On the Resistance and Propulsion Performance of a Small-Waterplane-Area-Twin-Hull (SWATH) Ship

Abstract

Recently a keen attention has begun to be paid to what is called "SWATH" because of its highly valued seakeeping and high speed performances. Instead of its high degree of design freedom to be expected, the SWATH desing is liable to be governed by the choice of power generation and transmission system and the wave resistance which is the main resistance component in the high Froude number (Fn) region. Besides, its transport efficiency is not so high, therefore the so-called "Optimum desing procedure" should be especially needed. For that purpose, it is essential to grasp the hydrodynamic performances in still water. As the SWATH, on the other hand, becomes unstable in the high Froude number region, the motion control system with fins is indispensable. And for the desing of this system, it is necessery to get the characteristics of fins to be acted under the effects of free surface, hull, etc. This paper shows the results of investigation of resistance and propulsion performances of a high speed type of SWATH, including its fin lift characteristics.