Choosing the Best Bottom Paint For Your Boat

Antifoulant Paints – How They Work

Antifouling paint forbids aquatic growth such as barnacles, mussels and sometimes oysters, and plant growth from attaching to your trawler. Most antifouling paints use the diffusion of metallic elements within the paint to halt these foul critters from bonding. Copper (cuprous oxide) and tributyl tin are 2 metals that have proven to be successful as biocides, but tin, banned worldwide on ship hulls in 2009, was so poisonous that it decimated whole marine ecosystems.

Copper compounds are now universally accepted, but the price of the copper raw material has risen substantially. In addition, high copper concentrations have dissolved in the water in some places in the USA placing limitations on the application of copper-based paints.

Paint producers continue to produce a number of different antifouling technologies that tackle these and other problems.

New Paint Products

Composite Copper: Exchanges the traditional cuprous oxide with silica, lowering the copper content by up to 40%. The consequence is a copper based biocide that gives superior protection for your yacht, with a base that is made from materials found in the ocean.

Water-Based ablatives: Water substitutes the solvents found in traditional bottom paints. Low-odor formula permits painting inside. Application is trouble free and clean up involves only soap and water.

White copper: Clean and white in color, white copper (cuprous thiocyanate) necessitates 50% less content than the dark copper used in conventional antifouling paint.

Econea: Paint producers think that, a metal-free biocide produced by the pharmaceutical industry, is the future of antifouling paint. Advantages include protection at low usage levels, they degrade quickly and are biodegradable. Unlike some metal-based antifouling agents, ECONEA can be used to easily develop lighter and brighter paints, resulting in bright colors with better uniformity. Because it is a metal-free compound, ECONEA will not cause galvanic corrosion on aluminum hulls. This rules out the trouble and price of thick barrier coats. ECONEA-based paints also add less weight to a yacht when applied at the same film thickness as metal-containing paints.

Antifouling Paint Options

Copolymer paints are typically used on slow vessels such as trawlers and sailboats and release biocide at a steady controlled rate all through their lives, wearing away or “ablating” very much like a bar of soap. Paint wears off faster in high drag areas on the hull and appendages. These paints work well in high-growth areas and continue to be efficient after haul-out and relaunch. Copolymer paints offer true multi-season protection, lasting as long as there is an satisfactory coating thickness. Because they reveal new biocide until the application is worn completely away, additional coats add to their length of service. We advocate a covering of two coats on each new bottom job. Copolymer paints with anti-slime additives are best for nutrient-rich, heavy fouling areas.

Modified epoxy paints are best if you have a fast planning – hull boat. Contact leaching paint releases the biocide at a steadily decreasing rate, leaving the hard coating of the original thickness at season’s end. Higher copper content, rather than the type of paint binder as with ablative paints, generally means greater effective performance in this paint type. Modified epoxy paints stick to most surfaces, and can be applied over most types of paints. On the down side, they lose strength when the yacht is stored out of water. In addition, after several applications, the existing paint will begin to build up requiring removal.

Dual Biocides

Paint suppliers often add a second biocide to some versions of their applications, usually in the final coat, using formulas such as Biolux, Irgarol and zinc pyrithione and zinc omidine. These additives further limit the growth of algae.

Aluminum Hulls and Underwater Metals