Getting the prop deeper in the water may help BUT it may also cause the system to run hotter too. I think you just need to find the right prop for the hull. Does it cavitate just on take off and then hook up and go fine? I have had some custom made props that would cavitate real bad on take off and then once the hull was on plane it was fine. I have also had some props that would cavitate any time I let off the throttle. On a 7XL with 14 cells I am not sure I would trust those carbon props, you might want to get a Octura metal prop instead. That is a pretty hot setup even on Nimh cells in my opinion, you might be better off with a 9XL and a larger prop which will also help with the cavitation.