Experimental study of the influence of catamaran parameters on water resistance

Abstract

The advantages of multihulls over monohulls are better running characteristics at high speeds and a larger deck area, which is critical for passenger ships. When designing, it is necessary to choose geometric parameters, which include the distance between the hulls. A brief description of the existing methods for calculating the towing resistance of multihull vessels is provided in the paper. New results of an experimental study of the effect of transverse clearance and the ratio of the one hull width to draft on the resistance of a displacement catamaran are also provided. The studies are carried out by testing a small non-self-propelled model of a multihull vessel in the towing tank. The model length is 1.84 m; the width of one hull is 0.15 m; the draft varies from 0.07 m to 0.11 m. The experiment is carried out in the towing tank of the Admiral Makarov State University of Maritime and Inland Shipping. The results are processed according to the Froude method without taking into account dynamic heel and they are presented as a dependence of the residual resistance coefficients on the Froude number. By approximating the experimental data, an expression allowing evaluating the influence of these parameters on the value of the residual resistance in the range of Froude numbers 0.30–0.70 is obtained. One hull is also tested at two draft values in the same speed range. These data are not approximated, but they are presented in the paper in the form of experimentally obtained points. The results of the work can be used at the initial stages of designing catamarans and at studying the influence of these factors on the residual resistance.