We use the Interlux stuff that you buy in the paint aisle, sprinkling it on to just-applied paint with a mozzerella-cheese shaker. It goes into the second-to-last coat of Brightside or Perfection or Awlgrip. The last coat, over it, seals it in as though it's been epoxied.
This is what's on C44s and the Cherubini speedboats.