Eco-Friendly Anti-Fouling Paint

boat outdrive dirty
A dirty boat bottom robs you of fuel-efficiency, performance and handling, but how to keep it clean in the most eco-friendly way?

A search has been on for some years to find more environmentally friendly bottom paints and anti-fouling methods. Environmentalists have pushed scientists and chemists for better solutions. Green marinas that capture and filter runoff from waterfront boatyards are in vogue. And more and more cities and towns are banning divers from cleaning their bottoms in the harbor to avoid releasing clouds of copper oxide onto shellfish beds and fish breeding grounds. Something that will keep aquatic plant and animal life from growing on your boat’s bottom is, by its nature, unfriendly, repellant, or downright toxic to those organisms. But there are some greener alternatives in anti-fouling protection.

A slippery surface that repels growth because nothing can hang onto it is a step toward eco-friendly. Thin film technology paints, like Interlux VC-17 containing Teflon, create hard slippery surfaces that require fewer toxins. Forespar has created a non-toxic slippery surface product called LanoCote Prop and Bottom that can actually be applied underwater.

But if boats don’t move often or fast enough to shake the growth loose, a slippery surface alone is not enough. Many boat owners scoff at racing sailors who wet-sand their boats’ painted bottoms, but in fact hard slick surfaces that include biocides are even better at anti-fouling.  Most racing sailors I know take it one-step further, using hard anti-fouling paint, wet-sanding before launch, and then cleaning the bottom regularly during the season.

Paint companies have developed products that limit the range of toxic material from the eco-system at large by adjusting the release process of the biocides in their products.  Soft ablatives or sloughing paints are less popular and less eco-friendly, because they wash away indiscriminately. The “controlled-release” nature of hard ablatives, as an example, allows for the use of fewer toxins.

Heavy metals in anti-fouling paints have long been the effective, yet toxic, component of bottom paints. Some metals, like tin or tributyltin (TBT) and graphite have been banned outright in some locations. California and Washington State have legislation pending that would outlaw copper based anti-fouling on new construction. And while copper oxide is still the most prevalent and effective biocide in bottom paints, chemical alternatives like copper thiocyanate (white copper used in Petit Vivid and Interlux Trilux 33), Zinc Omadine (which creates a hydrogen peroxide chemical reaction and is found in E-Paints EP-ZO), along with slime fighters like zinc pyrithione, have been employed by paint companies trying to find alternatives to copper oxide while also staying within regulations.

Three companies, Petit (Ultima Eco), Interlux (Pacifica) and Sea Hawk (Smart Solution) now have zero-metal products based on Econea, a biocide that is reported to be as effective in 6% solutions as paint containing 50% copper oxide.

boat bottom clean
Regularly wiping down your boat's bottom might be eco-friendly, but is it practical?

Water-based paints with lower volatile organic compounds (VOC’s) are also becoming favored over solvent-based paints for ecological reasons. These are safer for humans during application and are more biodegradable. Bionimetic silica encapsulation is a technology being touted as a natural eco-friendly alternative: non-metallic biocides encapsulated in silica that polishes away to release the biocide. Look for products with this technology in the near future.

An area of concern that doesn’t get enough attention, in my opinion, is compatibility between paint types. Some formulations require that an old non-compatible paint be removed completely. Removal by sand or soda blasting leaves contaminated residue, and mechanical sanding and chemical peels can cause skin burns and breathing problems. Co2 blasting with dry ice is a commercial alternative that leaves no secondary contaminated residue, but it has not been widely accepted yet. Most boatyards now require that any old bottom paint removed from your hull be captured and properly disposed of.

Ultrasonic anti-fouling  is one method of anti-fouling that does not require a toxic paint formula, biocides, or a slick surface. The technology is based on a series of ultrasonic sound frequencies generated through onboard transducer(s). The up-front cost for a system for a 30-foot boat is approximately $1,300.

As boaters, we all appreciate and enjoy our water world, but let’s face it, there is presently a tradeoff between more toxic anti-fouling paint and more eco-friendly, albeit unrealistic, solutions like wiping down your boat’s bottom by hand every day.  Based on how and where you use your boat, you’re going to have to experiment to find which combination of products and actions works best for you.

Written by: Peter d'Anjou

A USCG licensed captain and former merchant mariner, Peter d'Anjou is now a freelance writer and editor. A one-time executive editor at Sailing World magazine, he writes about his passion for racing and boating. Having managed a large yacht repair facility in the NE U.S. his background in boat construction and repair translate to the practical side of boat ownership.