Improvement of the hydrodynamic performances of planing craft in waves using flat-chines

Abstract

This study investigates effects of the flat-chine on hydrodynamic performances of a planing hull both in calm water and waves. A prismatic hard-chine hull as a reference hull and three hulls fitted with flat-chine are selected for analysis and comparison. Initially, a set of model experiments are conducted on the reference hull for evaluation of the numerical method. Then, the numerical simulation is extensively employed using SIEMENS PLM STARCCM + to analyze effects of chine breadth ratio, defined as b-to-B ratio, on planing craft's performances. This study shows that the vertical acceleration in waves significantly reduces, 15% or more, by fitting the flat-chine to a hard-chine hull. It is also concluded that a larger b-to-B ratio triggers the lower acceleration. However, increasing b-to-B ratio results in a marginal increase of drag in the calm water, about 1%. Considering both advantages and disadvantages of the flat-chine, fitting appropriate flat-chine to planing hulls is justified.