Best Antifouling Paint for Cruising Boats: Micron vs Trilux vs Coppercoat

Antifouling paint is the consumable that keeps your boat's underwater surfaces free of marine growth — barnacles, tube worms, algae, and the biofilm that precedes them all. Without it, a hauled boat returned to tropical water can develop measurable growth within days and performance-destroying fouling within weeks. The drag penalty from heavy fouling can exceed 40%, which translates directly to reduced speed, increased fuel consumption, and a boat that handles like it's towing a mattress.

The antifouling market offers dozens of products, but for cruising boats the decision typically comes down to three categories: ablative copper-based paints (the traditional standard), hard copper-based paints, and copper epoxy coatings (the semi-permanent alternative). This comparison covers a representative product from each category.

How Antifouling Works

All antifouling paints work by releasing biocide — a substance toxic to marine organisms — from the painted surface. The most common biocide is cuprous oxide (copper), which has been used for antifouling since the Royal Navy cladded ships' bottoms with copper sheets in the 18th century.

The rate and mechanism of biocide release defines the paint type:

Ablative (self-polishing) paints release biocide as the paint surface gradually wears away through water flow. Fresh biocide is continuously exposed as old paint erodes. When the boat sits idle (at anchor, in a marina), erosion slows and biocide release decreases. When the boat moves, erosion resumes. This self-regulating property means the paint lasts longer on boats that sit more and wears faster on boats that sail frequently — a natural match for cruising patterns that alternate between passage-making and extended stays.

Hard (contact leaching) paints release biocide through the paint surface without eroding. The biocide leaches out over time, leaving behind an increasingly depleted paint matrix. Hard paints are smoother than ablatives (better for racing), can be scrubbed and pressure-washed without removing paint, and maintain a consistent surface over the haul-out cycle. The tradeoff: they build up in layers over multiple applications and eventually need to be stripped.

Copper epoxy coatings embed copper particles in an epoxy matrix that's applied once and lasts 10+ years. The copper is exposed at the surface through abrasion and biocide release is sustained by the high copper loading. These are semi-permanent systems — expensive to apply initially but eliminating the annual repaint cycle.

The Contenders

Interlux Micron Series (Ablative)

The Micron series from Interlux (AkzoNobel) is the most widely used ablative antifouling in the cruising fleet. The range includes Micron CSC, Micron Extra, and Micron 66 — each with different copper content and polishing characteristics.

Key products: