Originally Posted by V129
I always thought that the cavition plate should be level or just below the bottom of the boat.
Depends on the boat. Generally a good starting place is anti-ventilation plate even with the lowest part of the hull, but quite often, the motor can be raised without causing problems (which puts less leg in the water, which decreases drag, which increases efficiency.)
A lot of it is trial and error; no "rule of thumb" that I know of to get a definitive placement. Well, other than start at even, that is.