T-Pain Is On A Boat: RE: [Electric Boats] Re: does anyone have current real world performance figures please

Thursday, March 28, 2013

RE: [Electric Boats] Re: does anyone have current real world performance figures please

I'm running 2-12hp motors with 18x18 props on a 41ft Cat at around 8-9 tons.
At 8 knots I'm using 5kw ea. Don't know what the RPMs are because I've never run her at W.O.T. but the motors are rated at 1500 RPMs ea.

Steve in Solomons MD

Thanks for the input Tom.

Since Julian's props are right around $1300 USD each, I would be very hesitant to modify them at all, but re-pitching them could nudge the power demand by about 10%. Cutting would only be a last resort.

And with the cost of two new props roughly equal to the cost of 5kWh of lithium cells, I would work pretty hard to figure a way to use the ones that I had already paid for.

Eric

--- In electricboats@yahoogroups.com, Julian Webb <julian.proto@...> wrote:
>
> cheers tom, i was about to ask the prop man what the "plan b" was. thanks
>
>
> On 28 March 2013 02:47, Tom <boat_works@...> wrote:
>
> > **
> >
> > Hi Julian,
> >
> > If the motors are overloaded with the 23 x 22 props I'd have them
> > repitched before I resorted to reducing their diameter. You want to keep
> > all the disc area you can.
> >
> > Assuming that the props will be either bronze or Nibral, a prop repair
> > shop should be able to take up to 2" of pitch out of them.
> >
> > -Tom
> >
> > --- In electricboats@yahoogroups.com, Julian Webb <julian.proto@>
> > wrote:
> > >
> > > Hi Eric
> > >
> > > - have them As no prop man would guesstimate speed for my boat, maximum
> > efficiency
> >
> > > was all I could head for that they seemed able to calculate to.
> > >
> > > - I know I'm a bit on my own when it comes down to it, just didn't want
> > to
> > > be at the "bleeding edge" and be first-in-my-class but hey someone has to
> > > do it as they say.
> > >
> > > - I'll publish/post all my results and hope I don't have to either new
> > > props made or the proposed ones turned down (the only cheap mod I can
> > think
> > > of) as they are costing me £1000 each!!!
> > >
> > > - I know I could have had off-the-shelf guesses way cheaper but I thought
> > > if I went to a "proper" prop maker I would get what was optimum for my
> > > boat............... time will tell I guess, "a fool and his money" as
> > they
> > > say.
> > >
> > > Cheers, Julian
> > >
> > >

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