I repainted frames I think were anodized "silver" aluminum, on a previous boat. I sanded lightly and used etch primer. I may have done 2 primer coats, it does not apply well. Note Gaston`s advice to use a foam brush, conventional brushes don`t work well. I think I even sanded the primer smooth. I applied 2 coats of "silver" single part "epoxy"paint. Not sure how you can have single part epoxy but it was good paint to apply, with an excellent durable finish, very like the original.
Aluminum oxidizes fast, so prime immediately after sanding prep. This may be less of a problem with repainting than with bare metal. Ever seen an alloy Muir windlass cover without large bubbles under the finish? Perhaps prompting the change to a composite cover/case.
2005 Integrity 386 "Sojourn"