On the Estimation of Current Force Induced on a Ship Hull by Some Model Tests

Abstract

For the design of mooring system and dynamic positioning system of a ship, it is fundamentally important to estimate the external forces induced on the objects. Current force is one of external steady forces, and only few formulas and experimental results for estimating it are presented up to date, besides they are not sufficient to apply to any kind of ships. Authors carried out the obliquely towing experiment for various kind of ship models, spheroids and flat plates to measure the current force coefficients, and showed a new method to calculate current force on any type of ships by means of analyzing our experimental results. In the case of model tests, Reynolds number has to be smaller than actual ship condition, because of towing speed to be restricted in low to exclude free surface effect, in other words wave making resistance. Accordingly, some differences in such current force coefficients between model test and actual ship conditions may exist, and in this paper authors also presented a soiution about that.