Wondering about using a 1HP GE ECM? Someone got 400W with wind. Must have been running slower than 2400RPM? Slower may make it last longer than an auto alternator. No brushes. Most (all?) have a long shaft, maybe ~4", that could be supported with extra bearings, and give it a bit more distance from the water. Still has the higher voltage options.
Might have less losses than a car alternator, but would need some kind of control. Plus they are only rated at 1400RPM. G-
