Experimental investigation of the wetted surfaces of stepped planing hulls

Abstract

In the current study, experimental tests are conducted to evaluate the hydrodynamic characteristics and the bottom wetted surfaces of the planing hulls equipped by one transverse step. For this purpose, total resistance, dynamic trim angle, dynamic sinkage, reattachment lengths of the separated flow and forebody and aftbody wetted areas are quantitatively measured at different geometrical parameters of the step and hull velocities. Moreover, the bottom wetted surfaces are qualitatively investigated by analyzing the underwater photographs. Our experimental results are also compared by archival data with good accordance. Based on our experimental observations, dynamic trim angle and dynamic sinkage are enhanced by increasing in the height of the step and decreasing the longitudinal position of step from transom. However, lower total resistance is achieved for greater height of the step. In addition, total wetted area is enhanced by decreasing the step height and hull velocity. However, larger total wetted area is detected by an increase in the longitudinal distance of the step from transom. Finally, we formulated the wetted areas of one step planing hull according to the reattached flow patterns.