Characteristics of Motion for Planing Craft in Head Wave at Very High-Speed

Abstract

It is known that planing craft suffer significant wave load and impact force=when they run in wave at high-speed. Some peculiar violent motions for planing craft occur in severe seas. For example, jumping from wave crest and falling down to wave surface and so=on. Recently, this type of craft is widely used as a leisure boat and Froude=number of such craft is over 6.0. For such super high-speed craft, even small waves cause dangerous. However, =it has not been clarified what sea state are the limiting criteria for full=speed running. In the present study, the ship motions of such a craft at super high-speed, =that means at Fn=2.0 to 5.0, in regular head waves are measured in a=towing tank. The results shows that the motion can be divided into some different types=those are linear motion, non-linear motion with and without jumping. The criterion of each type is determined according to running conditions ; =Froude number, wave period and wave height and so on. In addition, it is studied that the existent theoretical method based on=potential theory(non-linear strip method^<4)-9))>and a proposal method, =in which some hydrodynamic forces are replaced by experimental data, apply=to estimate motions of planing craft at super high-speed to compare with=measured ones.