COMPARISON OF SOME FEATURES OF HIGH SPEED MARINE CRAFT

Some of the principal features of the main types of high speed marine craft are examined as an aid to assessing their present effectiveness. The craft considered are those which have service speeds greater than 30 knots and which are large enough to serve a practical commercial or naval purpose. The three main types are high speed displacement or planing craft, hydrofoil ships, and hovercraft. Power requirements are considered for these craft in calm water, and in waves representing conditions likely to be met in typical service operations. This performance comparison is extended to include some trial and service data. Published and other available information on the disposable load factors for various types of craft are then summarized, and it is suggested that apparent variations in structural efficiency are largely due to technical choices based on commercial considerations and to differences in certification requirements. Simple methods are used to compare some design features selected on economic considerations rather than technical efficiency. Cost criteria are examined and used in a broad discussion from which tentative conclusions are drawn about the present relative overall operating costs for foilcraft and hovercraft. Some characteristics of various types of craft which can affect their use in particular practical operating conditions are considered.