A bit off topic, but mention was made of the high cost of larger props.
I originally was looking for a used prop, but couldn't find one with the correct hand, diameter, pitch, and shaft size. There are many used props out there for ski boats and other planing hulls, not so many for displacement boats.
It looked like I would need to buy a new prop. I shopped around quite a bit, and no local suppliers came close to matching the price of these guys:
http://www.deepblueyachtsupply.com/propellers/michigan-wheel-inboard-props
They also do machine work in-house, I got a great deal on a prop shaft there, too. Even with shipping added to the cost, there was no contest.
I have no connection with these folks other than being a happy customer.
-Tom
--- In electricboats@yahoogroups.com, Aaron <akenai@...> wrote:
>
> I am thinking I will be able to cut in a 20" opening so that should give me room for a 16" prop. Maybe I can get 18" It just depends on how I cut the skeg.
>
>
> From: Eric <ewdysar@...>
> To: electricboats@yahoogroups.com
> Sent: Tuesday, September 20, 2011 2:17 PM
> Subject: Re: [Electric Boats] 3201 BROWNING GEARBOX
>
> Hi Aaron,
>
> For a 10kW system, a 3301 seems like the right selection from the Browning Helical gearbox line.
>
> Since you're building the boat from scratch, you might be able to work in a larger prop. It would take a bigger reduction ratio, but it should be more efficient (on the general theory that larger slower props are more efficient). Browning has gear ratios past 5:1 for their gear boxes.
>
> I had to enlarge my aperture just to fit my 13 x 15.5 prop as part of my conversion. Given that maximum prop size, the ratio that James selected of 2.55:1 seems to strike an effective balance between power and speed across my normal operating range.
>
> Eric
>
> --- In electricboats@yahoogroups.com, Aaron <akenai@> wrote:
> >
> > I am back looking at installing an electric motor in the 36' steel sailboat I am building. 31' LWL, 10'6" Beam, 10 ton disp. I have a used Westerbeke 44B 40hp diesel but would rather not use it.
> > EBay has a 3201 gearbox but I was thinking it was too small.
> >
> > From: James Lambden <james@>
> > To: electricboats@yahoogroups.com
> > Sent: Tuesday, September 20, 2011 10:25 AM
> > Subject: Re: [Electric Boats] 3201 BROWNING GEARBOX
> >
> >
> > Aaron,
> >
> > The limitation is most often the continuous thrust rating of the bearing at the back of the motor, though torque and input rpm are issues too.
> >
> > The 3301 is rated at 550 lbs of continuous thrust and the 3401 is rated at over 1,000.
> >
> > The larger gearboxes can't spin as fast as the smaller gearboxes.
> >
> > What is the torque of the motor, and the rpm where you are producing that much power?
> >
> > We don't exceed 2,000 input rpm with the gearboxes we use on our units, and most often set the drive up at 1900 rpm.
> >
> > James
> >
> >
> > http://www.propulsionmarine.com
>
>
>
>
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