Capt. Bill,
You might want to look at this from another direction. 500 pounds of Lead/Acid batteries (10kWh) is equivalent to less than 1 gallon of gasoline, already adjusted for the increased efficiency of electric drive. (1 gallon of gasoline = 33kWh) These batteries will cost about $1200.
So if you add 1000 pounds of batteries to your boat ($2500) you've got an electric gas tank that holds the equivalent of about 1 3/4 gallons. How far will your houseboat run on that size tank? A full ton of batteries ($5000) will last almost as long as 3 1/2 gallons through the ICE that drives the boat today.
But how about high tech Lithium batteries?(like the ones that I have in my 30' ketch) $10,000 will buy 24kWh of lithum batteries that only weigh 600 pounds and will last as long as 2 1/2 gallons of gas through an ICE. $35,000 will buy 1 ton of LiFePO4 lithium batteries that can replace an 8 gallon tank of gas.
These quotes don't include the chargers and charge management equipment that should be used for installations of this scale.
The gas equivalents are probably a little optimistic. Switching to electric might not work this well, but these are good ballpark numbers to do a quick calculation when you're considering the feasibility of converting large power boats to electric.
So pick the hull of your choice, imagine throwing whatever size IC engine you want (inboard or outboard) and figure out how long a 3 gallon tank of gas will last at whatever speed you desire. That's what you can expect from 2000 pounds of deep-cycle batteries.
Even for a hybrid, the math stays the same for "silent running" mode. The battery bank with an electric motor is just like a little gas tank with an ICE drive.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, Bill Spires <spiresac@...> wrote:
>
> we are talking displacement speeds here so the weight will have more effect on
> acceleration than speed and he will need 40' of water line length to hit 8.47
> knots so he will have lots of load capacity. I'm thinking 43' or so to keep him
> below hull speed and 2 - 10 hp motors that would run at 60% power most of the
> time and only put out max power for short burst to maneuver or accelerate. A
> light weight structure built out of aluminum and maybe a trampoline area like a
> big catamaran. Another advantage of slowing down the speed is that the genset
> will supply more of the power for movement. Some of the 40-50' house boats here
> on the lake idle at say 5-10 hp at 4-5 knots and at full throttle (140 hp) get
> all the way up to 7-8 knots. These are barge type hulls and develop resistance
> and skin drag really fast. Catamarans and Proas can beat the hull speed
> formula. If this boat is only going on the river and waves are less of an issue
> and it can be built to flex you could keep the weight down. I am thinking a
> proa might be a really fast electric boat design. If you took and old rowing
> shell and put an outrigger on it I think it might go pretty well on electric
> power. Anybody have an old shell they want to donate to try it out?
>
> We should build a spreadsheet that we can through the numbers in and get some
> predictive results. Or does that spreadsheet already exist?
>
> Capt. Bill
>
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