Wind generators produce electricity when the wind spins their blades, and the harder the wind blows, the more power they produce.
Many larger sailboats and powerboats -- especially those based in the Caribbean, where the wind blows hard almost continuously -- mount marine wind generators to capture that wind energy and use it.
But boats in other areas can benefit from wind power as part of an overall electricity generation plan that might also include solar panels or even a diesel generator.
Marine wind generators on the market today can be grouped into two categories: smaller, six-bladed wind power turbines such as the Rutland 913, and larger, three-bladed units, such as the Air-X Marine.
Smaller Wind Generators Spin in a Light Breeze
Smaller, six-bladed wind generators tend to start up and begin to charge the batteries at lower wind speeds than larger, three-bladed wind turbines.
For example, the Rutland 913, which measures 36 inches across, begins to produce electricity when the wind is blowing at 4 knots (4.5 miles per hour), as does the Rutland 504, a very small unit designed for trickle charging with the weekend boater in mind. Both are produced by Marlec Engineering Co. Ltd.
Low start-up speeds make six-bladed wind generators better suited for areas such as the Chesapeake Bay and Long Island Sound in the summer, where winds tend to be light. These units also make less noise when running than their three-bladed cousins.
However, they also produce far less electricity when the wind blows hard. The 12-volt Rutland 913 produces up to 18 amps per hour when the wind is blowing near 40 knots (45 miles per hour), but at more common wind speeds of 15 knots (about 17.2 miles per hour), it produces only 3 amps per hour, or enough to run a small marine refrigerator (assuming the wind is continuous).
Larger Wind Generators Suited for Windy Areas
Three-bladed marine wind generators can be noisy; one cruising sailor who mounted two of them on his 40-foot sailboat notes that the power they generate is wonderful, but in winds higher than 15 knots, "they sound like two Cessna airplanes warming up on the foredeck."
But boaters get plenty of power to make up for the noise. The 12-volt Air-X Marine produced by SunForce Products Inc., for example, measures 46 inches across and starts charging at wind speeds of 7 knots (8 miles per hour).
In ideal conditions (25 knots/28 miles per hour, as per the manufacturer), it produces upwards of 30 amps per hour. At a wind speed of 15 knots, it produces about 7 amps per hour (enough to run a large marine refrigerator), making it twice as powerful as the Rutland 913 in those conditions.
Marine Wind Generators Tricky to Mount
To obtain the best performance from a marine wind generator, the unit needs to be placed as high as possible, but out of the way of anything that could interfere with its spinning.
Powerboats and sailboats with only one mast (sloop or cutter rigs) generally mount wind generators on tall poles set on the stern of the vessel, while ketch- or yawl-rigged sailboats with two masts have the option of mounting theirs on the aft mast (usually called a mizzen mast).
Regardless of where a wind generator is mounted on a boat, boat owners need to pay careful attention to manufacturers' instructions on how to install the unit in order to avoid excess vibration. Some vibration and noise with marine wind generators is inevitable, however, and boat owners learn to live with the noise in order to have the power.
In addition, many units must be assembled prior to installation, and the boat owner or installer must pay careful attention to screws or bolts connecting the blades to the center hubs. These blades have been known to fly off in high winds and have the potential to seriously injure someone nearby if installed incorrectly.
High Winds Dangerous for Some Wind Generators
High winds pose dangers to both the boat's electrical system and the wind generator itself. If the wind generator produces too much electricity, it can damage the vessel's batteries or even in rare instances cause a fire.
Some units have internal safeguards to avoid this; for example, they might stop generating electricity at high winds or include an internal charge regulator that will control the amount of electricity sent to the batteries. Others require external charge regulators to be added in the electrical wiring between the wind generator and the batteries.
In addition, hurricane-force winds can destroy wind generators, and in that case, owners need to tie down the blades or remove the unit completely during the storm.
Jane Anderson - Jane M. Anderson spends as much time as possible on the water, working and sailing on boats. She grew up sailing Sunfish and Rhodes 19s on ...
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