electric engine in sailboat

[dvideohd]

Hybrids are great!!!

Keep the Diesel - add some Minn-Kota 80# trolling motors!! As was pointed out, Most (90%+) of the time - you won't need much power - sometimes you NEED a lot... So you can get small electrics for normal times - and avoid those $10K+++ solutions....

 

[DanW9494]

Another source of efficiency is that the propeller could be much larger, slower, and less likely to cavitate than your present prop, which is the biggest inefficiency of the whole system. Yes, more drag for regeneration, or a folding prop.

 

[emkay]

1 gallon of diesel is about 140,000 btu.
That converts to about 41,000 Watts.

Lets say you burn 1/2 gallon every hour mucking about in your sailboat.
That converts to 20Kw/Hour.

Your Group 31 battery will give you at best 1.2Kw/Hour.

You can derate for engine efficiency and bla bla.... but, you cant beat the energy storage of good old fossil fuels.

Your math is flawed, because you forgot to subtract the wasted energy from the diesel. So take that 41,000 watts and reduce it by the 70% that is wasted. Now take that one group 31 battery and make it 6. How's it stack up now?

 

[Dave Groshong]

I don't know much about it, but the guy who bought my 37ft IOR design boat swears by his new electric motor.

http://www.electricyachts.com/

 

[Bill Roosa]

a really special purpose solution

While electric motoring would seem to be a great idea it has limited practical application in boating. Unless someone can figure out how to get the sails to turn a genset (they have BTW) as they also move the boat you are stuck converting between chemical fuels, rotation, chemical storage and back to rotation.......
Numerous changes in energy "form" and numerous losses in doing so. As a general rule the fewer times you change the "form" of the energy the better for overall efficiency.
From an efficiency standpoint using the sails to power the boat is the most efficient as the forces are never converted from one form to another. And it is free.
From a $$$ standpoint, I think I'd rather spend the thousands of dollars it would take to get some limited electrical motoring capability on beer and wild women. The amount of money spent to get the electrical motor, massive battery bank and high voltage controls all bought and installed could fund a pretty long stay in the location of your choice. Diesel is not that expensive (yet).

 

[Steve Dion]

Tesla car is currently about $120k.

 

[Ross]

If you are willing to sacrifice speed for economy then it becomes difficult to improve on a small diesel engine, a large gear eduction, and a big prop. 3-4 knots is a very low demand speed for a rather large boat. Canal boats can move 40 tons at 3 knots with a single horse.

 

[BobM]

Hybrid Cat's

Lagoon 42 with Hybrid setup -

"Built on Leroy Somer's Motor Technology, the new motors offer strong savings in carbon dioxide emissions and engine maintenance.
All Lagoon 420s coming out of the Lagoon Factory will be standardized on the new propulsions system, which typically require only one simple bearing change per 20,000 hours.

Complete installation comprises of two electric motors connected to propellers by straight shaft transmissions, one generator and two set of 6 batteries. When batteries are 100 % charged, the boat will be able to function with both motors for approximately two hours (depending on speed).
When batteries are 80% charged, the generator will automatically start and charge the batteries in order to provide electricity for the motors. When sailing, propellers will recharge the batteries."

These boats probably require less power to move them along when compared to our average 35 ft mono hull. As you can see you need a LOT of battery reserve to move it along for a prolonged period of time without the aid of a generator to recharge the battery bank/s.

A large battery bank is going to be a larger load on smaller boat as a percentage of the overall weight of the vessel. Until some new proven battery technology, these systems are not very practical.

Friends of mine routinely charter in the BVI. This year they chartered a hybrid Cat and hated it. They do a lot of motoring in the BVI and in consequence ended up running the gen set a lot at anchor, which they found annoying. Also, they said they used a lot more diesel (over twice as much) this year with the hybrid than in past years when they rented non-hybrid Cats.

 

[CarlN]

The auxiliary sailboat is a much better hybrid than any hybrid car. The hybrid car is still just petroleum powered (at least until the the plug in hybrids come along). The sailboat offers a choice of fuels - wind power or petroleum - as the situation may require.

Using a genset to drive a sailboat is just silly. You start with a diesel engine in the genset that is no more efficient than a diesel propulsion engine - assuming they are both running at a torque efficient RPM. In the best case, the genset directly drives an electric motor so you only lose only about 10% more than a traditional transmission and shaft. If you instead try to store the energy in batteries and then get it out again, you've lost about 40% more.

You can't fit enough solar panels on deck to directly drive a propulsion engine. With a whole day of battery charging, you might get 2 hours of running. Even a calm day usually has more than 2 hours of wind.

The only thing on the horizon that might give diesel propulsion an honest challenge is charging batteries from a propeller when sailing. Once a sailboat hits hull speed the extra energy is available without hurting speed. Hasn't worked out great so far but Nigel Calder is including it on his new project boat.

Until that works out, I'll help out the planet by putting my money into better sails instead of better batteries.


Carl