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Old 15-07-2019, 15:15   #46
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Re: DIY towed generator

Check out last couple of issues of Practical Sailor. Addresses this issue very well.
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Old 15-07-2019, 15:26   #47
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Re: DIY towed generator

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There is no free lunch. Resign yourself to the basic truth that you are taking electrical energy out of your boat's performance through drag. There are reasons these devices have not become mainstream. Sailboats are slow enough as is.
Models I've seen require 6+kts speed over water at least, for meaningful output (i.e. better than 300w of solar when its overcast). In good wind, going close to hull speed anyway, no problem. Anything but good wind, it's a waste of money and hassle. One thing: they produce nil at anchor, where the average cruiser consumes the most, unless you anchor in a 10kts stream...

As a consequence, hydo generators are used by racing circumnavigators in 60' boats on the Southern Ocean.
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Old 15-07-2019, 16:00   #48
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Re: DIY towed generator

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Have you considered using the propshaft? ...

Yep, see post 34. Feathering prop rules it out. Also, only planning to use this thing very infrequently so better on balance to take the drag penalty of the rowed prop.
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Old 15-07-2019, 16:11   #49
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Re: DIY towed generator

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Yep, see post 34. Feathering prop rules it out. Also, only planning to use this thing very infrequently so better on balance to take the drag penalty of the rowed prop.
The hydro gen defeates the purpose of the feathering prop by creating more drag...
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Old 15-07-2019, 21:43   #50
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Re: DIY towed generator

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The hydro gen defeates the purpose of the feathering prop by creating more drag...

If you read my original post I point out that this thing would only be used in very specific conditions. Downwind at night. And then only if I feel power is low.
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Old 15-07-2019, 21:45   #51
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Re: DIY towed generator

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Check out last couple of issues of Practical Sailor. Addresses this issue very well.


What? They do they tell you where you can buy decent quality generators?
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Old 15-07-2019, 21:47   #52
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Re: DIY towed generator

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30 years ago when I lived in a retired boxcar, in the woods, in Northern Maine, and had just a few solar panels, I bolted an old 5hp 4 stroke B&S and a car alternator to a piece of channel iron and connected them with a drive belt.

I did something similar with an old roller mower engine years ago. About 1.5 HP at a guess. Not the most elegant device but it worked... sort of.
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Old 15-07-2019, 21:49   #53
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Re: DIY towed generator

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Clamp a trolling motor to the stern. An 80 lb MinnKota is very durable and lasts for thousands of miles. Remove the electronics and add a fuse and a diode of appropriate amp capacity to keep the motor from motoring and draining the battery. You might want to run it through a solar charge controller to regulate the output and save the battery. This should be a cheap and easy solution to your need.


Discussed earlier. Looks good at first glance but turns out they don’t work at all well. When I thought about it some more I could see the problem. The prop pitch is too high and the props themselves are way too small. A pity, because they’d make a good solution otherwise.
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Old 15-07-2019, 21:51   #54
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Re: DIY towed generator

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Have you given any thought to using the new bladeless, wobble type technology?


Ummm. No. I didn’t even know about it until your post made me look. That’s just plain weird. Haven’t had time to understand how they work yet. But I am intrigued.
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Old 15-07-2019, 21:55   #55
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Re: DIY towed generator

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Discussed earlier. Looks good at first glance but turns out they don’t work at all well. When I thought about it some more I could see the problem. The prop pitch is too high and the props themselves are way too small. A pity, because they’d make a good solution otherwise.
DIY prop?
Either make a fibreglass one or find something with a better diameter and pitch and adapt the boss to fit??
???

You know you want to
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Old 15-07-2019, 21:58   #56
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Re: DIY towed generator

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DIY prop?

Either make a fibreglass one or find something with a better diameter and pitch and adapt the boss to fit??

???



You know you want to

You sir, have too much time on your hands.

But now that you mention it... a DIY prop has some merit.

Anyway, I gave up yesterday and bought a washing machine.
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Old 15-07-2019, 22:00   #57
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Re: DIY towed generator

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You sir, have too much time on your hands.

But now that you mention it... a DIY prop has some merit.

Anyway, I gave up yesterday and bought a washing machine.
radio control model airplane motor propellers would work quite well and are not expensive
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Old 15-07-2019, 22:10   #58
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Re: DIY towed generator

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radio control model airplane motor propellers would work quite well and are not expensive


What an interesting idea. When I picture one I can see how they might work well.
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Old 15-07-2019, 22:44   #59
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Re: DIY towed generator

You could also try placing 'wanted' ads in various sailing forums. That's how I got my tow genny cheap last year.
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Old 16-07-2019, 01:53   #60
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Re: DIY towed generator

i've not read all the posts so this may have been mentioned but i believe if your using any prop that is designed for thrust then you have to turn it around for it be efficient as a generator when being towed.
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