Features March 2006 Issue

The Bottom Paint Report

Seahawk Monterey, Interlux Micron Optima score highest in our test.

Testers inspect the painted panels after roughly six months in the water in Florida (above) and Connecticut. At this point, the paints are anonymous. Later, a code of drilled holes is used to indentify the paints.

Indicative of the tangled web sailors enter when trying to select an anti-fouling paint, this year’s Practical Sailor anti-fouling paint test featured a huge field of 53 different paints. Aside from allowing us to nail down what we believe are the best paints on the market today, the test gave us the opportunity to home in on a trend that is gaining traction: paints with anti-slime additives. Twenty-four of the paints we tested for this year’s test include some kind of slime fighter. These paints cost slightly more than similar paints that lack these additives, and so far, our tests indicate that having an anti-slime agent in your bottom paint is no guarantee of better anti-fouling protection. However, we have put all of our test panels back into the water to see if these paints perform better over the long haul, as their manufacturers claim.

Another trend we’re watching is the introduction of lines of paint that tout a broader selection of colors, including white. The latest entry into this group is Blue Water Paints, which has come out with a line of colorful paints, called “Kolor,” that includes green, red, yellow, white, black, and two types of blue — royal and bright. This follows in the wake of last year’s launch of Pettit’s Vivid line, which includes a bright white paint and several bright colors. Like Pettit, Blue Water claims to have the whitest whites, the blackest blacks, the reddest reds, and so on. Interlux has long offered a wide range of colors in its Trilux line. Pettit’s Vivid came out on top in this group, but none of these paints produced particularly stellar results.

While color is certainly a consideration for a bottom paint, what matters most is how well it works. One key decision when choosing an anti-fouling paint is knowing whether you want a “hard” or a “soft” paint. The difference between the two is fundamental, so the tables (see sidebars), which show the results of our test, are divided into these two groups. On the facing page, you’ll also find a list of our top picks in each of these two groups, as well as our recommended paints in three other sub-groups: water-based paints (which make for easier cleanup), white paints (examples of paints with broader palette choices), and less toxic eco-paints.

Bottom Paint Basics
A “traditional” bottom paint consists of either metallic copper powder or copper oxide biocide mixed into a film-forming coating that also includes binding agents and pigmented solids. In a hard paint, this coating is not water soluble; the formulation allows the biocide to leach out at a fairly consistent rate. A soft paint is somewhat soluble in water, with its outer layer washing off in time to expose fresh paint. Also called ablative or self-polishing paints, soft paints typically fall into two sub-categories, less expensive sloughing ablatives that simply wear away to expose fresh paint, and the more expensive co-polymer ablatives, which are formulated to better control the rate at which the biocide is released. As our tests show, hard and soft paints can be equally effective in combating marine growth, so the choice between the two comes down to certain personal preferences and how your boat is used (see “Choosing antifouling” sidebar).

A bottom paint typically contains between 45 percent and 77 percent copper, and some manufacturers make a big deal about how much copper their products contain. Copper is a powerful biocide (though not as effective as the now-banned tributyltin), but the days that you could just grab the paint with highest copper content and be done are over. This year’s test, like those of recent years, shows no clear link between copper content and effectiveness. The paint with the highest copper content in our test, SeaHawk Tropikote (76 percent copper), finished near the bottom, while Interlux Optima (28 percent copper) was one of our top picks.

Three tested paints don’t use any copper; all are from E-Paint. Along with Kolor from Blue Water, newcomers include Interlux’s Super Ablative with Slime Fighter, Super KL with Slime Fighter, Fiberglass Bottomkote with Irgarol, and Fiberglass Bottomkote ACT with Irgarol. Pettit has one new paint in this test, SR-21, a paint for fresh- and low-salt water. We also tested for the first time Sea Hawk’s Tropikote Biocide Plus and Cukote Biocide Plus.

The Test
The testing method hasn’t changed in recent years. It’s simple and, we feel, realistic. We start with brand new polyester/fiberglass panels, wash them with a de-waxing solvent, sand them lightly with fine-grit sandpaper, and wash them again with solvent to remove any traces of wax or mold-release agent. We then apply the bottom paint, following the instructions supplied with each paint. Label instructions for drying time and number of coats required are followed. A pattern of holes drilled in the panel sections identifies each paint. The identification system keeps us impartial, because we don’t refer to the codes until after we’ve evaluated the panels.

One set of panels was suspended in a saltwater canal in the Florida Keys, the other tied to the docks at a boatyard in eastern Long Island Sound in Connecticut. The panels took the plunge in July and were retrieved and rated in early January. Before rating the paints, we look at the growth both before and after sluicing them with a bucket of water.

Ratings and Results
Today’s bottom paints are so effective at keeping growth at bay over a five-month period that it’s becoming much more difficult to pick out winners and losers. Said one of our staffers who inspected the Connecticut panels: “I wouldn’t hesitate to put any of these paints on my boat.”

We’ll see if this report is just as glowing later this year when we retrieve the same panels in the fall after a total of 10 months immersion.

Only three paints allowed hard growth — and that growth was sparse, just some specks. There were no full-grown barnacles. So the final score usually came down to an evaluation of the amount of slime on each panel section. The paints that were absolutely clean — they looked like they had just been painted — were given Excellent ratings. Those with any hard growth were given a Poor rating. We weeded out the Fair and Good paints by comparing the amount of slime on the panels.

For the second straight year, the Connecticut panels had more growth than the Florida panels. In fact, none of the paints could muster an Excellent in Long Island Sound. In the Keys, six paints earned scores of Excellent. Top honors went to the two paints that earned Excellent ratings in Florida and Good minuses in Connecticut: Micron Optima and Sea Hawk Monterey, both of which have done well in previous tests. Micron Optima is a two-part paint with a copper content of 28 percent. It uses Zinc Pyrithione to prevent slime. Sea Hawk calls its Monterey a “semi-hard ablative,” and it has a 55 percent copper content and no anti-slime additive. Both Micron Optima and Monterey are water-based paints rated as multi-year, meaning they are meant to be used for more than one season.

Interlux Fiberglass Bottomkote Aqua, West Marine PCA, which is made by Pettit, and Interlux Regatta Baltoplate Racing also rated high overall. The Baltoplate was one of only five paints that fared better in Connecticut than in Florida.

Blue Water Paints had a strong showing for the second year in a row. Its Copper Pro 67 and Sea Bowld Ablative 67 Pro (available through Boater’s World) looked very clean to our testers in both locales. So did Interlux Micron 66 (a previous overall winner), Micron Extra and West Marine’s CPP. In the category of water-based paints, Flexdel Aquagard and Pettit. Hydrocoat stood out in Florida.

Only three paints scored Poor, all in Florida water: Interlux VC 17m and VC 17m Extra, and Pettit SR-21. The latter is a fresh and low-salt paint, so the result was tenable.

The effectiveness of white paints was spotty. In Florida, the Vivid earned a Good+, and Trilux II was awarded a Good. EP 2000 scored a Good in Connecticut. But no white paint did well both places.

Did copper content make a difference this year? No. Only one paint with a copper content higher than median 42 percent received an Excellent rating in Florida; four with less copper earned Excellents. And in Connecticut, the paints with lower copper content scored more Good ratings (seven) than those with higher copper (four).

The vast majority of these paints performed very well. The ratings are based on the amount of soft growth. In most cases, a sponge or soft brush can be used to wipe the slime away (although scrubbing soft paints is banned in some waters), and if we’d taken the panels for a short cruise, that alone might have wiped them clean.

Overall, the Sea Hawk Monterey deserved top honors because it performed as well as the Interlux Micron Optima, and costs less. In addition, Micron Optima is an anti-fouling that requires mixing two parts, so application is a bit more involved than with the Sea Hawk.

Budget Buy rankings go to the Pettit’s $80-per-gallon West Marine PCA and Interlux Bottomkote Aqua ($70). The "Value Guide" tables also indicates our Recommended paints, those that were among the top performing hard paints, white paints, and ecofriendly paints in both Connecticut and Florida.


Also With This Article
"Choosing Antifouling"
"Value Guide: Hard Bottom Paints"
"Value Guide: Ablative/Copolymer Bottom Paints"
"Anti-slime Bandwagon Bursting at the Seams"
"Pettit Scores High On Test Boat"

• Blue Water Marine Paint, 800/628-8422, www.bluewatermarinepaint.com
• E-Paint Co., 800/258-5998, www.epaint.net
• Flexdel Corp., 888/353-9335, www.aquagard-boatpaint.com
• Interlux Yacht Finishes, 800/468-7589, www.yachtpaint.com
• Kop-Coat (Pettit), 800/221-4466, www.pettitpaint.com
• New Nautical Coatings, 800/528-0997, www.seahawkpaints.com
• SeaLife Corp., 310/338-9757, www.sealife1000.com
• West Marine, 800/BOATING, www.westmarine.com
• Boater’s World, 800/826-BOAT, www.boatersworld.com

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