Bottom Painting & Antifouling
You haul the boat and the yard manager walks over with a scraper. He taps the hull and a chunk of green slime the size of a dinner plate falls off. Underneath, the paint is thin, patchy, and missing entirely in places where the propspeed wore off. He looks at you the way a doctor looks at an X-ray. "When did you last do this?" he asks. You mumble something about two years ago in Florida. He nods. Florida isn't the tropics. The tropics eat bottom paint like popcorn.
We've bottom-painted in five countries. We've tried hard paint, ablative, hybrid, copper-free, and one experimental silicone that was supposed to be "revolutionary" and turned out to be a $400 lesson in marketing. Here's what actually works, what it costs, and where to get it done.
Hard vs. Ablative: The Real Difference
Hard (Modified Epoxy)
Hard paint dries to a smooth, sandable finish. It doesn't wear away — it stays on the hull until you sand it off. The biocide (usually copper) leaches out slowly, leaving a skeleton of resin behind. It's great for high-speed powerboats and for boats that get scrubbed regularly by divers. It's terrible for cruisers who stay in one place for months, because the slime layer builds up and the biocide can't leach through the crud.
We used hard paint in the Chesapeake. It lasted two years and cleaned up beautifully with a pressure washer. We used the same paint in the Caribbean and it was furry in six weeks. Wrong paint for the wrong place.
Ablative (Self-Polishing)
Ablative paint wears away like a bar of soap, exposing fresh biocide constantly. It's designed for boats that sit still — which is most sailboats in the tropics. The downside? It doesn't last as long. 12–18 months in warm water. And you can't scrub it aggressively without removing the active layer.
We switched to ablative in Grenada and the difference was immediate. The bottom stayed cleaner longer, and the diver could clean it with a soft cloth instead of a scraper. In 18 months, we hauled and the paint was thin but effective. Perfect for the cruising life.
Hybrid / Copolymer
The middle ground. Harder than ablative, softer than hard paint. Can be scrubbed lightly without losing effectiveness. Lasts 18–24 months. Popular brands: Interlux Micron CSC, SeaHawk Sharkskin, Pettit Ultima. This is what most cruisers in the Caribbean use now.
Copper-Free
Required in some marinas and countries (Netherlands, parts of California, New Zealand). Uses Econea, zinc, or organic biocides instead of copper. The early formulations were terrible. The new ones work — not as well as copper, but acceptable. If you're cruising in regulated waters, carry the paperwork proving your paint is compliant.
What It Costs (Real Numbers, 2026)
| Location | Haul + Wash + Prep | Paint (2 coats, 40ft) | Labor | Total |
|---|---|---|---|---|
| Trinidad | $600 | $800 | $600 | $2,000 |
| Grenada | $900 | $1,200 | $800 | $2,900 |
| Martinique | $1,100 | $1,500 | $900 | $3,500 |
| St. Maarten | $1,400 | $1,800 | $1,000 | $4,200 |
| Florida (ref) | $1,200 | $2,000 | $1,500 | $4,700 |
| New Zealand | $1,450 | $2,300 | $1,800 | $5,550 |
| Thailand | $500 | $600 | $400 | $1,500 |
PropSpeed & Running Gear
Your prop, shaft, and strut will grow barnacles even if the hull is clean. PropSpeed is a silicone-based coating that prevents growth on metal. It works — for 6–12 months. Then you need to reapply. We've tried everything: PropSpeed, Velox, Trinidad, and good old fashioned grease. PropSpeed is the best balance of effectiveness and duration. Apply it to a clean, sanded prop. Don't get it on the bottom paint — it prevents adhesion.
The DIY Option
Most yards allow owner painting on the hardstand. You pay for haul, pressure wash, and stand rental. The paint itself costs $150–250 per gallon. A 40-foot sailboat needs 2–3 gallons for two coats. You'll also need rollers, brushes, solvent, masking tape, and a respirator.
We've done two DIY bottom jobs. The first looked like modern art — streaks, drips, and a cloud of blue dust that settled on every boat in the yard. The second looked professional. The difference was preparation: sanding, cleaning, taping, and taking our time. A bottom job isn't rocket science. It's just miserable, hot, dusty work. But it saves $800–1,500 in labor.
How Often to Paint
- Tropics, full-time cruising: 12–18 months. Diver cleaning monthly extends this to 18–24 months.
- Tropics, seasonal cruising: 2 years if you haul and store for hurricane season.
- Temperate water: 2–3 years. Less growth, slower biocide depletion.
- Fresh water: 3–5 years. Or never, if you don't mind a little slime.
Ports with Strong Bottom Painting Services
- Trinidad — Cheapest, good quality, fast turnaround
- Grenada — Clarke's Court, cruiser-friendly DIY allowed
- Martinique — European paint brands, professional application
- Thailand — Excellent value, fast work
- New Zealand — High quality, strict environmental standards