On the hydrodynamic characteristics of a high-speed catamaran with round-bilge hull: wave resistance and wave pattern experimental tests and numerical calculations

The paper deals with the hydrodynamic resistance of a round-bilge catamaran hull form in the Froude number range Fn = 0,5 – 1,1. The wave resistance and the wave pattern have been measured at different hull separation ratios. The tests were carried out in the towing tank of the University of Naples (140 m x 9.0 m x 4.2 m). The experimental results, obtained by using the multiple longitudinal cut method, and the wave profiles, measured both outside and inside the hulls, were compared with those obtained from a numerical boundary element method based on Rankine sources. The model experimental resistance data have also been analysed by using the classical ITTC'57 and ITTC'78 ship-model correlation methodologies, in order to highlight the various interference phenomena. A comparison with the numerical method is carried out with in terms of wave resistance, wave pattern, dynamic sinkage and trim and free wave spectra. These spectra are also obtained from the numerical wave pattern by operating transverse cuts downstream of the catamaran. The theoretical wave resistance coefficients are obtained both from pressure integration on the wetted hull and from wave pattern analysis.