Wind Generator Performance Improvement

[Rich Stidger]

In 2008 I installed an AirX 400W wind generator. I researched the wind speeds in my home harbor and calculated the potential energy benefit. I did my homework.... or so I thought.

In reality, the energy benefit that I achieved was much less than I had anticipated. I had expected to gain 30-40AH per day on average, but actually gained about 15AH.

The wind speeds that I observed were about what I had anticipated, but the wind generator was not always using the wind efficiently. At anchor I would observe the generator to point into the wind, speed up, output good amps, then yaw so that it was no longer pointing into the wind, slow down, and stop. Then it would repeatedly re-position itself into the wind and repeat the cycle over and over.

I theorized that the yaw out of the wind was due to a quick wind shift, wave action that moved the boat, or some sort of gyro-scopic action. I puzzled on how to keep the generator pointed into the wind all the time so that I could maximize the AH output.

I tried tying the boom off to one side thinking that the air would be "cleaner" to the generator if the boom was causing turbulence. That seemed to help a little but the generator still swiveled out of the wind repeatedly.

Today I was thinking again on this problem- I was wondering if a larger vane on the back would help? But shouldn't the designers of the AirX have figured out the optimum size of the vane?

Then I saw another sailboat with TWO of these wind generators mounted. It looked like something that could take off and fly! But I noticed that both of the wind generators seemed to always point into the wind- unlike mine. Closer inspection revealed a clue......

I noticed that at the tail of each generator there was tied a short piece of line. This line trailed out when the wind was blowing. I likened it to the technique of trailing a line overboard to help keep a boat headed into seas. But maybe that line was just there to be able to tie down the generator?

Well, I tried it myself. I tied roughly a two-foot piece of 1/8" line on the tail of the generator. Lo and behold, the generator stayed pointed into the wind MUCH more than before! Not perfect, it still occasionally yawed out of the wind, but the AH being generated is at least twice as much than without this simple line. Before I attached this line, the current output was about 2-3A and then it would drop to zero. Now the output is a steady 4+ amps! Cool!! See pix below.

I pass this idea along to others who may have a similar issue.

 

[Maine Sail]

In 2008 I installed an AirX 400W wind generator. I researched the wind speeds in my home harbor and calculated the potential energy benefit. I did my homework.... or so I thought.

In reality, the energy benefit that I achieved was much less than I had anticipated. I had expected to gain 30-40AH per day on average, but actually gained about 15AH.

The wind speeds that I observed were about what I had anticipated, but the wind generator was not always using the wind efficiently. At anchor I would observe the generator to point into the wind, speed up, output good amps, then yaw so that it was no longer pointing into the wind, slow down, and stop. Then it would repeatedly re-position itself into the wind and repeat the cycle over and over.

I theorized that the yaw out of the wind was due to a quick wind shift, wave action that moved the boat, or some sort of gyro-scopic action. I puzzled on how to keep the generator pointed into the wind all the time so that I could maximize the AH output.

I tried tying the boom off to one side thinking that the air would be "cleaner" to the generator if the boom was causing turbulence. That seemed to help a little but the generator still swiveled out of the wind repeatedly.

Today I was thinking again on this problem- I was wondering if a larger vane on the back would help? But shouldn't the designers of the AirX have figured out the optimum size of the vane?

Then I saw another sailboat with TWO of these wind generators mounted. It looked like something that could take off and fly! But I noticed that both of the wind generators seemed to always point into the wind- unlike mine. Closer inspection revealed a clue......

I noticed that at the tail of each generator there was tied a short piece of line. This line trailed out when the wind was blowing. I likened it to the technique of trailing a line overboard to help keep a boat headed into seas. But maybe that line was just there to be able to tie down the generator?

Well, I tried it myself. I tied roughly a two-foot piece of 1/8" line on the tail of the generator. Lo and behold, the generator stayed pointed into the wind MUCH more than before! Not perfect, it still occasionally yawed out of the wind, but the AH being generated is at least twice as much than without this simple line. Before I attached this line, the current output was about 2-3A and then it would drop to zero. Now the output is a steady 4+ amps! Cool!! See pix below.

I pass this idea along to others who may have a similar issue.

Good fix Rich! Over the winter you may want to check your swivel bearings. Tim R. had to replace his over the winter (Air Marine 400) and they were toast. One would suspect that "by design" the wind gen should stay pointed into the wind by itself so it possibly could be a bearing issue that does not allow the tail to produce enough effect to over come the bearing drag..?

 

[John Nantz]

When the wind blows they are really good!

Rich - very interesting post.

I've got a Rutland 6-blade wind generator that I have a tether line tied to the rudder vane but it was for a different purpose which was to just tie the wind generator off to prevent it from spinning. The line goes from the tail to one of the blades where I make a loop and then to the mast near the blade. This allows the wind generator to rotate but prevents the propellers from spinning.

One place where a wind generator is exceptionally useful is when sailing to windward because the apparent wind is usually pretty good and the output is fantastic.

Several years ago we were in Ucluelet on the southwest side of Vancouver Island when a storm was forecasted to come in. The marina was full of commercial fishing boats and we had to anchor out in an fairly unprotected area. The seas were about 3-ft and the wind generally was in around the 25 knot range. We ran all the lights, stereo, and even the hot water heater.

Slip rings: If the output falls off over time be sure to check the slip rings. The brushes will deterioriate in contact with the copper slip rings after a time so you'll need to get in there with some very fine sandpaper and knock the tarnish off.

It would be nice to have a regulator like the Blue Sky one with the "boost" technology for when the voltage drops below the charge voltage. My solar panels have that but the wind generator does not.

Picture below: Southeast Alaska below Sitka. Radar to starboard, wind generator to port.

 

[RAD]

Thanks for the info....I had thoughts of installing a system but a few years ago my summer/winter neighbor installed a wind generator on his Hunter and last spring while working at the boat yard on a few windy days it was doing what you described and the boat was on the hard so I thought maybe it had a brake that was failing cause all day long it would run then stop,start for awhile then stop and I thought to myself I don't know if I'd like one of those on board....I'll have to report your info to my neighbor

 

[Rich Stidger]

MS-

I will check the bearings but my observation is that the generator moves easily, even as the boat rocks with no wind. Maybe Tim will chime in with info about expected life of the yaw bearings. I bought this AirX 400 on eBay and I am not sure how old it is.

John-

Thanks for the tip on the slip rings. I'll be mindful of that in the future.

In the owner's manual, according to Southwest Power, manufacturer of the AirX, the bearings are designed for a 10-year life. However, they also recommend replacing the bearings and blades every 5 years for "optimal performance". I think the bearings they are referring to are the prop shaft bearings and not the yaw bearings. They also state that the copper brushes should last a lifetime and that the yaw shaft has been tested over 100,000 revolutions with no visible wear on the brushes or slip rings.

My mileage may vary.......