rp592 (rp564) investigation into the safety of ro-ro passenger ships fitted with long lower holds...
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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
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Cru
ise
Mo
de
Pro
pS
yste
m
Re
du
ced
Pro
pS
yste
m
Ste
eri
ng
Sys
tem
Sta
bili
tyS
yste
m
Th
rust
ers
ElS
yste
m4
40
V
ElS
yste
m2
20
V
MS
1_
44
0V
MC
C
Pro
ba
bili
ty o
f fu
nc
tio
n u
na
va
ilab
ility
giv
en
1-z
on
e f
loo
din
g
Option 1.1
Option 1.2
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Cru
iseM
od
e
Pro
pS
yste
m
Re
duce
dP
rop
Sys
tem
Ste
erin
gS
yste
m
Sta
bili
tyS
yste
m
Th
rust
ers
ElS
yste
m4
40
V
ElS
yste
m2
20
V
MS
1_4
40
V
MC
C
Pro
bab
ility
of
fun
cti
on
un
ava
ilab
ility
giv
en
1-z
on
e f
loo
din
g
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
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
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
10
10.5
11
11.5
12
12.5
13
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
10
10.5
11
11.5
12
12.5
13
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 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
10
10.5
11
11.5
12
12.5
13
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
-40
-35
-30
-25
-20
-15
-10
-5
0
0 20 40 60 80 100 120
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
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 60 120 180 240 300 360 420 480 540 600
t, time to capsize [min]
FT(t
), c
um
ula
tive
pro
bab
ility
dis
trib
uti
on
fo
r t
mm
mm
m
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
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60
length [m]
CD
F f
or le
ngth
[-]
0
0.02
0.04
0.06
0.08
0.1
0.12
PD
F f
or le
ngth
[-]
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
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 5 10 15 20 25 30 35 40
t, time to capsize [min]
FT(t
|DS
), c
um
ula
tive
pro
bab
ility
dis
trib
uti
on
fo
r t,
m
mm
g
iven
load
ing
co
nd
itio
n is
DS
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
10
10.5
11
11.5
12
12.5
13
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
(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?
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
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
ilit
y d
istr
ibu
tio
n f
or
t,
giv
en
lo
ad
ing
co
nd
itio
n i
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.