Hi Eric,
"Grace" is our 21'x7'x21" Zimmer launch variant we launched last year.
She swings a big prop for her size, 15x12 three blade, which shoves her along very nicely.
She was designed to motor efficiently with a small diesel. We modified her extensively, but left the hull lines alone. Her waterlines forward are slightly hollow, her transom clears the water when running at cruising speeds, and she has enough beam for capacity, but not too much. Except for the high bow (meant to deal with Great Lakes chop), her lines would make a nice sailboat. I pondered adding a simple gaff or lug rig at one point, but then came to my senses. That's another boat...
She looks very different now, with a canopy with windows all around. They used to call these "glass cabin launches", I kinda like that.
Some sort of enclosure is pretty much essential for year-round use on Puget Sound.
Here's a link to our web page featuring Grace:
http://www.grapeviewpointboatworks.com/zimmer.html
Thanks for letting me brag a bit.
-Tom
--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:
>
> Tom,
>
> I forget what type of boat your running your conversion in but even at 48V, 25A is great for 5.2kts. My old ketch needs 50A to cruise at 5kts.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, "Tom" <boat_works@> wrote:
> >
> >
> > ... In my case, I found the motor was only turning 1610RPM when I was running 5.2kts at 25A. Looks like I could use a smaller gearbelt pulley on the motor to step up the RPM and get the motor's cooling fan turning faster. Not enough room to put a larger pulley on the prop shaft.
> >
> > I have never tried to run at max current the motor is capable of, since the max output voltage of my Hall effect throttle gets too high for the existing configuration of my controller. When the controller sees too much throttle voltage it shuts down until you cycle the throttle. Even as it is, I can easily exceed hull speed at 80A (for a while). I never knew I was operating at such low motor RPM.
> >
> > Until now.
> > -Tom
> >
>
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