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Old 24-03-2014, 08:36   #1
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Hydro generator DIY

Does anyone know where I might find some DIY plans or ideas for a hydro generator that could tow behind our sailboat or attach to our transom. I can't believe the price that company's want for an off the shelf unit $4-6,000, really?
Has anyone had any luck modifying a trolling motor? Any ideas, suggestions, comments welcome... Cheers.
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Old 24-03-2014, 08:46   #2
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Re: Hydro generator DIY

Have a look at slow DIY electric generating windmills. Several designs for slow speed generators , of course you have to make the whole thing survive the salt !

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Old 24-03-2014, 09:01   #3
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Re: Hydro generator DIY

... you will find 'homebrew' or low-budget versions on the net. For instance this one: sailnsea MyEsell.Com - Schleppgenerator :: SailingGen

After I compared several units I will go with the newer Watt&Sea model - your mileage may vary ;-)


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Old 24-03-2014, 09:02   #4
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Re: Hydro generator DIY

I'd think it would be harder to engineer a tow-behind unit, with the motor in the water.
Might be easier to use an outboard drive leg that mounts firmly to the boat,
and have an alternator on top, out of the water.
This would lead to the idea of a tow-behind boat.
I just picked up an old standup jetski for free, strip it down to just the jet drive and minimal hull and attach an alternator to the shaft.
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Old 24-03-2014, 09:10   #5

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Re: Hydro generator DIY

Or something like this:

Ampair Wind, Hydro and Packaged Power specialists +44 (0) 1258 837 266 | Aquair 100
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Old 04-07-2017, 13:18   #6
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Re: Hydro generator DIY

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 in.
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Old 04-07-2017, 14:26   #7
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Re: Hydro generator DIY

We paid for an expensive gimbaled generator with a stiff line and long prop towed behind our boat.

I used it only a few times before I gave up. It functioned as advertised, but it was a pain to use. We had to change props according to boat speed and the line kept getting tangled in knots.

Our Aerogen wind generators and solar panels made the towed generator essentially obsolete.
Dave -Sailing Vessel Exit Only
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Old 05-07-2017, 13:15   #8
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Re: Hydro generator DIY

Oh I agree, they are a pain to use in practice, but you can get away with building yourself one for pennies on the dollar for a commercial one.

The Wind and Sea one is a design that would be hard to DIY, but deals with everything you mentioned here. It uses a gearing system and a carefully designed prop to compensate for boat speed, and it lowers and raises easily, with just two lines to accomplish that. It sloughs off weed pretty much all the time.

It also generates very little noise, and isn't on deck, so is superior to aerogen (and any wind turbine setup you might think of). Plus it is essentially maintenance free, and you only have to have the prop seal changed every 2 years.

There are other designs that give more consistent power in more conditions.. some use diving planes and are sort of "half towed" to eliminate some of the hassle, but these are susceptible to weeds. So it all depends on what you want.
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DIY, generator, hydrovane, Power generation

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