DIY Alternator Wind Generator for Boats

Part of the charm of long-distance cruising or living aboard a boat is power management: With electronics that draw a specific amount of current per day, a sailor has to find ways to generate electricity to keep the boat's battery bank properly charged. Wind generators feeding an alternator are a popular, safe and pollution-free to get extra juice to power the boat's systems.

  1. Equipment Selection

    • Make sure all equipment is capable of performing in a marine environment. An alternator designed for a car, for example, is less likely to resist internal corrosion from the humidity of an inland lake or the salty spray of the sea than an alternator designed for a boat. Use lightweight materials like aluminum to reduce weight, and consider using a serpentine belt instead of a chain to transfer the rotary motion of the wind turbine to the alternator--it will be easier to replace at sea and less likely to reduce efficiency because of friction arising from corrosion to the chain's metal pins.

    Positioning

    • Most sailors place their wind turbines off the transom--this location reduces the chance of injury from a head collision with a spinning blade, and the odds that a rope will cross over the turbine is smaller when the blades are over the stern. If you must cut a hole in the hull to pass wire through, put the hole well above waterline and include a quick disconnect and brass seacock to reduce the risk of flooding. On a sailboat, avoid putting a thru-hull fitting low enough that it will be submerged during normal heeling.

    Connecting to the Batteries

    • Install a voltage regulator to reduce the potential damage to the batteries from overcharging or voltage spikes. Make sure that the incoming circuit from the generator can be properly isolated from the batteries and the house circuits, as well as from any incoming shore-power line.

    Safety Issues

    • Do not allow the wind generator to spin freely when not charging the battery bank--not only are the free-spinning blades a safety risk to crew and to birds, but any errant charge produced can damage electrical components or the batteries, or increase the risk of galvanic corrosion for improperly grounded boats.