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© 2012 MITSUBISHI HEAVY INDUSTRIES, LTD. All Rights Reserved.

MHI’s New System

Enhancing Damage Stability

SHIPBUILDING & OCEAN DEVELOPMENT

October 23,2012

Masanori Onzuka

Development & Initial Designing Section

Shimonoseki Ship & Ocean Engineering Department

1 © 2012 MITSUBISHI HEAVY INDUSTRIES, LTD.

All Rights Reserved.

Contents

1. Introduction

2. Outline of the new system

(Righting moment recovery system)

3. An example of damage stability calculation

with and without the new system for RoRo ship

4. Conclusion

INTERFERRY 37th ANNUAL CONFERENCE 2012

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Contents

1. Introduction





4. Conclusion

© 2012 MITSUBISHI HEAVY INDUSTRIES, LTD.



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Short review of the damage stability rule

1st January 2009, Revised SOLAS was entered into force.

- Harmonization of damage stability rule for both passenger ships

(deterministic concept) and dry cargo ships(probabilistic concept)

- Passenger ships: RoRo Passenger ships, Cruise ships (Passenger ≧ 13 persons)

- Cargo ships : RoRo ships, Car carriers, General Cargo ships (Passenger ＜ 12 persons)

- The probabilistic damage stability requirement was adopted

to the passenger ships.

- Strengthened requirement in probabilistic damage stability (ex) Required Index

Vertical extent of damage

Permeability of damage compartment




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Formula of probabilistic damage stability rule

R ≦ A

R :Required subdivision Index A :Attained subdivision Index

A ( As,Ap,Al )= Σ pi x si

pi :the probability of compartment or group of

compartments may be flooded

si :the probability of survival after flooding

the compartment or group of compartments

A = 0.4 As + 0.4 Ap + 0.2 Al

As: A index at the deepest draught

Al : A index at the light service draught

Ap: A index at the partial subdivision draught (light service draught + 60%difference between ds and dl)

Cargo ships( Ls ≧100)

R = 1 - 128

Ls + 152

Passenger ships

R = 1 - 5,000

Ls + 2.5N + 15,225

N = N1 + 2N2

N1 : number of persons for whom

lifeboats are provided

N2 : number of persons the ship is

permitted to carry in excess of N1

Formula of probabilistic damage stability rule

Ls : subdivision length

si = f (Gz, heel angle), 0≦si ≦1




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Gz : righting lever of the residual stability

Heel angle: equilibrium heel angle

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Difference of the required damage stability rules

Dry Cargo Ships Passenger ships

Probabilistic damage - A≧R

- A=Σ pi x si

- As ≧0.5R Ap≧0.5R Al≧0.5R

Probabilistic damage - A≧R

- A=Σ pi x si

- As ≧0.9R Ap≧0.9R Al≧0.9R

- Collision bulkhead damage (Minor Damage) -si=1.0

- Side shell damage (Minor Damage)

-2 compartment damages

-si≧0.9

Double bottom damage -Any part that is not fitted with a double bottom shall

be capable of withstanding bottom damages

-si =1.0

Double bottom damage -Any part that is not fitted with double bottom shall

be capable of withstanding bottom damages

-si =1.0

Difference of the required rules between dry cargo ships and passenger ships




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* ) Cross flooding time for equalization shall not exceed 10min.

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General approaches to the strengthened damage

stability rule

General approaches to satisfy the damage stability rule

Approach Demerit

Increasing the ship breadth

(Increasing the GoM)

-Increasing the hull resistance

(Decreasing the propulsive performance)

Loading the ballast water into

ship bottom tanks

(Increasing the GoM)

-Decreasing the cargo payload

Dividing the lower cargo holds

into small compartments

(Limiting the sea water flooding)

-Decreasing the space for cargos

-Decreasing the operability of car’s and

truck’s handling within the cargo holds

- MHI developed a new system for enhancing damage stability. (Righting moment recovery system after flooding)

- MHI recieved the international patent for the new system. Japan(2012), South Korea(2012), U.S.A.(2012)




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Contents

1. Introduction





4. Conclusion




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Basic idea of the new system

Basic Idea

Lowering the center of gravity by enforcing the flooded sea water

entering quickly into the void space near the ship bottom

( = Downflooding )

Void space for downflooding

(ex) fin-stabilizer rooms, duct keels

Increasing the GoM after flooding and enhancing damage stability ( = Righting moment recovery)

Cargo holds




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Overview of the new system

Conceptual drawing of the new system




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②Stability monitoring and control system

③Valve control signal line

Tank (B.W.TK., F.O.TK., F.W.TK.)

④Void space for downflooding

①Seawater inlet & Watertight hatch (Downflooding hatch)

Sea water Sea water

Side shell

Car deck (Watertight deck)

Side shell

Elements of the system Purpose of the elements

①Seawater inlet & Watertight hatch -Feeding the sea water into the void space through inlet

(Watertight door is closed during usual voyage.)

②Stability monitoring and control system -Detecting the sea water on the car deck in case of ship damage

-Ordering the watertight door’s opening

③Valve control signal line -Signal line for opening valve of the watertight hatch

④Void space -Space for downflooding near the ship’s bottom

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Downflooding sequence diagram

Water level detection sensor

The ship’s hull is damaged

and seawater floods into ship

Lower cargo hold The Wheel house

Electric cylinder

-The water level sensors detect flooding

and send an aｌarm signal to wheel house.

-The electric cylinders get the operation

signal and open the downflooding hatch

(The opening action will be finished in

less than 2 sec)

Alarm

signal

Operation

signal

Stability monitoring

and control system

-The crews notice the flooding

in the lower cargo hold and

order the downflooding.

Downflooding




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Detailed structure of down flooding device

Car deck

Electric cylinder(water-proof) x 2

Grating

Downflooding hatch

Car deck(Watertight)




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Bar(200mm stroke)

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Contents

1. Introduction





4. Conclusion




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Principal Particulars of RoRo ship

Principal Particulars

Item

Length (overall) abt.166.9 m

Length (b.p.) 158.0 m

Beam (mould) 27.0 m

Draft (scan.) 6.70 m

Depth(upper deck) abt.23.3 m

Service speed 23.0 knots

Passenger 12 persons

Main engine MR 13,920kW x 120rpm

Service route Limited greater coasting(Domestic)




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Downflooding hatch position

Downflooding device Tank Top

Void Space for downflooding (Duct keel)

Downflooding hatch position




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B.W.TK. F.O.TK.

Cargo holds

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Damage extent




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1 2 3 4 5 6 7 8 9

1-2

2-3

3-4

4-5

5-6

6-7

7-8

8-9

1-3

2-4

3-5

4-6

5-7

6-8

7-9

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Calculation results of each damage case




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(Calculation soft; NAPA)

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Result of A index

Without

new system

Equipped with

new system

R Index 0.598

0.2 Al 0.1191 0.1583

0.4 Ap 0.2836 0.2968

0.4 As 0.2723 0.2827

A index 0.6750 0.7378(+0.0628)

Calculation result of A index with and without the new system




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Corresponding to loading

350t ballast water in the ship bottom

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Contents

1. Introduction





4. Conclusion




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Conclusion




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- MHI developed a new system enhancing damage stability

in response to the revised SOLAS.

- MHI received the international patent for the new system

in Japan, South Korea and U.S.A.

- MHI targets installation of the new system on new ships to which the

the revised SOLAS is applied such as

; RoRo ships, PCTCs and ROPAX ships. - 170m-long RoRo ship equipped with the new system will be delivered

on March 2013.

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