ok. Some better information. Now I am new to this game so any thoughts, help or fixes would be good.
My prop is 10 1/2 dia with 13 pitch. I am not sure I want to go that way but lets start there. Oldish lower unit. My lower unit has a 7/4 ratio (drv Shaft to Prop) so my math works like this....
If I want a cruising speed of 12 mph, 2 hr run time, at an efficiency of 50%, I'll need a prop speed of 1950 rpm. That translates to 3411 rpm at the drv shaft (allowing for gearing).
If my battery bank produces 225 and operates to 40%, my run consumption needs to be about 1750rpm and based on the feedback, about 3.5hp, 67amps. (all 48v). So I will likely gear up 2/1 (emtr to drv shaft) which gets me to 3500. That seems close enough.
everyone pick holes....I need all the help I can get.
I also have built a few boats, both stitch and glue as well as traditional. But I just purchased a CNC machine capable of cutting 4X8 sheets. So my son's and my boat building is about to take a leap forward. The Sneakeasy will be the first one we do with CNC parts. (and also the first one my wife chose)
Thanks
--- In electricboats@yahoogroups.com, "luv2bsailin" <luv2bsailin@...> wrote:
>
> George,
> I'm not a Sneakeasy builder (yet) but have built a couple stitch-and-glue dinghys and done a few electric conversions. I'm in So. Cal. this winter, but my home is in MN.
> On the HP question, the simple answer is:
> Volts times Amps equals Watts. Watts divided by 746 equals HP. Multiply that times your motor's effeciency (typically 80 to 90%) to get shaft HP.
> Jim
>
> --- In electricboats@yahoogroups.com, George Schnellman <vectorges@> wrote:
> >
> > Where are yoe sneakeasy builders located?
> >
> >
> >
> > On Fri, Feb 4, 2011 at 11:50 AM, b504now <b504now@
> ------snip------
> . Is there a simple way
> > > to verify hp on an electric motor.
> > > > >
>
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