David,
I'll typically run 10 or 15 miles around the lake before recharging, but the numbers seem to indicate that I could do 20 miles at 4.5 kt. running down to about 80% discharge. Keep in mind that this set of numbers were taken against a light breeze and chop to keep things conservative. Hopefully I'll get a chance to do some high-wind testing before the lake freezes this fall!
Based on some previous tests, it looks like 20 miles plus is easily achievable at 4kt in calm conditions. At 3.5 kt over 30 is possible. At 3kt, maybe even 40.
These are rough eyeball predictions, but I think they are reasonable. I need to cobble up a spreadsheet to lay it all out.
Next summer I will install some solar panels which will extend the range some more, or allow me to be self-sufficient entirely and able to do maybe 10 miles a day at decent speed. I have room for about 900W rated capacity which, by my rough estimation, should give me 50 to 75 AH per day at my latitude (45 deg North).
The prop is a 3-blade, and yes I have a belt reduction.
Jim
--- In electricboats@yahoogroups.com, David Goldsmith <suntreader@...> wrote:
>
> Hi Jim,
>
> Yes, I find this very useful! I'm installing a very similar system in my
> Islander 32. I've got more displacement (probably 10k all loaded up and
> ready to go), I'll use the Sevcon controller, and I'm using a marine gear
> box rather than a belt reduction, which I'm assuming you have.
>
> Is your prop 2 or 3 blades?
>
> It looks like you get about 20 miles of range out of your bank? Has that
> been your experience, can you stretch it by reducing speed or is 20 miles
> starting to wear down the batteries?
>
> Thanks,
> David
>
> On Tue, Oct 5, 2010 at 12:34 AM, luv2bsailin <luv2bsailin@...> wrote:
>
> >
> >
> > Hi Folks,
> > I thought I'd post the results of some testing I did today on my electric
> > Albin 25. Wind was 5-7 knots on the nose with a light chop. Boat was loaded
> > to what I would consider a normal cruising weight of about 5000 lb. (about
> > 3500 lb. empty weight plus about 1500 lb. ballast).
> > System consists of a 7HP Mars brush motor, Alltrax controller, and eight
> > 220AH golf car batteries. Prop is 17x12. Don't remember the reduction ratio,
> > but I can check tomorrow if anyone is interested.
> > There is room for some efficiency improvement as the motor and drive are
> > not an ideal match, which results in the motor running hotter than it
> > should. Even so, I'm real happy with the performance and have put on a
> > couple hundred miles messing around on the lake this summer.
> >
> > Amps Volts Knots Watts HP
> >
> > 10 51.0 2.7 510 0.7
> > 20 49.9 3.9 998 1.3
> > 30 49.4 4.5 1482 2.0
> > 40 48.9 4.9 1956 2.6
> > 50 48.4 5.2 2420 3.2
> > 60 47.9 5.4 2874 3.9
> > 70 47.5 5.5 3325 4.5
> > 80 47.1 5.6 3768 5.1
> > 90 46.7 5.7 4203 5.6
> > 100 46.4 5.8 4640 6.2
> >
> > I hope someone finds this useful.
> > Cheers!
> > Jim McMillan
> >
> >
> >
>
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