-original message-
Subject: RE: [Electric Boats] electric prop and re-charging
From: Gene Fusch <gfusch@hotmail.
Date: 11/13/2009 1:43 PM
Hi Andreas
Consider the AC 50 at http://www.thunders
Gene
To: electricboats@
From: sailwithandreas@
Date: Thu, 12 Nov 2009 10:58:16 -0800
Subject: Re: [Electric Boats] electric prop and re-charging
My name is Andreas and this is my first post. very green here, Full time cruiser on 41 feet Morgan Out Island Ketch, name Savana in Florida. Have Kiss wind generator, 4 big solar panel and just had my 1967 Perkins 4/107 rebuild for 7000 dollars, but did not put it in the engine room. Pushing with a 4 hp Tohatsu 4 stroke on dinghy at 3.5 kts in calm wind and no current. Boat weighs 30000 lbs loaded as is. I do not want the diesel in it , who can help me figure out the electric alternative. Hull speed is 8 kts. I have read somewhere that 500 Watt per Ton will give me 70 % or 5.6 kts of speed, That would be around 8 kw motor for my boat, is that possible or is my boat to big and heavy ? thanks for the help out there.
--- On Thu, 11/12/09, reino urala <reino.urala@
From: reino urala <reino.urala@
Subject: Re: [Electric Boats] electric prop and re-charging
To: electricboats@
Date: Thursday, November 12, 2009, 11:45 AM
Thank you Denny for these interesting reference data!
However, some questions remain:
1.
"long narrow hull"? It would be essential to learn, how narrow, as a
really narrow means low drag at speeds higher than "hull speed".
Perhaps "narrow" was here app. 6 feet at waterline?
I am planning an e-boat hull of 30' * 4' and a maximum speed up to
15mph (100A*72V). Batteries weight at keel line should give a good
stability for this only 4' wide hull? Tested using a model hull. What
du you think about a 4' hull?
2.
A long and narrow hull may be wet inside? Seas may come in like in
VolvoOcean sail boats? Or did you learn better while experimenting with
your WolfEboat?
redu
dennis wolfe wrote:
Tom,
I don't think your requirements are
too 'out there'. Seems to me there are just a few constraints on your
project. 1) You must be willing to accept slow speed and maybe even no
speed (i.e. don't go) when adverse wind or current conditions occur.
2) Recharging from shore power must be convenient because that's the
energy source that's cheap and quiet. All the other options, when
sized to be practical for every-day use are either very expensive or
bring with them the downsides of ICE power. Plus most of them would
work better driving the prop directly instead of the daisy chain of
prime mover to generator to battery to motor to prop.
I could see a long narrow light hull
( a catamaran would be even better) optimized for a speed/length ratio
of perhaps 0.6. A boat with a 30' waterline length, weighing 3000#
with (16) 220ah 6v batteries could go 140 miles at 4 mph.(11 amps at
48v) 100 amps would give 8 mph for 22 miles. Total battery weight
would be about 1000# and cost maybe $3500 for top of the line AGMs.
Maybe 1/3 that for wet batteries. You could cut the bank size in half
in you were happy with less E range or more reliance on a gen set.
A 2kw quiet generator like Honda
EU2000 ($900, 50#) hooked to a 1.5 kw battery charger would drive the
boat about 5 mph with no battery drain. You'd want the generator out
in the open for cooling and gasoline safety. They are not marine rated
and not safe in an enclosed area. They are very quiet though, I'd say
as quiet as a little four stroke outboard. It could recharge your 80%
depleted bank in about 15 hours.
You stated you don't want a
'regular' sailboat with aux E power. Just about anything will sail
down wind, though, and that's what I'd set up, making the rig easy to
strike when not sailing. A 150 sq ft balance lug rig would have spars
short and light enough to be taken down and stowed without any
mechanical advantage (build them hollow) and would perform well off the
wind. You don't want any foils sailing down wind and a simple lee
board would give you a modest reaching ability.
Denny Wolfe
www.wolfEboats. com
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