One of the things we added to Rode Zora was a wind generator. In my view a wind generator adds a level of independence. I hate having to connect to shore power or, even worse, starting up the engine just to charge batteries. In Northern Europe there is generally not so much sun but plenty of wind and when sailing it almost always comes from forward of the beam! So, a wind generator is a more logical solution than solar cells.
There is quite a variety of models on the market to choose from starting at 200 € up to several thousands. There are also good reviews to be found on youtube covering most models that are commercially available. From the review it becomes clear quickly that buying one of the cheap models is a waste of money and effort. The work and/or cost for Installing one of these units on the boat should not be underestimated. In fact this outweighs the generator itself.
In our case we quickly converged on the SilentWind. It has good reviews, the cost is in the mid range and the fact that it comes with a voltage regulator that allows to add solar cells made it even more attractive. SilentWind also advertises that their generators are being used in the Volvo Ocean Race. So, our reasoning: If it is good enough for these guys, it should be good enough for us. SilentWind is a German-Portuguese company based in Porto. And this is why I write about it here.
After the unit arrived the first observation was about the size: A 400 W wind generator is a sizeable object. The diameter of the rotor is in excess of 1m and hence the mounting point must be high enough so that the blades cannot harm anybody who might be standing below the thing. In our case, the mast on which the generator is mounted is about 3m above deck level and correspondingly heavy. Nothing that I could bricolage together. Definitely a job for the yard which delivered beautiful work for a not insignificant amount of money. The mast has a hinge a the bottom because with the mast up, Zora would not fit through the door of the boat shed in Wedel. (Note that the mast cannot be laid down with the mast up since it interferes with out double back stay, unless you are willing to remove the backstay…)
During our first season with Windy we had a lot of trouble with vibrations. No effort of ours could remove them and they were so bad that the massive stainless steel mast developed a crack close to one of the welds where the support struts are attached. During the winter we sent it back to Portugal and SilentWind worked on it. In fact, when we got it back, we noticed that they had machined the support flange where it is attached to the axle of the generator. They also gave the generator a new coating as the paint was coming off in places and aluminium oxidation was setting in. After this the vibration problem was a lot better. It did not completely disappear though. But it was so much reduced that we have had no more trouble with the mast
After this second season, Zora stayed in the water during the winter with her mast up. I decided not to take down the generator as it is rather difficult to do this with the mast up, balancing on a ladder that is hard to set up on the deck. I dismounted the blades though. When trying to recommission the generator again this spring for our tour d’Atlantique, the bearings in the generator were seized up. Apparently water had entered into the ball bearings.
I contacted SilentWind again and they reacted very quickly and shipped spare bearings from Portugal by express mail. They arrived in Hamburg within 24h. Amazing! However, I decided not to install them. An engineer friend looked at the bearings and recommended to install fully sealed bearings from SKF. These are standard ball bearings one can order from dedicated web shops for ball bearings for approximately 4 Euros a piece. There is a video on youtube about how to install them. Now Windy is spinning again and making electricity on board. Time to sum up our experience:
First observation: A 400W generator is a sizeable beast and significant forces are involved requiring good support. The effort to provide this support is not to be underestimated. Second observation: 400W is a bit of an exaggeration. At 12 V, 400 W would require 33A. Even when it is windy I typically see maximum currents of 10 A and the most I have seen is 20. There might have been 30, but under those circumstances I would typically not care so much about how much the generator is charging. Third observation: Sailing across the North Sea, our batteries are kept well charged as there was always enough wind and typically from ahead. You notice quickly when the batteries are full because you notice the brake of Windy setting in. Fourth observation: The SilentWind is a reasonable unit with some deficiencies in the design. I think the most serious is the flange that holds the blades. Both the way it is attached to the generator axle and the way the blades are attached is not defined well enough for the requirements. Things can be fiddled but it takes a lot of effort and time. Finally, the support from the company in Porto, Portugal, has been very forthcoming and friendly. Had I been on board, I would definitely have take the time and visited them. I actually exchanged a number of emails with a guy called Edgar and even met him during Boot Düsseldorf. Would have been nice to chat and exchange experiences…
