Windmill ship
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A windmill ship, wind energy conversion system ship or wind energy harvester ship propels itself by use of a windmill to drive a propeller.
They use wind power[1] through a mechanical or electrical transmission to the propeller. Where transmission is electric, storage batteries may also be used to allow power generated at one time to be used for propulsion later on.
Windmill ships should not be confused with rotor ships, as they do not rely on the Magnus effect for propulsion.
Points of sail
Due to the fact that a windmill can rotate 360° into the wind, no matter what direction the ship is facing, a windmill ship can sail in any direction.[2][3] Conventional sailing vessels are restricted to sailing downwind, or with limited ability to sail upwind according to the design of their sails.
Types
Several types can be made; these include windmill-only ships,[4] windmill/rotorsail ships[5] as well as hybrid ships which store wind power from the windmill when the ship does not need to be propelled. To reduce the energy required to propel the boat, windmill ships are often equipped with low-friction hull designs, such as multihulls, or they are hydrofoils. Boats without low-friction hulls or hydrofoils can be equipped with windmills, but often the force generated by the windmills alone is not sufficient to propel the craft. In this case, the windmills only provide supplemental force to conventional sails or other propulsion systems.
At present, research is still going on and the best types of bladed rotors still needs to be determined. For example, high horizontal axis wind mills are proven to make the ship less stable. Therefore, vertical axis wind mills (eg Savonius turbines) are sometimes preferred.[6] Also, the wind mill needs to be highly durable as marine environments tend to degrade windmills more quickly than what is common on land.[7][8]
Current ships
Few windmill ships have been built to date; these include:[9]
- Jim Bates' Te whaka
- Lindsay Olen's Thrippence
- Peter Worsley's windmill-driven boat
- Jim Wilkinson's Revelation 2[10]
References
- ^ Windmill sailboats
- ^ Windmill powered boats
- ^ Windmill ship video demonstrating sail points and boat specifics
- ^ Windmill-only ship image
- ^ Image of windmill/rotor sail hybrid ship
- ^ Rotor sails schematic and model boat construction
- ^ Windmill ship research
- ^ Vertical axis windmill on windmill boat
- ^ Current windmill ships
- ^ "UK | Design puts boat in a spin". BBC News. 2001-08-24. Retrieved 2010-06-16.