---

Sounds like your motor is mounted using OMC's "blind holes" - see a description in the Rigging folder of the articles section at this site. The blind holes rig the motor "all the way down" which is not optimal. You could improve the performance of your current motor by rigging it 2 or 3 holes up.

5200 RPM is not horrible, but you really should be up around 6000 when running light, so you are overpropped by a couple of inches of pitch at least. That is contributing significantly to your poor performance when loaded.

So if you feel like trying to make it better, as opposed to getting a new motor, you can move your current motor up, and then try a different prop. It will make quite a difference, and cost a lot less than an F60 or 70. On the other hand, it will still be an old-tech 2-stroke, so it's going to be quite noisy, smelly, and thirsty compared to a modern motor.

Tim