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Saturday, June 20, 2015

Electric sailboat test

With our little trip on the lake yesterday I thought I'd get to see how the boat performs with an electric rather than a gas engine.

We launched from the boat ramp directly into a 10 mph wind. That wasn't too bad, but there were rocks to the west and a campground boat dock to the east -not a lot of room to tack out into the open water.

The motor did a fine a job of getting us out into more open water. A couple of hundred yards later we were past the docks so we shut down the motor and raised sails.

Then we sailed and sailed some more. Now and then the wind died down to where we were barely moving. Occasionally we'd get a huge gust of wind from out of the mountains and we'd sail at full speed for a few hundred yards. Overall, we generally had enough wind to maintain between 2.5 and 5 knots. For us, that's good enough.

No doubt some folks would have fired up an engine to get through narrow passes between islands and underwater obstructions. We find that's when you really learn how to sail. There's a huge sense of accomplishment after successfully negotiating those sorts of hazards.

At the far end of the lake it occurred to me that if the wind totally died we'd have about a 8 mile motor back to the boat ramp. I think the battery would have been up for it, but I wasn't sure. Instead of the wind dying, it shifted direction to directly on our nose. It seemed like forever to tack out of that bay, but eventually we made it to wider and deeper water. We still had to tack, but big long tacks make more progress than a lot of short ones. Time is lost turning the boat's direction, finding the line and trimming the sails.

Our final tack brought us close to the boat ramp, but not directly to it. That's where we once again used the electric motor to bring us in. Not much of an electric motor test after all.

Right now the whole boat runs on one large battery -lights, radios, depth gauge, and the electric trolling motor. That's probably not a good design for long distance travel. It was fine on a lake. The 30 watt solar panel kept up with our scant electrical demands.

It would have been a bad situation at night if the motor ran out of juice, killing the navigation lights and VHF radio at the same time. The smart thing would be to have a separate battery system for the motor. When the boat ran on gas I built a box to hold a 6 gallon auxiliary tank. That same box would be ideal for holding a couple of deep discharge batteries. A small solar panel could even be mounted on the top.

What I really need to do is to take a couple of batteries and run one down until it's close to dead, then come back on the second. Then I'd really know what kind of range I'm getting.

Why do I even want to know? Knowing one's range under power would be key information should we take this boat down the ICW in the fall. The trip from mile one in VA to FL is a long slog. Sailboats generally motor most if not all of the way. I think much of it could be sailed and an electric motor assist could fill in the rest. It might take longer, but that only means I have to start a bit earlier.



  1. Sounds like a really handy, utilitarian set up.

    1. It's nice to not have to deal with the noise and smell of a two stroke engine. Cheap too!

  2. I think the test you have in mind is a very good idea! Better to have this knowledge now, other than have to learn it later.

    1. Better to test on friendly lakes than discover problems in the big bad ocean.