Okay, I am confused. New Boat 1 month old. RPM was too low topping at 4400 rpm before porpoising at WOT trimmed out. Prop is H1317, Im assuming 13 inch, 17 pitch. SLAMMED my prop through something solid last night, all three blades trashed, skeg is smashed a tad bit but just needs filed smooth I hope, no cracks. Manufacturers recommended RPM is 4500-5500 so what size do I buy to get me in a more efficient operating range? Shouldn't I be at the upper end of the rpm range at WOT? Oh yeah. 2072 SeaArk with 2007 90hp Yamaha, 2 stroke Thanks.