An Investigation of Fuel Efficiency in High Speed Vessels by Using Interceptors

Abstract

In the initial step of ship design, it is helpful to perform preliminary design and analysis on many ship configurations. One of the most important analyses is power prediction analysis. To be more efficient in powering, hydrodynamic optimization using energy saving devices is a growing field of interest in many areas of ship design. To calculate the propulsion power for a vessel, the resistance has to be determined with the highest possible accuracy. It is of practical importance to include sinkage and trim effects in the calculation of the wetted surface and so calculation of ship resistance for high-speed marine vessels. Wetted surface area varies significantly with speed, so approximate dynamic wetted area was estimated using distance laser meters, photography and 3D CAD/CAM software. Interceptors are employed in this research since they have been widely used in recent years in fast passenger ferries, high-speed motor yachts, sailing yachts, high speed fishing vessels, and military crafts. The main reasons for using interceptors are for ride and trim control, and for steering. By controlling trim during the voyage, a remarkable water resistance reduction can be achieved. The drag reduction varies by speed and by vessel type. In this study the results of preliminary experiments conducted in Istanbul Technical University’s Towing Tank are given. The experimental results revealed a noticeable reduction in total resistance over a broad speed range between Fn = 0.116 and Fn = 1.302, with benefits of 1.5–14%, and the trim reductions observed are 1.6° and 4.7°. The improvements observed are much larger at higher speeds. Also, a multiple regression analysis is utilized to make suitable predictions of the C_T. The suggested model predicted the total resistance coefficient C_T quite well, with an average error, compared to the model experiments, of 6.9% in chine location of the interceptor.