Monday, November 1, 2010

[Electric Boats] Re: converting a 42 foot sloop to electric propulsion

 

Rob(Wilk) [or is that Rob(Wild)?]

Mark Stafford here with a similar sailboat: H55 (longer, narrower, electric). Do-able, fairly cheap, quick and easy. It took me much learning and planning, but only a few days of work.

Now the bad news: every electron counts. No wasting energy, if you want that performance. 4 knots will more likely be your "sweet spot" in terms of range/safety margin. Use at least eight NEW 6v golf cart batteries (preferably 16). 48V system, gear or belt reduction, optimum prop diameter (15?% prop tip clearance), brushless permanent magnet motor(s). Everyone likes regen, but no-one relies on it: one hour of fast sailing will get you 1 minute of cruise power.

More bad news: use Paktrakr, ampmeter, voltmeter, marine GPS, knotmeter, maybe CycleAnalyst and RPMs too. With electricity, you can't make intelligent decisions without information.

Can you cannibalize a golf cart? Yes, but expect 1/3rd your desired performance. Arby Bernt and James Lambden are the kings of efficiency, having spent years optimizing. ThunderStruck and ElectricYacht are great sources of parts/systems. There are more: check the "links" section on the left side.

This ElectricBoats YahooGroups list is indispensable! You have used it perfectly.

FLA batteries are great on sailboats, especially if they are oriented posts-fore-and-aft. The tipping back and forth (tacking) keeps the electrolyte well mixed for even plate charge-discharge cycles. Hydrogen rises (let it escape!).

Call me or anyone else. We are here to learn/share.

Mark Stafford
mstafford@natca.net
925-586-0839 cell
GreenMarineRePower.org

--- In electricboats@yahoogroups.com, "robwilk37" <robwilk37@...> wrote:
>
> hello...
> first post and havent done any searching yet but thought id toss this project into the mix. ive got a 42'LOA, 32'LWL, 19,000 pound sloop. cut-away fore foot/full keel. barn door rudder with prop aperture. shes and old school cca design with beautiful (to my eye) lines, and a bare hull restoration. and since i dont have a diesel id like to incorporate and electric drive.
>
> my requirements are as follows...
>
> the boat will be a liveaboard cruiser. not interested in racing, and the bottom will always be impeccably clean (its a pet peeve).
>
> i only need 75% of hull speed (@5 kts) for 2 hrs a day, basically in and out of the slip and down and back the fairway.
>
> i can charge from a shore chord but will have some solar/wind/towed log charging when anchored out.
>
> i like the idea of regen capability while underway.
>
> i dont mind carrying a gas/propane genset for emergency/general charging or continuous running in flat calms.
>
> im quite handy and can do all the work myself.
>
> so...ive only got about 5,210 questions. among them...
>
> can i cannibalize an electric golf cart and "marine-ize" as much as possible and fullfill the above requirements?
>
> ive got deep bilges, do i put one big forklift battery down there or are many smaller ones a better idea?
>
> i like lead/acid as they are cheap and available worldwide but how do they hold up to the sloshing around and outgassing in the bilge? and 24 or 48vdc?
>
> roughly how large a battery bank for propulsion only would i need and how big a prop (3 blade i presume for the regen) and what size motor?
>
> and if these questions are too basic for this forum just point me in the right direction and ill get out of your hair. thanks so much in advance for any help..
>
> rob
>

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