Evinrude 18 Prop Ventilating

I have a 1970 something Evinrude 18 horse electric start outboard. The motor runs pretty good, and at low speeds, everything does fine.  At higher speeds, however the prop seems to "slip" out and the boat loses speed rapidly. Someone told me the motor had a clutch inside that needed tightening, but I have since learned that this is not true as there is no clutch.  I have also heard that maybe my prop is "cavitating" or something, but I don't know what that means, or how I can fix it.  If you could give me a definite answer I would greatly appreciate it because spring fishing will be starting soon enough.
Thanx- Dave Postle

It sounds like the prop is ventilating. Unfortunately, on a motor of this age, there is not much available to correct it. Try lowering the motor deeper and see if that helps.




Please submit whatever questions you have to IHRTechTalk@yahoo.com.  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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