Many countries, states, and regulatory agencies are monitoring the current state of the art in antifouling technologies. Studies in harbors have noted high levels of the poisonous substances mainly found in bottom paint. Mainstream paint companies still sell lots of bottom paint containing copper (mostly in the form of cuprous-oxide) and one or more other biocides — all of which may soon face legal limitations or banishment.
This has spurred a flurry of experimentation, which appears to hold out the possibility of new environmentally friendly paints that not only perform a stellar job of preventing fouling, but also hold the promise of side benefits like improved longevity, reduced water resistance, and less health implications for those handling the materials.
Anyone who has scrubbed and sanded a dirty boat bottom readily understands the need to seek more environmentally benign alternatives to traditional antifouling coatings. A mid-season scrub is often done in some pristine cove where the water is clear, so you can see what you are doing. You are soon floating in a cloud of red, green, blue, or black paint that you know is both poisonous to the stuff that grows on your boats bottom and to the sea life around you. Or, you may live in a cloud of colored dust for a few days, as it is thrown up by a sander in the boatyard. One rainstorm and your old paint washes back into the harbor, if it hasn’t been properly collected. You have to scrub it off your face, out of your hair, and you can taste it in your mouth. If it eliminates the bad stuff, it probably eliminates the good stuff too, not to mention what it may be doing to your health as you breathe and ingest the noxious material. You wonder if it kills a barnacle, can it kill you too?
On the other hand, there is an environmental cost to sailing around with a fouled bottom and prop, slowing your boat, burning up excessive amounts of fuel, and possibly delaying the completion of your trip. Imagine the cost to the world of all those fouled commercial ship bottoms now slowly plying the world’s oceans? A tiny improvement in running efficiency could mean a huge savings in oil burned and costs incurred.
Antifouling solutions elusive
The need for antifouling paints that are both environmentally friendly and efficient is evident, but the answer has been elusive. New technologies have been spurred by the banning of tributyltin, or TBT, in all bottom paints, and now there are moves afoot to either limit or eliminate copper as the antifouling agent of choice. Already, copper has been banned in antifouling paints in parts of Sweden, Denmark, and in the Netherlands.
As in other environmental arenas, California leads the U.S. in research and regulation of antifouling paints. The Shelter Island Yacht Basin in San Diego has been the subject of Total Maximum Daily Load (TMDL) regulatory studies with regard to copper levels in the water. It has been concluded that around 98 percent of the copper originated in antifouling paints. This has led to a series of initiatives designed to reduce the copper load, including: refining hull cleaning operations, refining painting procedures, getting a percentage of boats to use non-copper paints, and many more boats to use lower-copper paints. However, recent studies (2009) indicate that more drastic measures may be required, including a possible ban on copper in antifouling paint. Several non-toxic coatings have been studied in California, but it was determined that frequent (in some cases every week) scrubbings were required to keep antifouling at bay.
Ultrasonic Antifouling has reintroduced a system that has been tried before. It utilizes high-frequency, low-power sound waves to destroy algae and therefore prevent weed and barnacle growth, according to the company. One (for up to 32-foot boats) or two (for up to 64-foot boats) transducers are mounted inside the hull, along with a control box. The units can run off shorepower or use 12 to 24 volts onboard, and utilize around 1 to 1.7 amps per hour. The manufacturer states that this new digital system uses up to 40 percent less power than previous analog versions. A single Ultra 10 system sells for roughly $1,300. One interesting advantage of installing one of these units, according to the manufacturer, is that you can do so even after the hull is fouled, with the sound waves gradually killing off the algae and the fouling, though it is recommended to start with a clean hull. This system is reported to be effective at preventing fouling on metal parts, like props and outdrives.
John J. Kettlewell
Interestingly, the popular ablative antifouling paints used now by many boaters are considered to be more unfriendly to the environment, according to boating guidelines put out by the Port of Los Angeles. Ablative paints gradually wear away, exposing new surface with new biocide, but that also means that paint and biocide is gradually eroding into the water around your boat. Users of ablatives like the fact that boats can remain out of the water for long periods without losing antifouling effectiveness, and there is much less paint build up over time, eliminating or reducing the need to strip the bottom frequently. However, the Port of Los Angeles recommends the use of harder bottom paints, even with high copper loads, because more of the biocide remains trapped in the paint that stays attached to the hull.
This problem has caught the attention of officials in the state of Washington where they have banned the practice of underwater, or near-the-water, scrubbing of boat hulls coated with soft or ablative antifouling paint. Violators can face fines of up to $10,000. The state also has strict regulations on the collection of paint sanding dust and scrapings for boats that are hauled out.
In addition to water pollution problems, regulatory agencies are also concerned with air pollution from volatile organic compounds, or VOCs. Traditional bottom paints used strong and hazardous solvents (lots of them), creating that incredible smell boaters associate with spring time in the boatyard. In fact, many marine coatings, including resins and glues used in boat construction, are now subject to ever-stricter air pollution regulations.
However, there are now several widely available water-based antifouling paints, such as Pettit Paint’s Hydrocoat, which dramatically reduces VOCs, makes clean up easier, and still uses copper for strong antifouling properties.
New principles, new paints
Marine paint companies have been following these developments closely and have been working hard to get ahead of the regulatory curve. Spurred on by the TBT ban for large commercial vessels, which use a lot more antifouling paint than the yachting market, the switch back to copper in traditional antifouling paints is complete. However, the need to gradually move away from copper and to reduce VOCs has led paint companies to try new materials that can reduce the need for copper, and hopefully eliminate the metal entirely.
For example, International Paint, a division of AkzoNobel, the largest marine paint company in the world, is offering several new Interlux paints that are copper free. Pacifica Plus utilizes something called Econea created by pharmaceutical company Janssen PMP. Pettit also has its Vivid Eco, which utilizes Econea as its biocide, instead of copper. Econea is a trade name for a pesticide commonly called Tralopyril. The New York State Department of Environmental Conservation (NYSDEC) reports that Tralopyril “is very toxic via acute oral exposure, slightly to moderately toxic via dermal and inhalation exposures, but only slightly irritating to the eyes and skin. Data from the available subchronic animal studies indicate that Tralopyril has the potential to cause some local and systemic toxicity, including neurotoxicity.” Janssen conducted tests on various paints using Econea in California, and results were comparable or better than copper-based paints.
So, this new material does sound like it might be good at killing critters on your bottom, but there may be other environmental and health issues to consider down the road. Interlux reports that Pacifica Plus also utilizes its Biolux Technology, utilizing “organic boosting biocides” to fight algae and slime.
Other Interlux and Pettit paints use boosters from the pharmaceutical industry to increase performance, while reducing the need for heavy copper loads. For example, Interlux’s Fiberglass Bottomkote ACT and Pettit’s Ultima SR-60 utilize both Irgarol and copper. However, some studies indicate elevated levels of Irgarol may be found in busy harbors with an unknown future effect on marine life, and these products still rely on a heavy copper load — the more copper the more effective, and the more they cost. There are reports that worries about Irgarol and an herbicide called Diuron may lead to a ban in Europe in the near future.
Interlux has also produced a paint for California boats that utilizes no biocides. A spinoff from AkzoNobel’s commercial paint division that provides paint for freighters and supertankers, Intersleek 900 is basically so slippery that stuff can’t hang on to your bottom. Quoting the Interlux brochure: “The finish has what is known as ‘low surface energy.’ Fouling organisms generally have a difficult time forming an attachment to a ‘low surface energy’ finish and when they are successful only do so very weakly. Fouling can be easily removed with simple hand cleaning methods using sponges, window squeegees, soft bristle brushes, and fleece mitts. The frequency and amount of cleaning required will depend on fouling conditions and how often the boat is used.”
Other companies are manufacturing and marketing these “low surface energy,” or slippery, paints. Ecological Coatings makes a paint with a silicone-epoxy chemistry that the company says makes the product tough and durable. These slippery products don’t kill marine organisms, and they don’t rely on leaching products into the water, so they are inherently better for the environment. Ecological Coatings says its product is also low in VOCs.
KISS Polymers and Aurora Marine make polymer-based coatings that also make boat bottoms very slick. Aurora makes VS721 Bottom Coat, which is a clear polymer coating. An advantage of this approach, according to Aurora and KISS, is that it also makes your boat faster and more fuel efficient.
KISS-COTE’s MegaGuard Marine LiquiCote is designed to apply over a substrate of conventional bottom paint, combining a super-slick surface with the antifouling capabilities of the biocides below. KISS says that polymers alone will not provide complete antifouling protection, but the two products together can provide long-lived protection with additional advantages. KISS claims the product forms a permanent chemical bond with the substrate. The product is also said to produce a lower level of biocide released from the paint, greater longevity of the underlying antifouling paint, reduced friction and greater speeds for the boat, and reduced maintenance requirements. The product has been tested and used on America’s Cup boats and offshore power raceboats. The company claims a 1 percent increase in speed at 12 knots on America’s Cup boat Kiwi Magic.
One interesting, and somewhat alarming, thing to keep in mind is that these slippery coatings can make hauling slings or hydraulic trailer pads slip also. They all include warnings about taking extra precautions when having your boat hauled out of the water.
International and other paint companies have participated in research into a new antifouling principle conducted by the University of Gothenburg, Sweden, along with the Swedish Chemicals Inspectorate. The paint, which is not on the market yet, utilizes traditional biocides that are strongly held within the paint’s binding matrix agent, resulting in only small releases of biocide to the environment. This paint relies on a principle called post settlement inhibition. Barnacles and larvae are allowed to settle on the painted surface, but when they penetrate the surface to more strongly attach themselves they come into contact with the biocide. This causes the barnacles to release their grip on the hull. Researchers reported that barnacle attachment was reduced by 90 to 100 percent. Eventually, researchers hope to use this principle to create a paint that prevents fouling not just from barnacles, but from algae and other animals.
Does your boat have dandruff?
Entrepreneurs have seen the future and hope it is theirs. The company ePaint began researching paints for the U.S. Navy in 1985, and subsequently they’ve developed specialty antifouling coatings for the U.S. Coast Guard, the Woods Hole Oceanographic Institute, the U.S. Geological Survey, and the National Oceanic and Atmospheric Administration.
Amongst several other specialty coatings, the ePaint product that is recommend for cruisers is ePaint ZO (EP-ZO), with Zinc Omadine. It doesn’t utilize organotins or copper. The paint utilizes a “photoactive ablative matrix,” which basically means that sunlight activates the antifouling properties and encourages ablating.
Though the paint is compatible with most other pre-existing paints in good condition, there are some new considerations. The photo ablative aspect means that you’ll need more near the waterline, where it gets more sun. Also, lighter paint colors provide more protection and are recommended for high-fouling areas. The paint is less effective in silty waters where less light reaches the paint.
Zinc Omadine is a fungicide-algaecide that is accepted for both industrial applications and personal care products. It’s the active ingredient in anti-dandruff shampoos you may have in your bathroom.
John J. Kettlewell has been sailing between Labrador and the Caribbean for more than 30 years. He’s the author of The Intracoastal Waterway Chartbook: Norfolk, Virginia to Miami, Florida, now in its fifth edition.