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INTERNATIONAL MARITIME ORGANIZATION
E
SUB-COMMITTEE ON STABILITY AND
LOAD LINES AND ON FISHING VESSELS
SAFETY
47th session
Agenda item 8
SLF 47/INF.11
9 July 2004
ENGLISH ONLY
LARGE PASSENGER SHIP SAFETY
Results of model experiments on flooding large passenger ships
Submitted by Japan
SUMMARY
Executive summary: This document provides the results of experimental model tests on flooding process of a large passenger ship carried out by Osaka Prefecture University of Japan to contribute to large passenger ship safety issue.
Action to be taken: Paragraph 5
Related documents: SLF 47/8/1 and SLF 46/INF.14
Introduction
1 The Sub-Committee, at its forty-sixth session, regarding large passenger ship safety, decided to re-establish a splinter group for the SDS Correspondence Group to carry out collaborating studies on survivability of a damaged large passenger ship. Osaka Prefecture University of Japan carried out a model experiment to reveal survivability in intermediate stages of flooding on a model of the same un-built large passenger ship used by MARIN and a two-dimensional model of the centre part of the ship.
Executive conclusions
2 In intermediate stages of flooding of two compartments, the model slowly inclines, and reaches to large heel angle about 17 degrees, where part of the bulkhead deck is submerged. This large heel angle is caused by shallow water accumulated in each deck of multiple decks in the flooding compartments. The approximate maximum degrees of heel angle can be predicted by static calculation.
3 If there is no super-structure above the bulkhead deck and the deck is flat and there is no restriction for spreading water, the model capsizes in the intermediate stage. This fact can be theoretically confirmed by the GZ curve obtained by a static calculation. These results suggest that the restriction of flooding water on the bulkhead deck is critical issue to ensure the safety of the large passenger ships.
4 The time to reach to the maximum heel angle is 13-18 minutes from the start of flooding in full scale ship. Behaviour of the ship in the intermediate stage depends on location and size of the damage opening and arrangements on each deck. The maximum heel angle is independent from these factors.
Action requested of the Sub-Committee
5 The Sub-Committee is invited to note the information provided.
***
For reasons of economy, this document is printed in a limited number. Delegates are kindly asked to bring their copies to meetings and not to request additional copies.
ANNEX
AN EXPERIMENTAL STUDY ON TRANSIENT MOTION OF A DAMAGED LARGE PASSENGER SHIP IN THE INTERMEDIATE STAGES OF FLOODING IN CALM WATER
By Yoshiho Ikeda
Osaka Prefecture University
1 Model
The model used in the experiment is the same as the un-built large passenger ships designed by Fincanteri, but two dimensional scale model of the mid-ship section of the ship. Length, Beam, draft and displacements of the model are 1.1618m, 0.728m, 0.168m and 194kg, respectively. The scale is 1/50. The GM value is adjusted to the corresponding one of the three dimensional ship. The model has a super-structure above the bulkhead deck. The damage opening of 210mm length is located below the bulkhead deck. The size of the opening is changed in the experiments.
2 Behaviour of the ship
In calm water, the opening located on the side hull is released, and the behaviour of the model (roll and heave motions) is measured until end of flooding.
An example of time histories of measured roll of the ship for two-compartment-damage is shown in figure 1. The result show that the model rolls gradually, reaches a maximum angle, and returns to upright condition. In most cases, the maximum roll angles are around 18 degrees. When the damage opening is located in lower position, such large roll motion does not appear.
Figure 1 Time history of measured roll of model in flooding experiments
3 Maximum roll angle
In most cases, the maximum roll angles are around 17 degrees in the intermediate stages of flooding as shown in figure 2. Figure 3 shows the comparison between the calculated roll angle by static calculation and measured maximum roll angle. In the calculation, the super-structure above the bulkhead deck is assumed to be intact. The results demonstrate that the angle of 17 degrees almost coincides with the calculated one, which is up to about 20 degrees as shown by the solid line in figure 3 at the worst case of accumulation of water on each deck of three decks in the compartments. This means shallow water on each deck create the almost largest roll moment, respectively.
The time to the maximum roll angle is shown in figure 4. The results show that the roll motion reaches the maximum angle in 100-150 sec in model scale, or 13-18 min in full scale. The results also show that the time to maximum roll angle decreases with increasing size of damage opening.
Figure 2 The maximum roll angle in the intermediate
Figure 3 The comparison between the calculated roll angle by static calculation and measured maximum roll angle
Figure 4 Time to maximum roll angle in intermediate stages of flooding
4 Capsizing in the intermediate stages
A capsizing was observed for the model for which the damage opening extended to above the bulkhead deck. In the case, there is no wall to restrain flooded water over the bulkhead deck. Figures 5 and 6 show the calculated GZ curves and obtained roll angle for various volumes of water on each deck. The results suggest the ship can capsize in the intermediate stages of flooding if damage opening extending to above the unrestrained bulkhead deck.
Although the designed ship has some watertight wall on the bulkhead deck, it may be important to guarantee not to spread flooded water widely on the bulkhead deck.
Figure 5 Calculated roll angles for the opening under BHD and above BHD.
Figure 6 GZ curve of model for water on each deck
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