Ive owned a X22F/C pontoon for a few years now. It has planing strakes on the pontoons. It's powered by a yamaha 4 stroke 115hp. before last year it would only run 17 to 18 mph GPS also it came with a 14p SS prop and i could only give it around 3/4 throttle before it started slipping. Last year i purchased a 15p aluminum prop and this increased my speed to around 22mph but when i get to around 5,000rpm this prop starts slipping as well. i can continue to 5800-5900 rpm and gain speed up to 24mph but it has a lot of slip. the motor is as low on the transon as it will go. I'm just wondering if the planning strakes at speed are lifting the motor to high up causing the slip? or would i benefit any by going up another pitch?