90 4 stroke Yammy - cavitation plate

Bozol

Seaman
Joined
Jul 24, 2007
Messages
70
When my engine was installed on my 17' whaler three years ago I noticed that the cavitation plate (that is what I call the short fins just above the prop) was above the bottom level of the boat by about 2 inches. I asked at the time if it was alright and was told it was. Since then I have received several differing viewpoints as to whether I should drop the engine so the plate is roughly 1" below the level of the boat - some say yes, others say 'if it ain't broke don't fix it'. I have not noticed any problems to date - the boat takes off great from idle and does not lose power or 'scream' when in sharp turns. To drop the engine 3" would necesitate drilling new holes into the mounting bracket.

Any advice? What is this plate intended for?

Cheers,

Bozol
 

BaileysBoat

Senior Chief Petty Officer
Joined
Sep 29, 2008
Messages
716
Re: 90 4 stroke Yammy - cavitation plate

Seems like the installer knew what he was doing with your Whaler.
I would never drop the engine if the setup was working well. You would loose speed and rpm.

I run the F150 on the 3rd hole, just about 1.5" high.

The plate is actually a ventilation plate to keep surface air from reaching the prop.
 
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