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Old 03-20-2018, 03:14 AM
  #3  
OutputCoupler
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Join Date: Oct 2017
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Why do I need gearing if the motor is already turning the prop at the speed I need? Seems there are plenty of motors that advertise about the right speed at about the right power.

Gas motors are out. Maximizing runtime is not my concern, reliability is. Also, the batteries have plenty of juice, they're 120 Ah each and can handle 900A sustained current draw. I have no intention of running the boat at full speed unless there's a very good reason to do so, like needing to outrun a storm to get back to shore. Otherwise, this will be plodding along at ~3 mph, which the batteries should be able to handle for much longer than I care to operate the boat at any one time.

Revisiting the math, I don't think it's worthwhile to bother with RC motors. Optimistically it would cost ~$500 for a pair after all is said and done, and give a top end speed of 10 mph. A pair of 24V trolling motors with high pitch props is about $300, and gives a top speed of ~7 mph. Using trolling motors is also going to be way simpler than using RC motors. The efficiency gain of brushless motors would be nice, but I'm not so sure extending a ~100km range to ~110km is all that meaningful, considering the added cost and complexity.

Last edited by OutputCoupler; 03-20-2018 at 03:42 AM.
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