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Old 16-12-2009, 07:38   #46
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interesting topic. I have been thinking of an idea, since sitting at anchor in peaceful coves all last week hearing one boat after another fire up a motor to charge batteries in the USVI.

I was thinking of something that would work at anchor. Think of a little pully with a rachet that only lets it turn in one direction, that clips between the anchor chain and the hull somewhere. Might be a second, small anchor dedicated to the generator. Function is to hold one end still while the buoyancy of the boat rising on waves provides the energy. A self winding wristwatch kind of thing. Could be a bow cleat. the up and down motion of the boat pulling against the fixed anchor would turn the wheel, providing power. Motion on the upward movement would both turn the pulley and stretch a bungee at the same time. When the boat moved downward the energy stored in the bungee would continue to pull the wheel in the same direction until the boat started back up on the next wave, again pulling the wheel and stretching the bungee.....

In cross section my idea looks a lot like a jib furling thing, with two drums. One for line, one for bungee...etc.

Lots of force in the bouyancy of the boat. Could trickle the batts all night without making that damned racket of starting a diesel.

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Old 16-12-2009, 10:05   #47
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Solar is king, in my opinion...

Originally Posted by Canibul View Post
....since sitting at anchor in peaceful coves all last week hearing one boat after another fire up a motor to charge batteries in the USVI.....
I can relate, as I love the peace and quiet myself......
Which is why I have a large solar array....

I love thinkers, inventers, etc....
But, in my opinion, I think you'd find a decent-sized solar array to be more practical......since I believe the invention you're describing may be a bit too complex, and certainly a bit too cumbersome to stow, for most average-sized cruising boats.....
Over the years, there's been much talk about harnessing tidal flows, and making use of ocean waves/swells....on a very large scale, to generate power, but I've not heard of much developement......
However, if you put together something that works, please keep us informed...


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Old 16-12-2009, 10:35   #48
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A new one to be available next summer year...but pricy (estimated around 5000 €uros!):

Watt and Sea - L’hydrogénérateur - Une solution simple et efficace
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Old 16-12-2009, 10:47   #49
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Old 16-12-2009, 11:27   #50
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5000 Euros seems like a bit much for something that must be retracted with a manual cord. I would think one might expect similar performance from a modified trolling motor for a lot less money. 12.5 V also seems a bit low if you want to charge a battery from it.
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Old 20-12-2009, 09:35   #51
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You can buy an 'Underwater' unit from Ampair right now, designed for use in streams and rivers, for a fraction of the Watt & Sea cost. It would need to be rigged to an outboard bracket-like affair off the transom...but the hard work is already done.

Canibul, something similar to what you are visualizing is in fact in use right now off the E coast of Britain - a tide generator. Of course, your boat is bobbing up & down a foot or so, their tides are in the 4-6 meter range and the devices are just a wee bit bigger... <g>

FWIW the shaft & tow generator write-up I mentioned earlier is now posted at:
Tow Generator

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Old 12-01-2010, 22:32   #52
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I wrote to "watt and sea" few weeks ago to have more details about the futur price...and I am still waiting for an answer.

I agree that the price announced is way too high for a simple stuff (although performing well apparently) like that.

I am currently installing a lot of power generators aboard (wind generator, solar panels...) and I'd like to have a quick answer from them to decide if I go for their solution or an Aquagen, in order to erect a welded aluminium support for it and before all the paint work start (the boat is under refit...).

If they do not answer in the next week, I'll go for an Aquagen.

My other concern about the Aquagen, is that the boat speed can be way above 10 knots, I am wondering if it will stay in the water (the propeller) or not at these speeds ?
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Old 13-06-2015, 05:22   #53
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Re: Towing Generators / Update, Anyone?

Thanks for all of the info in here guys. I know that I LOVE my Redwing in wind gen. mode, but I can see now that I'll Definitely have to try this!

And GordMay, thanks for the tip towards this thread!

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Old 14-06-2015, 18:27   #54
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Re: Towing Generators / Update, Anyone?

I don't know if any of you remember Estralita(sp?) but they used to be regulars until they left the docks. They have been cruising for sometime now and have commented that they don't get a great deal of power from their towed generator. Often its just 2 or 3 amps. But that adds up and they are glad that they have it. They have a number of videos on YouTube, some better than others.
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Old 15-06-2015, 11:42   #55
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Re: Towing Generators / Update, Anyone?

Originally Posted by Euro Cruiser View Post

The 'Fish ate my tow gen' stories are, from everything I've heard/read, bogus. Especially with the H-F unit (but also the Aquair to a lesser extent), chafe can be a big problem where the tow line joins the generator and the shaft. You can read multiple accounts of this - and efforts to resolve it - over at the SSCA DB. I'm sure there have been times when boats have been offshore, in the presence of big pelagic species, and lost their shaft & prop. But if you felt the weight, saw the dimensions of the shaft and line involved, and could appreciate the inertia of this quite heavy assembly, spinning to beat the band, you'd conclude that chafe, perhaps aided by fouling on some floating junk, is the far more likely culprit.

]I don't really know what ate my H-F unit, but I was beating up the coast of Australia one night about 0230 and hear a loud clunk and bang at the back of the boat. Checked it out and the water generator mount had been broken AND the safety line snapped. If it was floating junk, there would have been a hell of a bang when the boat hit it.

Finally, props don't 'jump out of the water' unless the wrong pitched prop is used for a given boat speed. The Ampair unit e.g. is offered with two props, one for use above 8 kts and the other roughly up to that speed. For most of us and most of the time - sadly - using the a normally pitched prop never produces this problem, which does need to be avoided so as not to have the shaft/prop assembly foul the line.

I had the high speed prop and two big brass weights on the shaft, and my H-F prop regularly jumped out of the water downwind in 25-30+ knots and waves to match. You could look back and see the wave steepen behind the boat and the prop was just pulled out of the steep face of the wave. Boat speed was 7-11 knots. The problem was that when it jumped out the line would kink and then cut the output way down, not to mention increasing the vibration and chafe at the prop end of the line. I tried putting a hose over the last 25 feet of line to stiffen it, but that increased chafe at the prop end--in retrospect maybe I should have kept the hose from going closer than a foot or so of the prop.
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Old 15-06-2015, 12:13   #56
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Re: Towing Generators / Update, Anyone?

Yves Gelinas on Jean du Sud's circumnavigation relied on a water generator to charge the batteries. Something ate his propellor(s) and he was left without generating ability. He made a crude replacement propellor out of wood that worked well enough that he didn't completely lose electrical generating capacity. Yves trip was quite a few decades ago before commercial wind generators, solar panels, etc were available. Believe he home brewed his system.

Yves is quite an inventive guy and is the creator of Cape Horn Self Steering and still sailing Jean du Sud, his much modified Alberg 30. He made a film of his trip which is quite good. It's available on his web site
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Old 17-06-2015, 16:55   #57
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Re: Towing Generators / Update, Anyone?

I know that this thread is old, but I thought it worth posting in case someone is interested in a DuoGen.

I'm in the process of buying a 2011 Elan 444. This is a European boat that was sailed across the Atlantic. It was equipped with a DuoGen. As someone noted in the thread, they are recommended for the ARC. It looks like it is in excellent condition (just like the entire boat) and will be checked at survey next month.

Unfortunately, I will not be able to use it when I add davits. Therefore I will be taking it off the boat and selling it. I will be pricing it competitively with a high quality wind generator, e.g. a D400, but I have not figured the price yet; too busy with getting other ducks in line.

Please contact me if you are interested in this unit. The boat is in the Tampa, FL area and I will work with you on transportation if not local.

The reason for posting this now is that you might want to see it before it is taken off the boat in late July (if you happen to live in the area).

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