Investigation of the Effect of Geometric Parameters on the Hydrodynamic Characteristics of the Stepped Planing Hull Vessels by Analytical Method

Using transverse steps is a way to reduce friction resistance and also increase the velocity of stepped planing hull vessels. In stepped planing hull vessels, by increasing the velocity and entry to the planing regime and finally separation fluid flow from the step, the wetted area decreases and as a result, the drag force will decrease. In this research, an appropriate analytical method is presented to study the hydrodynamic characteristics of the stepped planing hull vessels and the results of this procedure are validated with experimental data of a specified stepped planing hull vessel for three step heights of 2, 4 and 6% of width. In the mentioned approach, using available semi-empirical relations for the geometric dimensions of the produced waves at heel of the stepped planing hull vessels, the Savitsky method is developed. The results reveal that the developed method has a much better performance compared to the Savitsky method and has an acceptable agreement with the experimental data. After validating the proposed analytical method, the effect of geometric parameters including step height, center of mass location and transvers step position on the hydrodynamic behavior of the stepped planing hull vessel is examined and the optimal value of the mentioned parameters are achieved.