Abstract
Recently, fast car ferries of catamaran type have become larger and larger. In beam waves, motion of catamaran is relatively severe because of its large stability. Therefore, in beam waves, tilt or turn over of cars is concerned for such catamarans. If relationship between wave height and tilt of cars is clarified, safety voyage without lashing will be able to judge before sailing from port.A method of judgment of tilt of cars on deck was proposed by Kuwano. In this method, however, only rolling motion is taken into account. It is necessary to take other motions into account for higher precision of the judgment of tilt of cars on deck. A new method considering heave, sway and pitch as well as roll motion is developed in the present paper. Model experiments to check out the relevance of the new method and the effect of motions except rolling on behavior of vehicles on decks are carried out.The method is applied to a 112m wave piercing catamaran, and criteria of wave height for tilt of vehicles on decks are predicted.The predicted results demonstrate the effects of other motions except rolling are significant in some cases. It is confirmed that the most critical wave period of tilt of vehicles on decks of the wave piercing catamaran is about 6.0 to 8.0 seconds.
