I have meet two who had Watt & See hydro-generator installed, further one of my cruising colleges, just installed one. From the first two, one was on an Amel SM who had done the World ARC, the other on an Allures 45.Both was very satisfied with the concept, but acknowledge the fact, that it does not give any input when at anchor. But it's when sailing you have the highest consumption. By the way, these two boat was in a Rally Ile de soleil, I was crewing on one of the other boats for 10 weeks so I got in good contact with them. There was two Amel participating. one with the Hydro unit, the other just as it comes, and I ask him why do you not install solar panels? He said I have a genset no need! I think it's very personal what you like
I have a different thinking, genset is excellent as "last resort" or back up or when you run your washing machine. I have installed 450 watt of solar cells, and considering either to add another 2x100 watt on the rail, or the Watt & See. No decision yet, maybe I'm chasing silence to much but I do not like when my neighbor run his genset, so I try to avoid running ours when in a bay, I usually wait until someone close start his genset or his engine to charge, then if I need I start ours.
Since we installed the Solar cells, we only need to run the genset every second day, at the most compare to 3x 45 minutes every day before they where installed. We have however no experience when crossing as we installed it just a month ago. We do not run the freezer either. A solution which might be more cost efficient is as JP says go for low consumption equipment our fridge/freezer just stop working so maybe that's my solution install a water cooled fridge/freezer
Regards Paul S/Y Kerpa SM#259