Re: Thanks Coots, getting started on "stuff"
Tuffy ghosts along pretty good in almost imperceptible breezes, despite having a dead motor like one of Cal's bolted to the side of her keel. At such low speed surface friction is just about all of the drag, there's no turbulence from the motor, propeller and struts. That's probably the case up to maybe about 2 mph (I could check, but I'm lazy), so running Cal's boat on only one of its motors should win out at slow speeds. Things get more interesting when we go a little faster... <g>toggle quoted messageShow quoted text
Cal can turn off one of the motors, but there's no way to control their speeds separately. It's well known that running an electric motor very slowly when a boat is sailing reduces drag significantly.
It'll be fun to do some experimenting with Surprise. :o)
On 9/3/2020 10:33 AM, Myles T wrote:
It would be an interesting experiment to compare running one vs two motors driving the boat at a given speed. It's likely a wash in terms of loss in the controller and given near identical prop characteristics between the two, you're talking about doubling the prop loading in the 1-motor scenario compared to 2. At low loads (and speeds), that might not amount to much of an efficiency reduction to drive with just 1 prop, and might even result in the prop operating closer to its higher efficiency zone (Gerr's prop manual might inform here). But as the boat drag goes up with the square of the speed, at the higher speeds, having the dual props and dual motors sharing the load likely wins out big time assuming we're talking about speeds where the loading nears the high end of the motor's rating. And motor torque via motor current delivers that force.
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