Experimental investigation of the impact of geometric characteristics of the spray rail cross-section on the hydrodynamic parameters of a high-speed craft

One essential component attached to the high-speed crafts is the spray rail, whose optimal design, when accounting for various influencing factors, holds the potential to enhance the hydrodynamic performance of such vessels. This investigation employs experimental tests to manipulate geometric aspects of the spray rail, such as the underlying angle and the ratio of its width to the hull width in a particular section. Testing is conducted at NIMALA using a high-speed craft based on the Fridsma model in three configurations: without spray rail and with spray rail in two different modes. The tests cover velocities ranging from 2 to 10 m per second. The ratio of the distance between the spray rail and the keel to half the model's width in each cross-section is set at 25 %, 50 %, and 75 %. The findings indicate a 7 %–15 % reduction in hull resistance compared to a bare hull. Additionally, specimens with a narrower width ratio and a larger underlying angle generally exhibit better performance. However, a definitive conclusion regarding improvements in trim and rise-up behaviour cannot be drawn for all cases.