Cavitation Height

Machino

Cadet
Joined
Jul 27, 2009
Messages
26
Hello all. I tried to find my answer here searching but just couldn't find it. I have a 14' boat (old I don,t know what it is) with a 15hp Evinrude. Problem is is the old transom that was on this boat was hooked. That is to say that it angled down, below the hull. This was a problem for dragging the boat over bars (duckin), but seemed to take away performance as well. My buddy and I replaced the transom and it is parallel with the hull about 1" higher and I can't get the boat to plane.

The cavitation plate is about 1" under the water and I'm sure many of you will tell me it needs to go up. One thing that had me scratching my head was when I had this boat out on the water the other day, it would almost get up to plane, but then make a weird sound. Like it was over revving or the prop was almost in air. It was obviously not functioning right. Tell me what do I do. The fish are waiting.

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hoytvectrix

Petty Officer 2nd Class
Joined
Jul 6, 2009
Messages
114
Re: Cavitation Height

"One thing that had me scratching my head was when I had this boat out on the water the other day, it would almost get up to plane, but then make a weird sound. Like it was over revving or the prop was almost in air."



This sounds like a problem i had. Check to make sure the prop nut is tight. I had mine a little too loose one time and it did the same thing that you are describing about running like it was in the air.
 

Machino

Cadet
Joined
Jul 27, 2009
Messages
26
Re: Cavitation Height

Thanks for the advice Hoyt. This is what I found. Should have noticed it earlier but never thought of looking there. Any idea what this spacer in between the prop and the nut is called?

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Machino

Cadet
Joined
Jul 27, 2009
Messages
26
Re: Cavitation Height

Thinking about it how would this cause the "running in air" problem. Just curious to understand the mechanics.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: Cavitation Height

Well, if you say so. But I find it hard to believe.
 
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