Voyagers recount wind generator installation
From Ocean Navigator #123 July/August 2002
After all these years of sailing, Kathy and I have finally admitted that we spend much more time at anchor than at marinas or on passages. The places we love most usually are pretty remote with no services. To keep our little ship functioning in our favorite places, we can burn diesel for one to two hours every day to spin our 135-amp engine-driven alternator to charge our batteries, or we can harness the sun and the wind. Where we go, the sun shines most of the time and the wind frequently blows 15 to 20 knots or more night and day. To harness the sun, we installed a 64-watt solar panel a couple of years ago. When the sun shines all day, the solar panel works well and provides about 30 percent of our daily energy needs. Lying in our berth at night, however, listening to the wind in the rigging is a constant reminder of the additional energy we could capture if we installed a wind generator.
We have a strict daily energy budget. We have most of the "big boat" electrical appliances, including reading lights, pressure water, inverter, 12-volt refrigeration with a small freezer, single-sideband, Ham and VHF radios, notebook computer, and a 1.2-gallon-per-hour watermaker. But we don't have a microwave. We use seawater for everything possible and strictly limit our freshwater consumption. Our biggest users of electric power are the radios, refrigeration and the watermaker. Originally, we installed 200 amp-hours of house-battery capacity plus a 70-amp-hour starting battery.
With the wind generator charging, we converted our starting battery to a 100-amp-hour house battery, giving us 300 amp-hours of house-battery capacity with no reserve for starting. Since we live on the boat, we watch the batteries all the time and rarely let our house batteries drop below a 75 percent charge — plenty of capacity left to start the diesel. The additional 100 amp-hours of battery capacity will provide more energy storage capacity and fewer diesel-engine charging runs. When we are motoring, all three house batteries are being charged. In the event of low batteries, we could, with simultaneous wind and solar charging, shut off all electrical equipment on the boat and bring the batteries up enough in a few hours to start the diesel.
The installed cost of a wind generator can be between $1,000 and $2,000, depending on the brand and type of installation. You can buy a lot of diesel for $1,000 to $2,000, particularly when the cost is spread over several years of voyaging. However, like solar panels, wind generators have special appeal, even after doing the math; wind energy is free, non-polluting and does not consume non-renewable energy resources. Our 64-watt solar panel combined with the 400-watt wind generator will not provide all our electrical needs unless the wind blows hard all the time which we hope it doesn't.
We chose to put the wind generator on an aft port-side post, rather than build an arch, because we already have radar on a post on the starboard side, and we don't have a mizzenmast. We wanted the wind generator to be small, reliable, light, reasonable in performance, relatively quiet, and up and out of the way back aft, all at an affordable cost. We chose an Air-X Marine 12-volt model, a third-generation device with good reports from the anchorage.
Unlike solar panels, which provide known maximum amps when the sun is directly overhead, a wind generator output goes up as the cube of the wind speed. At 25 miles per hour of wind speed, a wind generator can produce more than 15 amps. This is more power than some shore-powered battery chargers! Since the wind generator is the largest provider of charging power on the boat, second only to a high-output alternator, the installation must be carefully thought out.
We could have saved money by shopping for pole and support components separately, but we chose to buy the pole and installation kit complete. Like most sailors with vintage boats, we try to use holes already in the deck whenever possible, rather than drilling new ones. On our boat, we were able to use the existing, discontinued, loran antenna base on the port quarter. Using this base with the hardware included in the pole installation kit, we were able to mount the 9-foot wind-generator pole so that it tipped down fore-and-aft not side-to-side. I didn't want to hang over the side making up the electrical connections protruding from the top of the 9-foot pole, much less remove the generator and blades when the boat is in the yard for storage.
The first step is to locate the mounting pole on the boat, without electrical wires or the wind generator installed on top. The pole should be roughly vertical to the boat and lashed firmly at the base and to the stern rail so it won't fall overboard. The tough problem is where to locate the two support struts. The struts were loosely attached, so the connection brackets were easily able to slide up and down the pole. The struts are supposed to be at about a 90 deg angle to each other to provide maximum support, one athwart ship, one fore and aft.
The struts were moved around until we located some clear deck space for the base plates. Before drilling the holes, remember someone has to be able to install and tighten nuts under the deck. Locating the athwart-ship support was the toughest. Naturally, other devices were in the way, including our trusty self-steering wind vane, propane tanks, outboard motor bracket, stern rail and flag. The fore and aft pole support had to clear the winch handles, lifelines and deck cleats. The support struts are disconnected at the bases to allow the pole to tip down.
A red and black pair of no. 8 wires were run inside the boat (a project much easier said than done) up through the deck with 11 feet extra sticking out of the deck to feed up inside the pole. The former loran-antenna through-deck fitting was used for the generator wires. With the pole attached to the deck at the base, the pole was tipped down forward, and the wires were fed up inside the pole, leaving approximately half a foot of wire hanging out the top. I couldn't find a suitable two-wire connector that could handle 30 amps and no. 8 wire that couldn't possibly become disconnected inside the pole. I fabricated a connector using two pairs of no. 6 copper lugs, which could be bolted together. Wires were inserted into the lugs and the lugs filled with solder. The generator was connected electrically, observing polarity, by bolting each pair of lugs together and carefully taping them. The generator was installed on the top of the pole. The blades were installed and the whole assembly tipped up and the struts reinstalled.
Since we use fuses on all our DC circuits, including the solar panel, I chose to use automotive-type spade fuses, rather than circuit breakers. I wanted the only external controls in the cabin to be a single-pole single-throw (SPST) switch each for solar and wind and a 25-amp DC meter showing the combined DC amps. The solar or wind power can be switched on and off individually to observe the current produced by each one. The remaining electronics were mounted in a space under the navigation station.
The solar and wind components were mounted on a 6-inch-square plywood board. I used 14-gauge for solar wiring, since the panel provided a maximum of five amps DC and it was a short run. The longer the run, the heavier the wire gauge.
We bought the wind-generator components from Radio Shack, the single-pole, dual-throw (SPDT) 70-amp relay, fuse holder and terminal strip. The SPDT 70-amp relay is very important, since it shorts out the wind generator when the relay is non-energized in the "off" position and isolates the main battery bank. The panel switch in the "on" position energizes the relay, and the wind generator provides energy to the batteries. The same with the solar panel, except the "off" position simply opens the circuit to the solar panel charge regulator. The DC amp meter was purchased from West Marine. We mounted the solar regulator on the board next to the wind-generator relay. A terminal strip allows for easy and neat connection of the solar and wind SPST switches and the DC amp meter. No isolation diodes are required with either the Air-X Marine wind generator or the solar panel, since both have built-in isolation.
The first test of the system was in a narrow river with gusty 10- to 20-knot winds. Unlike a solar panel, which reacts instantly to changes in sunlight, the wind generator takes a few seconds to get up to speed in gusts. The unit generated 1 amp at 8 to 10 knots. A steady wind of 15 to 20 knots, as expected in an island anchorage, produces 7 to 10 amps. The wind generator does vibrate, but the rubber shock mounts work well. At 25 knots or greater, more than 10 amps are produced and the generator sounds like an airplane trying to take off; at least you know it's back there working. How much energy is generated during a season of voyaging in windy places remains to be seen.
Dick de Grasse and his wife Kathy sail in the Caribbean in the winter and summer on an island in Maine.