The effect of ship length scale on bow foil efficiency gains in waves

For a ship operating in waves, bow foils can significantly reduce the delivered power required to maintain a given speed in waves, saving fuel and reducing emissions. As a result, bow foils are receiving a significant interest as an innovative energy efficiency technology to reduce CO
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and comply with increasingly stringent regulations set by the International Maritime Organization (IMO). However, currently information on the suitability of bow foils for different ship types is limited. It remains unclear, which ship scales and areas of operation provide the greatest efficiency and emission savings.This paper assesses the efficiency of passive bow foils over a range of scales and sea states. Given that a ship’s seakeeping response relative to the incident wave directly affects the response of the bow foil, there exists an optimal wavelength to ship length ratio for optimal (passive) bow foil operation. This article uses an experimental dataset to demonstrate the effect of ship length scale on the bow efficiency gains achieved in different sea states. Using a range of ship length scales, the bow foil efficiency gain was determined for different irregular sea states at regular intervals of wave period. Combined with wave statistics, these results were employed to generate contour plots of optimal ship length for various oceans and seas. Since the wavelength and ship length are predefined parameters, these results can be used by researchers, engineers, ship owners to assess whether bow foil technology can improve a particular ship’s performance and reduce emissions.