T-Pain Is On A Boat: Re: [Electric Boats] Outboard.. from scratch (was: Electric speedboat revisited)

Monday, June 4, 2012

Re: [Electric Boats] Outboard.. from scratch (was: Electric speedboat revisited)

yup lol, back in 96-97 was a poor college kid and didnt have an angle grinder.. so I made do with drawing down the skin hardening and the good ol hacksaw, primative-effective.

might have had 150 bucks total into my 12ft tinny and lawnmower outboard, wasnt "fast" but it'd literally run around all day on a gallon.

likely a better idea, extend the driveshaft with a couple bearings, crankshaft spline and shaft above, then belt driving to an inverted motor. the ratio changed with pulleys..

but, is it still gonna fit under the hood?

many model boat outboards are using flex cable, is constant drag and power loss too,

U-joints? how long are they gonna put up with being power-stressed?

might be better to look into changing out the bevel gears, the oldie merc's had the quickie lower units for the 10-20hp racing hydro's. might get lucky with Grainger's or another supplier for a pair that can be bored or trimmed to fit in a lathe or mill?

theres maybe some big 1:1 right angle drives available too if scratch building a lower.

--- On Mon, 6/4/12, Craig Carmichael <craig@saers.com> wrote:

From: Craig Carmichael <craig@saers.com>
Subject: [Electric Boats] Outboard.. from scratch (was: Electric speedboat revisited)
To: electricboats@yahoogroups.com
Date: Monday, June 4, 2012, 4:53 PM

>crankshaft was in hand.. oh heck no my trusty hacksaw wouldnt touch it

An angle grinder with thin 'zip' cutting blade would make short work
of it. They aren't pricey. (Saw one 'on sale' yesterday for 20$.)
Vital for most any metalwork. Always Eyewear when using.

>how big a motor, where to get it, will it spin up some 5-6000 rpm's
>for the lower unit's gear reduction (typically 1.7:1 to 2.2:1
>ratios)? are there gonna be appropriate props for a possibly lower
>output electric motor (is gonna be a lot to do with amp draw etc)?

This is the aggravating part of converting a gas outboard, since the
gas is lower torque but higher RPM than most electric motors. I've
seen no practical solution except a double frequency drive for 3550
RPM induction motors. This means it can run double the speed it was
designed for, over 7000 RPM, which isn't the safest or the most
efficient.

My Honda 75 has about 2.8:1 reduction at the foot, so I need 5600 RPM
out of a 2000 RPM motor... to get 2000 RPM at the prop.

My pancake motor also doesn't quite fit under the hood - a bit wide
for the tapered hood - grr! A bigger outboard *might* be better, but
the Honda is wider than some.

So I'm planning to do an electric outboard from scratch for my
"Electric Hubcap" 5KW/36V pancake motors. I have the idea to put in 2
or 3 or 4 U-joints, probably something like those for 1/2" socket
wrench sets, at the foot (in oil) to turn the shaft 90º to become the
prop shaft - no gears, so extra thin profile foot. I'm planning to
soften 4" PVC pipe in the oven to bend it into a teardrop profile for
the lower end of the leg/foot. (Perhaps I can pinch it off into a
skeg under the prop?) At the top, an ABS toilet flange can be the
base for the motor mounting. (Many details are still to be
determined.)

>with all the make-model-year outboards out there, I really doubt
>you're going to find anything "standardized" available plans or kits

This is the other advantage to making one from scratch: you can duplicate it.

Cheers,
Craig
http://www.TurquoiseEnergy.com/