Experimental validation of spray deflectors for high speed craft

Abstract

A planing craft is a type of marine vehicle that is supported predominantly by hydrodynamic forces at high speeds. It has widespread applications in recreational and military use as well as for search and rescue operations. Although spray rails are a mature technology, there is limited experimental data illustrating their hydrodynamic effects. Furthermore, continuous efforts are being made to improve the efficiency, safety and performance of planning craft. In this paper, the efficiency of the spray resistance reduction technologies – spray rails and spray deflectors – are compared in model scale through towing tank testing in calm water and irregular waves. This study examines the influences of the technologies on the total resistance and running position of the hull in calm water and on impact accelerations experienced at the center of gravity and bow in irregular waves. The experimental results are discussed in connection with established semi-empirical methods for predicting the performance of planing craft and improvements for further testing of the spray deflection methods are proposed.