Abstract
Recent systematic model experiments demonstrate that broaching and bow-diving are major causes of ship capsizing in following and quartering seas. Once these dangerous phenomena happen, even a ship complying with the current Intact Stability Criteria of the IMO could capsize. To get over this situation, we proposed the wing-type appendage fitted into the bow above the water line as a new capsizing prevention device. When a ship heels significantly, one of two wings is submerged into water geometrically. Then a ship obtains an additional restoring moment induced by lift force acting on a submerged wing. In a previous paper, we conducted free running model experiment and confirmed that the proposed wings can prevent capsizing due to broaching and bow-diving in extremely severe astern seas while a ship without the wings capsizes in the same condition. In this research, several wings are tested by a captive model experiment to examine the effects of the wing parameters on lift and drag forces, and interaction between the wing and ship hull. Then a mathematical model is developed for broaching prediction of a ship with the wings for quantitative assessment or designing tool in place of free running model experiments. Finally the developed mathematical model is applied to other high-speed slender vessel, and the effectiveness of designed wings and the reliability of numerical simulation are investigated by comparing with newly conducted free running model experiment.
