Tony - you can't or shouldn't use a cuprous-based (copper) anti-fouling paint on an aluminum motor bracket. You need to use Tri-Lux II (made for use on aluminum) or ePaint anti-fouling paints (both expensive, ePaint more so, as it's new technology non-cuprous based).
To do so otherwise would be to promote or accelerate electrolysis and galvanic corrosion, which means in the salt environment that the aluminum bracket would be eaten away.
I can show you pictures of this happening. "Whomever" owner my boat used copper-based paint. I caught it this far and note this is occuring in the weldment area, which is typical (welding changes the metallic structure of the parent metal). I ground it out with a Dremel bit and filled it with epoxy and it has been sound since ... plus I use Trilux II on it for anti-fouling.