An underwater spoiler on a warship: why, when and how?

Abstract

Abstract There are a lot of energy saving devices for ships on the market, but few have seen wide adoption on naval ships, with one exception: the bulbous bow. The bulbous bow was developed for naval ships in the early 20th century and is now widespread on a variety of ship designs. Many have wondered if the effect of the bulbous bow — reducing the resistance of a ship by reducing the bow wave — could be replicated somehow at the stern — by reducing the stern wave. This is exactly what is done by a novel and patented energy saving device called Hull Vane®. Invented by Dutch hydrodynamicist Dr Peter van Oossanen for an America’s Cup sailing yacht in the early 21st century, research over the years has shown that this wing-shaped appendage works best on ships that combine a relatively high displacement with a relatively high top speed requirement — even if most sailing hours are done at half speed. Examples are certain offshore vessels, superyachts, patrol vessels and naval ships. On offshore patrol vessels, the resistance reduction from the Hull Vane® ranges typically from 10 to 20% over the entire useful speed range. In this paper, the working principles of the Hull Vane® will be described to give a better under-standing of the device. An overview will be given of the work carried out on naval ships and coastguard ships (25 to 142 m), based on Computational Fluid Dynamics studies, model tests and full-scale applications. The question ‘Why?’ will be answered by translating the hydrodynamic effects to concrete capability improvements for naval ships: a lower fuel consumption, a longer range, reduced signature, a higher top speed and improved seakeeping. The question ‘When?’ will zoom in on whether a Hull Vane® is something to be included in a newbuild or if it is something to be retrofitted to an existing ship. Finally the answer to the question ‘How?’ will explain the process of either integrating a Hull Vane® in a newbuild project or retrofitting it during a midlife upgrade of an existing ship.