曳航中の振れ回り運動による針路安定性評価法におよぼすプロペラ流の影響

抄録

The course stability of a ship is a difficult task to be determined from the quantity of the performance in the initial design stage.Most of newly-designed ships' maneuver abilities are examined by the model tests in a towing tank. Although, the drawback of this experimental method is that it will have high running costs to investigate the course stability. In the present state, it is too costly to conduct the experiments of maneuvering motions with a fishing vessel in the towing tank. The authors have proposed the simple evaluation method of the course stability by using a circulating water channel. However, the model of the ship is too small to mount its power motor and propeller. The simple evaluation method neglected the influence of propeller race on the course stability.In this paper, the simple evaluation method is improved and takes into account the influence of propeller race on slewing motions in a circulating water channel. As the towing point moves forward at a constant speed, the amplitude of slewing motion decreases and its period gets longer. The index of evaluation (aT) is represented by the point of towing from the center of gravity. Accordingly, the influence of propeller race (ΔaT) is the difference between the index of evaluation on a propeller working and the one of a dummy boss. The results are checked and compared with the course stability of sea trials. By using the present method, new fishingvessels can be designed to achieve the improvement of course stability.