Experimental study on water entry of twin wedges

Abstract

This article presents an experimental study on the water entry of twin wedges commonly used as sections of catamaran craft. A twin wedge is a combination of two single asymmetry wedges connected by so-called wet-deck. The single asymmetry wedge has a vertical side and a non-vertical side with a range of deadrise angles. This study is carried out on a set of twin wedges of 7°, 15° and 20° deadrise angles. For calibrating the experimental equipment, the twin wedges symmetric quality, tank depth effect, three-dimensional effect, repeatability and sampling rate effects are examined. The water entry experiments are conducted through a drop test method. Time histories of impact pressure are recorded for different deadrise angles, drop heights and space between two single wedges. The results show that the effect of space on the peak pressure is negligible. In water entry experiment, the pressure on the non-vertical side of an asymmetry wedge is considerably lower than that on the equivalent symmetry wedge. The vertical side of an asymmetry wedge is under the effect of air entrapment. It has much less pressure than the non-vertical side.