Capsizing experiments were carried out in both long-crested irregular and short-crested irregular waves. Here a self-propelled model of purse seiner and one of container ship ran with auto pilots in following and quartering waves. To examine drafts of operational guidance that were recently proposed to the IMO, dangerous conditions in ship speed and heading angle were identified. The experimental results demonstrate effects of short-crested wave nature on capsize in following and quartering waves. In addition, effects of group wave were also discussed. Long-crested irregular waves, which were used in the

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In order to investigate capsizing caused by low cycle resonance of ships running in irregular astern seas, an analytical approach has been conducted for computing the fluctuation of metacentric height in irregular astern seas and the power spectrum of metacentric height has been obtained from the time histories of it. The unstable regions of low cycle resonance have been discussed for a container ship and a purse seiner on the basis of Mathieu's equation.

When a person falls overboard at sea, the ship has to return to the scene to help the person. But it is quite hard to steer a ship back to a particular spot in the water, so some manoeuvers that make this easier are proposed.The Williamson turn is one of them. It was named for John Williamson who used it in 1942. This turn is most appropriate at night or in poor visibility, because the ship gets onto a reciprocal course when you take the proposed procedure. However, hull forms and the performance of rudders have changed greatly from when this turn was first proposed. Recent ships find it difficult to effectively use the original procedure. This paper, examines how manoeuvering factors influence the ships track using the training ship and a ship handling simulator.