Don’t Hesitate to Renovate

CAPT. FRANK LANIER is an award-winning journalist, boat maintenance guru and owner of Capt F.K. Lanier & Associates, Marine Surveyors and Consultants:

The Power of Wind

How to install a wind turbine.

Since wind is an unpredictable animal, you might want to consider a hybrid system that combines both wind generators and solar panels. Cloudy days are often accompanied by higher winds, while sunny days often mean lighter air. Using solar and wind gives you the best of both worlds. Unlike solar panels, which require sunlight to operate, wind turbines have the potential to autonomously generate electricity 24 hours a day, 365 days a year. Here’s a look at the basics of choosing and installing one.

Wind turbine 101 While the output from a wind turbine can sometimes power equipment directly, marine installations will utilize batteries. Batteries not only provide a more constant power source (one that doesn’t fluctuate during changes in wind speed), but also allows users to store excess energy generated for later use.

Wind turbines are generally classified as either small rotor units (blade diameters less than 48 inches) or large rotor units (60 inches or more). Although they have less output, small rotor units have the advantages of reduced size, weight and lower start-up speeds (the wind speed a unit actually starts producing power). The benefits of large rotor units are increased power production upon reaching start-up speed and, in some cases, quieter performance.

Wind turbines obviously depend on the presence of wind, but at some point (typically around 35 knots of sustained wind) you’re approaching too much of a good thing and will need some form of blade speed control mechanism to prevent physical damage to the unit. Also required is some form of voltage regulation to prevent battery overcharging. Some units have built-in regulators, while others rely on separate, external units installed as part of the system.

Braking or blade speed control can be accomplished in a number of ways. Some wind turbines have specially designed blades that “feather” or stall out at certain speeds, while others gradually turn away from the wind if it becomes too powerful.

“The Superwind 350 is a commercial-grade, autonomous wind turbine that utilizes auto-pitch control of the rotor blades,” says Mark Dettmer of Mission Critical Energy. “This allows continuous, unattended operation and full charging of batteries, rather than shutting down before batteries are completely charged, as many hobby wind turbines do.”

Most wind turbines also offer the option of installing an electronic stop switch, which essentially shorts out the unit and slows it down while allowing you to safely tie it off if required. The nature of wind The main challenge confronting any wind generator is the unpredictable nature of wind itself. Wind generators are most effective in steady winds with your boat at anchor; however, the most sought-after anchorages tend to be sheltered from the very winds needed to generate power. This means the start-up speed of a wind generator and its output in lower winds (10-15 mph or less) can sometimes be more important than maximum rated output.

Multi-blade types have an advantage in this respect. Their smaller, lighter blades require less wind to start turning, meaning they’ll reach kick-in speed and start producing power sooner in light winds.

The power of wind is another factor. If wind speed doubles, wind power (the amount of work it can do) increases eight-fold. This means that if you’re anchored in that nice, quiet cove, but every now and then a strong gust of wind blows through, the generator output can approach or exceed what you’d get while anchored in a steady, moderate breeze. This is where wind generators with larger blades and higher maximum outputs have the advantage, as they can generate more power quicker than smaller bladed units. The catch, however, is whether these puffs occur often enough to keep up with power demand.

Mounting options “A wind turbine will work best in the wind,” notes Dettmer, “so it’s important to have the turbine high enough to be clear of curious fingers and other errant crewmember body parts, but to also take advantage of any laminar flow (unobstructed wind force) that might be available onboard. If the turbine is mounted too low, turbulent air may push the blades around, but you won’t get the best power generation.”

Stern poles are a popular mounting choice, as they hold the unit in place and ready for use anytime while keeping it up and out of the way. They consist of a stainless steel or aluminum tube about 2 inches in diameter firmly mounted with rail clamps, guy wires and/or rigid metal struts to provide diagonal support from the pipe to the deck.

Arcs are another choice that provide some excellent mounting options. They cost more than a pole, although the added expense of having one fabricated can often be justified, particularly if it will serve multiple purposes (e.g. for davits or antennas). ★