Bill
There is no way that you can beat the power to weight ratio, economy, or simplicity of regular outboards with any type of electric propulsion. That said, If you're trying to maneuver your boat in wind higher than 6 knots or so, why not sail the boat... ;) If you're deep offshore and a hurricane sneaks up on you, then go to bare poles and continue sailing, the only time you'll really to power upwind is crawling off a lee shore, usually not problem when you're way offshore.
If your problem is trolling at 6 knots in a dead calm, then go with ICE outboards.
BTW, using lead acid batteries, 1000 pounds will get you 22.5 Kwh total, 13.5Kwh usable. With LiFePO4, 800 pounds can get you 32Kwh total, or 24 Kwh usable for almost three times the cost. As somebody else mentioned, 8 PV68 panels will only provide 544w under optimum conditions, usually less than 400w, which won't drive you at 2.5 knots, or would take 4 sunny days to charge 12Kwh at anchor.
Try to remember, there's no free lunch. Everything is tradeoffs. There is a reason that a hundred people before you haven't succeeded with a similar plan.
Fair winds,
Eric
Marina del Rey, CA
PS. 36' x 22' demountable to 8'? Check the Newport to Ensenada 2009 results. Minnette is is a 40' demountable cat that finished the 125 nm course in 14 hours. She was built over 20 years ago by Mike Leneman. I was second in the crew of four with Mike this year for her latest international offshore win. Minnette has 2 conventional outboards, current electric technology is not an effective propulsion solution for this boat or most un-ballasted boats like multihulls.
--- In electricboats@
>
> Hello Group!
>
>
>
> I just joined today. The reason for my interest is finding help in planning
> out an electric alternative to conventional internal combustion engines on a
> catamaran I'm beginning to conceptualize.
>
>
>
> The dimensions will be ~ LOA 36', Beam 22', Mast Height 60'. It will be a
> light, fast, demountable sailboat that will fit on a trailer ~ 8' wide for
> towing anywhere. I may consider going into production if this works as I
> plan. The first one will be used to do a lot of fishing in the Pacific Ocean
> from Mexico to Panama. Weight is critical! Reliable power is critical. The
> boat will have all the necessary systems to sustain 4 adults for extended
> voyages, maybe even an ocean crossing some day. 3 or 4 knots in calm waters
> is of no use to me. I have to be able to control my boat in high winds and
> surging ocean currents and troll or motor at above 6 knots for extended
> periods. I have a couple things most sailboats do not, twin hulls = less
> weight for a much larger usable space and a huge hard bimini top for solar
> (~13'X14'). I'd like to cover this bimini with something like the Uni-Solar
> (http://www.uni-
> them up there and they'll weigh less than 100 Lbs.
>
>
>
> It looks like my bogey is battery weight. There is no way I'm adding a ton
> of lead to this boat! I can get great performance from a couple 20HP
> outboards that weigh less than 120 Lbs each. Is there any hope of electric
> propulsion or am I dreaming?
>
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