Motorizing a Sunfish...

#21
Actually... get the ESC rated for 10% to 50% more current than the motor.

The size prop will be dependant on the motor power... and with a 9 v rated motor its probably going to be small. (probably too small to move the Sunfish)

I'd expect to need a 1500 watt minimum (appx 2 hp) and probably want 2500 to 3000 watts to be able to "motor out" at a reasonable speed.

Its not going to spin a standard trolling motor prop. Its going to spin an RC boat prop. Much smaller and much faster RPM and very inefficiently.
 

L&VW

Well-Known Member
Thread starter #22
"...If there is enough wind to bend the mast the drill is not going to have enough poop to do anything..."
My point was to have some additional poop to beat the cell home. (I should have lowered the sail, and used the "bare pole" to get me home).
Actually... get the ESC rated for 10% to 50% more current than the motor. The size prop will be dependent on the motor power... and with a 9 v rated motor its probably going to be small. (probably too small to move the Sunfish). I'd expect to need a 1500 watt minimum (appx 2 hp) and probably want 2500 to 3000 watts to be able to "motor out" at a reasonable speed. Its not going to spin a standard trolling motor prop. Its going to spin an RC boat prop. Much smaller and much faster RPM and very inefficiently.
The Sunfish shouldn't need 2-HP to move reasonably fast, but my take on the above advice is that a brushless motor powered by a 9.7 volt Makita battery isn't going to be efficient. :( For more torque, could a couple of brushless motors (and one propeller) be mounted in tandem, and mounted in such a way that they could be lowered through the daggerboard trunk?
 
#23
Nothing off the shelf is going to be very efficient... The off the shelf stuff will have the motor mostly trying to whip the water behind the boat.

Custom wound motor and a prop designed for the purpose would need less power.
 

L&VW

Well-Known Member
Thread starter #24
So I'm back to this $50 item...:oops: Maybe use it as a "surface drive" offset through the transom--with one blade in the water at a time?


Video of surface-piercing prop:

 
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