was chatting about a non river/creek concept Water moving between tanks. yes it can be quite successful in the right areas. was looking at one the other day that sits just below your boat to produce about 100watts Good idea on a swing mooring and out 1000 bucks. Cannot find the one I was looking at but an example an example https://www.emarineinc.com/Hydrogenerator-24V-Crusing-24-by-Watt-and-Sea
