Wavefoil - Retractable bow foils

New Rostein Wellboat to Feature Wavefoil WF3970 Foil Module

Wavefoil has signed a contract to deliver another WF3970 foil module for a new Rostein wellboat under construction at Larsnes Mek. Verksted. The vessel will be a sister vessel to Ro Spirit, delivered in 2023.

The WF3970 foil module features retractable bow foils with a wingspan of more than eight metres, designed to reduce resistance in waves, improve vessel motions and contribute to lower total energy consumption. The repeat order from Rostein confirms that Wavefoil’s technology has proven its performance in daily operation.

Odd Einar Sandøy, owner of Rostein, says:
“After more than two years of experience with retractable bow foils from Wavefoil on Ro Spirit, we are very pleased with the performance, both in terms of fuel savings and motion reduction. Rostein is committed to operational and environmental excellence, making Wavefoil a natural part of the new vessel’s overall energy-efficiency package. Furthermore, we are proud to support the maritime cluster in the region, with the foil module being built at our neighbour, I. P. Huse.”

The fuel saving on Ro Spirit has been validated by thorough full-scale testing, showing a reduction in propulsive power of 10 per cent under representative test conditions. See the report here.

The 79-metre vessel is designed by Skipskompetanse AS and arranged for both open and closed transport of fish and smolt.

Wavefoil offers retractable bow foils for a wide range of vessel types and sizes. Since 2023, the company has been part of the Eitzen Group, a privately owned maritime and industrial group with more than 140 years of shipping heritage.

For more information:

Erlend N. Vastveit
CTO, Wavefoil Technologies AS
erlend@wavefoil.com

Retractable bow foils

STATE OF THE ART BOW FOIL TECHNOLOGY

Wavefoil has developed retractable bow foils that provide significant fuel savings, reduced motions and a more comfortable experience at sea.

Combining a smart retraction mechanism with the use of light but strong composite materials, Wavefoil has brought wave propulsion to the market.

"There is no doubt that this is of interest for smaller passenger vessels where comfort is important, including yachts!"

Exploiting the potential of wave energy

It has been known for over 150 years that vessels with wings – or foils – in the bow can be partly or solely propelled by wave energy. The foils generate lift when the vessel is moving up and down in waves, and the lift typically has a forward thrust component larger than the drag.

Put simply, wave power is directly converted into propulsive power.

A vessel in waves experiences additional resistance compared to calm-water operation. For wave lengths similar to the hull length, this additional resistance will be amplified due to resonance, implying large heave and pitch motions. Wavefoil’s retractable bow foils dampen these motions so that the additional resistance decreases.

So how much fuel can you save? That depends on the ship, its speed, the foil size and location, and the wave conditions.

Fuel saving for suitable ships is in the range of 5-15%.

Saving fuel is not the only benefit of bow foils. Increased comfort, reduced vibrations, less spray, increased operability and the ability to maintain higher speeds in waves for a given power are some other perspectives.