container feeder ship part 3
TRANSCRIPT
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SAFETYATSEALTD:
RESEARCH PROJECT 552
IMPACT ASSESSMENT ON THE DESIGN OF NEW
CRUISE LINERS, RO-RO PASSENGER SHIPS ANDCARGO VESSELS OF THE FORTHCOMING REVISION
TO SOLAS CH II-1, PART A, B & B-1 RELATING TO
SUBDIVISION AND PROBABILISTIC DAMAGE
STABILITY
CONTAINER FEEDER
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Client: Maritime Coastguard Agency
Project:
Research Project 552: Impact Assessment On The Design Of New
Cruise Liners, Ro-Ro Passenger Ships And Cargo Vessels Of The
Forthcoming Revision To SOLAS Ch II-1, Part A, B & B-1 RelatingTo Subdivision And Probabilistic Damage Stability CONTAINER
FEEDER
Deltamarin Ltd
Project No: P6111
Report No.: P6111-5-001
Address: DELTAMARIN LTDPurokatu 1
FIN-21200 RAISIO
Tel. +358-2-4336 300
Fax. +358-2-4380 378
Telex 62702 delma fi
Email: [email protected]
Safety At Sea Ltd
Project No: NA
Report No.: NA
Address:
SAFETY AT SEA LTD
280 St Vincent Street
Glasgow
G2 5RL
Tel. +44-141-5725570
Fax. +44-141-5725590
Email: [email protected]
Prepared by: Deltamarin
Date: 22 June 2006
Author(s): A. Kiilunen Checked by:
_________________ ______________________
Approved by:
__________________ ______________________
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CONTENTS
CONTENTS I
INTRODUCTION 2
APPROACH 3
EXISTING CONTAINER FEEDER 4
CONTAINER FEEDER DESIGN SOLAS90 LIMITING CURVES 6
EXISTING LOADING CONDITIONS 8
COMPARING THE A-VALUE CALCULATIONS 10
CONCLUSION 17
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INTRODUCTION
The draft text of the major revision to the subdivision and damage stability sections of
SOLAS Chapter II-1 based on a probabilistic approach has now been completedfollowing final amendments in January 2005 to regulation 7-1 involving calculation of
the p factor. The revised regulations were adopted in May 2005 at the IMO MSC
and will be entering into force for new vessels with keels laid on or after 1st January
2009.
Concerning dry cargo and containerships, the new forthcoming regulations are in
principle very similar compared to the present rules. The current probabilistic damage
stability rules, so called IMO Dry Cargo Index, have been in force since 1992.
Initially it was relevant for ships over 100 m in length, but since 1998 the rules also
include ships over 80 m in length.
The MCA are concerned about the following issues
Equivalence between the new rules and the existing damage stability
regulations i.e. do the new rules allow more flexibility and hence result in less
safe designs
The MCA need to be able to provide advise with regards to the effect different
design options may have on the performance of a vessel under the new rules
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APPROACH
To address the issues raised by the MCA the following approach was adopted for
studying a container feeder
Analyse an existing container feeder designed originally with the IMO Dry
Cargo Index (SOLAS, Chapter II-1, Part B-1, Reg. 25) regarding both the
current and new regulations
Compare the index calculations and KG limits regarding both the current and
new rules
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EXISTING CONTAINER FEEDER
The following existing container feeder was chosen for use in this project. The
vessels general particulars can be seen in Table 1 and the profile view can be seen in
Figure 1 Profile view
MAIN SHIP DIMENSIONS
Length, Over All LOA 132.82m
Length, Between Perpendiculars LBP 120.00m
Breadth Moulded B 22.70m
Depth, to Main Deck D 10.80m
Draught D 7.65m
Displacement (for draught = 7.65 m) 13718 tDeadweight 9125 t
Container capacity 699 TEU
Table 1 General Particulars
The ship has been built in Malaysia in 1997. The cargo space in divided into four
holds as shown in Figure 2 Layout of tanks and cargo holds
Figure 1 Profile view
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Figure 2 Layout of tanks and cargo holds
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CONTAINER FEEDER DESIGN SOLAS90 LIMITING CURVES
The KG limiting curves are defined from the current damage stability regulations i.e.
IMO Dry Cargo Index and the current IMO intact stability standards.
Damage stability
Damage stability criteria are in accordance with SOLAS90 Part B-1 Chapter II-1
Regulation 25
Intact Stability Requirements in accordance with IMO Resolution A.749(18).
The area under the curve of Righting Levers (GZ Curve) shall not be less than
(3.1.2.1):-
0.055 metre-radians up to an angle of 30 degrees.
0.090 metre-radians up to an angle of the lesser of 40 degrees or the angle at
which the lower edges of any openings in the hull, superstructures or
deckhouses, being openings which cannot be closed watertight, are immersed.
0.030 metre-radians between the angles of heel of 30 degrees and 40 degrees
or such lesser angle us referred to in (b).
The Righting Lever shall be at least 0.20 metres at an angle of heel equal to or greater
than 30 degrees (3.1.2.2).
The maximum Righting Lever (GZ) shall occur at an angle of heel not less than 25
degrees (3.1.2.3).
The initial transverse metacentric height (GM) shall not be less than 0.15 metres
(3.1.2.4).
Weather criteria as detailed in diction 3.2.
Additional intact stability criteria for containerships greater than 100 m are presented
in chapter 4.9. These special criteria may be used instead of the basic criteria for all
ships. This is referred as A.749 Ch4.9 in the KG limit diagrams.
Regarding this example ship, the original loading manual of the ship does not includethese special intact stability criteria for containerships. However, these criteria are
dominant at draughts over 6.6 m as can be seen in Figure 3 Existing Limiting KG
curves.
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Figure 3 Existing Limiting KG curves
KG limits
6.00
6.50
7.00
7.50
8.00
8.50
9.00
9.50
10.00
10.50
4.70 5.20 5.70 6.20 6.70 7.20 7.70
Draught
KG
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EXISTING LOADING CONDITIONS
The existing designs loading conditions are shown in the table below and presented in
Figure 4 Existing Limiting KG curves with loading conditions
Draught [m] KG [m]
Trim
(+ by head) [m]
LC3 Ballast departure 5.56 6.65 -1.51
LC4 Ballast arrival 5.02 7.03 -1.48
LC5 504 TEU T=7.50 m design departure 7.50 9.31 -1.07
LC6 504 TEU T=7.50 m design arrival 7.48 9.21 -1.25
LC7 520 TEU T=7.65 m scantl departure 7.65 9.36 -1.50
LC8 520 TEU T=7.65 m scantl arrival 7.61 9.38 -1.41
Table 2
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Figure 4 Existing Limiting KG curves with loading conditions
KG limits
6.00
6.50
7.00
7.50
8.00
8.50
9.00
9.50
10.00
10.50
4.70 5.20 5.70 6.20 6.70 7.20 7.70
Draught
KG
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COMPARING THE A-VALUE CALCULATIONS
The idea behind probabilistic damage stability is to define all potential collision
damages and to assign a probability of occurrence p and a probability of survival s to
each of them. The individual contribution for each damage case is the product of pand s. Finally the attained subdivision index A is obtained by the summation of the
partial indices calculated for the chosen draughts.
Each partial index is a summation of contributions from all damage cases taken in
consideration, using the following formula:
A = pisi
The requirement for the attained subdivision index A is to exceed the required
subdivision index R.
The probability of a damage case p depends on its longitudinal position and the
longitudinal, transverse and vertical extent of the damage.
The survivability index s of a damage case is calculated based on the GZ curve
characteristics during intermediate stages of flooding and at the final stage of
flooding. Openings causing progressive flooding have to be accounted for in these
calculations.
The subdivision defined for generating the damages is the same for both the present
and new rules. The damage zones are presented in Figure 5 Subdivision layout.
Required subdivision index R is a function of subdivision length LS.
The definition of the subdivision length LS is shown in Figure 7 Subdivision Length
LS= 131.85 m , the same in REG25 and MSC194(80)
The required subdivision index R for cargo ships is calculated according to
MSC.194(80) using the following formula (LS> 100 m):
152
128
+=
SLR
54905.0=R
In REG25 the required index R is calculated as follows (LS> 100 m):
( )31
0009.0002.0 SLR +=
49415.0=R
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Figure 5 Subdivision layout
The subdivision layout used for the calculation in the existing ship design is shown in
Figure 5. The subdivision layout should reflect the vessels watertight arrangement and
is used by NAPA to generate damage cases automatically.
Relevant openings (weathertight) are defined in the corner points of the cargo
hatchway coaming edges.
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INITIAL VALUES FOR DRAUGHT, TRIM, GM
MSC.194(80) requires the probabilistic damage stability calculations to be carried out
at three different intact draughts. These are;
DS; Deepest subdivision draught is the waterline corresponding to the summer
load line draught.
DL; Light service draught is the service draught corresponding to the lightest
anticipated loading.
DP; Partial subdivision draught is the light service draught plus 60% of the
difference between DS and DL
A = 0.4As + 0.4Ap + 0.2Al
REG25 defines two initial draughts. Partial load line is the light ship draught plus
60% of the difference between the light ship draught and deepest subdivision load
line. For attained index A the mean value is taken at these two draughts.
Permeability of the cargo spaces
REG25: permeability = 0.70
MSC194(80): permeability = 0.70 at draught DSpermeability = 0.80 at draught DP
permeability = 0.95 at draught DL
Criteria for s-factor being 1.0 (maximum)
(minimum values for the characteristics of the GZ curve)
REG25 DRAUGHT [M] KG [M] GM [M] TRIM [M]
DEEPEST SUBDIVISION LOAD LINE DL 7.65 9.44 0.30 0.00
PARTIAL LOAD LINE PL 5.75 8.81 0.80 0.00
MSC194(80) DRAUGHT [M] KG [M] GM [M] TRIM [M]
DEEPEST SUBDIVISION DRAUGHT DL 7.65 9.44 0.30 0.00
LIGHT SERVICE DRAUGHT LL 5.00 8.86 1.00 -1.50
PARTIAL SUBDIVISION DRAUGHT PL 6.60 9.03 0.58 0.00
Table 3
GZmax Range
MSC194(80) 0.12 m 16 deg
REG25 0.10 m 20 deg
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Figure 6 A-value limiting curves
KG limits
6.00
6.50
7.00
7.50
8.00
8.50
9.00
9.50
10.00
10.50
4.70 5.20 5.70 6.20 6.70 7.20 7.70
Draught
KG
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Figure 7 Subdivision Length
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Figure 8 Survival scenario Deepest subdivision draught
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Figure 9 - Survival scenario Light service draught
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CONCLUSION
Regarding this kind of cargo ship as an example, the new forthcoming subdivision
and damage stability rules do not differ remarkably from the current rules. The KG
limit curves derived by setting A=R are surprisingly close to each other. This shipdoes comply both the current and new damage stability regulation with a small margin
in KG.
The vessel has originally designed to comply the basic set of intact stability criteria
IMO Res A.749(18)
The additional criteria for containerships over 100 m are dominant at draughts over
6.8 m. These special intact stability are not met.
The range of applied initial conditions is quite large compared to e.g. pass ships. The
light draught condition differs quite a lot from the deepest subdivision draught. This
can be seen also in the damage survival scenarios.