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The Hull Vane is a fuel saving device in the form of a fixed foil, located below the stern of a ship.

The Hull Vane influences the stern wave pattern and creates hydrodynamic lift, which is partially oriented forward. This results in a reduction in of the ship’s resistance. The performance of the Hull Vane depends on the ship’s length, speed and hull shape in the aft sections, and ranges from 5 to 15% for suitable ships. In specific cases, savings up to 20% are possible.

The Hull Vane was invented by Dr. Ir. Pieter van Oossanen and is protected by patents in all major shipbuilding countries.

Thrust Force
The Hull Vane is able to recover energy from the ascending water flow near the stern of the ship. The lift force that is generated by the Hull Vane has a component facing forward. When the foil’s own resistance is less than this forward thrust, the net result is a push in the back of the ship.

Wave Reduction
By accelerating the water over the top of the Hull Vane, the stern wave of a ship is reduced, much like a bulbous bow reduces the bow wave. The wave pattern generated by a ship is energy spent by the propulsion engines. Reducing the stern wave therefore reduces the fuel consumption.

Trim Reduction
Many ships sailing in the higher displacement range benefit from a trim correction at higher speed. The upward lift generated by the Hull Vane reduces the running trim and keeps the ship at even keel at higher speeds.

Reduced Pitching
Moving a large horizontal plane vertically through the water requires a lot of force. The same goes for the Hull Vane. This effect significantly reduces the pitching and heaving motions of the ship in waves, which in turn reduces the added resistance caused by these motions. Added benefits are an increased level of comfort for passengers and crew onboard, and a reduced probability of cargo damage in heavy weather.

Effectiveness
While the Hull Vane has a positive contribution to most ships, model testing has shown that it is particularly effective on ships that sail relatively fast. In naval architectural terms, this means a Froude number between 0.2 and 1. For planing vessels, the Hull Vane is not suitable, as it would generate too much lift. For relatively slow vessels, such as bulk carriers or tankers, the effect can be positive but the pay-back period will become longer, as the percentage of savings is smaller.

The ideal candidates for a Hull Vane are ferries, container ships, cruise ships, patrol boats, supply vessels, navy vessels, large motoryachts, reefer ships, car carriers and roro vessels. In these cases, fuel savings between 5% and 15% are common, and in some cases, fuel savings of 20% have been achieved.

Comparative sea trials on MS Karina, a 55 m Fast Supply Intervention Vessel, showed a reduction in shaft power of 10% at 12 knots up to 15% at 21 knots with the application of a Hull Vane.