On the movement of ships in restricted waterways

Abstract

In this paper some simple theoretical considerations concerning the movement of ships in restricted waterways are discussed, and it is shown that for a ship towed from the bank, or by any external force, there are three distinct speed ranges: subcritical, critical and supercritical. In the subcritical and supercritical ranges, Bernoulli's equation and the continuity equation are satisfied everywhere by a state of steady motion relative to the ship, but in the critical range these laws require that a quantity of fluid is piled up continuously ahead of the ship in the form of a bore. Experimental confirmation is given by means of photographs of model tests.