Farfield waves created by a monohull ship in shallow water

Abstract

Interference effects between the dominant waves created by the bow and the stern of a monohull ship, of length L, that advances at constant speed V along a straight path in calm water of uniform finite depth D are considered. The largest waves due to constructive interference result in an apparent wake angle ψmax that can differ greatly from the cusp or asymptote angles associated with the wave pattern of a ship when interference effects are ignored, as in Kelvin’s classical analysis. Thus, wave interference has a very large effect on the wave signature of a ship in shallow water and cannot be ignored. Water-depth effects on the wake angle ψmax are found to be insignificant for water depths dL≡D/L greater than ddeepL≈0.89 or for Froude numbers F≡V/gL greater than Fdeep≈0.5/dL. Furthermore, the water depth dL has only a relatively small influence on the wake angle ψmax for 1.5<F, and the deep-water approximation ψmax≈0.14/F2 can then be used.