Transcript SDS-LPS Overview

Harmonization of Subdivision &
Damage Stability Regulations in
SOLAS Chapter II-1
Robert Tagg
• Herbert Software Solutions, Inc.
James Person
• U.S. Coast Guard (G-MSE-2)
December 1, 2004
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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
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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 – 1st 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
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Weaknesses in Criterion of Service, Floodable
Length, and 2-compt. standard approach
The Fundamental Fallacy
Wendel and the probabilistic framework
– Probability of damage size and location
– Probability of ship condition (draft and
permeability)
– 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
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Damage statistics (Damage Cards)
– Damage sizes and locations
– Seastate at time of casualty
Wave Height at collision
1.2
Cumulative Probability
1
0.8
Raw Data
0.6
exp(-exp(0.16-1.2*Hs))
0.4
0.2
0
0
1
2
3
4
5
Wave Height (Hs - meters)
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Development of Probabilistic Standards
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Survivability Model Tests
– Capsize mechanisms
– Level of stability required to survive
specific seastates
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Application of Probabilistic Standards
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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
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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 1
Damage
statistics
WP 2
Probability
of damage
("p"-factor)
WP 3
Probability
of survival
("s"-factor)
WP 4
Validation and
verification of
"A"
WP 5
Equivalence
level
of safety ("R")
WP 6
Design
WP 7
Regulations
Classification
society
(GL)
University
(DTU)
University
(SSRC)
Research
institute
(DMI)
University
(NTUA)
Yard
(HDW)
Administration
(MCA)
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SLF 46
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Considered HARDER Project results & proposals
– Majority accepted subject to some further validation
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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
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Coordinate validation of sample ship calculations
regarding:
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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
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Initial task – validate and finalize the calculation
methodology
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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
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Re-calculation of sample ships using agreed
formulas from Questionnaire results
– 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
– 52 sample ship calculations conducted
• 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
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Revised SOLAS Chapter II-1 Parts A, B and B-1
– reviewed and updated draft text
– submitted version in SLF 47/3/1
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Proposals for “R” and minimum values of “A”
– no exact consensus for “R”, but general
support for “R” proposals
– no exact consensus on minimum values of “A”
but general support for min “A” proposals
– summary of results in SLF 47/3/8
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MSC 78 Decisions –
Confirmed SLF 46 opinions
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Same survivability standard “R” for all dry cargo
ship types
– even if ro-ros must meet a higher standard
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Survivability standard “R” for passenger ships
should increase with ship size and number of
persons onboard
– even if this means exceeding current SOLAS
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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
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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
– Italy strongly opposed – they want to delay to allow
further validation work (specifically the “p” and “s”
factors for large passenger ships)
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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
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Reg 7-1 “p” factor
– Due to alternate proposal by Italy, damage
distributions and statistical analyses for “p”
factor were reviewed
– 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
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Reg 7-2 “s” factor
– based on residual GZ, range, and heel angle
– intermediate stage flooding criteria only for
passenger ships (similar to current SOLAS)
– additional heeling moments applied only to
passenger ships (similar to current SOLAS)
– SEM method dropped
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SLF 47 Outcome –
SDS Working Group actions
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Reg 6 Required Subdivision Index “R”
– Passenger ships
• 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”
• 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
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Reg 6 Required Subdivision Index “R”
– Cargo ships
• 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
• 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
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Reg 9 Double Bottoms
– Harmonized for passenger & cargo ships
– DB height = B/20 (min 0.76m & max 2.0m)
– If full DB not fitted, then must comply with
bottom damage survivability standard
– Current passenger ship DB length applicability
limits deleted
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SLF 47 Outcome –
Final action
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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
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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
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MSC 79 – December 2004
– considered for approval
– IMO procedural issue: 6 month interval
between approval and adoption; Germany &
Denmark sponsored IMO Adoption Circular Ltr
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MSC 80 – May 2005
– considered for adoption
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Into force date (1 January 2007?)
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