An investigation into the wave wash and wave resistance of high speed displacement ships

Experimental tests on models of high speed craft have been carried out in deep and shallow water. The models used were of round bilge form with transom sterns derived from the NPL and the Series 64 round bilge series. Longitudinal wave cuts, model total resistance, sinkage and trim were measured. The effects of length to displacement ratio (L/V⅓), catamaran separation to length ratio (S/L), speed, transom immersion, shallow water and propulsion systems on wave wash and resistance were investigated. The data can be used directly for assessing the influence of the main hull parameters, speed and water depth, for the validation of theoretical wash prediction methods and for input into wave propagation models. For the theoretical investigation, thin ship theory was used and developed in order to predict the wave pattern resistance and wave wash of slender hulls with transom sterns. In particular, the theory was extended to cover the supercritical speed range. The theoretical work included the investigation and use of transom stern corrections, establishment of a regression analysis of dynamic sinkage and trim and the investigation and use of the thin ship theory to estimate the wave profile around the hull. The theory was validated for the physical wave patterns and profiles, especially in shallow water and at supercritical speeds using the experimental results. The validation included the effects of hull form parameters, trim changes and depth Froude number on wave pattern resistance and wave profiles. It is found that numerical methods, based on the thin ship theory, can be satisfactorily employed as a simple and effective means of estimating wave pattern resistance and wave profiles with low computational effort.