Types of Antifouling PaintEvery antifouling falls into one of a few families. The differences come down to how the paint releases its biocide and how it behaves when the boat is hauled. One rule worth repeating: never paint over old, unknown bottom paint without checking that the two are compatible. Slime—a slime layer greatly reduces or stops the paint’s antifouling action. Boats in warm Caribbean water usually need repainting more often than boats up north.