Experimental Study Of Resistance And Motion Characteristics Of Trimaran Hull Form

The resistance and motion characteristics of a typical trimaran have been studied through model experiments. The experiments are composed of two parts:resistance experiments in calm water and motion experiments in regular waves. The tested trimaran model consists of a single mainhull and two small sidehulls.The resistance experiments for different trimaran configurations in calm water were carried out over a range of Froude Numbers, which varies form 0.1 to 1.0. The experimental results show that the best trimaran configuration for calm water resistance varies with the Froude Number. The most important discovery of the tests in this thesis is that at high speed Fn> 0.6, placing the sidehulls in front of the mainhull's midship yields better resistance performance. The tested Froude Number interval was divided into seven sections, and the best configuration for trimaran resistance performance in calm water was presented for each section.The motion experiments in regular waves were conducted in four typical Froude Numbers. The trimaran motion characteristics, including heave RAO, pitch RAO, roll RAO and total resistance in regular waves, were studied. The peak values of each motion response and total resistance were compared between different configurations. The experimental results show that, for the semi-planing high speed section of Fn> 0.6, placing the sidehulls in or in front of the mainhull's midship yield relatively better motion performance.Based on the experiment results, for the semi-planing high speed section of Fn> 0.6, a new type of trimaran configuration named "semi-planing fore-body trimaran", is developed in the thesis.A numerical computation method, based on Von Karman slamming theory, was presented for slamming pressure of two-dimensional section with arbitrary shape. Moreover, the method was applied to the tested trimaran model.