Water-powered generator

I can't believe it makes sense on a powered boat under way. It seems to me that it would certainly use more stored energy (gas or diesel) to overcome that drag it creates than electrical energy it could possibly generate. And how often would you be anchored or moored with the water rushing by at 7 knots? Now on a fast sail boat, where you're not using stored power to move, all the drag would cost you is speed.
 
While it might not make sense for a boat, I have thought of putting one of these in the river in front of my house to supplement our power. I just can't see spending the big $$ they want for the thing.
 
With all of this "green" hype bs your are going to see a ton of inefficient products to hit the market. New victims every day. I've got this perpetual motion machine I am almost ready to go to market on . But that has to wait till I get some returns on my water hydrogen busting thing.
 
Towed type of prop generators have been around for a long time. One of the marine sources (Jack Rabbit or Spa Creek) had conversion kits for an alternator. I have a book from the 50's which shows how to make one from an alternator, towing a 6 HP outboard prop on a shaft (watch out for sharks biting the prop off).

A number of sailboats have used either the towed generator, or used the free wheeling prop (many Borgwarner transmissions allow the prop to free wheel). They would have a large pulley on the boat's prop shaft, and then a small pully on the alternator. One of my friends used this to supply most of his power when sailing the S. Pacific in the 60's. One of the problems is the noise and vibration of these larger units. The small units have the same problems as a trolling motor with shaft seals to keep the water out. Actually you can run a trolling motor allowing it to free wheel and generate some power--is it worth the drag? Not sure. We just went with diesel generators.
 
They want 700 English pounds sterling for this goodie, which should be around $1000 (without checking the conversion rate).

A 12-V DC trolling motor has a permanent magnet motor with brushes that will work as a generator in reverse mode. It will produce a pulsating DC, and may require enlarging the propeller to get enough leverage (torque) to overcome some of the extra friction going the other way for efficiency, but the trolling motor should charge your battery just fine, though it won't be regulated, and you'll have to monitor it yourself or design a circuit that will.

Undoubtably there might be some developmental issues, but it would be fun to develop, and a good used trolling motor should cost $50-$100, instead of $1000 plus shipping for starters! :lol:

Joe. :teeth :thup
 
Just put a paddle wheel on the side of the boat and hook the trolling motor to it. You could put one on each side. Now do you think you could hook it to the electric on your main engine and you wouldn't have to have all those batteries?
 
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