Hello,<br />I have a 61 glaston 16' w/ a 64 90 hp evinrude. When I get about 3/4 throttle it starts vibrating. Like the prop isn't getting good bite or the trans is slipping. When i'm wet docked on the lift I can run full throttle with no vibration. <br /><br />What is wrong. This is a ski boat and I haven't tried to pull a skier. Is the prop a torque prop or is there something else wrong. <br /><br />New to boating any info would be nice. 