Experiments and Predictions of the Resistance Characteristics of a Wave Cancellation Multihull Ship Concept

This paper presents results of both analytical predictions and towing basin validation experiments for the basic resistance characteristics of a new small waterplane area, tri hull ship concept termed the Wave Cancellation Multihull (WCM). This is a variant of the O'Neill Hull form (OHF) type arrangement but which exploits extensive wave cancellation effects between the various hull elements: the center body, the center strut, and the two outer hulls. Significant reductions in total ship wave making resistance have been predicted in a high speed range normally associated only with fine form monohull ships. A tapered-strut-type center body shape bas been developed as an alternative to the original OHF center body and-strut configuration. Towing basin tests confirm the predictions of the thin ship theory wave making resistance variations. The resulting complete ship wavemaking resistance can be reduced to such an extent that the total resistance of a WCM ship geometry is comparable to that of a monohull at high ship speeds, despite the substantially larger wetted surface area. Summary comparison plots are presented for BHP/Displacement versus speed for several 4300 LT ship forms, including a candidate WCM arrangement.These show, for example, that at 30 knots it is possible to achieve a 28% reduction of effective horsepower with a realistic WCM configuration compared with the SWATH VII performance (best performing SWATH to date). It is also shown that the candidate WCM form bas about the same effective horsepower as a slim combatant monohull form at the speed in the neighborhood of 30-32 knots, despite 88% more wetted surface area.