I realize this is an old thread, however making a hydrogenerator isn't too difficult, assuming you have some experience with making things that move :-)
To make a DIY setup, you need a generator head
, a Universal joint that can be FIXED and rotates inside its housing, a length of non stretch line, a prop and a weight.
You mount the generator head
on your transom. You mount a Universal joint so that the strain of the line is not on the generator fitting itself. Then you attach the Universal joint to the line with a strong, detachable connector.
The weight gets attached after the prop. Then a short length of line, then the prop, then a "long "length of line, then the attachment point.
You also have to consider how fast the prop will spin at different speeds, and match that to your generator head, or put in a gearbox
to make it match what the generator is expecting as an RPM
That's pretty much it! Im sure the plans above, and others, have made their way onto the Internet
by now, so if I were building one myself, I would do some research
first before diving