Container Feeder Ship Part 3

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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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Maritime Coastguard Agency Container Feeder

SAFETY AT SEA LTD & DELTAMARIN LTD. i

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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SAFETY AT SEA LTD & DELTAMARIN LTD. 2

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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Maritime Coastguard Agency

SAFETY AT SEA LTD & DELTAMARIN LTD.

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.

Container Feeder Ship Part 3

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