Features March 1, 1998 Issue

Antifouling Paints: Year Seven

Pettit ACP 50 still reigns as the best multi-year owner-applied bottom paint. Among professionally applied ‘permanent’ systems, Interlux’s Veridian and Hi-Tek Chemical’s Epco-Tek 2000 work very well, though they do require periodic light scrubbing.

The summer of 1997 was the seventh consecutive year we’ve been running tests on antifouling bottom coatings. It was a year that saw an expansion in our project’s scope; a lot of extra work and, at the season’s end, the loss of our flagship test bed, the Foulbottom. All in all, the kind of “interesting times” that are referred to in the well-known Chinese curse.

Last summer we set up a test station in Florida to supplement our Greenwich, Connecticut site. We had intended to also set up a test facility on Lake Erie this season; unfortunately our assistant on the Great Lakes sold his boat after just a couple of weeks of testing and the panels had to be pulled (we’ll be starting up again next spring, to see how well the various paints deal with freshwater organisms, including the Zebra mussel). We also prepared new test panels for all three sites, plus made up panels for the two new sites that duplicated the 30 or so panels that were already under test at Greenwich. The Foulbottom’s loss with all panels attached—a mooring chain succumbed to corrosion and parted in a storm—was a painful one, making our end-of-season inspection impossible. Fortunately, we had done a three-month inspection, so all was not lost.

After staring morosely at the dark clouds for a while, our intrepid testers have discerned a few faint silver linings. The Foulbottom was becoming severely overcrowded, in light of the huge number of products on the market. A larger raft, which will be ready for next season, will allow us to re-test some products we haven’t looked at for several years. We did obtain (almost) another season’s worth of data from our Connecticut tests and one season in Florida. And we received a forceful impetus to evaluate different types of anchor chain, a study which we’ll start shortly.

Seven Years of Testing
For anyone who’s unfamiliar with what we’ve been doing, Practical Sailor has been conducting a series of tests to determine which products offer the best long-term protection to a boat’s hull against barnacles, mussels, tube worms, algae, grass and all the other forms of marine flora and fauna that are looking for a permanent home. It’s a problem that has beset saltwater boaters from time immemorial, and one that—thanks to the Zebra mussel—has now started to bother freshwater boaters as well.

Zebra mussels are only the latest entry in a long list of water-dwelling organisms that attach themselves to boats’ bottoms and add weight and drag while subtracting dramatically from performance and fuel economy. The barnacle is the pest that receives the most attention, but there are over two thousand different species of plants and animals that have been identified clinging to hulls, ranging from microscopic bacteria to yard-long remora fish.

The search for an effective bottom coating is an ancient one. Copper sheathing of wooden boats was for a time an adequate solution. Much more recently, tin-based (tributyl tin or TBT) bottom paints proved very effective but because they also tended to kill non-fouling marine organisms, they were banned almost a decade ago. Since then, paint companies have been scrambling to develop alternative coatings, the most common being cuprous oxide. It works well, but not as well as tin. Because some paints release VOC’s (volatile organic compounds) into the atmosphere, clean air restrictions have prompted chemists to work harder on water-based paints, so far with less than perfect results.

Over the years, we’ve tested just about every kind of paint or coating available: ablative paints, vinyls, modified epoxies, copper-loaded gelcoats, slick bio-release coatings designed to prevent barnacles from gaining a firm attachment, paints with cayenne pepper, paints that use zinc oxide as a biocide and water-based paints. Even those that require professional application. Those that performed poorly were dropped from tests in subsequent years. Those that performed well were stored over the winter, scrubbed according to the manufacturer’s instructions, and put back into the water for a second season of exposure.

For this year’s round of testing, we returned the 25 survivors of last year’s tests to the waters of Greenwich Harbor, along with six products we hadn’t previously tested and a couple of products we hadn’t looked at in several years—32 in all. For our Florida test, we prepared fresh samples of all the paints we’d tested in Connecticut over the past two years and added the previously untested paints and the same couple of revisited ones, giving us a total of 36.

How We Tested
Our tests were conducted in much the same manner as the ones we have been performing in recent years. While we started out this program back in 1990 by applying the various coatings to actual boat bottoms, we found that the yearly chore of scraping, preping and painting a fleet of 12 boats was just too much to handle. Luckily for us, we found that we could obtain very comparable results with much less time and effort by coating fiberglass panels and suspending them from a raft—the Foulbottom. We’ve been using the raft for the past four years.

We periodically towed the raft behind a small powerboat to simulate occasional use of a real vessel, and inspected the panels on a monthly basis. We looked, primarily, for hard growth—those difficult-to-remove barnacles and mussels—but also noted any severe coating of grass or other soft plant growth.

We tried to be as realistic as possible in the preparation of our panels: All of them were sanded lightly and solvent-washed in preparation for coating. The paints were then applied according to manufacturers’ instructions. If a primer was specified, we used it. For products such as Epco-Tek 2000 and Veridian, which are not intended for DIY application, we sent untreated panels to the manufacturers and asked them to prepare them for our tests.

What We Found
Our findings are summarized in the accompanying table. It’s a large chart and warrants a bit of study. Last year we tried to simplify it, and apparently created some confusion. This year we’ve rated each paint’s antifouling performance for each of the years it was tested. We scored each one on a scale of 5, ranging from Poor through Fair, Good and Very Good up to Excellent.

A product that received a score of Excellent showed no hard growth at all; one that was rated Poor was totally ineffective or had such poor adhesion that its antifouling properties were irrelevant. A Very Good product had a very few barnacles; Good indicates scattered growth across the surface and Fair means widespread, heavy growth.

Soft growth, such as slime, grass and seaweed is a problem, but less of a consideration in saltwater. This isn’t true in freshwater conditions, where the only hard growth apt to be encountered is the Zebra mussel and vegetation is likely to be the major problem. From what we’ve seen in saltwater, antifouling paints don’t deal as well with soft growth as with hard growth; we’ll have to wait until next year, when we expect to have a freshwater test site in operation, for more definitive conclusions. In any case, soft growth this year, as last year, was slight enough so that we didn’t consider it a major ratings factor.

In Their Fourth Year
Our last inspection of the Foulbottom’s panels—representing three month’s exposure—indicated that three years is probably a reasonable upper limit for the effectiveness of a bottom paint. Pettit ACP 50, which had ridden out three years of service unscathed, displayed scattered barnacle growth across much of its panel’s surface earning it a rating of Good; Woolsey Premium Performance had a fairly heavy growth and was rated Fair. Interlux’s Veridian—an extremely expensive slippery silicone-rubber based product that’s not really a paint—once again permitted barnacles to grow, but they could be removed with a swipe of a soft brush.

Last year, we rated Epco-Tek 2000, a copper-loaded gelcoat, as Good in terms of repelling hard growth, and commented that the barnacles that did grow on its surface were easy to remove. This year—its fourth year of exposure—we buffed the surface a bit more energetically with some 600-grit wet-and-dry sandpaper before putting it in the water. Fourth year results? Very Good. However, there was more soft growth than on most of the other products. The long-term durability of copper-loaded gelcoats continues to look promising.

In Their Third Year
Our Greenwich test included six products—four paints and two gelcoats— that had successfully survived two years of exposure, and were trying for three. This year’s test, as we’ve noted, was cut short by the loss of our test raft, and our third-year results for these six products are based on a shorter-than-normal season, and panel examination under less-than-ideal conditions. We usually removed the panels from the raft at the season’s end, hosed them off and examined them ashore under good lighting conditions. This time our final examination was made from an inflatable boat in a choppy harbor on a day that could be charitably described as grungy.

Nonetheless, three of the paints and both gelcoats held up very well. U.S. Yacht Ultra CopperKote, a house brand of E&B Marine (which now is a house brand for West Marine) was rated Excellent. So was ShipBottom and Sea Hawk Tropikote. U.S. Yacht’s Coppercoat had barnacle growth scattered across its surface; it was scored as Good.

Last year, we commented that while Permashield, a copper-filled gelcoat, was rated only Fair in keeping barnacles off, but that the barnacles were easy to remove. We talked to American Marine Coatings, Permashield’s manufacturer, who suggested that Permashield may have a harder surface than the other gelcoats we tested, and that we may not have buffed the coating adequately to expose a fresh biocide surface. This year we were more aggressive about buffing, making sure that the surface was abraded. This seems to have done the trick. In its third year Permashield was Very Good in keeping off hard growth (although we did notice more soft growth than occurred with most of the other products tested.) Unfortunately, we weren’t intending to evaluate how difficult barnacles were to remove until we pulled the panels at the end of the season, so that we really can’t comment upon cleanability. CopperPoxy, in its previous season had been rated Very Good—it repeated its rating in its third (abbreviated) test year.

In Their Second Year
No fewer than 15 products entered their second year of testing. All of them had earned Excellent first-year scores in last season’s Connecticut testing. These paints represented a wide range of types and technologies. Seven of them—Aquagard, Hydrocoat, Aquarius, Aqua-Clean, Gloucester Sea Jacket II and Gloucester Super Sea Jacket II and Neptune II—are water-based paints. They provide easy clean-up as well as helping to comply with EPA’s Clean Air laws regarding VOC’s. One, Nautical Paint Racing Vinyl, is a hard-surface vinyl lacquer. Another, Nautical Paint’s Bio-C3 is an ablative copolymer-based paint. Five—America’s Cup, Nautical Paint Copper Plus, Grand Cayman, KL990 Epoxycop and KL-990 Super Epoxycop—are modified epoxies.

Most, though not all, of these also survived our truncated second season of testing. Four of the water-based paints were rated Excellent; Neptune II showed a few scattered barnacles that downgraded its performance to Very Good; KL990 Super Sea Jacket II and Sea Jacket II were also Very Good. Nautical Paint Racing Vinyl dropped to Good in its second season.

In Their First Year
In Connecticut, we added six more paints to our test program—three newcomers, and three that we had tested previously and were re-visiting. The newcomers consisted of Hotbottom’s White, a paint that’s joining Interlux’s Trilux E-Paint’s ZDF and U.S. Paint’ Awlgrip White in the competition to produce a white antifouling paint, and a pair of entries from New England Paint—908V vinyl and 248R modified epoxy. One of the products we re-tested was VC-17, a slick racing bottom paint which makes only modest claims for antifouling capabilities. Another was Interlux Ultra-Kote, a perennially popular antifouling paint. The third was Micron CSC Extra, which had previously stood up to a year’s worth of exposure, but whose testing was interrupted by the loss of the test panel—we were starting over.

Four of the six came through our short test season with Excellent ratings. The panel coated with VC-17 had enough scattered growth to be down-rated to Good. The sixth, Hotbottom White, exhibited just a bit of barnacle growth—Very Good.

In light of the spirited discussion that occurred about a year ago concerning the use of Desitin—a baby creme—as an antifoulant, we’ll once again state that a) it keeps barnacles off, as long as it stays on the boat, and b) it simply doesn’t stay on the boat. Even for part of a season. And it’s greasy, so difficult to clean off.

This was our first full season of testing in Florida. We had tried a different Florida site several years ago, but ran into too many logistics problems, so that all our results represent a single season’s exposure. We sent a total of 36 panels southward—essentially all the products we were testing in Connecticut over the past two years. Our results correlated well with those we obtained in Connecticut. With only a few exceptions, first year results were Excellent. E-Paint’s ZDF rated only Fair, Hotbottom White was Good, though we saw some erosion of the finish at the end of the test. The two paints from New England Paint arrived in Florida with slightly damaged surfaces (apparently these two products take longer to dry than do the others tested.) The undamaged portions of the surfaces were rated Excellent, although the damaged surfaces grew a healthy crop of barnacles. And Sea Jacket II had some slight growth, earning it a Very Good rating.

Conclusions/Recommendations
Today’s boatowner has quite a few choices that will avoid the necessity of a yearly bottom painting. This is a blessing, both to the environment and to the boatowner. If you pull your boat out at the season’s end, having used a long-lasting bottom paint means that you can plan on redoing the bottom only every two to three years, with in-between maintenance limited to touching up scratches and chips in the painted surface and a light buffing with a plastic scrubbing pad. If you leave your boat in the water, it means that you won’t have to pull it for bottom maintenance as often as you probably have been.

So far, we found no fewer than four paints that held up for three years in our Connecticut tests with no signs of barnacle fouling: Pettit’s ACP 50, U.S. Yacht Ultra CopperKote, Innovative Marine’s Super ShipBottom and Sea Hawk Tropikote. Interlux’s Veridian, a super-slippery (and super-expensive) silicone rubber coating that’s only dealer-applied was the only product to achieve an Excellent Rating for a fourth year of exposure. ACP 50 was the only paint that had been rated Excellent for three years that had been subjected to a fourth year, and its fourth-year performance dropped to Good. We expect others will be added as our on-going tests progress.

The three copper-loaded gelcoats—Epco-Tek 2000, Permashield and CopperPoxy—all proved Very Good after three years, although none of the three were particularly effective against soft growth. Epco-Tek 2000 was the only one of the three that had reached a fourth year of testing, and was Very Good in the fourth year, also.

We’ve learned a good deal from our extended tests, principally that multi-season paints are certainly available. In addition, price and things like copper content and type of paint are no sure guide to effectiveness; water-based paints can compete with more traditional copolymers and modified epoxies; and copper-loaded resin gelcoats offer the possibility of extremely long service lives, together with low levels of water pollution, but at the cost of periodic scrubbing to remove grass and weeds and the necessity of a buffing every year or so to “activate” the surface.

This summer, we’re planning on launching a larger Foulbottom II, which will enable us to test more panels simultaneously. This will eliminate any possible errors due to year-to-year variations in conditions. We’re also going back to re-evaluate some paints we haven’t looked at in several years. We’ll be continuing our warm-water tests in Florida, and hope to implement our Great Lakes testing program.

And we’ll be reporting on the durability of a variety of anchor chain types.


Contacts- American Marine Coatings, 1445 Northlake Way, Seattle, WA 998103; 206/633-3308. Barnacle Ban Corp., 1103 Parkway View Dr., Pittsburgh, PA 15205; 412/429-0673. E Paint Co., 19 Research Rd., E. Falmouth, MA 02536; 508/540-4412. Flexdel Corp., 1969 Rutgers University Blvd., Lakewood, NJ 08701; 732/901-7771. Hi-Tek Chemical Co., 106 Taft Ave., Hempstead, NY 11550; 516/538-0400. Innovative Marine Coatings Inc., 15870 Lake Candlewood, Ft, Myers, FL 33908; 800/466-7144. Interlux Yacht Finishes, 2270 Morris Ave., Union, NJ 07083; 800-INTRLUX. ITW Philadelphia Resins, Box 309, Montgomeryville, PA 18936; 215/855-8450. KL-990, 1999 Elizabeth St., North Brunswick, NJ 08902; 800/746-3995. Nautical Paint Industries, 1999 Elizabeth St., North Brunswick, NJ 08902; 800/432-4333. New England Paint Mfg. Co., 15 Higginson Ave., Central Falls, RI 02863; 401/722-4606. New Nautical Coatings, 2181 34th Way, Largo FL, 33771; 800/528-0997. Petit Paint Co., 36 Pine St., Rockaway, NJ 07866; 973/625-3100. Stargate, 6699 E. Peden Rd., Fort Worth, TX 76179; 817/236-6699. U.S. Paint, 831 South 21st St., St Louis, MO 63103; 314/621-0525. US Yacht, 1999 Elizabeth St., North Brunswick, NJ 08902; 800/566-5668. Woolsey/Z-Spar Marine Paint, 36 Pine St., Rockaway, NJ 07866; 800/221-4466.

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