: The ventilators located on the exposed deck over the forward0.25 L, where the height of the exposed deck in way of the itemis less than 0.1 L or 22 m above the summer load waterline,whichever is the lesser, shall comply with the requirementsgiven in 402 to 408.(IACS UR S 27)402 The pressures p, in kN/m2 acting on ventilator pipes andtheir closing devices to be calculated from:

p = 0.5 ρ V2 Cd Cs Cp

where:

ρ = density of sea water (1.025 t/m3) V = velocity of water over the fore deck (13.5 m/sec) Cd = shape coefficient:

0.5 for pipes, 1.3 for ventilator heads in general, 0.8 for an air pipe or ventilator head of cylindrical formwith its axis in the vertical direction

Cs = slamming coefficient (3.2) Cp = protection coefficient:

0.7 for pipes and ventilator heads located immediatelybehind a breakwater or forecastle,1.0 elsewhere and immediately behind a bulwark.

403 Forces acting in the horizontal direction on the pipe andits closing device may be calculated from 402 using the largestprojected area of each component.404 Bending moments and stresses in ventilator pipes shallbe calculated at critical positions: at penetration pieces, at weldor flange connections, at toes of supporting brackets. Bendingstresses in the net section shall not exceed 0.8 σy , where σy isthe specified minimum yield stress or 0.2% proof stress of thesteel at room temperature. Irrespective of corrosion protection,a corrosion addition to the net section of 2.0 mm is then to beapplied.405 For standard ventilators of 900 mm height closed byheads of not more than the tabulated projected area, pipe thick-nesses and bracket heights are specified in Table H1. Wherebrackets are required, three or more radial brackets shall be fit-ted. Brackets shall be of gross thickness 8 mm or more, of min-imum length 100 mm, and height according to Table H1, butneed not extend over the joint flange for the head. Bracketstoes at the deck shall be suitably supported.406 For ventilators of height greater than 900 mm, bracketsor alternative means of support shall be fitted according to therequirements in 302. Pipe thickness shall not be taken less thanas required in 201.407 All component parts and connections of the ventilatorshall be capable of withstanding the loads defined in 402.

408 Rotating type mushroom ventilator heads are unsuitablefor application in the areas defined in 401.(IACS UR S27)

I. Tank Access, Ullage and Ventilation OpeningsI 100 General101 The number of hatchways and other openings in thetank deck shall not be larger than necessary for reasonable ac-cess to and ventilation of each compartment.102 Hatchways, openings for ventilation, ullage plugs orsighting ports, etc. shall not be placed in enclosed compart-ments where there is a danger of accumulation of gases.Ullage plugs or sighting ports should be fitted as high abovethe deck as practicable, for instance in the cover of accesshatches.Access hatches to holds or other openings, for example fortank cleaning devices, shall be of substantial construction, andmay be arranged in the main hatch covers.

I 200 Hatchways201 The thickness of the hatch coaming shall not be less thangiven in Ch.1 Sec.10 for a deckhouse in the same position.202 The thickness of covers shall not be less than:

— 12.5 mm for cover area exceeding 0.5 m2

— 10.0 mm for cover area less than 0.25 m2.

For intermediate areas the thickness may be linearly varied.203 Where the area of the hatchway exceeds 1.25 m2, thecovers shall be stiffened.204 Covers shall be secured to the hatch coamings by fasten-ings spaced not more than 380 mm apart and not more than 250mm from the corners. For circular covers the fastenings shallnot be spaced more than 450 mm apart.205 Other types of covers may be approved, provided theirconstruction is considered satisfactory.

I 300 Air Pipes301 Where air pipes to ballast and other tanks extend abovethe freeboard or superstructure decks, the exposed parts of thepipes shall be of substantial construction; the height from thedeck to the point where water may have access below shall beat least 760 millimetres on the freeboard deck and 450 milli-metres on the superstructure deck. Where these heights may

Table H1 900 mm ventilator pipe thickness and bracket standards

Nominal pipe diameter

(mm)

Minimum fittet gross

thickness, LL36(c)

(mm)

Maximum projected

area of head (cm2)

Height of brackets

(mm)

80A 6.3 – 460100A 7.0 – 380150A 8.5 – 300200A 8.5 550 –250A 8.5 880 –300A 8.5 1200 –350A 8.5 2000 –400A 8.5 2700 –450A 8.5 3300 –500A 8.5 4000 –

Note: For other ventilator heights, the relevant requirements of 401 to 407 shall be applied.

DET NORSKE VERITAS


interfere with the working of the ship, a lower height may beapproved, provided the Society is satisfied that the closing ar-rangements and other circumstances justify a lower height.Satisfactory means permanently attached, shall be provided forclosing the openings of the air pipes.(ICLL Reg.20)302 For ships assigned timber freeboards the air pipes shouldbe provided with automatic closing appliances. (IACS LL10)303 Where required by 301 air pipe closing devices shall beweathertight. Closing devices shall be automatic if, while thevessel is at its draught corresponding to summer load line, theopenings of air pipes to which these closures are fitted sub-merge at angles up to 40° or up to a lesser angle which may beagreed on the basis of stability requirements. Pressure- vacuumvalves (PV valves) may, however, be accepted on tankers.Wooden plugs and trailing canvas hoses shall not be acceptedin position 1 and position 2.

Guidance note:The member Societies in formulating this interpretation realisethat pressure-vacuum valves (PV valves) presently installed ontankers do not theoretically provide complete watertightness. Inview, however, of experience of this type of valve and the posi-tion in which they are normally fitted it was considered theycould be accepted.


(IACS LL49)304 The thickness of air pipe coamings shall not be less thangiven in the following table:

For intermediate external diameter the wall thickness is ob-tained by linear interpolation. Coamings with heights exceed-ing 900 mm shall be additionally supported. (IACS LL36)305 Openings of air pipes shall be provided with permanent-ly attached efficient means of closing. The closing appliancesshall be so constructed that damage to the tanks by overpump-ing or occasionally possible vacuum by discharging is prevent-ed.306 In cases where air pipes are led through the side of su-perstructures, the height of their openings to be at least 2.3 me-tres above the summer water line. Automatic vent heads ofapproved design shall be provided.307 The height of air pipes may be required to be increasedon ships of type "A", type "B-100" and type "B-60" where thisis shown to be necessary by the floatability calculation.308 In a ship to which timber freeboard is assigned, air pipeswhich will be inaccessible when the deck cargo is carried shallbe provided with automatic closing appliances.309 All air pipes in cargo spaces shall be well protected.310 For arrangement and size of air pipes, see also Pt.4 Ch.6Sec.4 K.

I 400 Strength requirements for fore deck air pipes401 For vessels with L > 80 m: The air pipes located on the exposed deck over the forward0.25 L, where the height of the exposed deck in way of the itemis less than 0.1 L or 22 m above the summer load waterline,whichever is the lesser, shall comply with the requirementsgiven in 402 to 407.For tankers:The requirements given in 402 to 407 are not applicable forcargo tank venting systems and the inert gas systems.(IACS UR S 27)402 The pressures p, in kN/m2 acting on air pipes and theirclosing devices shall be calculated from:

p = 0.5 ρ V2 Cd Cs Cpwhere:

ρ = density of sea water (1.025 t/m3) V = velocity of water over the fore deck (13.5 m/sec) Cd = shape coefficient:

0.5 for pipes, 1.3 for ventilator heads in general, 0.8 for an air pipe or ventilator head of cylindrical formwith its axis in the vertical direction

Cs = slamming coefficient (3.2) Cp = protection coefficient:

0.7 for pipes and ventilator heads located immediatelybehind a breakwater or forecastle,1.0 elsewhere and immediately behind a bulwark.

403 Forces acting in the horizontal direction on the pipe andits closing device may be calculated from 402 using the largestprojected area of each component.404 Bending moments and stresses in air pipes shall be cal-culated at critical positions: at penetration pieces, at weld orflange connections, at toes of supporting brackets. Bendingstresses in the net section shall not exceed 0.8σy , where σy isthe specified minimum yield stress or 0.2% proof stress of thesteel at room temperature. Irrespective of corrosion protection,a corrosion addition to the net section of 2.0 mm is then to beapplied.405 For standard air pipes of 760 mm height closed by headsof not more than the tabulated projected area, pipe thicknessesand bracket heights are specified in Table I1. Where bracketsare required, three or more radial brackets shall be fitted.Brackets shall be of gross thickness 8 mm or more, of mini-mum length 100 mm, and height according to Table I1 butneed not extend over the joint flange for the head. Bracket toesat the deck shall be suitably supported.406 For other configurations, loads according to 402 shall beapplied, and means of support determined in order to complywith the requirements of 404. Brackets, where fitted, shall beof suitable thickness and length according to their height. Pipethickness shall not be taken less than as required in 304.407 All component parts and connections of the air pipe shallbe capable of withstanding the loads defined in 402.(IACS UR S27)

External diameter in mm

Wall thickness in mm

≤ 80 6.0≥ 165 8.5

DET NORSKE VERITAS


J. Machinery Space OpeningsJ 100 Openings101 Machinery space openings in position 1 or 2 shall beproperly framed and efficiently enclosed by steel casings ofample strength, and where the casings are not protected by oth-er structures their strength shall be specially considered. Ac-cess openings in such casings shall be fitted with doorscomplying with the requirements of B101, the sills of whichshall be at least 600 millimetres above the deck if in position 1,and at least 380 millimetres above the deck if in position 2.Other openings in such casings shall be fitted with equivalentcovers, permanently attached in their proper positions.102 Coamings of any machinery space ventilator in an ex-posed position shall be in accordance with H304(ICLL Reg. 17)103 Where casings are not protected by other structures,double doors should be required for ships assigned freeboardsless than those based on Table B in the ICLL. An inner sill of230 mm in conjunction with the outer sill of 600 mm is recom-mended.(IACS LL7)

104 Doorways in engine and boiler casings shall be arrangedin positions which afford the greatest possible protection.105 Skylights shall be of substantial construction and secure-ly connected to deck. If the upper part of the skylight consistsof hinged scuttles, effective means for closing and securingshall be provided.For skylights in position 1 or 2 the coaming height shall not beless than given for hatchway coamings. For skylights in posi-tion 1, deadlights shall be fitted.106 Side scuttles in engine casings shall be provided withfireproof glass.

K. Scuppers, Inlets and DischargesK 100 Inlets and discharges101 Discharges led through the shell either from spaces below thefreeboard deck or from within superstructures and deckhouseson the freeboard deck fitted with doors complying with the re-quirements of B101 shall be fitted with efficient and accessiblemeans for preventing water from passing inboard. Normallyeach separate discharge shall have one automatic non-returnvalve with a positive means of closing it from a position abovethe freeboard deck. Where, however, the vertical distance fromthe summer load waterline to the inboard end of the dischargepipe exceeds 0.01 L, the discharge may have two automaticnon-return valves without positive means of closing, providedthat the inboard valve is always accessible for examination un-der service conditions; where that vertical distance exceeds0.02 L a single automatic non return valve without positivemeans of closing may be accepted subject to the approval ofthe Society. The means for operating the positive action valveshall be readily accessible and provided with an indicatorshowing whether the valve is open or closed.All shell fittings, and the valves required by this Rule shall beof steel, bronze or other approved ductile material. Valves ofordinary cast iron or similar material are not acceptable. Allpipes to which this Rule refers shall be of steel or other equiv-alent material to the satisfaction of the Society, see Pt.4 Ch.6Sec.2.(ICLL Reg.22)102 It is considered that the position of the inboard end ofdischarges should be related to the timber summer load water-line when timber freeboard is assigned.(IACS LL22)

Table I1 760 mm air pipe thickness and bracket standards

Nominal pipe diameter

(mm)

Minimum fittet gross

thickness, LL36(c)

(mm)

Maximum projected

area of head (cm2)

Height 1) of brackets

(mm)

40A3) 6.0 – 52050A3) 6.0 – 52065A 6.0 – 48080A 6.3 – 460100A 7.0 – 380125A 7.8 – 300150A 8.5 – 300175A 8.5 – 300200A 8.5 2) 1900 300 2)

250A 8.5 2) 2500 300 2)

300A 8.5 2) 3200 300 2)

350A 8.5 2) 3800 300 2)

400A 8.5 2) 4500 300 2)

1) Brackets (see 405) need not extend over the joint flange for the head.2) Brackets are required where the as fitted (gross) thickness is less than

10.5 mm, or where the tabulated projected area is exceeded.3) For minimum permitted internal diameter, see Pt.4 Ch.6 Sec.4.

Note: For other air pipe heights, the relevant requirements of 401 to 407 shall be applied.

DET NORSKE VERITAS


103 It is considered that an acceptable equivalent to one au-tomatic non-return valve with a positive means of closing froma position above the freeboard deck would be one automaticnon-return valve and one sluice valve controlled from abovethe freeboard deck. Where two automatic non-return valves arerequired, the inboard valve must always be accessible underservice conditions, i.e., the inboard valve should be above thelevel of the tropical load water line. If this is not practicable,then, provided a locally controlled sluice valve is interposedbetween the two automatic non-return valves, the inboardvalve need not to be fitted above the SWL.Where sanitary discharges and scuppers lead overboardthrough the shell in way of machinery spaces, the fitting toshell of a locally operated positive closing valve, together witha non-return valve inboard, is considered to provide protectionequivalent to the requirements of 101.It is considered that the requirements of 101 for non-returnvalves are applicable only to those discharges which remain

open during the normal operation of a vessel. For dischargeswhich must necessarily be closed at sea, such as gravity drainsfrom topside ballast tanks, a single screw down valve operatedfrom the deck is considered to provide efficient protection.The inboard end of a gravity discharge which leads overboardfrom an enclosed superstructure or space shall be locatedabove the water line formed by a 5 degree heel, to port or star-board, at a draft corresponding to the assigned summer free-board.It is considered that the position of the inboard end of discharg-es shoul be related to the timber summer load waterline whentimber freeboard is assigned.See Table K1 for the acceptable arrangement of scuppers, in-lets, and discharges.104 Discharges with inboard opening located lower than theship's uppermost load line may be accepted when a loop of thepipe is arranged, extending not less than 0.01 L (minimum 0.5

Table K1 Acceptable arrangements of discharges with inboard endsDischarges coming from defined enclosed spaces (spaces below freeboard deck, in superstructures

and in deck houses defined by Reg.3 (10) with doors according to Reg.12 and defined by Reg.18 (2))

Discharges coming from open deck and from spaces not defined

General requirements (Reg.22 (1))

In engine rooms only

Alternatives where inboard end is:

(Reg.22 (1))

Outboard end > 450 mm below

FB DECK or < 600 mm above SWL (Reg.22 (3))

Otherwise Reg.22(4)

> 0.01 x L above SWL

> 0.02 x L above SWL

*) The control shall be so sited as to allow adequate time for operation in case of influx of water to the space having regard to the time which could be taken to reach and operate such controls

**) Substantial pipe thickness from the shell and up to the freeboard deck and in cases further up in closed superstructure to a height at least 600 mm above the summer water line

***) References: ICLL regulations

DET NORSKE VERITAS


m) above the summer load waterline. The top of the loop shallbe regarded as the position of the inboard opening, and thepipeline shall be provided with valves according to 101.105 Discharges from spaces above the freeboard deck shallbe of steel or material specially resistant to corrosion.106 Adequate protection shall be provided to protect valvesor pipes from being damaged by cargo, etc.107 Plastic pipes may be used for sanitary discharges andscuppers as permitted by Pt.4 Ch.6 Sec.2 A700.108 The portion of discharge line from the shell to the firstvalve as well as shell fittings and valves shall be of steel,bronze or other approved ductile material.109 In manned machinery spaces main and auxiliary sea in-lets and discharges in connection with the operation of machin-ery may be controlled locally. The controls shall be readilyaccessible and shall be provided with indicators showingwhether the valves are open or closed.110 Scuppers and discharge pipes originating at any leveland penetrating the shell either more than 450 millimetres be-low the freeboard deck or less than 600 millimetres above thesummer load waterline shall be provided with a non-returnvalve at the shell. This valve, unless required by 101, may beomitted if the piping is of substantial thickness.

K 200 Pipe thickness201 The wall thickness of steel piping between hull platingand closeable or non-return valve shall not be less than givenin Table K2.

For intermediate external diameter the wall thickness is ob-tained by linear interpolation.For wall thickness of distance piece for discharge coming froman inert gas scrubber, see Pt.5 Ch.3 Sec.11 D602.202 The wall thickness of steel piping inboard of the valveshall not be less than given in Table K3.

For intermediate external diameter the wall thickness is ob-tained by linear interpolation.(IACS LL36)

K 300 Scuppers301 A sufficient number of scuppers, arranged to provide ef-fective drainage, shall be fitted on all decks.302 Scuppers on weather portions of decks and scuppersleading from superstructures or deckhouses not fitted withdoors complying with B101 shall be led overboard.303 Scuppers led through the shell from enclosed superstruc-tures used for the carriage of cargo shall be permitted onlywhere the edge of the freeboard deck is not immersed when theship heels 5 degrees either way. In other cases the drainageshall be led inboard in accordance with the requirements of theInternational Convention for the Safety of Life at Sea in force.304 Scuppers led through the deck or shell, shall complywith requirements to material and thickness as given for dis-charges.

305 Scupper pipes shall be well stayed to prevent any vibra-tions. However, sufficient possibility for expansion of thepipes to be provided when necessary.306 Scuppers from spaces below the freeboard deck or spac-es within closed superstructures, may be led to bilges. Fordrainage of cargo deck spaces, see Pt.4 Ch.6 Sec.4 D.307 Scuppers leading overboard from spaces mentioned in306, shall comply with the requirements given for discharges.Scuppers from exposed superstructure deck, led through theship's sides and not having closeable valves, shall have wallthickness as required in 201 and 202.308 Gravity discharges from top wing tanks may be ar-ranged. The drop valves shall be of substantial constructionand of ductile material, and they shall be closeable from an al-ways accessible position. It shall be possible to blank- flangethe discharge or to lock the valves in closed position when thetanks are used for carrying cargo.The thickness of the pipe or box leading from the tank throughthe shell shall comply with the requirements given for dis-charges.309 Drainage from refrigerated cargo spaces shall complywith the requirements for class notation Reefer. Drain pipesfrom other compartments shall not be led to the bilges in refrig-erated chambers.310 Drainage from helicopter decks shall comply with therequirements for the class notation HELDK S.

K 400 Periodically unmanned machinery space401 The location of the controls of any valve serving a sea in-let, a discharge below the waterline or a bilge injection systemshall be so sited as to allow adequate time for operation in caseof influx of water to the space, having regard to the time likely tobe required in order to reach and operate such controls. If the lev-el to which the space could become flooded with the ship in thefully loaded condition so requires, arrangements shall be made tooperate the controls from a position above such level.(SOLAS Ch. II-1/48.3)402 If it can be documented by calculation of filling time thatthe water level is not above the tank top floor after 10 minutesfrom the initiation of the uppermost bilge level alarm, it will beaccepted that the valves are operated from the tanktop floor.

Guidance note:Various Flag Administrations have worked out their own inter-pretations of this regulation.


L. Side Scuttles, Windows and SkylightsL 100 Side Scuttles, Windows and Skylights101

1) Side scuttles and windows together with their glasses,deadlights and storm covers, if fitted, shall be of an ap-proved design and substantial construction. Non-metallicframes are not acceptable.Guidance note:Deadlights are fitted to the inside of windows and side scuttleswhile 'storm covers' are fitted to the outside of windows, whereaccessible, and may be hinged or portable.


2) Side scuttles are defined as being round or oval openingswith an area not exceeding 0.16 m2. Round or oval open-ings having areas exceeding 0.16 m2 shall be treated aswindows.

Table K2 Wall thickness of steel pipingExternal diameter in mm Wall thickness in mm

≤ 80 7.0= 180 10.0≥ 220 12.5

Table K3 Wall thickness of steel pipingExternal diameter in mm Wall thickness in mm

≤ 155 4.5≥ 230 6.0

DET NORSKE VERITAS


3) Windows are defined as being rectangular openings gen-erally, having a radius at each corner relative to the win-dow size and round or oval, openings with an areaexceeding 0.16 m2 .

4) Side scuttles to the following spaces shall be fitted withhinged inside deadlights:

a) spaces below freeboard deckb) spaces within the first tier of enclosed superstructuresc) first tier deckhouses on the freeboard deck protecting

openings leading below or consideredbuoyant in sta-bility calculations.

Deadlights shall be capable of being closed and securedwatertight if fitted below the freeboard deck and weather-tight if fitted above.

5) Side scuttles shall not be fitted in such a position that theirsills are below a line drawn parallel to the freeboard deckat side and having its lowest point 2.5 percent of thebreadth B, or 500 mm, whichever is the greatest distance,above the summer load line (or timber summer load line ifassigned) .

6) If required damage calculations indicate that side scuttleswould become immersed in any intermediate stage offlooding or the final equilibrium waterlines they shall beof the non-opening type.

7) Windows shall not be fitted in the following locations:

a) below the freeboard deckb) in the first tier end bulkheads or sides of enclosed su-

perstructuresc) in first tier deckhouses that are considered buoyant in

the stability calculations.

8) Side scuttles and windows at the side shell in the secondtier shall be provided with hinged inside deadlights capa-ble of being closed and secured weathertight if the super-structure protects direct access to an opening leadingbelow or is considered buoyant in the stability calcula-tions.

9) Side scuttles and windows in side bulkheads set inboardfrom the side shell in the second tier, which protecting di-rect access below to spaces listed in paragraph (4), shall beprovided with either hinged inside deadlights or, wherethey are accessible, permanently attached external stormcovers which are capable of being closed and securedweathertight.

10) Cabin bulkheads and doors in the second tier and aboveseparating side scuttles and windows from a direct accessleading below or the second tier considered buoyant in thestability calculations, may be accepted in place of dead-lights or storm covers fitted to the side scuttles and win-dows.

11) Deckhouses situated on a raised quarter deck or on thedeck of a superstructure of less than standard height, maybe regarded as being in the second tier as far as the require-ments for deadlights are concerned, provided the height ofthe raised quarter deck or superstructure is equal to orgreater than the standard quarter deck height.

12) Fixed or opening skylights shall have glass thickness ap-propriate to their size and position as required for sidescuttles and windows. Skylight glasses in any positionshall be protected from mechanical damage and where fit-ted in positions 1 or 2, shall be provided with permanentlyattached deadlights or storm covers.

Guidance note:Deviation for the fitting of deadlights may be accepted for ves-sels trading in domestic waters only, in accordance with Pt.1Ch.1 Sec.2 B 900.


(IACS LL62, ICLL Reg. 23)

L 200 Glass dimensions, side scuttles and windows201 Side scuttles and windows made and tested according toISO 1751 for side scuttles and ISO 3903 for windows, withglass according to ISO 1095 for side scuttles and 3254 for win-dows and glass tested and marked according to ISO 614 willnormally be accepted. The same applies to national standardsequivalent to the ISO-standards.202 The glass thickness can be calculated from the followingformulae:

1) The design load shall be in accordance with the rules asgiven in Ch.1 Sec.10 C100.For 2nd tier and below the design load for side scuttles andwindows is in addition to be in accordance with ISO/DIS5779 and 5780.

2) “The minimum design load for windows in sides and aftends of deckhouses located 1.7 Cw (m) or more aboveS.W.L., may be reduced to 2.5 kN/m2.L should not be taken less than 100 m.The thickness of windows shall not be less than:

— 8 mm for windows with area less than 1.0 m2

— 10 mm for windows of 1.0 m2 or more.

N = nominal diameter/light opening of side scuttle in mmb = the minor dimension of the window in mmβ = factor obtained from the graph in Fig.2p = design load in kN/m2

t = glass thickness in mmCw = wave coefficient as given in Ch.1 Sec.4 B200.

Fig. 4Diagram for factor β for windows

side scuttles: t N362--------- p=

windows: t b200--------- β p=

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M. Freeing PortsM 100 Definitions101 Where bulwarks on the weather portions of freeboard orsuperstructure decks form wells, ample provision shall be madefor rapidly freeing the decks of water and for draining them.

M 200 Freeing port area201 Except as provided in 202 and 203, the minimum free-ing port area (A) on each side of the ship for each well on thefreeboard deck shall be that given by the following formula incases where the sheer in way of the well is standard or greaterthan standard. The minimum area for each well on super-structure decks shall be one-half of the area given by the for-mula.Where the length of bulwark ( l) in the well is 20 metres or less:

A = 0.7 + 0.035 l (square metres),where l exceeds 20 metres:

A = 0.07 l (square metres).l need in no case be taken as greater than 0.7 L.If the bulwark is more than 1.2 metres in average height the re-quired area shall be increased by 0.004 square metres per metreof length of well for each 0.1 metre difference in height. If thebulwark is less than 0.9 metre in average height, the requiredarea may be decreased by 0.004 square metres per metre oflength of well for each 0.1 metre difference in height.202 In ships with no sheer the area calculated according to201 shall be increased by 50 per cent. Where the sheer is lessthan the standard the percentage shall be obtained by linear in-terpolation. 203 Where a ship fitted with a trunk which does not complywith the requirements of ICLL Regulations 36 (1)(e) or wherecontinuous or substantially continuous hatchway side coamingare fitted between detached superstructures the minimum areaof the freeing port openings shall be calculated from the fol-lowing table:

The area of freeing ports at intermediate breadths shall be ob-tained by linear interpolation.204 In ships having superstructures which are open at eitheror both ends, adequate provision for freeing the space withinsuch superstructures shall be provided to the satisfaction of theSociety.For superstructures that are open at either or both ends the ef-fective freeing area at the end of the superstructure may beadded to the respective freeing port area for the port and star-board side of the superstructure. The effective area of the open-ing at the end of a superstructure will be assessed on a case bycase basis weighing the following factors:

— the athwartship location of the opening— the slope of the deck towards or away from the opening— the length/breadth ratio of the well— the free fore and aft passage for the water to reach the

opening, unobstructed by deck equipment, fittings, or car-go stowage.

Guidance note:Reduced freeing port area may be accepted for vessels trading indomestic waters only, in accordance with Pt.1 Ch.1 Sec.2 B 900.


M 300 Location and protection of openings301 The lower edges of the freeing ports shall be as near thedeck as practicable. Two-thirds of the freeing port area re-quired shall be provided in the half of the well nearest the low-est point of the sheer curve.302 All such openings in the bulwarks shall be protected byrails or bars spaced approximately 230 millimetres apart. Ifshutters are fitted to freeing ports, ample clearance shall beprovided to prevent jamming. Hinges shall have pins or bear-ings of non-corrodible material. If shutters are fitted with se-curing appliances, these appliances shall be of approvedconstruction.(ICLL Reg.24)

M 400 Multiple wells401 On a flush deck ship with a substantial deckhouse amid-ships it is considered that the deckhouse provides sufficientbreak to form two wells and that each could be given the re-quired freeing port area based upon the length of the «well». Itwould not then be allowed to base the area upon 0.7 L.In defining a substantial deckhouse it is suggested that thebreadth of the deckhouse should be at least 80% of the beam ofthe vessel, and that the passageways along the side of the shipshould not exceed 1.5 m in width.Where a screen bulkhead is fitted completely across the vessel,at the forward end of a midship deckhouse, this would effective-ly divide the exposed deck into wells and no limitation on thebreadth of the deckhouse is considered necessary in this case.It is considered that wells on raised quarterdecks should betreated as previously, i.e. as being on freeboard decks.With zero or little sheer on the exposed freeboard deck or anexposed superstructure deck it is considered that the freeingport area should be spread along the length of the well. (IACS LL13)

M 500 Free flow area501 The effectiveness of the freeing area in bulwarks re-quired by 201 and 202 depends on free flow across the deck ofa ship. Where there is no free flow due to the presence of a con-tinuous trunk or hatchway coaming, the freeing area in bul-warks is calculated in accordance with 203.The free flow area on deck is the net area of gaps betweenhatchways, and between hatchways and superstructures anddeckhouses up to the actual height of the bulwark.The freeing port area in bulwarks should be assessed in relationto the net flow area as follows:(i) If the free flow area is not less than the freeing area calcu-lated from 203 as if the hatchway coamings were continuous,then the minimum freeing port area calculated from 201 and202 should be deemed sufficient.(ii) If the free flow area is equal to, or less than the area calcu-lated from 201 and 202 minimum freeing area in the bulwarksshould be determined from 203.(iii) If the free flow area is smaller than calculated from 203but greater than calculated from 201 and 202, the minimumfreeing area in the bulwark should be determined from the fol-lowing formula:

F = F1 + F2 – fp (m2)

F1 = the minimum freeing area calculated from 201 and 202,F2 = the minimum freeing area calculated from 203,fp = the total net area of passages and gaps between hatch

ends and superstructures or deckhouses up to the actualheight of bulwark.

(IACS LL44)

Breadth of hatchway or trunk in relation to

the breadth of ship

Area of freeing ports in relation to the total area

of the bulwarks40% or less

75% or more20%10%

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M 600 Type «A», «B-100» and «B-60» ships601 Requirements for freeing arrangements for Type «A»ships are given in N100.602 Type B-100 ships with bulwarks shall have open railsfitted for at least half the length of the exposed parts of theweather deck or a freeing port area, in the lower part of the bul-warks, of 33% of the total area of the bulwarks. For Type B-60ships there shall be freeing port area in the lower part of thebulwarks equal to at least 25% of the total area of the bulwarks.

N. Special Requirements for Type A ShipsN 100 Machinery casings101 Machinery casings on Type A ships shall be protectedby an enclosed poop or bridge of at least standard height, or bya deckhouse of equal height and equivalent strength, providedthat machinery casings may be exposed if there are no open-ings giving direct access from the freeboard deck to the ma-chinery space. A door complying with the requirements ofB101 may, however, be permitted in the machinery casing,provided that it leads to a space or passageway which is asstrongly constructed as the casing and is separated from thestairway to the engine room by a second weather tight door ofsteel or other equivalent material.

N 200 Gangway and access201 An efficiently constructed fore and aft permanent gang-way of sufficient strength shall be fitted on Type A ships at the

level of the superstructure deck between the poop and the mid-ship bridge or deckhouse where fitted, or equivalent means ofaccess shall be provided to carry out the purpose of the gang-way, such as passages below deck. Elsewhere, and on Type Aships without a midship bridge, arrangements to the satisfac-tion of the Society shall be provided to safeguard the crew inreaching all parts used in the necessary work of the ship, seeCh.1 Sec.10.

202 Safe and satisfactory access from the gangway levelshall be available between separate crew accommodations andalso between crew accommodations and the machinery space.

N 300 Hatchways301 Exposed hatchways on the freeboard and forecastledecks or on the tops of expansion trunks on Type A ships shallbe provided with efficient watertight covers of steel or otherequivalent material.

N 400 Freeing arrangements401 Type A ships with bulwarks shall have open rails fittedfor at least half the length of the exposed parts of the weatherdeck or a freeing port area, in the lower part of the bulwarks,of 33% of the total area of the bulwarks. The upper edge of thesheer strake shall be kept as low as practicable.402 Where superstructures are connected by trunks, openrails shall be fitted for the whole length of the exposed parts ofthe freeboard deck.(ICLL Reg.26)

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SECTION 7 CORROSION PREVENTION

A. General

A 100 Definitions101 The following definitions are used in this section:Anode: An electrode through which direct current enters anelectrolyte.Cathodic protection: A way of protecting a steel surface fromcorrosion by installing sacrificial anodes, in contact with thesteel in the electrochemical seawater corrosion cell.Hard coating: A coating which chemically converts during itscuring process, normally used for new constructions, or non-convertible air drying coating which may be used for mainte-nance purposes. Hard coating can be either inorganic or organ-ic.

Guidance note:Commonly used organic "hard coatings" are epoxy based, suchas pure epoxies and coal tar epoxies. Zinc silicate primers are ex-amples of inorganic hard coatings.


Primer coat: The first coating applied in the shipyard (to dif-ferentiate it from shop-primer).(IMO Res. A.798(19))

A 200 Documentation201 Specifications for corrosion prevention systems for wa-ter ballast tanks, comprising selection, application and mainte-nance, shall be submitted for information.

Guidance note:The Society’s involvement concerns the contents of the specifi-cation only and does not imply any approval of the surface prep-aration or coating as applied.


202 The purpose of the coating specification shall describethe scheme for selection, application and maintenance of thecorrosion prevention system. It is recommended that the sys-tem comprises of those items described in Table A1.203 Ballast tanks’ anode distribution drawings shall be sub-mitted for approval. Such drawings shall include details of theconnections to the hull, e.g. welding details.

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B. Corrosion prevention systems

B 100 General101 All steel surfaces except in tanks other than ballast tanksshall be protected against corrosion by paint of suitable com-position or other effective coating. Holds for dry bulk cargoeswill be specially considered. See also Ch.1 Sec.2 D203.102 Corrosion prevention of seawater ballast tanksThis regulation applies to oil tankers and bulk carriers con-structed on or after 1 July 1998. All dedicated seawater ballast tanks shall have an efficientcorrosion prevention system, such as hard protective coatingsor equivalent. The coatings should preferably be of a light col-our. The scheme for the selection, application and maintenanceof the system shall be approved by the Administration, basedon the Guidelines adopted by the Organization*. Where appro-priate, sacrificial anodes shall also be used.

* Refer to the Guidelines for the selection, application andmaintenance of corrosion prevention systems of dedicatedseawater ballast tanks, adopted by the Organization byresolution A.798(19).

(SOLAS Ch. II-1/3-2)Guidance note:The Organization in this context shall be understood as IMO.


B 200 Coatings201 Shop primers applied over areas which will subsequent-ly be welded, shall be of a quality accepted by the Society ashaving no detrimental effect on the finished weld. See «Regis-ter of Type Approved Products No.1 Non-Metallic Materials».202 The use of aluminium paint is generally not accepted intanks for liquid cargo with flash point below 60°C, in adjacentballast tanks, in cofferdams, in pump rooms or on deck above

Table A1 Contents of coating specificationScheme for (see SOLAS Ch. II-1/3-2)

Items to be described in specification

General The yard’s owner’s and coating manufacturer’s agreement on the specification.Selection of coating 1) Coating type, material and manufacturer's data sheets concerning items 2) to 5) listed below.

2) Definition of coating system, including number of coats and minimum/maximum variation in dry film thickness.

Application of coating 3) Surface preparation, including preparation of edges and welds, and surface cleanliness standard (e.g. blast cleaning to Sa 2.5).

4) Coating manufacturer's safety data sheets.5) Maximum allowable air humidity in relation to air and steel temperatures during surface preparation

and coating application.6) Yard's control and inspection procedures *) including:

- acceptance criteria- tests/checks (e.g. surface cleanliness, film thickness, air humidity, temperature controls)- handling of deviations from specified quality.

7) Details of anodes, if used.8) Evidence of yard's experience in coating application **).

Maintenance of coating 9) Coating manufacturer's recommended procedure, preferably alternative procedures, for future maintenance of coating on the ship in operation.

Notes:* The items listed in a) to q) should be described in the control and inspection procedures (and thus included in the coating specification) for the ship new-

building.

a) Organisation of operators, inspectors, facilities, equipment and procedures.b) Working conditions, e.g. access, stageing, illumination.c) Conditioning of steel temperatures and relative humidity.d) Methods of conditioning of steel temperatures and relative humidity, e.g. indoor facilities for blast cleaning and coating, heating/drying equipment,

etc.e) Storing of coating materials and abrasives.f) Preparation of sharp edges.g) Blast cleaning and any other surface preparationh) Cleaning, including removal of abrasives after blast cleaning.i) Cleanliness with respect to chloride content on surfaces to be coated, oil, weld smoke, dirt, etc.j) Shielding off painted surfaces from blasting operations.k) Blast cleaning equipment and type of abrasive.l) Coating application equipment and methods.m) Curing times for individual coats in relation to temperatures.n) Dry film thickness of individual coats.o) Total dry film thickness.p) Coating repairs in case of damage, and handling of coated surfaces.q) Installation of anodes, if specified. See B300.

** Minimum evidence will be a reference list stating (some or all) ships coated by the Yard. Other relevant evidence may be for example technical reportson the performance of coatings applied by the Yard, e.g. inspection reports on coating condition in ballast tanks after a number of years, or a qualitysystem certificate for the Yard's coating application division or subcontractor. It is essential that the evidence is acceptable to the Owner.

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the mentioned spaces, nor in any other area where cargo gasmay accumulate. Paint containing aluminium may, however,be accepted in places as mentioned above, provided it has beenshown by tests that the paint will not increase the sparking haz-ard.

Guidance note:Coating containing aluminium in gas hazardous areas limited toAl maximum 10% by weight in the dry film is acceptable. Areas containing "liquid cargo with flash point below 60°C" areconsidered as "gas-dangerous" areas.


203 Regarding coating of ballast tanks, see Ch.1 Sec.2 D203.

B 300 Cathodic protection301 The Society shall approve the fitting arrangement for ca-thodic protection of steel structures in tanks used for liquid car-go, with flash point below 60°C, with regard to safety againstfire and explosion. This approval also applies to adjacenttanks.

Guidance note:Approval of sacrificial anodes and their fastening devices is nor-mally given as a type approval. See "Register of Type ApprovedProducts No.3: Containers, Cargo Handling, Lifting Appliancesand Miscellaneous Equipment".


302 All anodes shall be attached to the structure in such away that they will remain securely fastened both initially andduring service. Fillet welds shall be continuous and have ade-

quate cross section. Attachment by clamps fixed by setscrewswill normally not be accepted. Attachments by properly se-cured through-bolts or other positive locking devices mayhowever be accepted.Anode steel cores bent and directly welded to the steel struc-ture shall be of a material complying with the requirements forgrade NV A or equivalent.303 Tanks in which anodes are installed, shall have suffi-cient holes for the circulation of air to prevent gas from collect-ing in pockets.304 In tanks, permanent anodes made of, or alloyed with,magnesium are not accepted. Impressed current systems shallnot be used in tanks due to development of chlorine and hydro-gen that can result in an explosion hazard. Aluminium anodesare accepted in general. However, with regard to tanks for liq-uid cargo with flash point below 60°C and in adjacent ballasttanks, aluminium anodes shall be so located that a kinetic en-ergy of not more than 275 J is developed in event of their loos-ening and becoming detached.

Guidance note:Aluminium anodes in gas-dangerous areas will be accepted whenattached to tank bottoms, on stringer decks and up to a certainheight above the tank bottom or stringer deck. The height abovethe tank bottom or stringer deck will be dependent upon anodeweight, whose maximum acceptable height in m is 28 divided bythe weight of the anode in kg. The attachment shall be arrangedso that the anodes cannot eventually become detached and fallthrough holes or scallops in stringer decks.


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SECTION 8 PROTECTION OF THE CREW

A. Protection of the CrewA 100 Guard rails101 Efficient guard rails or bulwarks shall be fitted on all ex-posed parts of the freeboard, and superstructure and deckhousedecks. The height of the bulwarks or guard rails shall be at least1 metre from the deck, provided that where this height wouldinterfere with the normal operation of the ship, a lesser heightmay be approved if the Society is satisfied that adequate pro-tection is provided.(ICLL Reg.25.2)102 The openings below the lowest course of the guard railsshall not exceed 230 millimetres. The other courses shall benot more than 380 millimetres apart. In the case of ships withrounded gunwales the guard rail supports shall be placed on theflat of the deck.(ICLL Reg.25.3)103 Effective protection for the crew in the form of guardrails or life lines shall be provided above the deck cargo if thereis no convenient passage on or below the deck of the ship.(ICLL Reg.25.5)104

a) Fixed, removable or hinged stanchions shall be fittedabout 1.5 m apart.

b) At least every third stanchion shall be supported by abracket or stay.

c) Wire ropes may only be accepted in lieu of guard rails inspecial circumstances and then only in limited lengths.

d) Lengths of chain may only be accepted in lieu of guardrails if they are fitted between two fixed stanchions and/orbulwarks.

e) Wires shall be made taut by means of turnbuckles.f) Removable or hinged stanchions shall be capable of being

locked in the upright position.

(IACS LL47 to ICLL Reg. 25.2 and 25.3)

A 200 Gangways, walkways and passageways201 Satisfactory means (in the form of guard rails, life lines,gangways or under deck passages etc.) shall be provided forthe protection of the crew in getting to and from their quarters,the machinery space and all other parts used in the necessarywork of the ship.(ICLL Reg.25.4)202 Acceptable arrangements referred to in Table E1 are de-fined as follows:

a) A well lit and ventilated under-deck passageway (clearopening 0.8 m wide, 2.0 m high) as close as practicable tothe freeboard deck, connecting and providing access to thelocations in question.

b) A permanent and efficiently constructed gangway fitted ator above the level of the superstructure deck on or as nearas practicable to the centre line of the ship, providing acontinuous platform at least 0.6 m in width and a non-slipsurface, with guard rails extending on each side through-out its length. Guardrails shall be at least 1 m high withcourses as required in 102, and supported by stanchionsspaced not more than 1.5 m; a foot-stop shall be provided.

c) A permanent walkway at least 0.6 m in width fitted at free-

board deck level consisting of two rows of guard rails withstanchions spaced not more than 3 m. The number ofcourses of rails and their spacing shall be as required by102. On Type B ships, hatchway coamings not less than0.6 m in height may be regarded as forming one side of thewalkway, provided that between the hatchways two rowsof guardrails are fitted.

d) A 10 mm minimum diameter wire rope lifeline supportedby stanchions about 10 m apart,orA single handrail or wire rope attached to hatch coamings,continued and adequately supported between hatchways.

e) A permanent and efficiently constructed gangway fitted ator above the level of the superstructure deck on or as nearas practicable to the centre line of the ship:

— located so as not to hinder easy access across theworking areas of the deck;

— providing a continuous platform at least 1.0 m inwidth;

— constructed of fire resistant and non-slip material;— fitted with guard rails extending on each side through-

out its length; guard rails should be at least 1.0 m highwith courses as required by 102 and supported bystanchions spaced not more than 1.5 m.

— provided with a foot stop on each side;— having openings, with ladders where appropriate, to

and from the deck. Openings should not be more than40 m apart;

— having shelters of substantial construction set in wayof the gangway at intervals not exceeding 45 m if thelength of the exposed deck to be traversed exceeds 70m. Every such shelter should be capable of accommo-dating at least one person and be so constructed as toafford weather protection on the forward, port andstarboard sides.

f) A permanent and efficiently constructed walkway fitted atfreeboard deck level on or as near as practicable to the cen-tre line of the ship having the same specifications as thosefor a permanent gangway listed in (e) except for foot-stops. On Type B ships (certified for the carriage of liquidsin bulk), with a combined height of hatch coaming and fit-ted hatch cover of together not less than 1m in height thehatchway coamings may be regarded as forming one sideof the walkway, provided that between the hatchways tworows of guard rails are fitted.Alternative transverse locations for (c), (d) and (f) above,where appropriate:

(1) At or near centre line of ship; or fitted on hatchways at ornear centre line of ship.

(2) Fitted on each side of the ship.(3) Fitted on one side of the ship, provision being made for

fitting on either side.(4) Fitted on one side only.(5) Fitted on each side of the hatchways as near to the centre

line as practicable.Additional requirements:

1. In all cases where wire ropes are fitted, adequate devicesshall be provided to ensure their tautness.

2. Wire ropes may only be accepted in lieu of guardrails inspecial circumstances and then only in limited lengths.

3. Lengths of chain may only be accepted in lieu of guard-rails if fitted between two fixed stanchions.

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4. Where stanchions are fitted, every 3rd stanchion shall besupported by a bracket or stay.

5. Removable or hinged stanchions shall be capable of beinglocked in the upright position.

6. A means of passage over obstructions, if any, such aspipes or other fittings of a permanent nature, should be

provided.7. Generally, the width of the gangway or deck-level walk-

way should not exceed 1.5 m.(IACS LL50 Rev.4.1 to Reg. 25(4), 26(2), 27(7) and SOLASCh. II-1/3-3.)

Guidance note:Deviations from some or all of these requirements or alternativearrangements for such cases as ships with very high gangways(i.e. certain Gas Carriers) may be allowed subject to agreement

case by case with the relevant flag Administration.---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---

Table E1 Protection of the crew

Type of ship Locations of access in ShipAssigned Summer Freeboard

Acceptable arrangements according to type of freeboard assigned

Type A Type B-100 Type B-60 Type B and B+

All shipsother than

Oil Tankers*Chemical

Tankers* andGas Carriers*

1.1 Access to midship quarters1.1.1 Between poop and bridge, or1.1.2 Between poop and deckhouse

containing living accommoda-tion or navigating equipment, or both.

≤ 3 000 mmabe

abe

ab

c(1)e

f(1)

ab

c(1)c(2)c(4)d(1)d(2)d(3)

ef(1)f(2)f(4)

> 3 000 mmabe

abe

ab

c(1)c(2)

ef(1)f(2)

1.2 Access to ends1.2.1 Between poop and bow (if there

is no bridge)1.2.2 Between bridge and bow, or1.2.3 Between a deckhouse contain-

ing living accommodation or navigating equipment, or both, and bow, or

1.2.4 In the case of a flush deck ves-sel, between crew accommoda-tion and the forward and after ends of ship.***

≤ 3 000 mm

ab

c(1)e

f(1)

ab

c(1)c(2)

ef(1)f(2)

ab

c(1)c(2)

ef(1)f(2)

> 3 000 mm

ab

c(1)c(2)d(1)d(2)

ef(1)f(2)

ab

c(1)d(1)

ef(1)

ab

c(1)c(2)c(4)d(1)d(2)d(3)

ef(1)f(2)f(4)

Oil Tankers*Chemical

Tankers* andGas Carriers*

2.1 Access to bow2.1.1 Between poop and bow, or2.1.2 Between a deckhouse contain-

ing living accommodation or navigating equipment, or both, and bow, or

2.1.3 In the case of a flush deck ves-sel, between crew accommoda-tion and the forward end of ship.

≤ (Af+Hs)**ae

f(1)f(5)

> (Af+Hs)**ae

f(1)f(2)

2.2 Access to after endIn the case of a flush deck ves-sel, between crew accommoda-tion and the after end of ship.***

as required in 1.2.4 for other types of ships

* Oil Tankers, Chemical Tankers and Gas Carriers as defined in SOLAS Ch. II-1/2.12, VII/8.2 and VII/11.2, respectively.** Af: the minimum summer freeboard calculated as type A ship regardless of the type of freeboard actually assigned. Hs: the standard height of superstruc-

ture as defined in ICLL Regulation 33*** Access to after end of ships is not applicable when crew accommodation is located aft.

Acceptable arrangements referred to in this table are given in 200.

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SECTION 9 STABILITY

A. Application, Definitions and Document Requirements

A 100 Application101 All vessels shall comply with the stability requirementsof this section, as applicable for the main class.102 The requirements in this section are in compliance withIMO Intact Stability Code (IMO Res. A. 749 (18)) and coverIACS UR L2.103 For vessels with service restrictions as described in Pt.1Ch.1 Sec.2 B400, modified stability requirements may be con-sidered if consistent with the applicable service restriction.104 Vessels with additional class notations shall complywith additional stability requirements as given in the appropri-ate rule chapters. 105 Ships with loading computer systems intended for sta-bility control shall comply with Pt.6 Ch.9 Sec.1 A200. 106 The stability for vessels for which lifting operations arethe main or one of the main functions shall also be in compli-ance with the criteria given in Pt.5 Ch.7 Sec.7.The crane criteria shall be applied when the maximum heelingarm created by the crane and its load exceeds 0.10 m at any op-erational displacement.

A 200 Terms201 External watertight integrityThe capability of the hull structure and its external closing ap-pliances to prevent downflooding to volumes assumed buoy-ant. The external watertight integrity includes position andtype of closing appliances, alarms, indicators, remote controlsand signboards fitted to such appliances.202 Weathertight

Weathertight means that in any sea conditions water will notpenetrate into the ship.203 WatertightCapable of preventing ingress of water during static submer-sion under a head of water for which the surrounding structureis designed.A watertight closing appliance is also considered weathertight.204 DownfloodingIngress of water through external openings to buoyancy vol-umes.205 Downflooding angle related to intact stabilityThe minimum heel angle where an external opening withoutweathertight closing appliance is submerged.206 LightweightLightweight is the displacement of a ship in tonnes withoutcargo, fuel, lubricating oil, ballast water, fresh water and feedwater in tanks, consumable stores, and passengers and crewand their effects.The lightweight definition stated in the Stability Manual indi-cates which items are included or not included in the light-weight.

Guidance note:The approved lightweight data are the data which are approvedfor the purpose of stability approval and control but not necessar-ily for determination of the deadweight.


207 Maximum allowable vertical centre of gravityThe maximum vertical centre of gravity of the vessel, correct-ed for free surface effect, which complies with the stipulatedstability requirements for the draught in question.

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208 Preliminary stability documentationThe stability documentation which is based on estimated light-weight data.209 Final stability documentationThe stability documentation which is based on approved light-weight data obtained from an inclining test or lightweight survey.

A 300 Documentation for approval301 The following documentation shall be submitted for ap-proval:

— preliminary stability booklet— inclining test procedure— inclining test report— final stability booklet.

302 All stability documentation submitted for approval shallhave a unique identification, i.e.:

— name and identity no. of ship— date of issue— revision number and date, if applicable— name of originator— table of contents (reports only)— consecutive page numbering (reports only).

303 For each vessel built by the same yard from the sameplans, it is sufficient to submit:

— lightweight survey procedure (inclining test procedure forpassenger vessels)

— lightweight survey report (or inclining test report for pas-senger vessels)

— final stability booklet.

304 If the assignment of class shall be based on the approvalof the Flag Administration according to Pt.1 Ch.1 Sec.3A1200, a copy of the final stability documentation stamped bythe Flag Administration and the approval letter issued by theFlag Administration shall be submitted to the Society.305 The following documentation shall be submitted for in-formation:

— general arrangement— body plan, lines plan or offset table— external watertight integrity plan or freeboard plan.

Guidance note:Details of the documentation are given in Classification NoteNo. 20.1 «Stability Documentation — Ships Newbuildings».


B. Surveys and Tests

B 100 General101 The following surveys and tests shall be carried out:

— external watertight integrity survey with respect to unpro-tected and protected openings together with their closingappliances, alarms, indicators and signboards, normallycovered by the load line initial survey

— checking of draft marks— remote draft measurement and tank gauging systems— inclining test or lightweight survey.

C. General RequirementsC 100 Stability book101 An approved stability booklet shall be provided on-board. The stability booklet shall include information as is nec-essary to enable the master by a rapid and simple process toobtain accurate guidance as to the stability of the ship undervarying conditions of service.

Guidance note:The format and content of the stability book is further describedin Classification Note No. 20.1 and IACS UI LL45.


102 Stability data and associated plans shall include a trans-lation into English, if English is not used as official language.

C 200 Fixed Ballast201 If used, fixed ballast shall be installed in a manner thatprevents shifting of position.

C 300 Draught Marks301 The ship shall have scale of draught marks at the bowand stern on both port and starboard side.

Guidance note:The draught marks should reflect the extreme draught at the lo-cation where they are fitted. The stability manual should containguidance on, from draught mark readings, how to utilise the sta-bility information contained therein. Norwegian StandardNS6301 may be referenced for further guidelines on the size andlocation of draught marks.


C 400 Loading Computer System401 Loading computers for stability calculation shall be con-sidered as supplementary to the approved stability booklet.402 Loading computers for stability control shall complywith Pt.6 Ch.9.

D. Intact Stability Criteria D 100 General stability criteria101 The following criteria are given for all ships:

— The area under the righting lever curve (GZ curve) shallnot be less than 0.055 metre-radians up to θ = 30° angleof heel and not less than 0.09 metre-radians up to θ = 40°or the angle of flooding θ f if this angle is less than 40°.Additionally, the area under the righting lever curve be-tween the angles of heel of 30° and 40° or between 30° andθf, if this angle is less than 40°, shall not be less than 0.03metre-radians.

— The righting lever (GZ) shall be at least 0.20 m at an angleof heel equal to or greater than 30°.

— The maximum righting lever should occur at an angle ofheel preferably exceeding 30° but not less than 25°.

— The initial metacentric height, GM0 shall not be less than0.15 m.

Guidance note:For ships carrying timber deck cargoes and provided that: - the cargo extends longitudinally between superstructures end,

or where there is no limiting superstructure at the after end,the timber deck cargo shall extend at least to the after end ofthe aftermost hatchway

- the cargo extends transversely for the full beam of the ship af-ter due allowance for a rounded gunwale not exceeding 4% ofthe breadth of the ship

- supporting uprights are secured and remain securely fixed at

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large angles of heelthe following criteria may be used instead of the criteria in 101:- the area under the righting lever curve (GZ curve) should not

be less than 0.08 metre-radians up to θ = 40° angle of heel orthe angle of flooding θf if this angle is less than 40°

- the maximum value of the righting lever (GZ) should be atleast 0.25 m

- at all times during the voyage, the metacentric height GM0should be positive after correction for the free surface effectsof liquid in tanks and, where appropriate, the absorption ofwater by the deck cargo and/or ice accretion on the exposedsurfaces. Additionally, in the departure condition, the meta-centric height GM0 should not be less than 0.10 m.


102 The following equivalent criteria are recommendedwhere a vessel's characteristics render compliance with 101impracticable (based on IMO Res. A. 749 (18), Ch.4.5.6):

— The area under the curve of righting levers (GZ curve)should not be less than 0.070 metre-radians up to an angleof 15° when the maximum righting lever (GZ) occurs at15° and 0.055 metre-radians up to an angle of 30° whenthe maximum righting lever (GZ) occurs at 30° or above.Where the maximum righting lever (GZ) occurs at angles

of between 15° and 30°, the corresponding area under therighting lever curve should be:

0.055 + 0.001 (30° − θmax) metre-radianswhere θmax is the angle of heel in degrees at which therighting lever curve reaches its maximum.

— The area under the righting lever curve (GZ curve) be-tween the angles of heel of 30° and 40°, or between 30°and θf this angle is less than 40°, should be not less than0.03 metre-radians.

— The righting lever (GZ) should be at least 0.20 m at an an-gle of heel equal to or greater than 30°.

— The maximum righting lever (GZ) should occur at an an-gle of heel not less than 15°.

— The initial transverse metacentric height (GM0) should notbe less than 0.15 m.

103 When anti-rolling devices are installed in a ship, the ap-plicable intact stability criteria shall be satisfied when the de-vices are in operation.104 For certain ship types additional or alternative intact anddamage stability criteria have been specified. These vessels (orclass notations) are given in Table D1.

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D 200 Weather criterion201 For ships with large windage area, such as passenger,container and Ro/Ro ships, the criteria listed below shall becomplied with (based on IMO Res. A. 749 (18), Ch.3.2): 1 The ability of a ship to withstand the combined effects ofbeam wind and rolling should be demonstrated for each stand-ard condition of loading, with reference to the Fig.1 as follows:1.1 - the ship is subjected to a steady wind pressure acting per-pendicular to the ship's centreline which results in a steadywind heeling lever 1.2 - from the resultant angle of equilibrium (θ0), the ship is as-

sumed to roll owing to wave action to an angle of roll (θ1) towindward. Attention should be paid to the effect of steadywind so that excessive resultant angles of heel are avoided.The angle of heel under action of steady wind (θ0) should belimited to a certain angle to the satisfaction of the Society. Asa guide, 16° or 80% of the angle of deck edge immersion,whichever is less, is suggested.1.3 - the ship is then subjected to a gust wind pressure whichresults in a gust wind heeling lever 1.4 - under these circumstances, area "b" should be equal to orgreater than area "a";

Table D1 Stability design requirements for different ship types and class notationsClass notation / Ship type Intact Damage Class Requirement IMO Reference1A1 X D101 IMO Res. A. 749 (18), Ch.3.11A1, offshore/harbour service vessels X D102 IMO Res. A. 749 (18), Ch.4.51A1, wind X D201 IMO Res. A. 749 (18), Ch.3.21A1, timber X D101 IMO Res. A. 749 (18), Ch.4.1

Cargo vessels

Freeboard Type A, B-60, B-100 X E103 ICLL 1966 Reg. 27 as amended by the 1988 Proto-col

* Cargo vessels, L > 80 m X E102 SOLAS 74 Ch. II-1, B-1Tanker for Oil X

XPt.5 Ch.3 Sec.3 APt.5 Ch.3 Sec.3 A

MARPOL 73/78 Reg. 25 A MARPOL 73/78 Reg. 25 and 13F

Tanker for Chemicals X Pt.5 Ch.4 Sec.3 A IMO IBC Code, Ch.2Tanker for Liquefied Gas X Pt.5 Ch.5 Sec.3 A IMO IGC Code, Ch.2

Offshore/Harbour service vessels Supply Vessel X Pt.5 Ch.7 Sec.3 D IMO Res. A. 469 (XII) Ch.2SF X

XPt.5 Ch.7 Sec.4 A102Pt.5 Ch.7 Sec.4 B

IMO Res. A. 469 (XII) Ch.3

Tug X Pt.5 Ch.7 Sec.2 E No IMO requirementsFire Fighter I (or II or III) X Pt.5 Ch.7 Sec.5 I No IMO requirementsCRANE X Pt.6 Ch.1 Sec.3 E No IMO requirementsCRANE VESSEL X

XPt.5 Ch.7 Sec.7 D200Pt.5 Ch.7 Sec.7 D100

No IMO requirements IMO Res. A. 534 (13) or SOLAS 74 Ch.II-1, B-1

DSV-SURFACE, -BOUNCE or -SAT) (diving support vessel)

X X Pt.6 Ch.1 Sec.4 H IMO Res. A. 469 (XII)

DEICE (de-icing/anti icing vessels) X X Pt.6 Ch.1 Sec.5 B IMO Res. A. 469 (XII)

Offshore vessels Pipe Laying Vessel X X Pt.5 Ch.7 Sec.7 E IMO Res. A. 534 (13) or SOLAS 74 Ch.II-1, B-1Well Stimulation Vessel X X Pt.5 Ch.7 Sec.10 H IMO Res. A. 469 (XII)Cable Laying Vessel X

XPt.5 Ch.7 Sec.17 E IMO Res. A. 534 (13) or SOLAS 74 Ch.II-1, B-1

Escort (n, V) X Pt.5 Ch.7 Sec.16 D No IMO requirementsStandby Vessel X

XPt.5 Ch.7 Sec.18 E No IMO requirements

Other vessels

Passenger Ship XX

Pt.5 Ch.2 Sec.2 F300Pt.5 Ch.2 Sec.2 F400

IMO Res. A. 749 (18), Ch.3.1.2.6 SOLAS 74 Ch. II-1, B

Car Ferry, Train Ferry or Car and Train Ferry

XX

Pt.5 Ch.2 Sec.3 F101 IMO Res. A. 749 (18) Ch.3.1.2.6SOLAS 74 Ch.II-1, B

Fishing Vessel or Stern Trawler

X Pt.5 Ch.6 Sec.1 F To cover IMO Res. A. 749 (18), Ch.4.2Torremolinos International Conference Ch.III mod-ified by the Torremolinos Protocol of 1993

Icebreaker / POLAR XX

Pt.5 Ch.1 Sec.4 L400Pt.5 Ch.1 Sec.4 L500

No IMO requirements No IMO requirements

Barge for Deck Cargo X Pt.5 Ch.7 Sec.15 I IMO Res. A. 749 (18), Ch.4.7

lw1( )

lw2( )

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1.5 - free surface effects should be accounted for in the stand-ard conditions of loading as set out in D301.

Fig. 1Severe wind and rolling

The angles in Fig.1 are defined as follows:

θo = angle of heel under action of steady wind (see 1.2 and3)

θ1 = angle of roll to windward due to wave actionθ2 = angle of downflooding (θf) or 50° or θc whichever is

less, where:θf = angle of heel at which openings in the hull, superstruc-

tures or deckhouses which cannot be closed weather-tight immerse. In applying this criterion, smallopenings through which progressive flooding cannottake place need not be considered as open.

θc = angle of second intercept between wind heeling lever and GZ curves.

2 The wind heeling levers and referred to in 1.1and 1.3 are constant values at all angles of inclination andshould be calculated as follows:

P = 504 N/m2 (wind speed = 29 m/s). The value of P, usedfor ships in restricted service and/or for ships with verylarge windage areas (due to coherence length for windspeed), may be reduced subject to the approval of theSociety

A = projected lateral area of the portion of the ship anddeck cargo above the waterline (m2)

Z = vertical distance from the centre of A to the centre ofthe underwater lateral area or approximately to a pointat one half the draught (m)

disp = displacement (t)g = 9.81 m/s2

The angle of roll θ1 1) referred to in 1.2 should be calculated as

follows:

1) The angle of roll for ships with anti-rolling devices should be determinedwithout taking into account the operation of these devices.

X1 = factor as shown in Table D2X2 = factor as shown in Table D3k = 1.0 for round-bilged ship having no bilge or bar keels = 0.7 for a ship having sharp bilges

= as shown in Table D4 for a ship having bilge keels, abar keel or both

r = 0.73 ± 0.6 OG/d, with: OG = distance between the centre of gravity and the water-

line (m) (+ if centre of gravity is above the waterline, -if it is below)

d = mean moulded draught of the ship (m)s = factor as shown in Table D5.

(Intermediate values in Tables D2 to D5 should be obtained bylinear interpolation).Rolling period

C = 0.373 + 0.023 (B/d) - 0.043 (L/100)

The symbols in Tables D2 to D5 and the formula for the rollingperiod are defined as follows:

L = waterline length of the ship (m)B = moulded breadth of the ship (m)d = mean moulded draught of the ship (m)Cb = block coefficientAk = total overall area of bilge keels, or area of the lateral

lw2( )

lw1( ) lw2

( )

lw1

PAZ1000 g disp------------------------------- (m) and=

lw21.5lw1

(m)=

θ1 109kX1X2 rs (degrees)=

Table D2 Values of factor X1B/d X1

≤ 2.42.52.62.72.82.93.03.13.23.33.4

≥ 3.5

1.00.980.960.950.930.910.900.880.860.840.820.80

Table D3 Values of factor X2Cb X2

≤ 0.450.500.550.600.65

≥ 0.70

0.750.820.890.950.971.0

Table D4 Values of factor k

k

01.01.52.02.53.03.5

≥ 4.0

1.050.980.950.880.790.740.720.70

Table D5 Values of factor sT s

< 678

12141618

≥ 20

0.1000.0980.0930.0650.0530.0440.0380.035

Ak100LB

----------------

T 2 C BGM

-------------- (seconds)=

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projection of the bar keel, or sum of these areas (m2)GM = metacentric height corrected for free surface effect

(m).

202 Other calculation methods of equivalent safety levelmay be accepted as an alternative to the above.

Guidance note:For some ships, the formulas may over-estimate the roll angle.As an alternative, the roll angle can be determined by model testsor direct calculations carried out for sea-states corresponding tothe recommended wind speed.


D 300 Assumptions concerning intact stability criteria and calculations301 For all loading conditions the initial metacentric heightand the stability curves shall be corrected for the effect of freesurface of liquid in tanks.

Guidance note:The free surface should be taken into account as described in theIACS UI LL61.


302 Compliance with the stability criteria shall be checkedfor the main loading conditions intended by the owner in re-spect of the vessel's operation.303 If the owner does not supply sufficiently detailed infor-mation regarding such loading conditions, calculations shall bemade for the standard loading conditions in 304 and 305.304 The following standard loading conditions apply to car-go ships:

— ship in the fully loaded departure condition, with cargo ho-mogeneously distributed throughout all cargo spaces andwith full stores and fuel

— ship in the fully loaded arrival condition, with cargo ho-mogeneously distributed throughout all cargo spaces andwith 10% stores and fuel remaining

— ship in ballast in departure condition, without cargo butwith full stores and fuel

— ship in ballast in arrival condition, without cargo and with10% stores and fuel remaining.

305 The following additional loading conditions apply tocargo ships intended to carry deck cargoes:

— ship in the fully loaded departure condition with cargo ho-mogeneously distributed in the holds and with cargo spec-ified in extension and weight on deck, with full stores andfuel

— ship in the fully loaded arrival condition with cargo homo-geneously distributed in the holds and with cargo specifiedin extension and weight on deck, with 10% stores and fuel.

306 In the fully loaded departure conditions in 304 and 305the ship shall be assumed loaded to the summer load waterline,or if intended to carry timber deck cargo, to the summer timberload line. The water ballast tanks should normally be assumedempty.307 In all cases, the cargo in holds is assumed fully homoge-neous unless this is inconsistent with the practical service ofthe ship.308 Where timber deck cargoes are carried, the amount ofcargo and ballast shall correspond to the worst service condi-tion in which all the stability criteria in D100 are met. In thearrival condition it shall be assumed that the weight of the deckcargo has increased by 10% due to water absorption.309 In all cases, when deck cargo is carried, a realistic stow-age weight shall be assumed and stated, including the height ofthe cargo.

Guidance note:For ships carrying timber deck cargoes conditions should beshown indicating the maximum permissible amount of deck car-go having regard to the lightest stowage rate likely to be met inservice.


310 Only those parts of the ship that are adequately protectedby weathertight closing are accepted included as buoyant in thestability calculations.

Guidance note:Reference is made to IMO Intact Code IMO Res. A. 749(18), Ch.3.6 and the IACS UI LL62.


311 The Society may allow account to be taken in stabilitycalculations of the buoyancy of the deck cargo assuming thatsuch cargo has a permeability of 0.25.

E. Damage StabilityE 100 Damage stability101 Vessels with additional class notations shall complywith the additional damage stability requirements as given inthe appropriate rule chapters.102 Cargo ships of 80 m in length (Ls) and upwards shallcomply with the damage stability requirements according toSOLAS Ch.II-1, Part B-1. Cargo ships that have to complywith other mandatory damage stability regulations, see thefootnote of SOLAS Ch.II-1, Part B-1, may be excluded fromthe application. 103 Ships having a reduced freeboard type A or reduced B-freeboard shall comply with Regulation 27 of the InternationalLoad Line Convention.

F. Determination of Lightweight DataF 100 Application101 Every passenger ship and cargo ship shall be inclinedupon its completion and the lightweight displacement and cen-tre of gravity determined.102 The inclining test required in 101 may be dispensed withprovided basic stability data are available from the inclinationtest of a sister ship and it is shown to the satisfaction of the So-ciety that reliable stability information for the exempted shipcan be obtained from such basic data.

Guidance note:Dispensation according to 102 is not considered applicable topassenger ships and other ships where the lightweight is morethan 75% of the total displacement.


F 200 Procedure201 The inclining test shall be carried out according to theapproved test procedure and in the presence of the Society'srepresentative.

Guidance note:Guidelines for conducting inclining test or lightweight survey aregiven in IACS Rec. No. 31.


202 The inclining test report shall be signed by the person re-sponsible for the test and by the Society's representative.

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203 The approved lightweight and centre of gravity shall beused in the final stability booklet.

F 300 Lightweight Survey301 A lightweight survey shall be carried out if an incliningtest has been dispensed with according to 102.302 In case structural strength limitations etc. make it impos-sible to perform an inclining test, a lightweight survey may beaccepted provided a detailed lightweight estimate including

VCG is worked out in advance and the estimate compared withthe result of the lightweight survey. If the lightweight surveyreveals a deviation of lightweight data from the estimate, thedeviation is assumed to be at the most unfavourable positionwhen calculating the vertical centre of gravity.303 If, compared with the sister ship, the lightweight surveyreveals a lightweight displacement deviation exceeding 2% oran LCG deviation exceeding 1% of the length of the ship, aninclining test may be required.

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SECTION 10 INTERNAL COMMUNICATION

A. General RequirementsA 100 Application101 This section contains all requirements pertaining to pub-lic address systems, systems for two-way voice communica-tion, and general alarm systems including relevant SOLASregulations with the latest amendments.102 If any part of this section contains requirements whichappear to be in conflict with SOLAS, then the interpretationbased on SOLAS takes precedence.103 The requirements of B applies to all ships, except fishingvessels, for the assignment of main class. Reference to similarSOLAS requirements is given after each item.Main class requirements for fishing vessels are listed in C100.104 The requirements of C apply to ships for the assignmentof service notations and additional class notations.

A 200 Classification201 Assignment of class requires the following elements re-garding the internal communication systems:

— approval of design documentation— onboard survey and testing.

A 300 Design documentation301 Plans, particulars and system descriptions shall be sub-mitted in order for DNV to verify that that:

— the functional, technical and environmental requirementsapplicable to Internal Communication systems have beenaddressed during the design of the ship

— all applicable requirements will be complied with whenthe ship has been completed, without requiring majorchanges and/or additions to the systems at a final stage.

Final approval of all internal communication systems based onthe approved documents shall be carried out during onboardsurvey.302 The documentation shall contain the information neces-sary to verify compliance with the requirements in this section,and all functional and environmental requirements as referredto in the Guidance note. Generally the documentation shouldbe kept as brief as possible, and may be divided in the follow-ing main elements:

1) Type approval certificate. Refer to Guidance note for ap-plicable standards. If type approval certificates based on the standards as list-ed in the Guidance note are not available then functional,operational, installation manuals and environmental spec-ifications showing compliance with all applicable stand-ards as listed in Guidance note are required for a case-by-case verification and approval.

2) Location requirements.3) Power supply requirements and cabling.

Guidance note:Item 1: The following standards and references define the appli-cable functional and environmental requirements for internalcommunication systems:- IMO A.830 (19) and the International Life-Saving Appliance

(LSA) Code adopted by IMO by Res. MSC.48(66) , applica-ble to public address system and general alarm system mainclass.

- MSC Circ. 808, applicable to public address system to pas-senger vessels.

- Functional requirements as defined in this section based ondifferent class notations, applicable to two-way voice com-munication systems.

- Environmental requirements according to IEC60945 or Certi-fication Note 2.4 apply to all internal communication systems.

Item 2: Drawings showing the physical location of componentsto be submitted. Alternatively this may be covered by tables/de-scriptions giving the necessary information regarding locationsof components, types, etc. to the satisfaction of the Society.Item 3: May be covered with a short description or a one-linegeneral arrangement drawing.


303 In addition to documentation approved by the Society,manuals and drawings providing operational and technical in-formation for service and maintenance purposes shall be deliv-ered on board.

A 400 Onboard survey or functional testing401 When completed, the systems shall be tested in order toensure compliance with the rules in regard to functionality.Furthermore, it shall be verified that the approved documenta-tion is consistent with the final installation.402 Final approval of the systems takes place following thesurvey, when comments, if any, have been complied with.

A 500 Terms, definitions and abbreviations501 The terms intercom and internal communications, whenused generally, apply to the following:

— public address systems— general alarm systems— two-way voice communication systems such as automatic

telephone systems, talk back systems, sound powered tel-ephones, portable UHF/VHF apparatuses, etc.

502 Where the Code is referred to in the text, this means theInternational Life-Saving Appliance (LSA) Code adopted byIMO by res. MSC.48(66).503 The term accommodation, when used generally, in-cludes the following areas: all public rooms, corridors, lavato-ries, stairways, offices, hospitals, games and hobbies rooms,barber shops and pantries containing no cooking appliances.

B. Ship Requirements - Main Class Cargo Ship and Passenger Vessels

B 100 Two way voice communication101 Two-way voice communication shall be provided be-tween the navigation bridge, the steering gear compartmentand emergency steering position, if provided.(SOLAS Regulation II-1/29.10)102 Two-way voice communication shall be provided be-tween navigation bridge and the position in the machineryspace or in the control room from which the speed and direc-tion of thrust of the propellers are normally controlled.(SOLAS Regulation II-1/37.1 regarding two way voice com-munication only)103 Two-way voice communication shall be provided be-tween the navigation bridge and the engine room and any other

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position from which the speed or direction of thrust of the pro-pellers may be controlled (including azimuth thruster compart-ment if provided with local control).(SOLAS Regulation II-1/37.2 regarding two way voice com-munication only)104 Two-way voice communication shall be provided be-tween emergency control stations, muster and embarkationstations and strategic positions on board.(SOLAS Regulation III/6.4.1)

Guidance note:Strategic positions are the bridge and engine control room.


105 Dedicated type approved portable two-way voice com-munication apparatuses, with charger arrangement, may beused for compliance with the requirements of B101 to B104provided that there is sufficient radio communication coveragein the specified locations.In addition to the type approval, or case-by-case approval, re-quirements in section A302, all national and international radiocommunication requirements and provisions, and require-ments in B106 to be complied with when portable two wayvoice communication apparatuses are used to comply with thetwo way voice communication systems.106 The two way voice communication system shall:

— have priority function. Navigation bridge and ECR shallhave the highest priority

— be capable of providing at least 4 simultaneous calls— have facilities for efficient communication in noisy envi-

ronment, if deemed necessary by the Society.

If portable two way voice communication apparatuses are usedfor compliance with two way voice communication require-ments, then the following applies:

— at least 4 channels to be provided (in addition to channel16 if VHF apparatuses are used)

— a dedicated channel for communication between thebridge and ECR to be provided

— facilities for efficient communication in noisy environ-ment to be provided

— chargeable batteries, with a capacity to operate the equip-ment continuously for at least 5 hours, to be provided foreach unit at the required position

— chargers to be type approved based on IEC60945 or simi-lar

— chargers installed on the Bridge to be supplied by mainsand emergency sources of power as required in B401

— chargers installed in other locations than the bridge to besupplied by mains and emergency sources of power as re-quired in B401, or from an emergency distribution boardinstalled near the location of the charger.

Guidance note:Continuous operation means sequences of 1 minute transmis-sions followed by 9 minutes reception, without signals at the re-ceiver input.


B 200 Public address system/General alarm, applicable to all vessels201 A general emergency alarm system complying with therequirements of paragraph 7.2.1. of the Code shall be providedand shall be used for summoning the passengers and crew tomuster stations. The system shall be supplemented by a publicaddress system complying with the requirements of paragraph7.2.2 of the Code. Any centralized entertainment sound sys-tems shall automatically be turned off when the general emer-gency alarm system is activated.

The general emergency alarm shall be capable of sounding analarm signal consisting of seven short blasts followed by onelong blast to all areas as specified in the subsequent para-graphs.The general alarm shall continue to function after it has beentriggered until it is manually turned off or is temporarily inter-rupted by a message on the public address system.Initiation of an emergency announcement on the public ad-dress system shall mute the general alarm system and the gen-eral alarm shall continue after ended public addressannouncement.In addition, general emergency alarm shall have priority overother alarms.(SOLAS Regulation III/6.4.2)

Guidance note:With reference to the Code and IMO Res. A. 830(19), soundpressure levels are defined as follows:

a) General alarm- Interior and exterior spaces: 80 dB (A) and at least 10 dB

(A) above ambient noise levels.- In sleeping positions and cabin bathrooms: 75 dB (A)

and at least 10 dB (A) above ambient noise level.b) Public address

- Interior spaces, including sleeping positions and cabinbathrooms: 75 dB (A) and at least 20 dB (A) above am-bient noise level.

- Exterior spaces: 80 dB (A) and at least 15 dB (A) aboveambient noise level.

c) In no cases should the audible alarm levels in a space exceed120 dB (A).


Guidance note:A centralised entertainment sound system is a system that is con-trolled by a central unit. This central unit can be part of the gen-eral alarm or public address central units; or can be a separateunit used only for distribution of entertainment sounds to the dif-ferent parts of the vessel.


202 The general emergency alarm system shall be arrangedeither:

— as one (or more) closed loop(s), or— with fuses/breakers provided at each deck such that fail-

ure/short circuit in any deck does not affect other decks orthe central unit.

Guidance note:Following examples show the two alternative solutions for de-sign of general alarm system:

a) Closed loop solution, meaning that the main loop from theGA central starts and ends at the central:

General Alarm Central

Closed Loop

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b) Open loop solution, with fuses/breakers at distributions ateach deck:


203 The general emergency alarm system shall be audible inaccommodation and all normal crew working spaces. In areaswith high ambient noise level, additional flashing light shall beused.(SOLAS Regulation III/6.4.2 and III/6.4.3)204 General emergency alarm shall be connected to the shipswhistle/siren/typhoon. 205 General emergency alarm buzzer or public address loud-speakers shall be provided in all cabins.Public Address announcements or general alarm signal shallbe audible in accordance with B201.206 Public address loudspeakers shall be provided in allspaces where crew or passengers or both are present such asaccommodation, all normal crew working spaces and musterstations.(International Life-Saving Appliance (LSA) Code Ch. VII7.2.2.1)207 If general emergency or fire alarm is integrated with thepublic address system then no single failure shall render bothsystems inoperative in the same area. The following applieswhen general alarm or fire alarm is integrated with public ad-dress system:

— The general alarm signal generator, amplifiers, centralcontrol unit and any other essential part of the system shallbe duplicated.

— In all public areas, at least two separated and segregatedcable routes shall be provided, one from each amplifier.The segregation of two cable loops shall be such that incase of failure of one loop in one area, the general/firealarm and public address announcements shall continue tobe audible in that area.

Guidance note:Provisions in IMO Res. A. 830(19) apply to general emergencyalarm and public address systems.


B 300 Public address system, applicable to passenger vessels301 All passenger vessels shall be provided with a public ad-dress system complying with IMO MSC/Circ. 808.The public address system shall be clearly audible above theambient noise in all spaces, prescribed by paragraph 7.2.2.1ofthe Code.Public Address control stations with an override function as re-quired in IMO MSC/Circ. 808 item 202 shall be installed onthe navigation bridge and such other places on board to the sat-isfaction of the society, so that all emergency messages will bebroadcast if any loudspeaker in the spaces concerned has beenswitched off, its volume has been turned down or the public ad-dress system is used for other purposes.(SOLAS Regulations III/6.5.1 and III/6.5.2)302 On passenger ships constructed on or after 1 July 1997:

— the public address system shall have at least two loopswhich shall be sufficiently separated throughout theirlength and have two separate and independent amplifiers,and

— the public address system and its performance standardsshall be in accordance with the performance standards forpublic address systems contained in IMO MSC/Circ.808.

(SOLAS Regulation III/6.5.3)303 The effect of one failure should be minimised as far aspossible. All public areas shall be served by at least two loopsand supplied by independent amplifiers so that announcementsin all public areas are audible in the case of failure of one loopor amplifier. Amplifiers shall be physically separated, and if only two am-plifiers are used for the complete system, they should not be lo-cated in the same fire zone.In addition, public address loudspeakers shall be provided inall cabins. Neighbouring cabins shall be supplied by differentloops as far as practicable.

Guidance note:Ships constructed before 1 July 1997 which are already fittedwith the public address system approved by the Administrationwhich complies substantially with those required by sections 302and 401 and 402 and paragraph 7.2.2.1 of the Code are not re-quired to change their system.(SOLAS Regulation III/6.5.5)


B 400 Electrical requirements401 Public address, general alarm and fixed two way voicecommunication systems (main class) shall be supplied by mainand emergency source of power as required in Pt.4 Ch.8 Sec.2.The capacity of the power sources for public address, generalalarm and fixed two way voice communication system shall bein accordance with Pt.4 Ch. 8 Sec.2 Table C1.

Guidance note:The above requirement does not prevent the use of self-containedcommunication systems, such as sound powered telephones orother battery operated communication systems, provided the ca-pacity of the energy source is sufficient to operate the system for18 hours.Refer to B107 for power supply, battery and charger require-ments for Portable two way voice communication systems.


Fuse Fuse

Fuse

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402 In addition to requirements in 401, public address sys-tem on passenger ships shall be supplied by ship's transitionalsource of power.403 Cables shall be in accordance with Pt.4 Ch.8.404 Communication cables screens shall be earthed at oneend only.405 Communication equipment located or used in areaswhere flammable gases may be present shall be certified intrin-sically safe.

C. Ship Requirements - Additional ClassC 100 Fishing vessels101 As a minimum, either a general emergency alarm or apublic address system, in accordance to B200, shall be provid-ed on all fishing vessels.102 In addition to the requirements in B100 and B400, if the'tweendeck is fitted with side openings, two-way voice com-munication shall be provided between the bridge and in theway of the doors in the vessel's side and stern. AlternativelyTV monitoring may be provided.

C 200 Oil production and storage vessels201 In addition to the requirements in B100 and B200 thefollowing apply:202 A two-way voice communication system shall be pro-vided, making it possible to call all areas likely to be regularlymanned from the control stations, navigation bridge and en-gine room(s).

Guidance note:Control stations are those spaces in which the radio, main navi-gating equipment, central fire detection or control systems, gasdetection system, central internal communication equipment,emergency shut-down system, or emergency source of power arelocated.


203 The two way voice communication extensions on con-trol stations and the navigation bridge shall have priority.204 The required internal communication systems shall becapable of being supplied from the emergency source of pow-er, for a period of at least 24 hours.205 The two way voice communication system shall func-tion during black-out.The capacity of the energy source during black-out shall besufficient to operate the system for at least 30 minutes.

C 300 Periodically unattended machinery space301 In addition to the requirements in B100 and B200 thefollowing apply:302 For ships above 500 gross tonnage a reliable means ofvocal communication shall be provided between the main ma-chinery control room or the propulsion machinery control po-sition as appropriate, the navigation bridge and engineerofficers' accommodation.(SOLAS Regulation II-1/50)303 The two-way voice communication, as required byC301, shall function during black-out.The capacity of the energy source during black-out shall besufficient to operate the system for at least 30 minutes.

C 400 Dynamic positioning systems401 In addition to the requirements in B100 and B200 thefollowing apply:

402 A two-way voice communication facility shall be pro-vided between the DP-system control centre and the naviga-tion bridge, ECR and relevant operation control centres.403 The two way voice communication, as required byC401, shall function during black-out.The capacity of the energy source during black-out shall besufficient to operate the system for at least 30 minutes.

C 500 Nautical safety501 In addition to the requirements in B100, B200, and B300(for passenger vessels) the following apply:502 Batteryless telephone systemsTo secure internal communications independent of an electri-cal power supply, a batteryless telephone system shall be pro-vided for two-way voice communication between thewheelhouse and the:

— engine control room— steering gear room— captain's living quarters— chief engineer's living quarters— radio room (when located outside of the bridge area).

In the steering gear room, facilities shall be provided to avoidnoise interference when using the batteryless telephone.503 Automatic telephone systemsThe automatic telephone network shall provide two-way voicecommunication between the bridge, all workstations and allrelevant spaces, and shall function during black-out. The capacity of the energy source during black-out shall besufficient to operate the system for at least 30 minutes.The wheelhouse shall be fitted with two independent user ex-tensions. Incoming calls on adjacent telephones shall be distin-guishable by lights and/or different ring tones. The telephonenetwork shall be designed with a minimum capacity for two si-multaneous calls. The telephones in the wheelhouse and en-gine control room shall have priority function over any otherextension.A reference list of extensions shall be permanently postedwithin reach of each telephone.504 Public address systemsThe public address (PA) system shall enable point-to-pointloud hailing intercom between the bridge and all relevant are-as, and shall function during black-out.The capacity of the energy source during black-out shall besufficient to operate the system for at least 30 minutes.The public address system control module shall be suitable forflush panel mounting in workstation consoles.Outdoor substations shall have enclosures with IP 56 or higher.Substations installed in watertight housings, e.g. forecastle,with extension cables for outdoors use shall have enclosureswith an IP of 53 or higher.Each substation shall be equipped with an activation light toindicate communication readiness. The talk-back speaker sys-tems shall have a volume control.The amplifier units shall be protected against failure in the in-tercom network or in the substation equipment.The public address control module, including microphone andtalkback devices (if used for compliance with 504), shall be lo-cated in the wheelhouse.Public address loudspeakers shall be provided in all crew cab-ins, offices and lounges.A reference list of all public address areas (where different ar-eas are selectable) shall be permanently posted within reach ofeach public address control module.

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505 Hands free two-way voice communication shall be pro-vided at the following locations:

— bridge wings— forecastle deck (fore mooring stations)— aft mooring station— midship mooring station— steering gear room— engine control room— cargo control room.

Any system used to comply with the above communication re-quirements shall be either type approved or approved on acase-by-case, as specified in A302 item 1 and B106.

Guidance note:The above may be implemented either by Talk Back, talkbackfunction through public address system, or alternatively by ded-icated UHF apparatuses with hands free operation and chargerarrangement for each location mentioned above provided thatthere is sufficient UHF radio communication coverage in thespecified locations. If the public address system is used for Talk Back as required by504 then the talk-back speaker systems shall have a volume con-trol.Any UHF equipment provided for compliance to the provisions

of 504 shall be in addition to UHF equipment required by 505with similar power supply requirements as defined in 505 and506.


506 UHF SystemTo assist in safety and navigation, the bridge shall be providedwith at least four portable UHF transceivers complying withthe requirements in B106 and operating in the 457 to 467 MHzband.The equipment shall include microphone, loudspeaker andchargeable batteries, with a capacity to operate the equipmentcontinuously for at least 5 hours. Refer to Guidance note inB106 for definition of the continuous operation.507 A battery charger having sufficient capacity to re-chargeall UHF transceivers simultaneously shall be installed in aneasily accessible location within the wheelhouse.

Guidance note:The charger unit or units should as a minimum have slots for 4UHF transceivers and be capable of re-charging the 4 UHF trans-ceivers.


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