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.