Experimental Study on the Configuration Hydrodynamics of Trimaran Ships

Abstract

This paper presents experimental results on configuration hydrodynamics. Three models are used in the model tests, which are typical of hard, round, and soft chines. Although specific values are different, the influence patterns are similar in the three ship models. A set of different outrigger positions is investigated in calm water and regular waves. A variety of interesting phenomena are observed, among which the splash resistance is the dominant component for a trimaran at high speeds (with Froude number Fr > 0.6). If two small outriggers are placed inside Kelvin’s wave systems of the main hull, a strong splash appears, resulting in a significant resistance increase. Moreover, short and long waves cannot be neglected, for they may excite the motions of much smaller outriggers. This condition leads to non-vanishing heaving at high-frequency and non-normalized pitches at low frequencies. Based on the tests, three spectra of optimum configurations for resistance, longitudinal motions, and transverse motions are presented. These results reveal the optimum configurations of a trimaran hull in terms of hydrodynamic performance, thus providing a very powerful tool for optimum design of trimaran ships.