Resistance and wash measurements on a series of high speed displacement monohull and catamaran forms in shallow water

Abstract

The paper summarises an experimental investigation into the resistance and wash waves of high speed displacement monohulls and catamarans in shallow water.Measurements of total resistance, running trim, sinkage and multiple longitudinal wave cuts were carried out for three round bilge hulls derived from the NPL series and one from Series 64. Parametric changes included length/displacement ratios of 7.4, 8.5 and 9.5, and hull separation/length ratios of 0.2, 0.4 and infinity. The tests were carried out in two depths of shallow water over a length Froude Number range of 0.25 to 1.0 and a depth Froude Number range of 0.5 to 3.0. The wave resistance was derived using wave pattern analysis and the principal particulars of the generated wave system are presented as maximum wave height, period, distribution of energy and direction of wave propagation.The results of the investigation provide a better understanding of the performance of high speed displacement monohulls and catamarans in shallow water, including the influences of speed, water depth, hull separation and length/displacement ratio. The data derived are very suitable for design applications and for the validation of theoretical analyses of ship wave resistance and wash waves