evinrude 30....cavitation ?? gears??

[rgibber34]

I'm having trouble with engine slipping when on plane...Thought it might be slipping gears at first...but then thought about prop out of water... it does not happen going out of the hole...only when up on plane and 3/4 to full throttle...the transom on the jon-boat has been cut down by previous owner to allow for a short shaft motor....i'm wondering if they didn't go short enough?? could it be something else?? prop or spline?? I adjusted to engine angle and it helped some.... thanks...

 

[Hooty]

Re: evinrude 30....cavitation ?? gears??

It might be a spun hub in the prop but I would expect that, like you said, coming out of the hole. You can put a mark on the prop and one on the hub and see if it's spinning. If it is caviation, trimming the engine in will help. If you have access to a prop shop, talk to those guys and maybe play around with some other props.<br /><br />g'luck & c/6<br /><br />Hooty

 

[adweeb]

Re: evinrude 30....cavitation ?? gears??

You may be on to something about the motor elevation. The flat plate just above the prop needs to be level with or maybe just slightly elevated above the bottom of the boat. <br />If it's too high it surely will cavitate when you plane out because your prop will be coming out of the water.

 

[KenOhki]

Re: evinrude 30....cavitation ?? gears??

I agree on the motor high as the suspect problem. I just today was playing with mount hight and angle, did just what you describe when mounted to high. turns out for my boat and my motor, the anti-cavitation plate should be 1 inch below keel, But I noticed wile WOT and planed, the anti-cavitation plate rides right at water level.<br /><br />when I had it level with the keel it blew out right after planning. My boat seams to make a good sized hole behind the boat wile under power.<br /><br />Could also be a trim issue.