DIY Towed Generator

[Phoenix of Hamble]

I guess the French have done it again! Lovely piece of sensible yachting equipment. Do you have info on the price as the website doesn't show it?

Selling in the US for $1250... so about £750... not cheap!... but does look like a great bit of kit that i'd be much happier with than a towed generator

 

[idpnd]

Common solution: Run alternator of free spinning propshaft. Works around your problem of getting the right driveshaft propellor etc

http://www.sailnet.com/forums/miscellaneous/22098-propshaft-alternator.html

 

[ianat182]

Would a paddle wheel offer a solution to pitch problems if fitted at rightangle to the strut and appropriate gearing/linkages. Whichever solution you select the drag is going to be significant, at least thats the argument for feathering /folding props vs fixed bladed.

 

[ff_nick]

Suggest a post on boatdesign.net, under the electrical/hybrid drive section of the propulsion forum or electrical systems forum. The shaft generator thing has been covered there.

 

[idpnd]

The shaft generator thing has been covered there.

I am well aware of this - was looking to point out a simpler solution to generate electricity under sails

 

[Neil_Y]

I am well aware of this - was looking to point out a simpler solution to generate electricity under sails

Rope straight to alternator tide with rope to pushpit works great, the rope does transmit the torque easily, and when it skips out of the water you change to a different pitch prop, I've got two. I got an average of 8 amps 24hrs a day on a 40' boat sailing between 5 and 13 knots. Less than 5 knots and we would usually motor.

Might work but your losses would be greater.

 

[Twister_Ken]

I guess the French have done it again! Lovely piece of sensible yachting equipment. Do you have info on the price as the website doesn't show it?

About £5K I believe

 

[nimbusgb]

Would a paddle wheel offer a solution to pitch problems if fitted at rightangle to the strut and appropriate gearing/linkages. Whichever solution you select the drag is going to be significant, at least thats the argument for feathering /folding props vs fixed bladed.

I like the idea of a paddle wheel too but a bit cumbersome, even a small one would be the size of say a bicycle wheel and hanging that off the transom is going to be a right pain.

This guy http://www.reuk.co.uk/Building-a-Waterwheel.htm appears to be generating about 100w ( 6A ) from a wheel 1.2 m in diameter and 600mm wide and his video looks like about the kind of flow you'd see behind a yacht. I think I'd try to either run the alternator off the rim of the wheel or even integrate the generating mechanism itself with the wheel. Permanent magnets on the rim?

You'd never live down having that on the back of your boat!

 

[Twister_Ken]

I think I'd try to either run the alternator off the rim of the wheel or even integrate the generating mechanism itself with the wheel.

Sounds like a hub dynamo to me. Example...

http://www.kinetics.org.uk/html/son_hub_dynamo.shtml

 

[pampas]

This guy http://www.reuk.co.uk/Building-a-Waterwheel.htm appears to be generating about 100w ( 6A ) from a wheel 1.2 m in diameter and 600mm wide and his video looks like about the kind of flow you'd see behind a yacht. I think I'd try to either run the alternator off the rim of the wheel or even integrate the generating mechanism itself with the wheel. Permanent magnets on the rim?


Thus guy would have a more efficient plant,since he has the option, of transmitting ac to his battery shed and thence to dc, wonder why he didnt go that route?

 

[oldvarnish]

I've got an Aquair and used it across the Atlantic. If you're approaching hull speed then the drag makes little difference and I certainly couldn't detect any drag although I hauled it in if we dropped below 4 knots.
At 5 knots plus, it gave an average of five amps. It doesn't run smoothly because of the wave action so you'll get bursts of 8 amps, and troughs of 2 amps.
Very good bit of kit. No skipping over the waves. Take a spare impellor - apparently sharks like them.

My guess would be that the Aquair people have got this one worked out and it is likely to be the most efficient way of doing it with that kind of technology.

 

[rob2]

I thought the clue was in the title. All the millionaires' toys linked into replies are only of interest in their design concepts. Actually, the concept of converting an outboard is similar to the French design. The paddle wheel would have all the club members humming "Mississipi Mud" as you pass by...

Advocates of hybrid drives all talk about charging from the main prop, so presumably that requires a variable pitch prop to be effective? If a suitable prop were fabricated to fit the hub ideally with a direct drive to minimise losses, it should work. Looking at the various commercial models, though, I can't see any commonnality in the type of prop chosen.

Compared to people trying many homebuilt designs of self-steering gear, it strikes me as an interesting project for experimentation. By comparison, once an outboard bracket is attached to the hull, at least you wouldn't have to keep making new holes in the hull!

Rob.

 

[idpnd]

Advocates of hybrid drives all talk about charging from the main prop, so presumably that requires a variable pitch prop to be effective? If a suitable prop were fabricated to fit the hub ideally with a direct drive to minimise losses, it should work. Looking at the various commercial models, though, I can't see any commonnality in the type of prop chosen.

I guess it requires a fixed prop if anything - an easy solution to my mind - http://www.ybw.com/forums/showpost.php?p=2751000&postcount=22