electric power
has anyone got ideas/experience with electric auxiliary? it seems like a windward ama would be a great place to put batteries (and solar panels). I can see a prop on a long driveshaft connected to a 90 deg gear, projecting from the tramp side of the ama, permitting it to swing to point either direction… maybe that’s a bit ungainly, 😊 Have you eve seen those wild canal boats in Bangkok, with a car engine sitting on a ball joint up in the air, a handle in the front and a huge long prop shaft out the back with a prop on the end? Fast, basic and deadly.
But I digress. I guess a simpler solution is to use an electric trawling motor mounted mishaps on the ama - even in a well, with 180 rotation, or simply reversible (?)
I used a 35lb thrust electric trolling motor for a while with a small canoe, and then with my Siren 17 sailboat.
The problem with electric, as I see it, is energy storage. I used a 100AH deep cycle battery, which weighed about 50lbs. That gave about 2 hours of operating time at maximum thrust. For the canoe, I didn’t need maximum thrust all the time, but for the Siren, I did, especially against the wind. I soon bought an outboard for the Siren. I wouldn’t make it out of Vancouver harbour with the trolling motor (can’t sail).
You’d need a big solar panel to charge a 100AH battery, and it would still take several hours.
I once met a guy with an all electric 28’ sailboat. He had 2 electric motors, and an array of solar panels, and several hundred pounds of batteries. I got the impression that he was willing to wait for sun if he didn’t have enough charge to move, or wind to sail. In the winter in the Pacific North West, he might be waiting for a while.
I guess it depends on your situation.
Simon,
There are several Rob Denny (WTW) proas in Australia which have electric auxiliary propulsion.
But unless you are an electrical engineer / naval architect boffin yourself, you need to find one near you who can advise you and do all the numbers specific to your design otherwise it may not work sufficiently well.
I am planning to use electric propulsion on my pacific proa which is currently in build. LOA / LWL: 9.5 metres. Loaded Displ: 1188kg. My local boffin put my design through Michlet and Flotilla software and to get 6 knots (flatwater) and 7.5 hrs range, I need:
2 x 80 lb thrust long shaft bow mounted trolling motors with 300mm props. Probably Minn Kota maybe Haswing if I can sort out sufficient shaft length. They are both wireless hand held controlled and can thrust in any direction though 360 degrees. They will be mounted on the leeward side of the vaka about 2.5 metres back from each bow and will be lifted up and tilted back to windward across the vaka deck when not in use. They are easily removable and can be stowed elsewhere if you are racing / doing long trips / leaving the boat on a mooring for a long time.
3 x 8 cell lithium batteries. Each cell 3.2v x 100 ah weighs 3.3 kg and are 67x142x220mm in size. Separately circuited, 2 batteries are reserved for propulsion with the third as the “house” battery and back up. They will be located in the ama, so that is around 80 kg of ballast (ie one crew member sitting on the ama all the time)
Power (re)generation will be 2 x 100 watt flexible solar panels mounted on the cabin roof and probably a small wind generator mounted (removable) near each bow in my case, but you could also mount them on the ama. You could also use a towing generator whist you are sailing along.
Rob
Rob
very interesting information. Thankyou. Happily I do have a contact in the electric boat engineering field, I may be calling on him 😊 At this point is all hot air, and no doubt by the time I build, technology will have changed. But the idea of putting the batteries to windward is cool. Can you tell me more about the towed charger? I had wondered if one couldn’t simply do regenerative braking with the outboard itself.
Simon
Can you tell me more about the towed charger? I had wondered if one couldn’t simply do regenerative braking with the outboard itself.
Simon,
Ampair do one, I am sure that there are others….
http://www.energymatters.com.au/ampair-aquair-24v-100w-towed-wind-turbine-for-yachts-p-673.html
Using the outboard itself was where I wanted to go, but currently it can’t be done, unless you know someone who can modify them for you and if it can even be done without staring from scratch. Ampair also do a micro hydro unit which is basically a braked outboard, but you can’t use it for propulsion…...One day….
Some other sites for you to look at
http://www.green-motion.com/site/
http://www.oceanvolt.com/
http://www.bruceschwab.com/watt-sea-hydrogenerators/
Rob
Rob
thanks for the excellent links!
“Using the outboard itself was where I wanted to go, but currently it can’t be done, unless you know someone who can modify them for you and if it can even be done without staring from scratch.”
From scratch, yes. a DC electric motor _is_ a generator, in principle. Burt getting from there to efficiency and robustness is all R+D 😊