I just bought a 2015 20' Starcraft pontoon with a 2015 115 4 stroke Mercury and I'm not getting the speed I assumed I would get. It currently has a 13 3/4" x 15" prop with 2.07 gear ratio. I've only had it out twice, but I was only getting 22 mph at 5700 RPM with the motor trimmed up and 3...