This example FT011 large scale RC boat was powered by a 775 motor. The problem with 775 is that it is very heavy, and it needs at least 4S to give reasonable performance. Still, from time to time it may be insufficient in handling a direct drive prop.
We attempt to change to a gear box system (gear reduction is 3:1) and use a smaller 550 motor instead. We use the original motor mount, but the mount base has to be modified so the motor mount can be located farther away from the shaft hub.
A slightly longer dog bone shaft is being used here.
A bigger coil is desirable.
Now with a water cooled ESC connected, the boat is ready to go.
The first round of test involves using the stock prop. Seems like the system is not powerful enough to push the boat.
There are two possible solutions. We either change the motor pinion to something larger, OR we use a larger prop, which is quicker and easier.
This is a comparison between the stock prop and a much larger one:
With a larger prop, we are now seeing acceptable performance level even on 3S. The boat can pick up speed real quick.
The use of gearbox is not without drawback…. the gearbox itself can be a point of failure. The bearing can fail. So is the gear…
