Anti-cav plate height (25HP rude, 14' aluminum)

Bindernut

Seaman
Joined
Jul 12, 2006
Messages
63
I'm curious about what would be the optimum anti-cav plate height for my boat.

It's a 63" wide 14' aluminum with a 15" transom. I've got a short-shaft 25HP Evinrude on the back. On the motor, the distance from the top of the transom clamp to the cav plate is 17.5", putting the plate about 2.5" below the keel of the boat.

I've read that the cav plate should be even with the keel for least drag. Does that apply to this motor too? Would I gain anything by using a jack plate to bring the motor up?

Right now, the boat planes out nicely with one person, but if I'm carrying a buddy with it has a heckuva time getting up on step. It's still got the stock pitch 9x10" prop. WOT rpm is about 5200-5300.
 

Esox

Petty Officer 1st Class
Joined
Sep 14, 2006
Messages
288
Re: Anti-cav plate height (25HP rude, 14' aluminum)

Usually the starting point is with the A/V plate even with the bottom of the hull. I think the Shaft measurement is taken from the bottom of the transom clamp - not the top.
 
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