T-Pain Is On A Boat: Re: [Electric Boats] Re: motor overheating

Friday, July 3, 2009

Re: [Electric Boats] Re: motor overheating

As others have probably explained, WOT = wide open throttle

md

On Fri, Jul 3, 2009 at 2:18 AM, perry924 <perry.mondesir@btopenworld.com>wrote:

>
>
> Been folloing this thread for a while, it's very informative but for the
> life of me I can't figure out what WOT is!!!!!
>
>
> --- In electricboats@yahoogroups.com <electricboats%40yahoogroups.com>,
> "aweekdaysailor" <aweekdaysailor@...> wrote:
> >
> > [Sorry if this is a dupe - groups keeps losing posts]
> >
> > I had a chance to test this today. ~15kt winds, 1' chop. I ran the boat
> downwind (no sails) at 40amps, got to 4.4kts. Turned 180 into the wind, and
> amp draw increased to 47amps, boatspeed dropped to 2.2kts. I ran in both
> directions long enough for a steady read.
> >
> > Similarly, I've seen amps drop when motorsailing and the wind comes up,
> but that's harder to measure (the ultimate form of that being [weak] regen)
> >
> >
> > -Keith
> >
> > --- In electricboats@yahoogroups.com <electricboats%40yahoogroups.com>,
> "dennis wolfe" <dwolfe@> wrote:
> > >
> > > Keith,
> > >
> > > Slip does increase as the headwind (or any extra resistance increases)
> increases. Water is 'sorta' squishy ( not really compressible but flows
> 'sorts' easily) The 'sorta' is why amp draw goes up.
> > >
> > > With increases resistance the amps go up AND the boat slows down. The
> slowing down is why the amps go up - because the slip increases. The work
> the motor does is based on accelerating a mass of water backwards. The
> faster the boat is going forward, the less the prop can accelerate it
> backwards - hence less work, less amps.
> > >
> > > Next time you are out in your famous windy bay try WOT upwind and
> downwind and let us know the results. Up wind will be more.
> > >
> > > Denny
> > >
> > > ----- Original Message -----
> > > From: aweekdaysailor
> > > To: electricboats@yahoogroups.com <electricboats%40yahoogroups.com>
> > > Sent: Tuesday, June 23, 2009 12:26 AM
> > > Subject: [Electric Boats] Re: motor overheating
> > >
> > >
> > >
> > >
> > >
> > > Thanks Denny,
> > >
> > > So tied to the dock, slip is 100%. Pushing into a headwind - doesn't
> slip increase as well? Based on experience and intuition the boat just slows
> down - amps stays constant at a given throttle. You have to up throttle
> (voltage) to compensate and try to maintain speed.
> > >
> > > If we were talking golf carts again, I'd buy into the amps increasing.
> But water is squishy and will follow the path of least resistance - and
> given enough wind that would be sideways.
> > >
> > > But I'll do some homework to make sure I'm not just talking through my
> hat.
> > >
> > > -Keith
> > >
> > > (and I'm wondering if I've got a problem in my motor or ammeter - I can
> pull 20amps at WOT no load, belt removed)
> > >
> > >
> > >
> > >
> > >
> > > [Non-text portions of this message have been removed]
> > >
> >
>
>
>

--
Mark Draper, Ph.D.
President
OurFinest.Org
www.ourfinest.org
(301) 294 6547

[Non-text portions of this message have been removed]