Select to expand quoteRamona said..
The average yacht sails at 4 knots [4 knot leadmine]. With a 240mm propeller it's going to generate 30 watts! Roughly 2.5 amps. Lets forget about the hp loss needed to get that prop revolving, lets remember there is no free lunch. So for just under 4 grand the average cruiser is going to get 2.5 amps while he is underway!
Propellers are very inefficient when driven. They operate at about 40% efficiency with major losses at the boss and tips in particular. Dragging one though the water the inefficiencies are still there but with added parasitic losses like drag. For 4 grand I could have a pretty phenomenal solar/lithium battery installation, enough to power a modest home!
Now if you were to develop a paddle wheel generator that would be more efficient but the size required would be a problem.
Absolutely true Ramona, even for a Top Hat 
but where would I put the B**** thing? 
Select to expand quoteRamona said..
The average yacht sails at 4 knots [4 knot leadmine]. With a 240mm propeller it's going to generate 30 watts! Roughly 2.5 amps. Lets forget about the hp loss needed to get that prop revolving, lets remember there is no free lunch. So for just under 4 grand the average cruiser is going to get 2.5 amps while he is underway!
Propellers are very inefficient when driven. They operate at about 40% efficiency with major losses at the boss and tips in particular. Dragging one though the water the inefficiencies are still there but with added parasitic losses like drag. For 4 grand I could have a pretty phenomenal solar/lithium battery installation, enough to power a modest home!
Now if you were to develop a paddle wheel generator that would be more efficient but the size required would be a problem.
Yes, and there is still no such thing as a free lunch. Using the yacht prop is quite batty, the blade curvature is all wrong and you are putting side load on your shaft and gear box bearings and introducing wear and friction to add to the losses.
Those TESLA house modules one day they may at make compact unit for rvs and marine use
Select to expand quoteStuman92 said..
Look what i found in a Hartley book from 1983
Wow, 20 amps per hour? Gosh.
Does that mean that at the start, it produces 0 amps, and then by the time an hour is up, you'll be getting 20 amps?
If I buy one and run it for 10 hours, then will I have 200 amps? I wonder if the wires are rated to 200 amps?
It should come with a warning. "Must not be run for more than 40 hours continuously, or you are likely to cause your boat to catch fire".
Well turns out the 4.5 evinrude of mine has died, so im going to have a crack at converting it to an electrical outboard that can also work as a drag hydro generator. considering it requires practically no extra "ingredients" it should keep it small and simple.
Select to expand quoteStuman92 said..
Well turns out the 4.5 evinrude of mine has died, so im going to have a crack at converting it to an electrical outboard that can also work as a drag hydro generator. considering it requires practically no extra "ingredients" it should keep it small and simple.
The first part sounds good. There will be some losses through the gearbox though. The prop might need modifying too depending on what electric motor you have in mind.
Ill be using a permanent magnet low RPM motor, i will try and use/build a more suitable gearbox.
looking into motor options today.
