Farfield waves created by a catamaran in shallow water

The farfield waves created by a catamaran with identical twin hulls that advances at constant speed along a straight path in calm water of uniform finite depth are considered. The catamaran is represented as two point sources at the twin bows of the catamaran. This simple approximation of a catamaran as a 2-point wavemaker is realistic for the high-speed regime considered here. Constructive interferences between the divergent waves created by the two point sources result in an apparent wake angle, where the highest waves are found, that can be much narrower than the wake angle associated with the cusps or the asymptotes of the well-known wave patterns radiated from a single point. The farfield wave pattern of a high-speed catamaran can then differ markedly from the wave pattern obtained in the classical analysis of the waves created by a ship modeled as a 1-point wavemaker, in which interference effects are ignored. Moreover, the highest waves created by a catamaran can be much shorter than the waves at the cusps of the wave pattern, and significantly shorter than the ship length. Indeed, the wavelength of the highest waves is equal to the spacing between the twin hulls of the catamaran at high Froude numbers. Wave interferences between the twin bows of a catamaran (dominant at high Froude numbers) are compared to wave interferences between the bow and the stern of a monohull ship or a catamaran (significant at moderate Froude numbers).