1st question - propeller<br /><br />First time out with my "new" 81 50 hp merc. Whoo Hoo I never ran anything larger than a 9.9. Am I under propped? Full Throttle 6,300 RPM - Don't worry, I did not run it there. 5500 rmp = 28mph (gps) Prop that came on the motor is a 48-73140-15. What do...