T-Pain Is On A Boat: Re: [Electric Boats] Any larger electric boat owners out there?

Sunday, May 24, 2009

Re: [Electric Boats] Any larger electric boat owners out there?

OK, so one assumption I made is that you have a planing, and not a semi-displacement hull. Those are not efficient at low speeds. If's its a semi-displacement trawler/tug type hull I'll reduce my guestimate by 2/3. But I just checked some pictures and they look like planing - and you mentioned it as well. I basically took 1/3 of 1 of your current engines for the 100KW guestimate.

Let's say I'm off by a factor of 10. That's a 70amp draw off your 200AH of battery - 3 hours cruising. Or 6 if you pop $40K for the 400AH pack.

At that point I'd say you're not only right, but far richer than I :)

Stumbled on this: http://www.hawaii-marine.com/templates/Products/Pwr-Disp/description.htm which might settle the matter.

-Keith

--- In electricboats@yahoogroups.com, James Sizemore <james@...> wrote:
>
> 100KW to drive it at what speed? Please supply the math your working
> in your head.
> I would be curious what assumptions your making here.
>
>
> On May 24, 2009, at 10:16 AM, aweekdaysailor wrote:
>
> >
> >
> > Denny is being too nice to say it outright, but what you're looking
> > for isn't practical today. You'd be needing nearly 100KW continuous
> > power to drive that boat -- a minimum of 12 100AH batteries would
> > last about 4 minutes. So multiply by 10 -- 120 batteries to get an
> > hour of range (Peukert helps here) at 80% depth of discharge. 120
> > batteries is ~7000lbs...300 connections to corrode...740 cells to
> > inspect...and one bad cell to ruin your day (or hour anyway).
> >
> > Steyr has some sweet-looking but undoubtedly pricey hybrid diesels
> > that might be worth looking at - that would give you a short period
> > of "silent running" before needing to power up.
> >
> > Otherwise - you can "go green" using biodiesel in conventional
> > engines. A 30' sailboat is near the practical limit for pure
> > electric due to hull form and battery weight factors - that's why
> > they tend to be the focus.
> >
> > -Keith
> >
> > --- In electricboats@yahoogroups.com, "dennis wolfe" <dwolfe@>
> > wrote:
> > >
> > > James,
> > >
> > > HP is HP, whatever the prime mover. The continuous (not max or
> > peak) power rating of your motor is the number to use.
> > >
> > > The battery bank is the real power constraint anyway, not the
> > motor. You want to consider speed and range. Not much sense setting
> > up an E boat that will go fast but drain the batteries flat in 5 or
> > 10 minutes. Start the design process by defining the speed and range
> > you require, select a possible motor/battery system, evaluate cost,
> > weight, performance. Repeat until you are confident you have the
> > best compromise.
> > >
> > > Get Dave Gerr's "Propeller Handbook" to figure the prop size and
> > rpm best suited to your boat.
> > >
> > > Google the "Peukert Effect" to see how rapid discharge affects
> > battery capacity.
> > >
> > > You will be removing around 2500 - 3000 lbs from the boat. You new
> > installation needs to maintain the original center of gravity or the
> > boat won't float level and if it floats bow down maybe hard to steer.
> > >
> > > Good luck.
> > >
> > > Denny Wolfe
> > > www.wolfEboats.com
> > >
> > >
> > > ----- Original Message -----
> > > From: James Sizemore
> > > To: electricboats@yahoogroups.com
> > > Sent: Sunday, May 24, 2009 3:25 AM
> > > Subject: [Electric Boats] Any larger electric boat owners out there?
> > >
> > >
> > >
> > >
> > >
> > > I see a lot of traffic on this list for smaller conversions
> > replacing
> > > A4's and such on 20-30 foot sail boats. Are there any folks that
> > have
> > > replaced larger motors on cruisers/trawlers?
> > > I will be replacing two 427 fords (350hp gas engines) on a 41 foot
> > > Chris-Craft. This if for a number of reasons including not wanting
> > > the ongoing expense of buying gas, second I really hate the
> > monstrous
> > > complexity of combustion engines. I have a computer science/
> > > electrical background so I am much much more knowledgeable and
> > > comfortable with electrical systems. And not to mention the smell
> > and
> > > noise of combustion engines. The knowledge I lack right now is boat
> > > related: prop size pitch ...etc...etc. I don't need the boat to
> > plane
> > > at 17 knots or anything like that, although if it does all the
> > better.
> > >
> > > My current thinking is to replace the fords with a pair of (Netgain
> > > Warp 11'' or Transwarp 11'')'s. The part I can not rap my head
> > > around is if I go direct drive with the Transwarp's will they spin
> > the
> > > props to fast? Or should I keep the transmissions that the fords are
> > > bolt to now and go with the Warp's. I would prefer not to have the
> > > extra complexity of the transmissions. The Netgains can move a large
> > > truck at freeway speeds 70+ MPH. My understanding of the
> > conversion of
> > > electrical hp to combustion hp is at 144v these motors should be
> > about
> > > the equivalent of a 150-200 hp gas motors with considerable more
> > > torque at the low end.
> > >
> > > The boat will soon have a fairly large solar array and already has
> > > 7.5 KWH generator. So keeping the battery bank feed should not be a
> > > problem. I know finding a solar charger/inverter for a 144v battery
> > > pack will be a real challenge. Any recommendations are welcome. I
> > > would also be very curious of other conversions of larger plaining
> > > hull boats, and what motors you use and performance you get now.
> > Also
> > > any recommendations on motors/charges/controllers or kits for boats
> > > this size would be most welcome.
> > >
> > > [Non-text portions of this message have been removed]
> > >
> > >
> > >
> > >
> > >
> > > [Non-text portions of this message have been removed]
> > >
> >
> >
>
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> [Non-text portions of this message have been removed]
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