Experience so far with our hydro-generator

Since we really wanted to avoid having a diesel generator on Wildling, we had to install a power generation system that would be a viable substitute. Solar panels are the central element of our charging systems, but they have their limits. During night passages, with all of our navigation, instruments, lights and radar running, followed by several days of cloudy weather, the batteries get depleted and need to be charged by other means. We have our Mastervolt 24V alternators, which are rated at 110A each at max rpm, and give us about 70-80 amps each at 1,500 rpm, so we can recharge our lithium batteries pretty quickly, but I hate running engines on a sailboat, so our supplemental plan is to use a hydro-generator.

I had no previous experience with hydro-generators before we purchased Wildling, but Outremer has been using the Watt & Sea generators for a while with good results, and a lot of the round the world race boats use them, so I decided to give one a try. These systems are very expensive, and they appear pretty fragile, so I was a bit skeptical about how well they would hold up in a long distance cruising environment.

Although we haven’t used ours extensively yet, we have used it quite a bit and so I can provide some initial feedback on how it’s going. What I can say for sure, is that it really works well on our boat. Between the solar panels and the hydro, we can keep our batteries fully charged without needing to run the engines. The downside of the hydo is that it of course won’t do anything at anchor, but we use less energy at anchor and usually don’t need any more than the solar to keep us topped up. Long periods of no sun will require running the engines though, which is still better than having a generator in my opinion.

Because of the speeds our boat reaches, we can’t use the cruising version of the Watt & Sea hydro generator. The high rpm destroys the turbine blades, and I know of at least one other 5X that had this problem. The racing version that we have is more expensive (of course!) but it has smaller, adjustable pitch blades that are continuously regulated by a hydraulic actuator depending on charging load and boat speed, so the turbine blades last longer. The downside of the racing version is that it really only produces a meaningful output above 8 knots of boat speed, and I have heard from other owners that the blades will still strip out over time, so you have to carry one or two spare blade kits. The turbine blades will not survive much of an impact either, so spare blades are a good idea no matter what.

Here’s a video that Lindsay and I made on our last trip to show how we have our hydro-gen setup. So far, I’m very happy with it, and I’ll post an update when we have done some more miles.

8 Comments on “Experience so far with our hydro-generator

    • Hi Ivan, I think wind generators are a viable option, especially the newer designs which are much quieter. The older ones tended to be very noisy! The benefit to a wind generator is they work at anchorage, provided you have enough wind, and that’s the issue! If you look at the output vs wind speed for the latest generators, they reach their rated output at around 30 knots wind speed. That’s a lot of wind, and most cruisers are trying to avoid being in conditions that strong, so you will be mostly putting out a lot less than the rated output. In the more realistic cruising wind ranges of 10-20 knots, they don’t do so well. They produce around 10% of their rated output at 15 knots wind speed. While they are quiet, they are certainly not silent. Quiet means it is possible to carry out a conversation standing nearby the wind generator. With a hydro generator you spend a lot more time above 50% output, they are silent, and you can stow them away when you aren’t using them. I don’t like the constant noise of the wind generators, even the quiet ones, which is why we didn’t install one. If the hydro isn’t able to put out enough power for us, I would add more solar before I would buy a wind gen.


  1. Maybe I am not understanding your post however, you seem to state that the standard version destroys the blades but that you have to carry spare blades for the racing ones because they strip as well. I am assuming based off of your choice that the Racing will last longer between need to be replaced but will still need to be replaced? We are a couple years off from pulling the trigger but the O45 looks like a boat that would work for us, and like you I am trying to figure out a way to avoid having a generator.


    • Hi Ben, from what I understand from other owners, the blades will strip out over time. I don’t know exactly how long they last, but my expectation is that we will probably need to replace them every few thousand miles. The cruising version will not last very long on a boat that is routinely traveling over 10 knots, so you would need the racing version on your 45. Watt & Sea sells blade kits, and they are simple and quick to change.


      • Doug,
        I really appreciate all that you write on here. Your explanations and justifications (not that you need any) are excellent. Have you had decent luck having enough power for everything on board with just the solar and hydro generator? Or do you wish you would either have had more solar installed or the generator? How often do you find yourself running your engines for the sole purpose of charging batteries?


  2. Hi Doug,
    What’s the procedure for removing the hydro-gen altogether? I’m not sure about having those lines blocking the port transom all the time – have you found that to be a problem/inconvenience?


    • Hi Jim,

      That’s a really good question, I should have showed that in the video. The generator slides into a stainless steel bracket that is permanently mounted on the transom. There are two machine screws at the top of the bracket that lock the generator in place. You just need to loosen the screws and slide the generator up. The power and hydraulic lines use quick connect fittings, so you just undo those. The generator is not heavy, so it’s easy to lift and carry. There is a mounting bracket in the forward sail locker, beside the access hatch, so I slide the generator into that and it’s all set. It takes about 5 minutes to complete the operation. If I’m not going to be using it for a few days, I rinse it with freshwater from the transom shower before storing it. I always remove and store the generator any time we are not underway.


  3. — Thanks for the feedback Ben! I very rarely need to run the engines just to recharge the batteries, mostly the little bit of motoring we do when departing and arriving at an anchorage is enough if we are day-sailing, and when we are on passage the hydro and solar are enough. We have been fortunate with the weather, but if we go for long periods at anchor with no sun, we will definitely need to run the engines to charge. If it’s sunny and we are at anchor, the solar easily keeps up with our daily power usage, including running the watermaker. Even with 6 people on board, we are fine with just the solar.


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