International Journal of Offshore and Polar Engineering (ISSN 1053-5381)

Copyright © byThe International Societyof Offshore and Polar Engineers

Vol. 15, No. 2, June 2005, pp. 109–116

Roll Motion of Ro-Ro Passenger Ship with Flooded Vehicle Deck

Toshifumi Fujiwara and Tomihiro Haraguchi

Advanced Maritime Transport TechnologyDepartment, National Maritime Research Institute

Tokyo, Japan

This paper tries to confirm the effectiveness of an estimation method of roll motion on a Ro-Ro passenger ship with

a flooded vehicle deck. Atime domain simulation of roll motion expressed by the 2-dimensional lump mass concept was

applied to the Ro-Ro passenger ship with no water ingress, but with a flooded vehicle deck. Measurements of the motion

of the ship with different amounts of water on deck were carried out in regular beam waves in order to compare with

calculated results. The trend of the calculated results on roll amplitude generally represents the experimental results.

INTRODUCTION

Baltic Sea in 1994, the safetyof damaged Ro-Ro passenger ships

has been discussed at the International Maritime Organization

(IMO). Because Ro-Ro passenger ships have large, flat vehicle

decks with no watertight bulkheads, large amounts of water can

enter the decks through damage holes causing the ship to lose stability.

To prevent such kinds of disasters, it is necessary to assess

the static and dynamic effect of the water on deck for ensuring

the stabilityof such kinds of ships.

Manye xperimental investigations of the Ro-Ro passenger ships

with a hole from damage and a flooded deck have been conducted

(Ishida et al., 1996; Hamano et al., 1997; Haraguchi et al.,

1998; Vassalos et al., 2000; and others). It is, however, difficult

to capture all dangerous conditions of a flooded ship deck using

limited sample ships and experimental conditions. Although calculation

methods on ship motion have been presented to predict

the capsize of the ships (Dillingham et al., 1986; Zaraphonitis et

al., 1997; Hasegawa et al., 2000; Papanikolaou et al., 2000), there

are manyuncertain points of applicabilityand detail.

To exactlyestimate ship motion with a deck flooded with water

entered from damaged holes, it is necessaryto deal with 2 subjects:

(1) to estimate the amount of water coming from damaged

holes, and (2) to estimate ship motion with flooded vehicle decks,

which means to calculate the dynamic influence of the water on

deck. In past investigations, both subjects were treated at the same

time. To be clear about the problems of the estimation method of

the Ro-Ro passenger ships with flooded decks, each subject must

be treated separately.

In this paper, the calculation method of roll motion for the sample

Ro-Ro passenger ship with the flooded vehicle deck is presented

from the viewpoint of subject (2). The 2-dimensional lump

mass concept for the flooded deck used byIshida et al. (1996)

and Murashige et al. (1997, 1998) that is applied to the flooded

box is used for the Ro-Ro passenger ship in the calculation. The

calculated results are compared with the experimental ones. The

Received March 16, 2003; revised manuscript received bythe editors

May4, 2005. The original version (prior to the final revised manuscript)

was presented at the 12th International Offshore and Polar Engineering

Conference (ISOPE-2002), Kitakyushu, Japan, May 26–31, 2002.

motion, flooded vehicle deck, model experiment, damage stability.

trend of the calculated results on the roll amplitude sufficiently

represents the experimental results.

MATHEMATICAL MODEL OF ROLL MOTION ON

RO-RO SHIP WITH FLOODED DECK

The Ro-Ro passenger ship is assumed to have a large, flat vehicle

deck flooded with water and no forward speed in beam waves.

In this case, it is assumed that the ship rolling and water moving

effects are main components of ship motion. The equation of 2

degrees of freedom for ship rolling and water moving is used in

the calculation, neglecting the effect of swayand heave motion.

Fig. 1 defines the coordinate system of the ship and water. The

of the gravitycenter of the water is defined

while the roll angle of the ship and the water surface slope are

partitions such as a central casing, and the center of gravityof the

vehicle deck, not moving with respect to the longitudinal direction

of the ship.

Fig. 1 Coordinate system on Ro-Ro passenger ship with flooded

deck