ストリップ法による横揺れ波浪強制力の推定について

抄録

As a practical method to calculate ship motions in waves, so-called strip methods now prevail through the world. According to the investigations which have been performed up to now, it is conceived that the wave exciting forces related to heave, pitch, sway and yaw motions can be evaluated by the strip method with accuracy enough for practical use, but, on the contrary, there is room for further investigating whether the strip method is valid for estimating precisely the wave exciting roll moment. Recently, Tasai and others manifested that when a ship has no advance speed the wave exciting roll moment acting on it was able to be evaluated well by New Strip Method if two-dimensional hydrodynamic forces were determined appropriately, for example, by the close-fit method. In this paper as well, the particular problem mentioned above is dealt with for the case where a ship has advance speed. As the result of the present investigation, it is concluded that Ordinary Strip Method (O. S. M.) yields good estimation of the wave exciting roll moment. However, if the wave exciting roll moment is required to be predicted more accurately, a method advocated by Salvesen, Tuck and Faltinsen (S. T. F.) is recommended rather than Ordinary Strip Method. Lastly, effects of the presence of heel of the hull on the amount of wave exciting forces are discussed on the basis of theoretical values of wave exciting forces obtained by the strip method. In consequence, it is shown that the wave exciting roll moment is affected to a great extent by the presence of heel of the hull compared with others.