T-Pain Is On A Boat: Re: [Electric Boats] Re: 17' sailboat

Friday, June 5, 2009

Re: [Electric Boats] Re: 17' sailboat

Mark Stafford wrote:
>
>
> James Hitchman,
>
> Why only two batteries, and what battery size limitation do you have?
> Other's know more, but a Mars or an Etek or an Agni motor would make
> you a happy/safe boat if you absolutely must have an inboard system.
>
> ThunderStruck's Mars basic system @ 36 or 48 volts is around $1200
> parts plus batteries. They are expensive, but 24volt aircraft
> batteries are available... two of those brings you to an efficient
> 48volts!
>
> ElectricMotorSport's Etek basic system @ 24 - 48 volts is around $1100
> parts plus batteries. Even a 24 volt system would give you the magic
> 4knots at 20amps for 4hours, or 10hours with big deep cycle 8D
> (160pound) batteries, if you had the right propeller.
>
> I'm not sure who sells Agni motors yet in the US. Arby Bernt (on this
> list) is on the west coast working on some new motors, though they may
> be much more power than your boat needs.
>
> The blessing/cursing about electric propulsion is the batteries and
> their amp-hour rating. Better batteries are rated at both 20hour and 5
> or 6 hour depletion rates: "in 20 hours, drawing "X" amps per hour,
> the battery is exhausted." X in amps would be that battery's 20ah
> rating. For a longer battery life, plan to cut that in half, or just a
> third (a 100ah battery should only normally supply 30 to 50
> amp-hours.) So if you had a good motor/controller/prop/battery
> combination, the magic 4hr 4kts 20a uses 80ah, so you need at least
> 200ah of lead acid battery. That is about 250 pounds @ 24volts.
>
> LiFePO4 (lithium) batteries are roughly 4 times the expense, but 1/4
> the size, 1/4 the weight, and 4 times the longevity. Ballpark estimates.
>
> With that size boat, and even for much larger ones, a rudder mounted
> motor instead of an inboard, makes owners very happy. Just find some
> place to put 3 or 4 batteries. Re-E-Power has more thrust than you can
> use, and a new rudder looking outboard. Some people glue a simple
> electric trolling motor onto their rudder.
>
> Ask this group some more (specific) questions, and we all will be
> appreciative of the honest real-world answers.
>
> Mark Stafford
>
> --- In electricboats@yahoogroups.com
> <mailto:electricboats%40yahoogroups.com>, "jameshitchman" <jimcar@...>
> wrote:
> >
> > Hi: I am looking for an inboard electric system to power a 17 ft,
> 4000 lb sailboat built of wood that originally had a 3.7 gas Kermath
> or Lauson engine. I contacted Elco, Asmo, solomon, Thunderstruck and
> only Oz Marine made a bid at $6500. The question seems to be how to
> obtain a 3-4 hr range with only two batteries. Do you know of a
> different company? Thanks, jim hitchman
> >
>
>
Mark: Thank you for your information. I am a novice on this subject.
The Teak Lady was plumbed for an inboard originally, but an outboard
would do. I could not get a reply out of Elco and Thunderstruck did not
answer all myquestions, so thanks for the prices. I don't know what
items like shaft, prop, i.e, entire system, would cost. My main
concern about more batteries is where to put them. When boat arrives, I
could measure bilge height. jim