Influence of the length-displacement ratio to ship resistance in a transitional mode

Abstract

When the vessel moves in transitional mode, water resistance increases and this phenomenon requires more careful calculations for estimating the value of this resistance. Accordingly, for a vessel it is necessary to choose a higher engine power, which entails higher fuel consumption and more significant air pollution. When calculating the water resistance, the change in the area of the wetted surface of the vessel is taken into account when moving at a high relative speed. Using the method least squares, a formula was derived to estimate the residuary resistance of ships moving at a different relative speed FrV The formulas for calculating the relative residuary resistance were differentiated and differential equations were obtained. With the help of these equations, it is possible to estimate the change in the residuary resistance displacement ratio, when the Froude numbers and the length displacement ratio of the vessel are changed. These formulas are based on an experience gained in various test tanks. A comparison of the test results of Yacht, Patrol boat and Passenger ferry models with water resistance values obtained using statistical formulas is proposed in this paper.