RP592 (RP564) INVESTIGATION INTO THE SAFETY OF RO-RO PASSENGER SHIPS FITTED

WITH LONG LOWER HOLDS – PHASE II

© Andrzej Jasionowski and Peter Blackwood / Safety At Sea Ltd / UK

Project Team Piotr Dolebski / Safety At Sea Ltd / UK

Pöyliö Esa, Aarno Liimatta / Deltamarin / Finland

December 2007 – March 2009

Funded by UK and Netherlands

31st March 2009

Outline

• Design development

• Impact of “s” formulation on A

• Impact of standards on KG limits

• Level of survivability (vulnerability)

• Recommendations

• Conclusions

Outline

• Design development

• Impact of “s” formulation on A

• Impact of standards on KG limits

• Level of survivability (vulnerability)

• Recommendations

• Conclusions

Two designs

Parameter Value

Ship’s length overall

182.6m

Ship’s Length Between Perpendiculars

166m

Ship breadth (moulded)

27.2m

Depth (moulded)

14.2m

Draught (design)

6.0m

Number of Passengers

1000 People

R = 0.74

Ship 1 & 2 Arrangement

Ship 1 & 2 Machinery

Ship 1Ship 2

Commercial feasibility

DS DP DL DS DP DL DS DP DL DS DP DL

0.12 0.74272 2.46 2.12 1.99 12.27 13.07 13.97 0.7450

0.25 0.73201

1.2 0.12 8.6 2.4 2.26 1.80 3.45 12.48 12.94 11.29 0.74209 2.82 1.96 1.05 11.92 12.78 13.69 0.7479

0.12 0.74176 3.79 2.82 2.09 10.95 12.38 13.87 0.7419

0.25 0.74086

2.2 0.12 5600 8.6 2.4 3.43 2.77 5.18 11.28 12.43 10.78 0.74198 4.12 3.02 2.09 10.61 12.18 13.87 0.7438

MC numerical simulations

UGD

Simulation of Stockholm Agreement Case

12.82

4800

5400

2.5

2.5

Ship 1

GZ max [m]

13.28 11.64

3.14 2.61 5.02 11.60 12.58 10.94

1.91

Ship 2

Column I - Marginal Compliance (S2009, R=0.742)

GM [m] KG [m]A index

Basis Design

Design No

1.91 4.33

8.7

1.1

2.1

8.7

Column II - Marginal Compliance (S2009, ADS=ADP=ADL~R=0.742)

GM [m]

Freeboard DS [m]

Deck 3 height [m]

Cargo Area [m2]

Ship 2 offers more Ro-Ro space (though higher GM required to comply with SOLAS2009)

Systems un-availability

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Option 1.1

Option 1.2

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Option 2.1

Option 2.2

Ship 2 has superior systems protection w.r.t. Ship 1!

Ship 1Ship 2

Outline

• Design development

• Impact of “s” formulation on A

• Impact of standards on KG limits

• Level of survivability (vulnerability)

• Recommendations

• Conclusions

“s” formulation

Adoption of GZmax = 0.12 for RoPax ships has been a historical error.

“Conventional ships”

RoPax

“s” formulation

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.2 0.21 0.22 0.23 0.24 0.250

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0.11

0.12

0.13

0.14

0.15

0.16

0.17

0.18

0.19

0.2

r GZmax

GZmax

4

1

max

4

1

max

1612.012.0,min

1625.025.0,min

1

RangeGZ

RangeGZ

r

12.025.0 )1( srs

Maximum reduction of ~16.8% to index “s” depending on the GZmax. Note that no reduction will apply when GZmax = 0 or GZmax > 0.25.

“s” formulation

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1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

s (GZmax=0.12m)

s (

GZ

ma

x=

0.2

5m

)

Gzmax < 0.12

Gzmax > 0.25and Range <

16deg or Heel > 7deg

0.12 < Gzmax < 0.25and Range < 16deg

Gzmax = 0 orRange = 0

Gzmax > 0.25

0.12 < Gzmax < 0.25and Range >16deg

Actual variations to s factors for different flooding cases …

“s” formulation

Option 1.1A_012 = 0.74272A_025 = 0.73201

DA = 0.0107

GZmax<0.12Swipivi = 6.7%

0.12<GZmax<0.25Swipivi = 6.8%

GZmax=0Swipivi = 18.7%

GZmax>0.25Swipivi = 67.8%

13.5% of possible flooding cases affected by change to s factor

Maximum possible reduction to A would be 16.8% reduction to s, applicable to 13.5% possible flooding cases, so = ~2%. When

accounting for actual reduction to s and pi for each flooding case, the reduction amounts to DA = 1.07%.

Outline

• Design development

• Impact of “s” formulation on A

• Impact of standards on KG limits

• Level of survivability (vulnerability)

• Recommendations

• Conclusions

Ship 1Option 1.2 Limiting KG curves

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10.5

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13.5

14

14.5

5 5.2 5.4 5.6 5.8 6 6.2Draught (m)

Lim

itin

g K

G

SOLAS 95 SOLAS 09 SOLAS 90 Intact

Ship 1.2 ADS=ADP=ADL REG8.1 limiting KG Reg8.2-3 limiting KG

ADS=0.67689 (ADS/R=0.91267 )

ADP=0.71181 (ADP/R=0.95975)

ADL=0.93304 (ADL/R=1.25805 )

wDS = 40%wDP = 40%wDL = 20%

ADS= 0.74369 (ADS/R=1.00274)

ADP= 0.74201 (ADP/R=1.00047)

ADL= 0.76831 (ADL/R=1.03594)

SA is the most stringent stability requirement (for DS).

Note that SA can be met by enforcing ADS=R

Ship 2

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Draught (m)

Lim

itin

g K

G

SOLAS 95 SOLAS 09 SOLAS 90 Intact ADS=ADP=ADL REG8.1 limiting KG Reg8.2-3 limiting KG

ADS=0.67199 (ADS/R=0.90606)

ADP=0.69273 (ADP/R=0.93402)

ADL=0.98048 (ADL/R=1.32201)

wDS = 40%wDP = 40%wDL = 20%

ADS= 0.74186 (ADS/R=1.00027)

ADP=0.74725 (ADP/R=1.00753)

ADL= 0.74089 (ADL/R=0.99896)

SA not MET!!

Ship 1 & 2

• Ship 1 (designed to ADS=0.9R) does not comply with Stockholm Agreement (SA) at deepest draught DS slightly.

• Ship 2 does not comply with SA by a big margin! It simply is prohibitive from viewpoint of SA.

• Is Ship 2 so much worse than Ship 1?

Outline

• Design development

• Impact of “s” formulation on A

• Impact of standards on KG limits

• Level of survivability (vulnerability)

• Recommendations

• Conclusions

Ship 1 & 2Option 1.2 & 2.2 Limiting KG curves

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10.5

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13.5

14

14.5

5 5.2 5.4 5.6 5.8 6 6.2

Draught (m)

Lim

itin

g K

G

SOLAS 95 SOLAS 09 reg 7 limiting KG Ship 2.2 SOLAS 95 Ship 1.2 ADS=ADP=ADL Ship 2. ADS=ADP=ADL

ADS=0.67689 (ADS/R=0.91267 )

ADS=0.67199 (ADS/R=0.90606)

wDS = 40%

wDP = 40%

wDL = 20%

Numerical MC Simulations

Ship 2 prohibited by SOLAS95

Either of Ship 1 or 2 would have survivability for any draught equal

to: R=A=ADS=ADP=ADL

Numerical Simulations for Damage case 5-6.1.1

Either of Ship 1 or 2 would have similar overall survivability equal to:

R=A=0.4ADS +0.4ADP +0.4ADL=R

Ship 1 has similar KG limiting for SOLAS95 as well as condition

that R=A=ADS=ADP=ADL

Simulation performed for Worst Case SA and “a” KG value.

Survivability assessed for Ship 1 and 2.

Worst SA case, Ship 2

Ship 2.2 KG=10.61m, Damage 5-6.1.1

-50

-45

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-35

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-5

0

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Time [s]

Ro

ll [d

eg]

-3

-2

-1

0

1

2

3

Wav

e at

CG

[m

]

Roll[deg]

Wave[m]

Worst SA case, Ship 2

Immediate Capsize!

This just verifies that attempt to seek compliance with SA by experiment would also likely fail at “reasonable” KG.

Vulnerability - UGD

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t, time to capsize [min]

FT(t

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Ship 1.1

Ship 1.2

Ship 2.1

Ship 2.2

Ship 1.2 (Ai=R, DS or DP or DL)

Ship 2.2 (Ai=R, DS or DP or DL)

… it seems that actually the vulnerability of both Ships, both of which meet MSC216 Reg 6-1, i.e. ADS=0.9R, is of the same level overall …

Note that this is result averaged according to wi for all draughts.

… the vulnerability implies probability of capsize within given time after collision. 25% implies that of every 4 statistically possible collisions, one would lead to rapid capsize say in ~120minutes

Monte Carlo Simulations

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length [m]

CD

F f

or le

ngth

[-]

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F f

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cdf, data

cdf, MC

99% confidence

pdf, data

pdf, MC

A series of damages are randomly chosen and numerical simulation for 40minutes is performed …

The result is a series of capsizes within simulation time! Make histogram of these times and derive CDF ….

Vulnerability – Numerical Simulations

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t, time to capsize [min]

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m

MC Simulation, Ship 1.2, DS

99% confidence

MC Simulation, Ship 2.2, DS

99% confidence

This just verifies through independent technique that the vulnerability of these two ships is of the same level despite SA implying vast difference!

Note that this is result for DS only

What is the meaning?Option 1.2 & 2.2 Limiting KG curves

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Draught (m)

Lim

itin

g K

G

SOLAS 95 SOLAS 09 reg 7 limiting KG Ship 2.2 SOLAS 95 Ship 1.2 ADS=ADP=ADL Ship 2. ADS=ADP=ADL

ADS=0.67689 (ADS/R=0.91267 )

ADS=0.67199 (ADS/R=0.90606)

wDS = 40%

wDP = 40%

wDL = 20%

Numerical MC Simulations

Ship 2 prohibited by SOLAS95

Either of Ship 1 or 2 would have survivability for any draught equal

to: R=A=ADS=ADP=ADL

Numerical Simulations for Damage case 5-6.1.1

Either of Ship 1 or 2 would have similar overall survivability equal to:

R=A=0.4ADS +0.4ADP +0.4ADL=R

Ship 1 has similar KG limiting for SOLAS95 as well as condition

that R=A=ADS=ADP=ADL

(1) The level of survivability is the same for both ships:

• SOLAS2009

• UGD or Numerical Simulation

(2) So the level of survivability would also be the same for these KG. However according to SA only Ship 1 is viable!

Hence – SA is not consistent!

What is the meaning?But what about the worst flooding case of Ship 2 that failed SA? How can rapid capsize be accepted?

Option 1.1A_012 = 0.74272A_025 = 0.73201

DA = 0.0107

GZmax<0.12Swipivi = 6.7%

0.12<GZmax<0.25Swipivi = 6.8%

GZmax=0Swipivi = 18.7%

GZmax>0.25Swipivi = 67.8%

13.5% of possible flooding cases affected by change to s factor

Well, according to MSC216, as many as 18.7% of cases which have ZERO stability is acceptable …

A further % of cases would be overcome by some waves

Only 67% would survive up to 4m sea states after a collision

… so, this capsize is one of 18.7% that are allowed under SOLAS anyway …

What is the meaning?

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0 60 120 180 240 300 360 420 480 540 600

t, time to capsize [min]

FT(t

|DS

), c

um

ula

tiv

e p

rob

ab

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y d

istr

ibu

tio

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or

t,

giv

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ing

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s D

S

mm

mm

m

Ship 1.2 (DS)

Ship 2.2 (DS)

FT(T|DS), Ship 1.2 (Ai=R, DS)

FT(T|DS), Ship 2.2 (Ai=R, DS)

Level of vulnerability implicit in SOLAS1995 for deepest draught

DS

Level of vulnerability implicit in SOLAS2009 for deepest draught DS

Note that this is result for DS only

This level of survivability can be achieved by ensuring that ADS=R

The difference between SOLAS’09 Reg 6-1 and SA is about 20% reduction in vulnerability. But it does not mean that all feasible flooding cases could be survivable by a SA-compliant ship. Far from it.

Outline

• Design development

• Impact of “s” formulation on A

• Impact of standards on KG limits

• Level of survivability (vulnerability)

• Recommendations

• Conclusions

Revise MSC216 (82) Reg 7-2-5 and 6

Revise MSC216 (82) Reg 6-1 and Reg 7-1

Revise MSC216 (82) Reg 6-2-3

Revise MSC216 (82) Reg 6-2-3

• SOLAS 1974 Chapter II-1• “The subdivision of passenger ships into watertight

compartments must be such that after assumedassumed damage to the ship's hull the vessel will remain afloat and stable.”

• “The subdivision of passenger ships into watertight compartments must be such that after any feasibleany feasible damage to the ship's hull the vessel will remain afloat and stable.”

Outline

• Design development

• Impact of “s” formulation on A

• Impact of standards on KG limits

• Level of survivability (vulnerability)

• Recommendations

• Conclusions

Conclusions

• Two different ships were designed to SOLAS’09.• Neither complied with SA, and hence SA is the most stringent

standard in force.• Impact of appropriate correction to “s” formulation amounts to some

1% reduction of index A.• The level of survivability between both designs was found to be the

same, despite vastly different level in the lack of compliance with SA (vastly different KG limits).

• Hence, the level of survivability implied by SA is not consistent.• The level of survivability implied by SA could be achieved by

ensuring ADS=R.• Neither of standards prevents catastrophic loss of stability.• Goals of SOLAS convention are revised to amend this serious ship

vulnerability.