Windmill ship

File:Windmill (oxy)hydrogen hybrid ship.jpg

A windmill/(oxy)hydrogen hybrid ship

A windmill ship, wind energy conversion system ship or wind energy harvester ship propels itself by use of a windmill connected to the propeller. Windmill ships should not be confused with rotor ships, as they do not rely on the Magnus effect for propulsion. They use direct wind power mechanically transferred (not electrically like with windturbines), allowing the force to be transferred to the propeller without conversion losses. In windmill hybrid boats, electrical conversion of the power is nonetheless done when the energy can not be used immediately and needs to be stored.

Points of sail

Due to the fact that a windmill can rotate 360°, a windmill ship can sail in any direction.

Types

Several types can be made; these include windmill-only ships , windmill/rotorsail ships 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. Also, the wind mill needs to be highly durable as marine environments tend to degrade windmills more quickly than what is common on land.

Current ships

Few windmill ships have been built to date; these include :

• Jim Bates' Te whaka
• Lindsay Olen's Thrippence
• Peter Worsley's windmill-driven boat
• Jim Wilkinson's Revelation 2