A Consideration on Vertical Wave Loads Acting on a High-speed Craft of Medium Size

Abstract

In the previous paper, the authors presented a method for calculating vertical motions and vertical wave loads of a high-speed craft which travels in regular head sea, and verified its validity comparing the computed motions and wave loads with the results of model tests. Furthermore in this paper, the above-stated method is applied to an existing high-speed craft of medium size in order to clarify the fundamental characteristics of vertical motions and wave loads of the medium-sized craft. The illustrative calculation is performed extensively for various cases of wave length, wave height and advance speed.As a result, it is found that the magnitudes of the vertical acceleration at the bow and the vertical bending moment correlate definitely to each other. This fact approves the propriety of the current design practice : the highest possible bending moment that is required to be predetermined for structural design of the hull is prescribed well as a function of the vertical acceleration at the bow.Besides, remarkable dependence of the maximum bending moment on the advance speed of a craft is demonstrated successfully by dividing the vertical bending moment into three parts and then clarifying the effects of advance speed on each part.