Synthesis on Steering Guidance of Ships in Quartering Seas

日本和国际海事组织制定了一些防止倾覆的规定或标准。然而，这些规则或标准只是在平静的水域中制定的。实际的倾覆发生在恶劣的海域，主要发生在尾随或停泊海域，而不是横流海域。本研究的目的是对船舶倾覆现象进行理论和实验研究，为船员的转向指导提出建议。本文的研究结果总结如下：将倾覆原因分为三种模式；(1)纯失稳；(2)参数共振；(3)拉削。通过一艘集装箱船和两条围网的模型实验，对每种模式进行了仔细的研究。在集装箱内，在低船速下观察到参数共振模态，在高船速下观察到纯失稳模态和拉削模态。在围网中观察到拉向模式和另一种模式。另一种模式是由于甲板上的波浪作用而使恢复力矩减小的波峰倾覆。目前的导引不能反映个别船舶特性和波浪条件的影响。因此不能包括参数共振引起的倾覆，参数共振可能发生在波能集中的频率范围外。本研究中提出的指导意见将由一个讨论日本提案和建议的国内委员会讨论和通过

Several regulations or criteria were settled for preventing capsizing in Japan or in International Maritime Organization. However, these regulations or criteria were settled only in still waters. Actual capsize has occurred in severe seas, mostly in following or quartering seas and not in beam seas. The purpose of the research is to investigate the phenomena of capsize in theoretically and experimentally and to propose steering guidance for seamen.The results obtained through this research will be summarized as follows :The causes of the capsize will be categorized into three modes ; (1) Pure loss of stability, (2) Parametric resonance and (3) Broaching-to. Each mode was carefully investigated through model experiments of a container ship and two purse seiners. In a container the mode of parametric resonance was observed in lower ship velocity, and the modes of pure loss of stability and broaching-to were observed in higher velocity. In purse seiners the mode of broaching-to and another mode were observed. The another mode was the capsize in wave crest with decrease of restoring moment due to the waves on deck.The present guidance cannot represent the effect of individual ship characteristics nor wave condition. Therefore it cannot include the capsize caused by parametric resonance, which may occur outer frequency range of concentration of wave energy. The guidance proposed in this research will be discussed and adopted by a domestic committee which discusses Japanese proposal and