The occurrence of marine disasters tends to increase in recent years. In many cases, a large quantity of crude oil spilled into the sea from shipwrecked tankers in addition to the damage of ship hull. These accidents strongly remind us the neceasity of marine environment protection. Based on this experience, we started a project to develop a new technology to recover spilled oil effectively in the open sea. We investigated the barge type Oil Recovery Vessel (length 70m, width 24m, water depth 2.5m), which is generally operated as a multipurpose work vessel for an offshore construction, sea surface cleaning and so on. In order to provide calm water surface in a moon-pool inside a barge type Oil Recovery Vessel, the motion characteristics of the vessel and water surface elevation in the moonpool in following and head wave have been examined with a 1/20 scale model ship of the Oil Recovery Vessel. The model ship consists of 3 parts; intake, waterway, and moon-pool.
The seas around Japan are very busy areas because of oil vessel traffic, and also has harsh weather condition caused by seasonal wind in winter and typhoon during the summer through autumn time. Under those conditions, it is quite possible that oil spilled accident will occur again, such as Nakhodka, the Russian oil tanker. When this kind of accident occurs, it is harmful because damaged vessel might crash into marine facilities and cause secondary disaster, or spilled oil might cause marine pollution in large area (Kihara 1998). It is important to prevent the vessel from drifting, and to prevent the spilled oil from spreading, under that kind of situation. The authors are now in progress of studying the development of oil recovery vessel and technique to calm down the water surface of oil recovering surface (Yamakawa 1999).