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Old 08-07-2010, 18:11   #1
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During my admittedly short perusal of these forums, I've found myself wondering about water-powered electrical systems. Has anyone tried putting a small impeller into the water and used it to motor a small generator? Granted, it would only work while underway, but it would still be something.....


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Old 08-07-2010, 18:24   #2
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The short answer is "Yes".
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Old 08-07-2010, 18:26   #3
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Towed generators aren't not really new and in my estimation not really popular.

Here are a couple of past threads.

Towing Generators / Update, Anyone?

Towed water generators

There have also been discussions related to using the spinning prop shaft to turn a standard generator.

In my mind it boils down to conservation of energy. Anything you use that takes energy from the boat reduces sailing efficiency.

Wind and solar take a new energy source - from outside the boat's system - to generate electricity.
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Old 08-07-2010, 19:38   #4
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I had a towed generator that I used when sailing across the Pacific. I ended up not using it that often because it was a pain to set up, and the impeller rope always get tangled up with hockles. I finally gave up.

It had really great output when it worked.
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Old 09-07-2010, 22:13   #5
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1) The short answer, again, is YES.....
Yes, many have done it, including myself....(I've used mine offshore across the Atlantic twice, and find it works very well....)

I'll give you just the highlights here, but refer you to some other discussions (and articles) for more details.....

2) In addition to the links from ex-calif, I'd recommend reading these discussions as well....
SSCA Discussion Board &bull; View topic - Water (towed) generator vs wind- recommendations?
SSCA Discussion Board &bull; View topic - Free-wheeling Prop while Sailing--Power Generator?

As well as an article and photos of my set-up.....
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3) The commercially manufactured "towed" units (by Hamilton Ferris and Amp/Aqua Air) are similar.......
Alternate Energy Power Products, wind generators and solar panels and Wind Powered Generators

Ampair microwind, microhydro, and small wind power systems.

The "Dou-gen" is very pricey, and I've read of many who were not satisfied with its performance and reliability......
Water and Wind Marine Generators, Welcome to DuoGen

a) IF you deploy the towed unit's prop and line by paying out the line in one big loop, keeping the prop/shaft on-board until the line is trailing you in one big loop (like you were trailing a warp), and then simply drop the prop/shaft in the water......there are NO issues with deployment.....

b) For retrevial. the "funnel-approach" DOES work, and DOES work well.....(although, for some reason the Aqua-Air guys don't seem to supply a funnel????, but Hamilton Ferris does, and it does work.....)
Even when flying downwind at 7+ kts, once you deploy the "funnel", and it has slid down the line, and stopped the prop from spinning, retrevial is not a problem......yes, it does take a bit of stength to pull the thing in, if you're still flying along at 7-9kts, but you will NOT end up with lots kinks and hockles......
(If you do not use a funnel, pulling the thing in while still sailing along at high speed IS a hassle, and you WILL get a horribly tangled line, and you will need gloves......but, it can be done, as I have done it....)

c) Not getting the towed-water-generator set-up correctly, and not taking the advice / tips of others (including other manufacturers) in regards to the deployment and retrevial, is the number one reason that some who buy / build a towed-water-gen, find they don't realy like it and/or don't use it much......
Everyone, and every boat, is, please take your time, and do the research....and whether you find a water-generator to be a good choice for you and your boat, or least you'll learn a lot!!!

5) For almost all of these units, if you've selected and installed it all correctly, you'll get a little more than 1amp per knot of boat speed....

Typically not much below 3 knots....and about 1 to 1.25 amps per knot, from 4 - 6 knots.....and about 1.5 amps per knot from 6 - 9 kts of boat speed.....

6) The main disadvantage that most write about, is that they do not of course make any power when you're not moving.....
But, this isn't really a disadvantage to most who use them, since it is when undersail (especially on long passages) that you'll need more electrical power than when anchored in a nice quite cove.....

I do hope this helps.....

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