The rotor of the SeaHawk should begin to rotate when the wind speed reaches approximately 1.8 m/s 4 mph. Battery charging will commence on
a 12 Volt battery system at about 3.1 m/s (7 mph), on a 24 Volt battery system at about 5.4 m/s (12 mph) and on a 48 Volt battery
system at about 10.8 m/s (24 mph)
All operational wind speeds given assume steady winds, sea-level altitude and moderate temperatures. Hot weather, high altitude, turbulence, and gusting winds will reduce system performance. The rotor speed will increase with increasing wind speed and the system will provide a higher output. This output increases rapidly because the energy available in the wind varies as the third power (cube) of the wind speed. For example, if the wind speed doubles from 5 m/s (11.2 mph) to 10 m/s (22.4 m/s), the energy in the wind increases by a factor of eight (23 = 2 x 2 x 2 =
. One result of this relationship is that there is very little energy available in light winds.
For the average site, winds in the range of 5.5 – 9 m/s (12 – 20 mph) will provide most of the system’s annual energy production.
B. High Winds
The SeaHawk VAWT performs extremely well under high wind conditions. Since there is no need to protect itself as do propeller based systems, the SeaHawk simply cannot spin any faster at above about 42.75 m/s (95 mph). The SeaHawk just appears as wind loading at that point and the wind simply goes around the SeaHawk as it is putting out full power. The SeaHawk puts out maximum power at about 27 m/s (60 mph)
The SeaHawk wind turbine must be placed on a tower that is tall enough to give the cage proper exposure to the wind. Putting a wind turbine on a tower that is too short is like installing a solar system in the shade. As a “rule-of-thumb” the SeaHawk should be 9 m (30 ft) above obstacles within 50 m (160 ft),
particularly in the prevailing wind direction. So, the minimum recommended tower height is 9 m (30 ft.). For most situations, a tower of at least 18 m (60 ft.) is recommended
for this unit.