Painting an aluminum outdrive - Mercruiser

Q. I would like to know of a preferred method of painting my Mercruiser outdrive lower units, which are aluminum castings. If you are not familiar with sterndrive power on boats, they are the used to transfer power from the boats engine(s) to the prop(s) and are usually remain submerged (in my case, in fresh water for 6 months each year), or in southern climates, a year or more in salt water. My drives are currently in a shop being bead blasted to remove all paint.

Because I don't have access to a oven, the process would have to include air dry times between processed elements.

I have tried using zinc dust ⇦ on eBay or Amazon [affil link] sprayed over the raw and cleaned aluminum surface, followed by a two-part urethane topcoat. You'll eliminate the lengthy sanding and recoating process you have with the epoxy primer. Good luck.