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?

James,
I'm currently replacing one of two AQ170 Volvos in my '76 Skipjack. I don't hope for a minute that I'll be able to match the fuelish motor to the electric, but I do look forward to displacement cruising on the electric, with the option of firing up old crusty for a trip home on plane. Granted, I'll be changing the 17" pitch props for a pair of 12's, so the +30 knots of yesterday won't be part of the new plan, but the boat should be able to plane at about 17 knots, using the electric to get over the hump. I suggest the same for you, if keeping one engine running is manageable. I'm considering an High Performance Golfcart AC motor from Thunderstruck-EV and a matching controller. I havedesigned and built some 30kW motors for other projects, but the prospect of a 300v string of lead-acids is a little more than I want to install in the bilge. If you really want to go pure electric, don't even consider the replacement of the V8's with similar sized
electrics, but instead use a pair of smaller motors suffient for displacement speeds, and stock the cooler using the change. Remember, on a boat, and in life, it's the journey, not the destimation...

Be Well,
Arby

________________________________
From: aweekdaysailor <aweekdaysailor@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Sunday, May 24, 2009 11:16:34 PM
Subject: Re: [Electric Boats] Any larger electric boat owners out there?

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.
>
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>
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