I ran your numbers on the Performance spreadsheet. Assuming a system efficiency of 80% your shaft horsepower is ~3.58 hp. The spreadsheet predicts ~4.6 knots at 1300 rpm swinging your 14 X 11. A pretty close match. Do you know what your actual rpm was?
With 14 x 14 prop it predicts 5.3 knots at 70 amps. If you get a chance to replace the prop it would be really cool to see how close the estimate was.
--- In electricboats@
>
> I though I would give the group a report on the results of my sailboat repower.
>
> The boat is a 1976 model Pearson 35, ~13,000 lb displacement. Over the last 6 months I took out the old Westerbeke 25 HP diesel and re-powered with an ElectricYacht model 130ib. The battery pack is 48V, 8- Trojan T105s in series. Overall I'm pretty sure I took out more weight than I put back in because the stern sits higher in the water.
>
> Today was the first chance I got to give the motor a real tryout. Motored about 6 miles on San Francisco Bay out of San Leandro..
> Bottom and prop freshly scrubbed.
> Conditions: light wind (5-8kt), smooth
> water, sunny and clear. Slack tide.
>
> At full throttle, the
> monitor reports 113A / MotorLimit. GPS reports ~4.9 to 5.3 Kt.
> 70A: ~ 4.3Kt
> 50A: ~ 4.0 Kt
> 20A: ~ 3.0 Kt
> Speeds were basically the same upwind and
> downwind.
>
> At 20A (My wife Katie: "Is it on? feels like we are
> gliding.") , it is whisper quiet. At 30A we start to feel some
> vibration (from the prop, hopefully), but even at full throttle it's
> pretty quiet.
>
> Overall I'm very happy with the performance.
> With the old 25HP Westerbeke I seldom cruised above 5Kt because the
> noise and vibration was so fierce.
>
> The prop is an old 2-blade bronze, 14x11. We could upgrade to 72V for more power or range, and/or upgrade the prop to a newer model. But rather than invest any more, I plan to leave it like it is for now and do more sailing.
>
> Regards,
> Bob
>
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