Singular and Simultaneous Effects of Step and Stern Wedge on High-speed Craft Behavior in Irregular Waves: Experimental and Statistical Assessment

Abstract

In the design process of high-speed craft, the motions and exerting acceleration on the craft in waves are of great importance. Due to the relatively small size of this type of vessel, they incur more intensive motions and higher accelerations in the presence of waves. In the current study, the behavior of five configurations of baseline, wedge-mounted, single-stepped, wedge-mounted single-stepped and double-stepped planing hulls in irregular waves were experimentally studied. All models have a length of 2.6 m, a beam of 55 cm, and weigh 86 kg. The considered irregular wave was generated using the JONSWAP spectrum and had a characteristic height of 12 cm and a peak period of 1.6 s. These models were towed at Froude numbers ranging from 2.15 to 3.44. The analysis of heave and pitch motions of these models demonstrated that simultaneous use of a single-step and a stern wedge can reduce the heave and pitch double-amplitudes of the planing hull up to 33% and 60%, respectively. That’s while, the double-stepped model was the least successful model in heave and pitch motions reduction, by a maximum of 27% and 18% reduction for heave and pitch motions, respectively. Regarding the acceleration of these vessels, the wedge-mounted single-stepped hull experienced 34% and 16% lower accelerations in its center of gravity and bow than what the baseline model experienced. However, using two steps could only reduce these two types of acceleration by 10% and 4%, respectively.