Is prop too big, too small, or wrong pitch?

[fenalx]

What you are experiencing is called cavitation. This concept is difficult to explain without drawing it. Google it if you want an explanation.

If you just want to fix it, easiest way is to change angle of stinger/ strut, which you can't since it is fixed. Consider adding a strut which allows slight changes in prop angle.

Secondly, 2300kv for a 32'' boat (which from pics seems quite heavy) is certainly asking for trouble. As Emmanuel said, get a bigger motor with a lower kv for that size of hull. Otherwise, your current motor and ESC will soon burn out.

[deshojo]

Thank you Emmanuel, and Fenalx. It all makes sense now :-)

It's funny how one can read pages after pages of technical information on motors and props (and believe me, I've read a lot recently), and yet one concise, well written paragraph can explain things so much better.

[ED66677]

Fenalx, it is as you said cavitation but remember that even a correctly sized prop do cavitates what he sees here is just "over" slippage.
In the surface piercing prop application the difficulty is to find the right balance between thrust and cavitation, especialy at startup. Compared to subsurface prop, a surface piercing prop has to be bigger as first it is cavitating, and second because only one blade is in the water at a time.
Almost as soon as you hit the throttle the prop starts to cavitate causing slippage, if the prop is not big enough the slippage is above the alowable limite causing power transfert loss, too big of a prop will torque roll the hull and eventually burn the motor/ESC/pack.
Do a search (google) on surface piercing prop you'll understand better the "how and why"!