Features March 2008 Issue

Bottom Paint Test: Practical Sailor Takes a Close Look at The Long-Term Performance of Two Dozen Antifouling Paints.

Long-term tests on hard and soft bottom paints in both Florida and Connecticut look at antifouling performance six months after application and 18 months after application.

Bottom Paint Test
In December, testers pulled our bottom paint test panels in Connecticut and Florida. Notice the hard growth on the non-painted portions of the panels that border each painted section of these Connecticut panels.

Results from years of Practical Sailor bottom paint testing prove that nearly all existing antifouling paints provide exceptional protection against hard growth. The devil is in the detail of how well they protect against the speed-robbing buildup of soft marine organisms. Manufacturers attempt to provide protection from hard and soft growth, while balancing environmental impact issues, increasing regulatory concerns, and rising prices for raw materials. To top it off, boaters demand easier application, brighter colors, and less toxic paints. All of these needs and wants have resulted in a plethora of paints hitting the marketplace.

At PS, we try to sort through this maze of antifouling choices and provide our readers with enough useful information to make the proper paint selection for their particular circumstance. When makers offer everything from hard racing paints to super-soft ablatives, bright colors, brilliant whites, eco-friendly paints, and water-based products with prices ranging from $70 a gallon to a staggering $250 a gallon, even an experienced hand needs some help. Our job is to help you find the right paint for your boat at the right price.

On this go-round of our biannual bottom paint review, we’ll present the first results from our most recently painted panels (June 2007), an 18-month update of our June 2006 panels, and the results of the head-to-head tests on our test boats.

The Value Guide tables are divided into hard paints and ablative/copolymer categories. Hard paints tend to have a smooth, hard finish with reduced water drag and the ability to stand up to hand scrubbing without shedding paint material into the water. For racers and trailer-sailers, a hard paint is a good choice. But as a boat is repainted year after year, a hard paint can build up layers on the hull. After several years, that buildup will need to be stripped and fresh coats applied. This extra work of stripping paint should be considered when pricing a hard paint for your boat.

Ablative paints prevent marine growth by slowly sloughing off material over time. These paints can vary in hardness from super soft to harder copolymers. Your boatyard bill will likely be somewhat lower with this type of paint, so long as your boat moves enough to shed the majority of the paint. Usually all it takes to clean an ablative-painted boat bottom is a quick pressure wash.

Not all ablatives are soft. In fact, some are quite hard and can even be burnished. One example is Pettit’s Vivid, which the company describes as a hard ablative good for racing boats and trailer-sailers.

How We Tested

Our modus operandus remains the same as it has been for the last several years of our bottom paint reviews. Maintaining consistent procedures and protocols keeps everything fair and evenhanded. This is how we prepare and paint the panels we set out during the summer each year. Testers start with brand-new polyester/fiberglass panels. They get washed with a de-waxing solvent to remove any wax or mold-release agent, then they get sanded lightly with fine-grit sandpaper to take the sheen off the glass. Finally, each sheet is handwashed with solvent to wipe the surface clean of any leftover fiberglass dust.

Panels are then taped into 10 sections. Each paint sample is bordered by an unpainted area. Panels are hung in the water to simulate the paint near the waterline on the side of a boat hull.

Testers follow the manufacturer’s instructions for the number of coats and method of application. Individual panels are identified by a code drilled into the panel. This identification system can be read no matter how much marine growth might obstruct the unpainted portions of the panels. When testers pull the panels, they rate the paints with no reference to the name or manufacturer.

All paints are tested in two geographical locations: a saltwater canal in the Florida Keys (Tavernier, Fla.) and along a boatyard dock in Long Island Sound (Groton, Conn.). At any given time, we have two sets of panels at each location. For this report, all the panels were pulled in December 2007. Before assigning ratings, testers sluiced the panels with buckets of seawater. An Excellent rating is given to paints that show virtually no growth. This is an absolute rating and does not vary from test to test. Good and Fair ratings are relative to the field and can vary from rating session to rating session, based on the overall condition of the paints on a particular panel set. Good ratings go to those paints with a minimum of soft growth while coatings with Fair ratings have clearly allowed more soft growth to occur. Poor ratings are given to panels with hard growth. Again, the Poor rating is an absolute and does not change from test to test.

We would like to emphasize that the difference between a Good and a Fair rating is relative and can change from one rating period or panel set to another. This means an individual paint could improve, for example, from Fair to Good depending on the overall condition of the group being rated. Over the years, most paints have received many ratings. Ratings do vary to some extent when reviewed over the long term based on a number of factors, including water temperatures, current flow, tide height, and the number and variety of marine organisms present in an area.

Once ratings are recorded, editors identify overall winners and the top paints in the various categories—ablative, hard, eco-friendly, and water-based paints. Most of the Recommended paints scored Good or better in both locations or a combination of Excellent and Fair. In our opinion, any paint consistently rating Fair or better is worth using on your boat. If some similar paints scored equally in both locales, we gave the nod to the lower-priced product.

Some paint manufacturers have pointed out that our testing does not involve moving panels, which puts some paints, the ablative ones in particular, at a disadvantage. We do follow up our panel testing with real-world testing on various boats. Generally, these real-world tests support the conclusions of the panel tests, leading us to believe that the biannual sluicing of the panels simulates the effects of boat moving through the water. Nevertheless, the variables in seasons and locations are so great that we advise readers to supplement this report with previous Practical Sailor tests, and other available information from users in your specific area.

For pricing, we scour the web to find the lowest price for each paint, but prices can change, so shop before you buy. This year, we saw only a limited number of prices increase and one price even decrease.

Narrowing the Field

The test panels that were painted and submerged in summer 2007 had fewer paints than in previous years. Even with the handful of new paint additions, testers trimmed the total number down to 58 from a high of 66 in 2006. We decided not to apply any rebranded duplicates this past year and will follow this protocol when we paint our 2008 panels this summer. Below is a short list of the products still being tested and their rebranded counterparts that were cut: Pettit Unepoxy Standard is West Marine Bottomshield; Pettit Trinidad SR is West Marine BottomPro Gold; Pettit Premium is West Marine CPP; Pettit Ultima SR is West Marine PCA Gold; Pettit SR-21 is West Marine FW-21; Blue Water Coppershield 45 Hard is MarPro Superkote Hard; Copper Pro SCX 67 is SeaBowld Ablative 67 Pro.

Rookies and Retreads

We applied a handful of new paints to our June 2007 test panels and reintroduced one paint that had been absent from our testing for the last several years. The December panel pull was our first look at these panels.

The majority of the first-year paints tested did not stand out in our six-month review. The two best were Aquagard Alumi-Koat, and the returning Super Ship Bottom from Innovative. These two each managed to get one Fair and one Good rating.

Two other newbies managed only to get Fair in both locales. They included Epaint ZO HP, a very expensive ($249) hard paint, and Sea Hawk’s AF33.

The worst performing rookie was PhaseCoat UFR from Microphase. It was rated Poor in Florida and Fair in Connecticut. Microphase recently pulled the paint from the market; read more about it in "We Want it All and We Want it Now," on page 30.


We singled out Interlux Micron 66 as our Top Choice. This $210 a gallon ablative/copolymer garnered across-the-board Good ratings in both locales for the last 18 months as well as earning an Excellent in Florida and Good in Connecticut on our newest test panels. According to Jim Seidel, Interlux assistant marketing manger, Interlux has removed the professional application line from the label of Micron 66 and will be stocking it on the shelves of marine shops, stores, and chandleries around the country, making it available for the DIY-er.

Our Budget Buy paint and one of the top three in Connecticut was Blue Water Copper Shield 45 Hard. This $80-a-gallon paint narrowly missed an Excellent rating in Connecticut due to a small amount of soft growth. It earned Fair and Good ratings long term and at six months. Our second Budget Buy is the Pettit Unepoxy Standard, currently priced at $80 a gallon. This was one of the top Florida paints with Good ratings at six months and mostly Fair with some Good ratings over the long haul.

Our top picks for water-based paints go to Interlux Fiberglass Bottomkote Aqua and Pettit Hydrocoat. Both earned Good ratings in Connecticut and Florida at six months. Fiberglass Bottomkote Aqua was one of three top paints in Connecticut and costs $112 per gallon. Despite its single-season rating, it managed to maintain at least Fair ratings through 18 months. At $105 per gallon, the Hydrocoat gets the Budget Buy rating for ablatives. It managed half-Good and half-Fair ratings over 18 months.

If you need a bright-colored or white bottom paint, our top choices remain Pettit Vivid and Blue Water Kolor. For an aluminum hull, we’d give Flexdel Aquagard Alumi-Koat a try. It earned a Good in Florida and a Fair in Connecticut at six months. At $149 per gallon, it is the least expensive aluminum-compatible paint in our test that earned a Good.

At six months, other recommended hard paints are Interlux Ultra-Kote and VC Offshore, and Sea Hawk Tropikote. Other recommended ablatives are Pettit Horizons, Copper Shield SCX 45, and Blue Water Copper Shield 45, which was one of the top performers in Connecticut.

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