Motivated by the disaster of ESTONIA in 1994, the safety standard for RO-RO passenger vessels was deliberated in IMO. One of the major parts of the discussion was the damage stability because wide non-separated car decks of this type of ships reduce the stability drastically once free flooded water through a damage opening is piled up on them. In order to contribute to the discussion, Ship Research Institute conducted the research project of “Study on the Safety of Flooded Ships in Waves” from 1995 to 1997. By model tests in beam waves, the motion of ship, the amount of accumulated water on deck and the occurrence of capsize in various test parameters were investigated. As the result, the effects of GM, initial heel angle, center casing, wave period and so on were clarified. It was characteristic that the time-averaged height of water on deck above the calm sea surface was within a narrow range in various model conditions and was confirmed that this quantity is the key index of the danger of capsizing. With these results the scope of the proposal by United Kingdom for IMO was also discussed. In addition, the coupling motion of the ship and the water on deck was examined by experiments and numerical simulations. It was found that two kinds of roll motion with different amplitudes and periods coexist in some conditions even in regular waves with moderate heights, and that some of these complicated roll motions have typical properties of low-dimensional deterministic chaos.
展开▼
