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Old 04-10-2021, 08:01 AM
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Retiredat38
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Originally Posted by acdii View Post
I started building my kit, and want to put a brushless in, but don't know what motor to use. Right now I just have the framing done, getting the last pieces glued up before sanding. I figure if there are any mods I need to do, now is the time.
Well, my first question for you is why a brushless for a boat like this? Nothing against it mind you but I consider a brushless as more of a performance motor. Not a pleasure craft motor. But to each their own.

While I am no expert so some of this could be off base. But given the response you've had so far (Why am I not surprised?......) I will attempt to get you going in the right direction.

On their web site Dumas recommends a motor/drive combo for this kit. While they recommend a brushed motor, it does give you a place to start. They show a motor that does 10,000 rpm unloaded and operates under load at around 8-10 amps. They recommend a 1.5" prop and a few pitches to pick from. I'd start by picking one or more props. The largest diameter with the greatest pitch will work the motor the hardest. And Brass ones don't flex like plastic will but they do cost more. So, where to next?

What voltage and battery type do you plan to run? Since weight or lack thereof = performance in a boat, I think I'd plan on a either a S2 (6.6 volts) or S3 (9.9 volts) LiFe.
Given the 10,000 rpm motor Dumas recommends, I'd start by looking for a brushless with a KV between 1000 (S3) and 1500 (S2). I'd be tempted to look for a 1200 KV and run it on the S3 battery. As for the specific motor, since Dumas lists a motor rated for 8-10 Amps I'd look for a brushless that runs in that general area on the voltage you select.
The speed controller or ESC. Given the 10 Amps Dumas lists I'd get an ESC rated at 20 Amps. Why double what Dumas shows? Safety margin is basically it. Plus the ESC won't work as hard and therefore run cooler. A 15 Amp would probably be OK but..................... Do you want reverse as well? Not as many brushless ESCs with reverse but they are out there and more all the time. Also get an ESC with the built in regulator for the radio receiver. Normally known as a BEC circuit. Last but not least, you can also go with water cooling on the ESC. If you get one with it, use it.

Hopefully this answers some of your questions. And probably raises more. Feel free to ask them. I'll do what I can for you.