There is a guy at Cape Marina with a custom 48' sailboat, all in aluminum. He bought the boat in bad shape, sanded the topsides, and finished with the mentioned etching primer and white Rustoleum topcoat. It was 2 years old when I saw it, and it looked beautiful. He rolled it, no spraying in marinas anymore. I on the other hand have had bad luck with Rustoleum products generally and I like to stick to Pettit or Interlux.
1975 32' Flybridge Sedan, twin Perkins 6-354 diesels, 1:1.53 velvetdrives, 16 X 19 props. Merritt Island, Florida