Wind Power

Power generation from the wind is one method to increase independence from shore facilities. We have now entered our second generation solution.

Starting with the first Maringret electrical power became a limiting factor when away from shore power. We installed a wind generator which we had for over 10 years. It was moved to the second Maringret and eventually replaced.

With our first boat we were marina based and the charging by the engine was sufficient for our sailing needs. As we ventured further and for longer we started to face battery depletion. We had three options:

In the late 90s very few boats had wind generators and we talked to those we could find. There seemed to be 3 sizes available: the smallest being for keeping batteries from discharging between use. We opted for the middle size which was for charging batteries but was also physically smaller than the largest size (which made it that much easier to fit). The 2 brands we found in 1999 were Rutland and Aerogen – we decided to go with the Aerogen 4 (there was a Aerogen 2 and Aerogen 6 which were smaller and larger).

The Aerogen sailed 10,000 miles with us before transferring to the second Maringret for a further 7 years. At the 2009 London Boat Show we stopped at the Aerogen stand and chatted about their products and asked what service was due our Aerogen 4 after 10 years of use. They replied that it should be disassembled and cleaned, the bearings and seals replaced. When we lifted out a couple of months later and lowered the rig we removed the Aerogen 4. Over the next 2 years we serviced the Aerogen 4, replacing the bearings and repainting it. We contacted Aerogen to order the replacement rubber seals for weather-proofing the unit and were told they were out of stock. This continued over the next 2 years, the story eventually migrated into “we relocated our factory and there are problems resuming production and have no idea when the parts will be back in stock”. After 2 years of hearing this and noticing that Aerogen had stopped selling their Aquagen (their water based generator which used the same armature as the Aerogen but towed a propeller in the water) we started to suspect that the company was not serious about customers. After 2 years we had to face the facts that we could not recommission our Aerogen 4 due to  ineptitudes with the manufacturer. The pieces we needed were custom rubber moldings which we could not find on the open market place. We had even phoned stockists in Europe and N America to try and find the seals but after 2 years of suspended production we could not locate any.

11 years after our first searches we found ourselves researching the same topic again. The biggest difference was that the internet was now available and it made various cruisers forums and online magazines available. We also had a decade of using the Aerogen under our belts and comparing notes with owners of other wind generators – both Aerogen and other makes. This time we knew that Aerogen was not a candidate for obvious reasons but other than that, we had not decided many things with one exception. Through years of sharing anchorages and mooring spots we had learned that the fewer blades on a wind generator the noisier it tended to be. The Aerogen had 6 blades and was a very quiet unit – putting out a low swishing noise when turning. The noisiest unit we had come across was a 2-bladed unit which put out enough noise to prompt anyone to relocate – we were surprised that the crew weren’t wearing ear protection! Talking to owners seemed to indicate that the fewer the blades (and thereby the higher the noise level) the more power was output. This was an impression and we left it as such as no owners we talked to had ever systematically measured their units production let alone compared the production of other units.

We were lucky enough to find some test articles:

The tests seemed to rate the Air Breeze as a medium unit in size while having an output that placed it in the low end of the large generators. It’s price was slightly more than other medium sized units but its output placed it well above the others. One thing that caused us to hesitate was that the Air Breeze had 3 blades which in our minds made it potentially a noisier unit. Although it was not unanimous, the people posting on cruisers forums did complain about the noise associated with the Air Breeze. Other posters said that the noise was associated with blades and by using a newer style of blades the noise was reduced noticeably. The test we found either mentioned the noisier performance of the units with fewer blades or alluded to it. The reason seems to be that the units with more blades turn more slowly than those with fewer blades. The tip of a 1.2m blade turning at 1,400 RPM will be something like 300 kph!

Another issue for us to solve with the Air Breeze was that of charging voltage, using Gel Cell batteries we needed to make sure that the charging voltage never passed 13.8 volts. We talked to the UK distributor who could only say that they had sold the unit to Gel Cell installations before and had never heard of any problems. We then phoned the manufacturer who is located in Phoenix Arizona.  For the first time ever we asked to be transferred to Technical Support and after explaining the question were met with giggling – not a good sign. The best thing seemed to be to ask to be transferred to the head of Technical Support and there we got excellent advice and attention. The answer to our questions was to manually reduce the charging cutoff voltage for the Air Breeze using a potentiometer located on the side of the unit. We also ascertained that Air Breeze would not work with other brands of regulators as it had its own regulator built into the unit. This disappointed us as we had hoped to keep using our FlexCharge charge regulators as we had 2 – one each for the wind and solar power generation. The FlexCharge regulators had served us extremely well. As the Air Breeze regulator is mounted aboard the generating unit it senses the battery voltage via the charging cable which means that any voltage drop due to cable length will effect the accuracy of the charging voltage. This means that large cables are even more important – which means more expense and more weight aloft.

As with the solar panels we moved the Aero4Gen wind generator from the Maxi. With 2 masts to choose from we were able to avoid mounting a support pole on the decks. We decided to mount the wind generator on the forward side of the mizzen mast, above the radar that was already mounted there. When we installed the Air Breeze we were able to adapt the existing bracket on the mizzen mast.

After installing the wind generator on the mizzen mast we found out that there was originally a mizzen staysail that the wind generator would interfere with. As we did not receive this sail when we bought Maringret we were unaware of its existence. From what we have been able to find out from other ketch owners the mizzen stay sail is a rarely set sail so perhaps we didn’t loose too much in our trade off?

  • more blades start turning at lower wind speeds
  • fewer blades generate more noise (due to high revolving speeds)
  • fewer blades generate more power (due again to higher revolving speeds)
  • in the 10 years since we chose our first wind generator the choices had changed due to new materials, designs and increased use of onboard electronics
  • windless and heavily overcast days occur more than you might initially think

The Aerogen 4 is a 6-bladed unit, it operates quietly and must be manually stopped when the wind passes approximately 35 knots. It generates up to 8 amps in 30 knots of wind. The supplied regulator is quite inefficient and we opted to replace ours with a newer unit.

Aerogen 4 Air Breeze
Blades 6 3
Noise level quiet medium to high
Output at 30 knots 6 to 8 amps 16 amps
Safety shut down none 32 knots
Braking manual tie off blades electrical via a supplied switch

The Air Breeze has turned out to be much noisier than the Aerogen it replaced. The noise is two part with radiant noise through the air and vibrational noise through the mounting (i.e. mizzen mast). We have noticed that the radiant noise level differs greatly depending on whether the air is disturbed or not: if the wind is from the stern then the wind must pass around the mizzen mast to reach the Air Breeze and this seems to make the blades much more noisier. With the Aerogen we were generally unaware if it was turning.

On the other hand the Air Breeze generates a lot more power than the Aerogen. It also has a safety feature to shut its self off when the wind passes 32 knots. We once were hit with 40+ knots of wind while using the Aerogen and it went wild. We wanted to shut it off for safety’s sakes but dared not approach it. Shutting the Aerogen off when it started spinning too fast was always a dangerous operation – especially on a moving boat. With the Air Breeze there is a switch that is part of the wiring that stops the wind generator.

The power output difference is remarkable. To avoid over-charging the batteries we use the Air Breeze much more like a shore power charger as opposed to a constant background charger. If the batteries are discharged and there is a wind blowing then we will switch on the Air Breeze to bring the charge level up and then switch it off. This is partially to do with the noise of operation also. Presumably the onboard regulator should prevent the Air Breeze from over charging and damaging the batteries but we have never left it on long enough to find out. In talking to Air Breeze in Arizona we were unable to determine if the regulator is a multi-step charger or is simply charging with a fixed amount of current. In monitoring it with the power manager the current and voltage are constantly changing so it is presumably following some charging regime but we have been unable to determine what charging algorithm it is following and whether that algorithm is appropriate for Gel Cell batteries..

The bottom line is that due to the vastly increased generating capacity and the higher noise level associated with that our usage pattern has changed dramatically.

Note: in the spring of 2014 it came to our attention that Southwest Windpower (the manufacturers of Air Breeze) has ceased trading. According to an article on the website of the Interstate Renewable Energy Council they ceased trading in February of 2013 without warning, click here for the article. According to the article they sold the Air product line to “Primus Wind Power” the previous month.

In the end both of our wind generators failed from bearing problems. The Aerogen was destroyed by the service personnel; the Air Breeze, having gone bankrupt, had one service person for all of Europe. That same service person was “unable” to insure the units against damage while in his possession.

At present the Air Breeze has been removed, and sits onboard, disassembled. Given the erratic nature of winds in the Mediterranean, it never contributed much anyway. The solar panels far surpassed it.

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