Outboard Corrosion - Painting?

[Calaban-Alleria]

Our sailboat, in a salt environment, has a older Yamaha 8hp long shaft.
The outboard has always been 100% reliable and overall looks quite presentable however there is an area of the aluminum exterior lower engine casting that has developed some corrosion.

It seems that the factory paint barrier has been breached allowing moisture, in the absents of oxygen, to form a white powdery oxide and further undermine the paint.
Last haul out I did a clean up of the area with a brass brush, emery cloth and a wipe down with acetone and a quick spray with a rattle can from HD.
This has lasted a while but I see the problem is coming back.


Is there a better process/paint that will allow me to touch up the engine or would it be better to just remove the flaking paint a ignore the cosmetics?

[a64pilot]

There are better processes, but it may not be worth the pain.
Start by cleaning and alodining the aluminum, then proceed to an Epoxy propolymide primer and then a two part Epoxy based paint.
Paint on aluminum, especially in salt water is a temporary thing, my opinion is over time any coating over aluminum will fail, done exceptionally well it may last years though.