Because they have a smaller footprint, vertical-axis wind turbines (VAWT) are better suited to boats than horizontal-axis wind turbines (HAWT). They are somewhat less efficient but can take advantage of turbulent and gusty winds. Cost performance and size remain barriers. Small turbines around 600 Watts (W ) capacity cost USD $5,000 or more and have a spinning diameter around 2 metres (m).
Vertical turbines are less efficient than horizontal ones, around 30%. In a design with a diameter of 2-3 m (6-9 ft) you can expect a maximum output of around 2.5 kiloWatts (kW ) (3.35 hp). Small (or “residential”) vertical systems may be suitable for boats. They range from 400 watts W to 500 kilowattskW.
== Cost ==
Small vertical turbines cost in the range of USD $5,000 to 10,000.
== Size ==
The problem of size remains. For example, the Windspire is a small 1.2-kilowatt (kW) vertical-axis wind turbine. The turbine tower is 9.1 meters tall, and its rotor area is 1.2 by 6.1 meters.
The WePower Falcon is sized as small as 600 W with a 1.6-m diameter and a rotor height of 1 m. <ref>http://wepowereco.com/ecolutions/renewable-energy/wind/</ref>
== Links ==
[http://www.indianwindpower.com Indian Wind Turbine Manufacturers Association]
[https://evergreensolar.com National Council for Solar Growth]
[http://www.jwpa.jp Japanese Wind Power Association]