Good afternoon all and thanks for reading.

I have just started getting into the world of RC boats and with the limited availability of models out here in dubai have had to make do with what is available. So the boat in question is a Joysway Sea Rider Lite.

In it original form it was running a small 390 brushed motor and performance was limited so I managed to acquire a 2040 4000KV brushless setup which has been installed and now during test runs has highlighted a big problem.

To start off with when the power was applied the boat would start to roll over, this was fixed with the addition of some trim tabs which work sort of but now when the power goes over about 45% the boat starts to pull badly to one side and I am at a loos why or how to fix this.

Below is a video of the problem and I would very much your input so I can venture out of the safe but small pool and into a lake for some real fun.

http://www.youtube.com/watch?v=wJXbRwCrv7Y&feature=youtu.be I look forward to your comments guys.....

My guess is that you have more rpm with the new motor and stock prop and therefore it rolls over from the torque.

Try a smaller prop or use less voltage (less cells).

Are you using 2S or 3S? 4000kv is a bit much for 3S so if you are running 3S try to step down to 2S.

I agree with BackEMF. If your motor is too big for your boat or your prop you will have issues. If prop spins too fast, it will cavitate more aswell Propeller generates lots of torque which has tendency to twist your boat.

Measure t he prop diameter so we know where to start here.