Transcript SDS-LPS Overview
Harmonization of Subdivision & Damage Stability Regulations in SOLAS Chapter II-1
Robert Tagg
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Herbert Software Solutions, Inc.
James Person
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U.S. Coast Guard (G-MSE-2)
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Harmonization of Subdivision & Damage Stability Regulations
Historical Background & Introduction to Probabilistic Damage Stability Regs
SLF 46
SDS Correspondence Group
MSC 78 Decisions
SLF 47 Outcome
The Way Ahead
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Historical Background
1854 – British Maritime Shipping Act 1891 – British Board of Trade (2-compt. Std.) 1895 – German 2-compt. Standard 1912 – Titanic casualty 1914 – First SOLAS Conference 1929 – SOLAS, “Criterion of Service” 1948 – SOLAS, damage stability added 1956 – Andrea Doria casualty, IMCO established 1960 – SOLAS, acknowledged deficiencies
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Historical Background (cont.)
1966 – Loadline Convention (B-60, B-100) 1971 – Tory Canyon casualty, USCG 2-compt. for tankers – MARPOL ‘73 1974 – 1 st Probabilistic Standard, A.265
1975 – MARPOL for chemical and gas carriers 1988 – Probabilistic rules for dry cargo ships 1990 – SOLAS, Herald of Free Enterprise
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Introduction to Probabilistic Regulations
Weaknesses in Criterion of Service, Floodable Length, and 2-compt. standard approach
The Fundamental Fallacy
Wendel and the probabilistic framework
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Probability of damage size and location
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Probability of ship condition (draft and permeability)
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Probability of seastate at time of casualty Probability of survival after flooding
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The Fundamental Fallacy
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Development of Probabilistic Standards
Damage statistics (Damage Cards)
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Damage sizes and locations
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Seastate at time of casualty Wave Height at collision
1.2
1 0.8
0.6
0.4
0.2
0 0 1 Raw Data exp(-exp(0.16-1.2*Hs)) 2 3
Wave Height (Hs - meters)
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Development of Probabilistic Standards
Survivability Model Tests
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Capsize mechanisms
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Level of stability required to survive specific seastates
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Application of Probabilistic Standards
Find all possible combinations of damaged compartments
Determine probability of occurrence for each damage
Calculate the probability of survival for each damage
Sum all successful cases to yield overall attained probability of survival - A
Compare with required probability of survival - R
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History of Probabilistic Damage Stability Regulations
1973 – A.265 Passenger Ship
1992 – SOLAS B-1 Cargo Ship
1993 – SLF begins Damage Stability Harmonization effort
2000-2003 – EU HARDER Project
2003 – SLF 46
2004 – SLF 47
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Overview – Project HARDER
March 2000, a 4.5M
€ 3-year project 19 organizations from industry and academia Systematically investigate the validity, robustness, consistency and impact Develop new harmonized damage stability regulations for consideration at IMO
WP 0 Administration (DNV) WP 6 Design WP 7 Regulations WP 1 Damage statistics WP 2 Probability of damage ("p"-factor) Classification society (GL) December 1, 2004 University (DTU) WP 3 Probability of survival ("s"-factor) WP 4 Validation and verification of "A" WP 5 Equivalence level of safety ("R") University (SSRC) Research institute (DMI) University (NTUA) Chesapeake Section SNAME Yard (HDW) Administration (MCA) 11
SLF 46
Considered HARDER Project results & proposals
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Majority accepted subject to some further validation Single “R” for all dry cargo ship types
Downward trend of survivability for larger passenger ships was unacceptable; the trend should be upwards for larger ships and for ships with greater numbers of passengers Requested guidance from MSC on the “equivalent level of safety” conflict
Established the SDS Correspondence Group
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Survivability of Passenger Ships – Downward Trend
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SDS Correspondence Group – Terms of Reference
Coordinate validation of sample ship calculations regarding:
– – – – – – –
p-factor; SEM method & possible introduction of an Hmin factor; transient & intermediate stages of flooding/equalization; minimum values of the index A at specific draughts; required index R; passenger heel and wind moments; and investigate the impact of the proposal on the design of ships, in particular large passenger ships
Finalize the draft revised SOLAS Chapter II-1
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SDS Correspondence Group – Actions
Initial task – validate and finalize the calculation methodology
– – – –
various studies, analyses, proposals, etc. an intersessional meeting in Malmö, Sweden Questionnaire voting Summary of results in SLF 47/3/2
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SDS Correspondence Group – Actions
Re-calculation of sample ships using agreed formulas from Questionnaire results
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Major formula changes for passenger ships – necessary to recalculate all passenger ships Minor formula change for cargo ships – not necessary to recalculate all cargo ships
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52 sample ship calculations conducted
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32 passenger ships and 20 cargo ships Analyses for “R” conducted by NTUA Summary of results in SLF 47/3/3
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SDS Correspondence Group – Actions
Revised SOLAS Chapter II-1 Parts A, B and B-1
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reviewed and updated draft text submitted version in SLF 47/3/1
Proposals for “R” and minimum values of “A”
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no exact consensus for “R”, but general support for “R” proposals
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no exact consensus on minimum values of “A” but general support for min “A” proposals
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summary of results in SLF 47/3/8
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MSC 78 Decisions – Confirmed SLF 46 opinions
Same survivability standard “R” for all dry cargo ship types
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even if ro-ros must meet a higher standard
Survivability standard “R” for passenger ships should increase with ship size and number of persons onboard
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even if this means exceeding current SOLAS
Complete harmonization task – finalize revised SOLAS Chapter II-1 for approval at MSC 79
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SLF 47 Outcome – Initial decisions in plenary
majority opinion that the proposed harmonized subdivision and damage stability regulations were a technically sound standard and that they should be finalized at SLF 47
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Italy strongly opposed – they want to delay to allow further validation work (specifically the “p” and “s” factors for large passenger ships)
agreed to delete inclusion of SEM method in “s” factor because effects of water on deck already adequately accounted for
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SLF 47 Outcome – SDS Working Group actions
Reg 7 1 “p” factor
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Due to alternate proposal by Italy, damage distributions and statistical analyses for “p” factor were reviewed
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General majority view that “p” factor in draft reg 7-1 was as accurate and correct as could be expected from the available collision damage statistics
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SLF 47 Outcome – SDS Working Group actions
Reg 7 2 “s” factor
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based on residual GZ, range, and heel angle
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intermediate stage flooding criteria only for passenger ships (similar to current SOLAS)
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additional heeling moments applied only to passenger ships (similar to current SOLAS)
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SEM method dropped
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SLF 47 Outcome – SDS Working Group actions
Reg 6 Required Subdivision Index “R”
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Passenger ships
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considered sample ship calculation results and methodology used to develop “R” considered alternate proposal by ICCL (with standard deviation) agreed to Correspondence Group proposal for “R”
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Added new minimum partial “A” requirement (0.9R) at each partial draft
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SLF 47 Outcome – SDS Working Group actions
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SLF 47 Outcome – SDS Working Group actions
Reg 6 Required Subdivision Index “R”
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Cargo ships
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considered sample ship calculation results agreed to Correspondence Group proposal for “R”, except for small ships less than 100m for ships less than 100m, knuckle point and lower “R” line similar to current Part B-1
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Added new minimum partial “A” requirement (0.5R) at each partial draft
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SLF 47 Outcome – SDS Working Group actions
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SLF 47 Outcome – SDS Working Group actions
Reg 9 Double Bottoms
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Harmonized for passenger & cargo ships
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DB height = B/20 (min 0.76m & max 2.0m)
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If full DB not fitted, then must comply with bottom damage survivability standard
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Current passenger ship DB length applicability limits deleted
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SLF 47 Outcome – Final action
SLF agreed to the draft revised SOLAS Chapter II-1 Parts A, B and B-1 for submission to MSC 79 for approval with a view to adoption
Italy reserved its position (with several others) & intends to submit a proposal to modify the Chapter II-1 draft text directly to MSC 80 for consideration
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The Way Ahead
MSC 79 – December 2004
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considered for approval IMO procedural issue: 6 month interval between approval and adoption; Germany & Denmark sponsored IMO Adoption Circular Ltr
MSC 80 – May 2005
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considered for adoption
Into force date (1 January 2007?)
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