Stability Indices of Ships in Following Waves

为了明确船舶在强后浪中倾覆的稳性指标，本课题在研究期间进行了以下研究项目：（1）船舶在大风浪中倾覆的分析;（2）小型客船横摇阻尼系数和有效波坡系数的检验; 3）基于倾覆概率的船舶稳性风险评估; 4）倾覆模拟器的初步研究; 5）高速船横稳性的改进; 6）描述船舶在波浪中操纵运动的新坐标系和方程; 7）船舶在波浪中响应的时域分析; 8）船舶在波浪中操纵运动控制方程的考虑; 9）有限高非对称波浪的表示;（10）低速条件下船体在大漂移和回转运动中所受水动力和力矩的物理数学模型。1）从理论和实验两方面给出了描述船舶在强随浪中运动的实用运动方程。通过数值试验指出了导致船舶倾覆的各种物理机制。3)船舶倾覆模拟器已经完成，这将有助于提供操作指导，以避免倾覆。4)对现行船舶稳性规则中规定的小型客船横摇阻尼和有效波坡系数进行了研究。

In order to clarify the stability indeces leading up to capsizing of a ship in severe following waves, the following research items have been done during the term of this project : 1) An Analysis of a Ship Capsizing in Quatering Seas, 2) Examination of Roll Damping Coefficients and Effective Wave Slope Coefficient for Small Passenger Crafts, 3) Stability Assessment of a Ship by Applying Risk Analysis based on the Capsizing Probability, 4) Preliminary Study Towards a Capsizing Simulator, 5) On the Improvement of Transverse Stability for High-Speed Craft, 6) A New Coordinate System and the Equation Describing Manoeuvring Motion of a Ship in Waves, 7) Time Domain Analysis of Ship Responses in Waves, 8) A Consideration on the Governing Equation of the Ship's Manoeuvering Motion in Waves, 9) A Representation of Asymmetric Waves of Finite Height, 10) A Physical-Mathematical Model of Hydrodynamic Forces and Moment Acting on a Hull During Large Drifting and Turning Motion Under the Conditions of Slow Speed. From this study the following results have been obtained : 1) The practical equations of motions to describe the motions of a ship in severe following waves have been shown from both theoretical and experimental considerations. Various physical mechanism that could be responsible for capsize have been pointed out by numerical experiments. 3) The capsizing simulator which will be helpful to give an operational guidance to avoid capsizing has been completed. 4) The prescribed roll damping and effective wave slope coefficients for small passenger crafts in the current Ship Stability Rule have been investigated.