mooring force analysis methods pianc_2003_mooring_waters

5/22/2018 Mooring Force Analysis Methods Pianc_2003_mooring_waters

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Mooring Force AnalysisMooring Force AnalysisMethodsMethods

with Application to Breakawayswith Application to BreakawaysCaused by Passing VesselsCaused by Passing Vessels

Jennifer K. Waters, Ph.D., P.E.Jennifer K. Waters, Ph.D., P.E.

Associate ProfessorAssociate ProfessorDept of Naval Architecture & Ocean EngineeringDept of Naval Architecture & Ocean Engineering

U.S. Naval AcademyU.S. Naval Academy

Annapolis, MDAnnapolis, MD


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OverviewOverview

PurposePurpose

BackgroundBackground

USCG MC Incident DataUSCG MC Incident Data

Findings from Actual CasesFindings from Actual Cases

DiscussionDiscussion

ConclusionsConclusionsAcknowledgementsAcknowledgements


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The PhenomenonThe Phenomenon

Ship 2

Moving

V

Moored

Ship 1

Pier or

Wharf

x

X-F

FY+

M-


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Why Develop & StudyWhy Develop & Study

Mooring Forces Methods?Mooring Forces Methods?Design of Navigation ChannelsDesign of Navigation Channels

Reducing Marine Casualty IncidentsReducing Marine Casualty Incidents(and Consequences)(and Consequences)

Property DamageProperty DamageShip & PierShip & Pier PollutionPollution

Injuries/DeathsInjuries/Deaths


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Motivation and Purpose of ProjectMotivation and Purpose of Project

DeepDeep--Draft navigation channel congestionDraft navigation channel congestion

TrafficTraffic BlockageBlockage

Ship berths in close proximity to transitingShip berths in close proximity to transiting

vesselsvessels

Tasked to investigate occurrences ofTasked to investigate occurrences of

vessel mooring breakaways due tovessel mooring breakaways due topassing vesselspassing vessels

Frequency; LocationsFrequency; Locations

Characteristics & preliminary analysis ofCharacteristics & preliminary analysis ofeventsevents


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Mooring Force Analysis MethodsMooring Force Analysis Methods

NumericalNumerical

AnalyticalAnalytical

PhysicalPhysical

Experimental / ModelExperimental / Model--ScaleScale FullFull--ScaleScale

Evidentiary or ForensicEvidentiary or Forensic


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BackgroundBackground

Literature ReviewLiterature Review

NavyNavyMILMIL-- HDBK 1026/4:HDBK 1026/4: Mooring Design Handbook (Mooring Design Handbook (replrepl..

NAVFAC DM 26.4)NAVFAC DM 26.4)

MILMIL--HDBK 1025/1:HDBK 1025/1: Piers and WharvesPiers and Wharves

DM 26.6:DM 26.6: Mooring Design Physical and Empirical DataMooring Design Physical and Empirical Data

TRTR--60056005--OCN:OCN: EMOOREMOOR --A Planning/PreliminaryA Planning/Preliminary

Design Tool for Evaluating Ship Moorings at Piers andDesign Tool for Evaluating Ship Moorings at Piers and

WharvesWharves USACEUSACE

EM 1110EM 1110--22--1100 (Part II):1100 (Part II):

CEM Harbor HydrodynamicsCEM Harbor Hydrodynamics


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Literature Review (contd)Literature Review (contd) Essential ReferenceEssential Reference

Guidelines and Recommendations for the Safe Mooring of LargeGuidelines and Recommendations for the Safe Mooring of LargeShips at Piers and Sea IslandsShips at Piers and Sea Islands, Oil Companies International Marine, Oil Companies International MarineForum (OCIMF)Forum (OCIMF)

Proceedings, North Atlantic Treaty Organization (NATO) AdvancedProceedings, North Atlantic Treaty Organization (NATO) Advanced

Study Institute on Analytical Treatment of Problems of BerthingStudy Institute on Analytical Treatment of Problems of Berthing andandMooring Ships (Lisbon, Portugal, 1965), Published by ASCE 1970Mooring Ships (Lisbon, Portugal, 1965), Published by ASCE 1970

NATONATO--ASI Advances in Berthing and Mooring of Ships andASI Advances in Berthing and Mooring of Ships andOffshore Structures,Offshore Structures, TrondheimTrondheim, Norway, 1987, E., Norway, 1987, E. BrattelandBratteland, ed., ed.

Design of Marine FacilitiesDesign of Marine Facilities, J., J. GaythwaiteGaythwaite, 1990, 1990

Port EngineeringPort Engineering, P., P. BruunBruun

Handbook of Port & Harbor EngineeringHandbook of Port & Harbor Engineering, G., G. TsinkerTsinker

SeeligSeelig (2001),(2001), FloryFlory (2001), Lean and Price (1977), King (1977)(2001), Lean and Price (1977), King (1977)Wang(1975),Wang(1975), MugaMuga and Fang (1975),and Fang (1975), RemeryRemery (1974)(1974)


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Mooring Analysis SoftwareMooring Analysis Software

NavyNavyEE--MOOR, FIXMOOR, PASSMOOR, FIXMOOR, PASS--MOORMOOR

CommercialCommercial

ShipShip--Generated Hydrodynamics (SGH)Generated Hydrodynamics (SGH)PIPIEngineeringEngineering MOSESMOSES

OPTIMOOROPTIMOOR -- Tension TechnologyTension Technology

AQWAAQWA -- WS AtkinsWS AtkinsSHIPSHIP--MOORINGSMOORINGSAlkyonAlkyon

OthersOthers


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Mooring Line ResearchMooring Line Research

Deepwater MooringDeepwater MooringAnalysisAnalysis Many StudiesMany Studies TAMU; MARINTAMU; MARIN

CaternaryCaternary; TLP; TLP

PiersidePierside Mooring LineMooring LineDynamicsDynamics

Not much in literatureNot much in literature Geometry much more complexGeometry much more complex

Usually based on linear or nonUsually based on linear or non--linearlinearelastic theory

Image from TAMU

elastic theory


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Mooring Line ArrangementsMooring Line Arrangements

123456

After BowSpring

Forward BowSpring

After QuarterSpring

Forward QuarterSpring

BowLine

SternLine

Spring Lines

OCIMF Guidelines OCIMF Guidelines Balanced load distributionBalanced load distribution

Loads


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Typical Mooring Force Analysis:Typical Mooring Force Analysis:

Begin w/ Hydrodynamic ModelBegin w/ Hydrodynamic Model((Example Shown: SGHExample Shown: SGH))


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Mooring Line Analysis Mooring Line Analysis


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Determine Vessel Motions Determine Vessel Motions


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and Mooring Line Loadsand Mooring Line Loads


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Approach of this StudyApproach of this Study

Investigated actual casualtiesInvestigated actual casualties

Worked with USCG Office of Investigations andWorked with USCG Office of Investigations andAnalysis (GAnalysis (G--MOA)MOA)

Looked at tenLooked at ten--year window (1991year window (1991--2001)2001)

Searched for Breakaway casesSearched for Breakaway cases

Reviewed cases individuallyReviewed cases individually

50+ Breakaways recorded due to passing vessels50+ Breakaways recorded due to passing vessels

20+ investigated in depth; preliminary analysis and20+ investigated in depth; preliminary analysis and

comparison to empirical mooring force analysiscomparison to empirical mooring force analysis


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USCG MC IncidentsUSCG MC Incidents

19911991--2001Breakaways2001Breakaways

1,000s of entries1,000s of entries 50+ cases of passing vessel breakaways50+ cases of passing vessel breakaways

ChallengesChallengesData:Data:


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USCG MCUSCG MC -- BreakawaysBreakaways

= Ship/Ship

Alaska

Hawaii

= Ship/Barge


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Vessel Critical Profile (VCP)Vessel Critical Profile (VCP)


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MC Investigation ReportsMC Investigation Reports


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Narrative

Supplement


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Analysis of CasesAnalysis of Cases

Used PASSUsed PASS--MOOR (MOOR (SeeligSeelig, 2001), 2001)

Simple, requires little input parametersSimple, requires little input parameters Still required to infer several characteristicsStill required to infer several characteristics

ShipShip

ChannelChannelMooringMooring

Sensitivity AnalysisSensitivity Analysis

Other tools reviewed/employed forOther tools reviewed/employed forconditions outside range of PASSconditions outside range of PASS--MOORMOOR


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-400

-300

-200

-100

0

100

200

300

400

500

600

0 50 100 150 200 250 300

TIME (sec)

Fx (kips)

Fy (kips)

APPLIED

FORCES

TOT

HEMOOREDS

HIP(kips)


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-150000

-100000

-50000

0

50000

100000

150000

0 50 100 150 200 250 300

TIME (sec)

APPLIED

MOMENT

TOT

HEMOOREDS

HIP(foot*kips)

M (ft*kips)


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FindingsFindings

Usually larger vessel passing smallerUsually larger vessel passing smaller

In most cases, estimated forces from empiricalIn most cases, estimated forces from empiricalanalysis methods were much smaller thananalysis methods were much smaller thanrequired for line breakagerequired for line breakage Other factors attributable to breakage occurrence?Other factors attributable to breakage occurrence?

A few cases did indicate excessive line forcesA few cases did indicate excessive line forcesResults are highly dependent onResults are highly dependent on Vessel VelocityVessel Velocity

Vessel ProximityVessel Proximity Current velocityCurrent velocity

Channel and berth depthsChannel and berth depths


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Additional FactorsAdditional Factors

Slack LinesSlack Lines SnapSnap--LoadingLoading

May Increase Line Load byMay Increase Line Load byan order of magnitudean order of magnitude

Lean and Price (1977),Lean and Price (1977), RemeryRemery (1974)(1974)

UnderkeelUnderkeel Clearance (UKC)Clearance (UKC) May Increase Added Mass values by factor of 2.0May Increase Added Mass values by factor of 2.0

Shoaling of Channels / Channel Sides / QuaysShoaling of Channels / Channel Sides / Quays Directly Affects UKCDirectly Affects UKC

Also Impacts HydrodynamicsAlso Impacts Hydrodynamics

Slack Mooring Lines andSlack Mooring Lines and


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Slack Mooring Lines andSlack Mooring Lines and

Snap LoadingSnap LoadingSlack Mooring Lines were directly implicated in many of the caSlack Mooring Lines were directly implicated in many of the casessesstudiedstudied

Snap loading arises when a mooring line transitions suddenly froSnap loading arises when a mooring line transitions suddenly from am aslack condition to a taut conditionslack condition to a taut conditionMay result in significantly greater forceMay result in significantly greater force

See, e.g.See, e.g. Farmer, A. (1999), Investigation Into Snap Loading of Cables UsFarmer, A. (1999), Investigation Into Snap Loading of Cables Used Ined In

Moored Breakwaters,Moored Breakwaters, VTechVTech thesis.thesis. Huang, S. andHuang, S. and VassalosVassalos, D. (1993). A numerical method for predicting, D. (1993). A numerical method for predicting

snap loading of marine cables. Applied Ocean Research, Vol. 15,snap loading of marine cables. Applied Ocean Research, Vol. 15, pp.pp.235235--242.242.

Huang, S. andHuang, S. and VassalosVassalos, D. (1995). Analysis of taut, D. (1995). Analysis of taut--slack marine cableslack marine cable

dynamics. OMAE 1995, Vol. Idynamics. OMAE 1995, Vol. I--B, ASME, New York, pp. 401B, ASME, New York, pp. 401--406.406. NiedzweckiNiedzwecki, J.M. and, J.M. and ThampiThampi, S.K. (1991). Snap loading of marine, S.K. (1991). Snap loading of marine

cable systems. Applied Ocean Research, Vol. 13, pp. 2cable systems. Applied Ocean Research, Vol. 13, pp. 2--11.11.

M d l Shi i T l ti U d C t t P lli FModel Ship in Translation Under Constant Pulling Force


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Model Ship in Translation Under Constant Pulling ForceModel Ship in Translation Under Constant Pulling Forceafter NATO, Analytical Treatment of Problems ofafter NATO, Analytical Treatment of Problems of

Berthing & Mooring Ships, 1971Berthing & Mooring Ships, 1971

0

0.5

1

1.5

2

2.5

0 20 40 60 80

Underkeel Clearance

Hydrodynamic

Mass

Coefficient

Mh/Ms


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DiscussionDiscussion

Mooring Breakaway

Vessel Data

Geometry ofMoored Vessel(s) and

Passing Vessel(s);

Vessel Speed,

Relative Attitude

Waterway DataBathymetry, esp.

Depth, Width, Channel Slope

Berth Characteristics

Mooring Details

Geometry of LinesTensioning

Type of Lines, Connections

Condition

Hydrodynamics

Accelerations,Forces

Other Forces

(Internal & External)Wind, Tug


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ConclusionsConclusions

Frequency of mooring breakaways due toFrequency of mooring breakaways due topassing vessels is significantpassing vessels is significant Reporting issuesReporting issues Several per year (conservative)Several per year (conservative)

Mooring analysis methodsMooring analysis methods [Conventional] Environmental[Conventional] Environmental ShipShip--ShipShip

Coupled effectsCoupled effects

Mooring force & responseMooring force & responsedynamicsdynamics

Limiting factors?Limiting factors?

Selected Recommendations forSelected Recommendations for


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Selected Recommendations forSelected Recommendations for

Additional WorkAdditional WorkSlack LinesSlack Lines PiersidePierside Breakaway DynamicsBreakaway Dynamics

PretensioningPretensioning TechnologyTechnology Alternative Mooring DesignsAlternative Mooring Designs

Passing Vessel Effects onPassing Vessel Effects on

Vessels MooredVessels Moored notnot parallel to sailing lineparallel to sailing line More complex issueMore complex issue

Potential for higher forces & momentsPotential for higher forces & moments

Impact of quay/pier construction and geometryImpact of quay/pier construction and geometry UKC effectsUKC effects

Hydrodynamics alongside [Hydrodynamics alongside [piersidepierside of] vesselof] vessel


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AcknowledgementsAcknowledgements

Dennis Webb,Dennis Webb,

USACE ERDC CHL (WES)USACE ERDC CHL (WES)

CDR Lyle Rice,CDR Lyle Rice,

USCG GUSCG G--MOAMOA--22

LCDR AlLCDR Al BlumeBlume,,USCGUSCG

BillBill SeeligSeelig,,

NFESCNFESC

Thank You Thank You Questions / Discussion?Questions / Discussion?


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Thank You Questions / Discussion?Q

Sovereign Maersks Stern Mooring Lines

(Photo: World Shipping Council)


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Interesting Cases from the Files Interesting Cases from the Files


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mooring force analysis methods pianc_2003_mooring_waters

Documents

safe mooring of largeguidel

studymooring forces

ship moorings

naval academyu

naval academyannapolis

close proximity

piers anddesign tool

actual casesfindings