Solar dinghy testing

[KTP]

Finally got a cooler day (77F instead of 105F) and took our Montgomery M17 equipped with a 10kWh battery bank, ePropulsion Navy 6 2024 outboard, pulling a Portland Pudgy dinghy that was carrying four 100 watt solar panels feeding a Victron 150/35 MPPT charge controller.

Dinghy was a drag, as expected, but maybe manageable. We did the same route as last trip except a bit longer (25nm instead of 24nm) over a period of 7 hours 45min, so average around 3.2kts. We did have some headwinds (both coming and going, go figure...canyon river life). Last trip was 24nm at about 3.7kts. 0.5kts is a big hit, no question. Current in the river seemed to be around 0.7kts again..more in the narrow sections.

Solar wise, I was quite impressed with this slap together of four 100 watt Renogy panels I had lying around. The day started with heavy clouds and yet we were still getting 95 watts. Around 12:30 the sun would pop out for a minute and I saw 372 watts, which is really decent for our latitude (NE Washington state). The clouds cleared up around 3pm and I was seeing a steady 250 watts, which declined to about 225 watts by 4:30pm, and was 175 watts by 5:30pm as the sun was getting quite low and the panels are just flat on the Pudgy.

We tried keeping the power to the motor about 125 watts higher than last time, to account for the drag of the dinghy (so about 625 watts average during the trip) and when the sun was out full, we were getting half of that from the solar panels.

I'll have to think if this is worth taking on the river section of the Great Loop. We kind of want the dinghy for when we have to anchor or tie up to mooring balls, but then again, that drag...

Next step is to get 600 watts of CIGS solar mounted to the boom tent on the sailboat itself and see what that does.

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