As a continuation of the work presented by Hadler (2003) at FAST'03 on model test work performed at Webb Institute on high length-to-beam ratio displacement ships, an analysis has been made of a number of systematic series of this type of hull form some of which were part of a catamaran or trimaran series. These series constitute a limited body of experimental data on the calm water resistance characteristics of a number of hull forms in the hi-speed range. Analysis of these data has shown, in the speed regime where the Fn is approaching 1.0 that the residuary resistance coefficients tend to converge largely independent of hull shape. This indicates that the frictional resistance, which is usually more than half of the total resistance, will predominate. This suggests that a hull form that minimizes the wetted surface for a given volume of displacement would tend to have lower resistance. As a consequence an analytical method for designing a hull form for high-speed catamarans and trimarans with minimum wetted surface and a variable transom stern based on a limited number of hull geometric parameters has been developed and verified by comparison with the resistance measured on model 4796 from Series 64.
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