Antifouling paint types: hard, ablative, epoxy, silicone

Antifouling choice depends on how the boat is used: how many hours underway, how often you haul out, saltwater or fresh, and how many boats-per-slip in the marina (galvanic pressure). HARD MODIFIED EPOXY (Pettit Hydrocoat, Interlux Fiberglass Bottomkote): cuprous oxide biocide in a hard binder that doesn't slough off. Best for fast boats and racing boats (smooth surface = less drag), lasts one full season, can be scrubbed if hauled and re-splashed. Downside: builds up over years, needs sanding down eventually. ABLATIVE / SELF-POLISHING (Pettit Trinidad SR, Interlux Micron): binder slowly dissolves as the boat moves through water, releasing fresh biocide continuously. Best for slower cruisers and boats that sit a lot, the fresh surface never fouls. Downside: quick softening when scrubbed, wears fast at 15+ knots continuous. HYBRID (Interlux Micron CF, most modern high-end paints): ablative with copper thiocyanate, better for aluminum hulls (copper alloys need to avoid electrolysis). EPOXY BARRIER (Interlux Interprotect 2000, before any antifouling): protects the gelcoat from osmosis, required on new fiberglass hulls, 3 coats minimum. SILICONE FOULING RELEASE (Interlux Intersleek, Hempel Silic One): expensive but no biocide, fouling doesn't stick, boat wipes clean. Best for very active use (racing, charter), needs professional application, ruins a rag when you touch it. Never mix systems without stripping to gelcoat first, old ablative and new hard paint delaminate within weeks.