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Lazlow 06-01-2010 05:04 PM

Electric Drive?
Hey Guys

Ok, this is my first post so be gentle, just in the dreaming stage so far.

Has anybody had any experience with the Asmo THOOSA(just google it) electric drive (or any electric drive)? I know it does not sound like a liveaboard question but hear me out. My eventual plan is to do a lot of moving around and marinas are just too expensive for stays less than a month. Which essentially means I need a generator. If I switch to an electric drive, I can replace the drive motor with a generator(diesel) and batteries, hopefully at about the same weight as the old drive motor.

Currently I am thinking about a F-36 but I am at least a year away from any serious purchases. Over the last five years I have been down sizing my life. I figured out that I had gotten WAY to involved in having stuff. Moved from a 5 bedroom house, down to a two bedroom house, and am now moving to a one bedroom apartment(about the same size as the master bedroom was in the 5 bedroom). With the exception of my computer stuff I have gotten rid of almost all my large stuff (TV, furniture, etc) and have been sleeping on an army cot for the last month(and will continue using it). I want to know that I can actually live in the small amount of space before I spend a lot of money on a boat.


Ulladh 06-01-2010 07:04 PM

Welcome Lazlow
Maybe I am assuming to much from your post, I apologize if I am.

I would suggest first getting more experience sailing, and discover what aspects of sailing you are seeking, and the best fit of boat to desired lifestyle.
Join a club, take sailing lessons, charter boats...

Look at propulsion systems as an optimal solution to fit your and the boats needs.

If I have put my "ass" before "u" and "me", please don't take in personally.

Lazlow 06-01-2010 07:10 PM

No, offense taken. I did some crewing(nothing serious, weekends, etc) in the early 80s out of Jacksonville and DC. The biggest thing I did was move a 27 footer from Galveston to St. Thomas single handed. Took my time and harbor hopped most of the way. If I had it to do over again I suspect me and the 27 footer would have gone to Belize and stayed there.

Ulladh 06-01-2010 07:56 PM

Except for some limited uses, electric propulsion is not yet ready for prime time, I hope it will be. The problem in truely green mechanical propulsion is the source of electricity and efficiency of storage.

"Green" diesel may be a more rational interim solution, diesel produced from the waste stream.

A project under contract for the navy at Philadelphia Navy Yard will produce marine diesel from residential and industrial waste;

page 1, bar on left trash to diesel

The loss of efficiency, diesel generator to battery to electric propulsion even with "green" diesel may be less optimal than diesel propulsion with a smaller generator for use as systems demand.

The energy source will be diesel either way but consumption of diesel may be higher due to efficiency loss with the battery to electric propulsion.

Lazlow 06-01-2010 08:12 PM


I think you misunderstood my intent. The drive I was looking at (suited for the f-36) is a 9Kw drive. I was intending to have a 9Kw (or at least close) diesel generator on board. That way the generator (and batteries) could serve double duty. When I need to move without sails (any real distance) I would fire up the generator. When I was at anchor I would use the generator to recharge the batteries(drained by me and not the drive). You could think of it as a hybrid drive. So storage would really not be an issue.

Edit: without sails instead of with sails

huguley3 06-01-2010 08:25 PM

I looked into this a bit. If you look in the engine forums someplace there are a few threads on electric drives.

Diesel generators are pretty large. Unless some advance comes along it is doubtful you could find one to even fit in the engine compartment. If you could it would cost just as much or more than a plain old diesel.

Maybe you could find the space on some larger boats and then deal with a reduced cruising speed but it does not buy you much except being able to run lots of electrical things while at anchor.

Maybe if they have some kind of a fuel cell breakthrough electric drives will be more feasible but right now it is just too hard to make that much electricity.

Some guy put a diesel electric in a motorcat then covered the top of it in solar panels. Its pretty ugly but on a sunny day he says he can run on solar power only. So there are people out there working on the problem and if you can make it work then you will be set for life.

T37Chef 06-01-2010 08:30 PM

I have no experience with electric drives but I see a lot of advantages to them combined with a generator and a decent size battery bank. I doubt it will be lighter, probably more weight with the drive, batteries, and generator...but certainly not more than a engine & generator.

I have been starting to research electric drives for our application, our engine has almost 4,000 hours on it and there is not a good fit replacement IMO, Yanmar would be the closest to the W50 we have now.

Some advantages I see with the little research I have done:
  • Unlimited control of the prop speed between stop and WOT
  • No shaft alignment to deal with
  • No stuffing box/shaft seal
  • No "transmission" to maintain
  • AC power to run things such as heat/ac/hot water, etc...with an engine designed to do so
  • Reduced noise and vibration, often you can find a generator complete enclosed in a sound dampening box and they can be very quiet with the right mufflers...unlike our engine which is not in an "engine room" but open to storage areas under the cockpit (hard to explain on a T37)
  • Oh yea, and I suppose you could put the generator just about anywhere it would fit, although on our boat I would thing where the current engine is would be best...and I could put it on a slide out to work on more contorting my body into inhuman shapes! LOL
Just few that I have been thinking are good one? Dunno for sure, but to me it makes a LOT of sense.

PS. I would also consider solar and wind generators to supplement and use the diesel only when absolutely needed.

T37Chef 06-01-2010 08:35 PM

One more thing, add two smaller drives...and now I would have a twin screw sailboat :) LOL

Ulladh 06-01-2010 08:36 PM

I would really like diesel-electric hybrid systems to work for sailboats, but simple diesel inboard motors currently will be more efficient and reliable for propulsion.

If your desired use involves on board equipment that has a large electric demand, then production of electric for that demand has priority and propulsion is secondary. An electric propulsion system may then be the smart choice.

Search for Nigel Calder articles in Sail magazine for research on hybrid systems.

Lazlow 06-01-2010 10:17 PM

Well I took a look around;

Yanmar 3ym30 (30HP)($2.3k without saildrive)
3600 rpm
346lbs (dry)
1.5gal/hr full out

Yanmar 9ny(9Kw)($8k)

So size is essentially a wash. Generator is 100lbs heavier but also uses quite a bit less fuel(~.6gal/hr). Price tag hurts at over three times the price, but you are also comparing a 1800 vs 3600 rpm motor(lives twice as long).

The THOOSA 9000(9kw drive) is also $8k,requires 48V, and weighs 50lbs.

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