STABILITY REQUIREMENTSSTABILITY REQUIREMENTS

Rob Gehling

Principal Adviser – Technical Marine Standards

Maritime Safety & Environmental Strategy

AMSA, Canberra

YOUR TASKYOUR TASK

Presumed to be to design your vessel with intact stability characteristics to meet the appropriate statutory criteria - and ultimately prepare trim & stability

booklet as would be required for submission to a regulatory authority

YOUR AIM!YOUR AIM!If under AMSA jurisdiction, to provide the Master

with “such information satisfactory to the Administration as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of the ship under varying conditions of service”– Refer SOLAS II-1/22.1– Load Lines Protocol (1988) reg. 10(2)(b) similar

Appendix 2 of Marine Orders Part 12 defines what is “satisfactory” to AMSA

Other jurisdictions (eg. State, Military) have similar, if sometimes less stringent requirements

MY BACKGROUNDMY BACKGROUND

3 years as Naval Architect in Drawing Office of large shipyard, preparing and gaining approval for stability booklets

12 years in AMSA and its predecessors, assessing and approving stability booklets

Australian delegate to IMO’s Sub-Committee on Stability, Load Lines and Fishing Vessels Safety (SLF) since 1988, taking specific interest in operational intact stability issues– Recently elected as Vice-Chairman of SLF

JURISDICTIONJURISDICTIONDetermined by ship type and trading pattern

– Military – DoD’s own rules but are often guided by commercial rules which they may make mandatory (ref. s.3, Navigation Act 1912)

– Trading ship (ref. s.2(a), Navigation Act) - State requirements (USL Code) for intra-state voyages incl charter boats, but AMSA (Marine Orders/SOLAS) for inter-state and international service

– Fishing vessel or fishing fleet support vessel (ref. s.2(b)/(ba), Navigation Act) – State requirements (USL Code) unless on international voyages, then AMSA

– Pleasure craft (ref. s.2(d), Navigation Act) - State Boating laws re equipment but refer AYF and relevant parts of AS.1799 re design and construction

DEFINITIONSDEFINITIONSPassenger ship (SOLAS) is ship which carries more

than 12 passengersCargo ship (SOLAS) is any ship which is not a

passenger shipSpecial purpose ship (Special Purpose Ship Code) is

a mechanically self-propelled ship which by reason of its function carries more than 12 special personnel (persons who are not passengers or crew and who are in board in connection with the special purpose of the ship or special work being carried out aboard the ship, number includes any passengers)

CODESCODES Offshore Supply Vessel (OSV) Guidelines

– Intact and damage stability requirements Mobile Offshore Drilling Unit (MODU) Code

– Includes intact & damage stability High-Speed Craft Code (2000)

– Alternative to SOLAS construction/equipment /certification requirements, includes intact & damage stability criteria

Special Purpose Ship Code– Modifies SOLAS for SPSs, includes intact & damage

stability criteria Uniform Shipping Laws (USL) Code

– Used by State/NT authorities, stability mainly intact

IMO INTACT STABILITY CODEIMO INTACT STABILITY CODEAdopted in November 1993 through res. A.749(18)

and has since been amended by res. MSC.75(69)Intended to be a consolidation of requirements and

guidance information adopted by IMO (eg. res. A.167(ES.IV), A.168(ES.IV), A.206(VII), A.268(VIII) & Codes for specific vessel types)– Non-mandatory but now under review again with view to

some parts being made mandatory

Useful reference but not implemented by Australia (refer Marine Orders Part 12) because of problems with weather criterion among other things

TYPICAL TRIM & STABILITY TYPICAL TRIM & STABILITY BOOKLET AS PER MO.12BOOKLET AS PER MO.12

General stability-related info– vessel particulars, draft mark diagram, immersion angle

& heeling lever diagramsInfo for Master and officers

– Instructions & stability criteriaWorked example of stability condition calculationCalculations for typical / “worst” loading conditionsSupporting data/tables/graphs

– Tank plan & table, tank calibrations, hydrostatic tables, KN tables, nomenclature, inclining report

NOTE – Actual required content varies with ship type

STABILITY CRITERIA –STABILITY CRITERIA –LANDING CRAFT LANDING CRAFT

Statutory Authority is Dept of Defence, so following info relates to hypothetical (?) application of commercial criteria

Criteria are at 6.2.2 and 6.2.3 of Appendix 2 to Marine Orders Part 12, most likely using 6.2.3(k), or 8.C.16 of USL Code– Allows for maximum GZ to occur at angles between

15deg. and 25deg, but requires higher area under GZ curve to 30deg. than normal IMO criteria

– Note that criteria not to vary between load conditions

STABILITY CRITERIA –STABILITY CRITERIA –MBD DAY SAILER/RACER MBD DAY SAILER/RACER

As “pleasure craft” no statutory stability requirements apply– But refer AYF stability requirements(?)

Refer yacht stability requirements(?) of AS.1799 Small Pleasure Boats Code– Not mandatory but have effect under consumer protection and

trade practices law

Statutory stability requirements could apply if vessel put into survey for commercial operations (eg. harbour sailing)– USL Code section 8.C.12 implemented by State authorities and

also called up by Marine Orders Part 12 (not AMSA jurisdiction!)

STABILITY CRITERIA –STABILITY CRITERIA –NWBS DAY TRIP BOATNWBS DAY TRIP BOAT

Apply relevant criteria from section 8.C.1 of USL Code– Assuming vessel is under State jurisdiction (not AMSA)

Could use criteria of 2.3 to 2.5 of 2000 HSC Code– Call-up standards of Annexes 7 and 8 of Code,

depending on whether craft is monohull or multihull

Note that 1.1 of Annex 8 to the 2000 HSC Code calls up the “Severe wind and rolling criterion” from the IMO Intact Stability Code– Absence of adjustments to tabulated factors to apply to

HSC renders such application difficult

STABILITY CRITERIA –STABILITY CRITERIA –NWBS DAY TRIP BOAT (CONT)NWBS DAY TRIP BOAT (CONT)

Note that Table 2.3.4 of 2000 HSC Code provides for some inter-changeability between the requirements of Annexes 7 and 8– Eg. trimarans’ stability is similar to monohulls but amahs

of can be tailored to meet the specified stability criteria

CFD may soon enable compliance with 2.4 to be verified by calculation but trials required for now

Intact stability criteria currently being researched as major part of review of 2000 HSC Code

AUSTAL MONOHULL AUSTAL MONOHULL CREW/SUPPLY VESSELCREW/SUPPLY VESSEL

Mexican flag and high service speed would normally pose questions– But these are answered by specification of IMO Code on

Intact Stability (IS Code)– Severe Weather Criterion NOT required

Note 2000 HSC Code could not be applied as HSC Code requires high-speed criterion to be met at displacement of maximum operational weight

Consider using 4.5.6 of IS Code in place of 3.1.2– Offshore cargo handling probably precludes fitting passenger

cabin above cargo deck

DAMAGE STABILITYDAMAGE STABILITY

(Not part of brief for this presentation but generally results in relevant operational information being

included in Trim & Stability Booklet)

ANY QUESTIONS????ANY QUESTIONS????

DAMAGE STABILITYDAMAGE STABILITY – SOLAS & MARPOL – SOLAS & MARPOL

SOLAS Ch. II-1 Part B provides deterministic requirements for subdivision of passenger ships, Res. A.265(VIII) is probabilistic alternative

SOLAS reg.II-1/8-1 covers probabilistic subdivision and damage stability of ro-ro passenger ships

SOLAS Ch.II-1 Part B-1 provides for probabilistic subdivision & damage stability for dry cargo ships of L>80m unless covered by deterministic criteria

MARPOL Annex I specifies oil tanker subdivision & damage stability requirements incl. double-hulls

DAMAGE STABILITY – DAMAGE STABILITY – SOLAS/MARPOL-RELATED CODESSOLAS/MARPOL-RELATED CODES

International Bulk Chemical (IBC) Code gives requirements for chemical carriers– note that where a chemical carrier can carry

petroleum grades in addition to noxious liquid substances in bulk, MARPOL Annex I also applies

International Gas Carrier (IGC) Code gives requirements for liquefied gas carriers

Other Codes cover existing ships – unnecessary to list here

NOTE RE PROBABILISTIC NOTE RE PROBABILISTIC

DAMAGE STABILITYDAMAGE STABILITYRes. A.265 (IX) (1973) is probabilistic alternative to SOLAS Ch.II-1 damage stability requirements– now applied to ro-ro passenger ships through

SOLAS reg. II-1/8-1Amendments to SOLAS Ch. II-1 scheduled for

adoption in May to “harmonise” probabilistic method for passenger & cargo ships (flood length)

Probabilistic principles likely to be extended to Load Line and MARPOL Conventions’ damage stability

MARPOL Annex I oil outflow and guidelines for double-hull equivalence are already probabilistic

INTACT STABILITY DATA -INTACT STABILITY DATA -DAMAGE STABILITY LINKDAMAGE STABILITY LINK

A given ship at a given displacement and trim will have a limiting intact KG at which it meets any damage stability criterion

Tracking this data over a range of intact displacements and trims gives a series of limiting KG curves within which the ship must be operated to maintain compliance with the criterion

Such curves are most useful to the Master when integrated into the intact stability booklet– preferably on the same page as similar limiting KG

information for intact stability criteria

OTHER ASPECTS OF OTHER ASPECTS OF STABILITYSTABILITY

SHIPS FOR DRY BULK SHIPS FOR DRY BULK CARGOESCARGOESThe most important criterion for such ships is in

relation to ships which may carry grain, which must comply with the International Grain Code which is given mandatory effect in SOLAS reg. VI/9– Most bulk carriers are designed to comply with this Code

even if they are intended to engage in the iron ore and coal trades – commercially important in terms of both resale features and being able to accept grain cargoes when they arise

– Involves provision of Grain Stability DataFor specialised bulk cargoes, Bulk Cargoes Code

should be checked for any extra requirements– Eg. transportable moisture limits, extra watertight

integrity / bilge requirements, gas sniffing (coal)

TIMBER CARGOESTIMBER CARGOES

Many Handy-size bulk carriers are arranged for carriage of timber on deck (clear side-decks, stanchions)

1966 Load Line Convention Annex I, Ch. IV provides for assignment of “lumber” load lines– stability requirements are as per 4.1 of Intact

Stability Code which in turn calls up the Code of Safe Practice for Ships Carrying Timber Deck Cargoes

SUMMARYSUMMARYIt is essential to establish the jurisdiction and

regulatory environment in which the ship will operate at the outset– This varies between your selected projects

AMSA intact stability requirements generally build on basic IMO stability criteria, HSC is exception

Looking beyond intact stability, relevant intact stability criteria related to cargoes and the operational linkage between intact and damage stability should not be overlooked

ANY QUESTIONS????ANY QUESTIONS????