Features March 2009 Issue

Bottom Paint Tests 2009 Spring Update

Practical Sailor takes a look at boat antifouling paint performance after 6 months and 18 months in the water.

Over the years, Practical Sailor has tracked the evolution in marine antifouling paints. Shaped by government regulations, environmental concerns, and industry innovations, the shift started with tin-based paints in the 1980s. After tin-based paints came under fire for the harm they cause marine life, copper-based paints grew in popularity. Now, concerns about the impact of copper on the environment have led to the development of copper-alternative paints, such as zinc-biocide and water-based antifoulings. We continue to sort through the data to help you find the best bottom paint for your boat. This report offers an update to our panel tests after six months and 18 months in the water as well as the head-to-head tests under way on our test boat fleet. Some of the best performers (out of 72 paints tested) at six months were hard paints and specialty antifoulings such as Copper Shield 45 Hard made by Blue Water, VC Offshore by Interlux, Copper Guard by Pettit, and Sharkskin by Sea Hawk. The best ablative paints at six months included Copper Shield SCX 45 by Blue Water, EP-21 by Epaint, and Hydrocoat and Vivid Free by Pettit. The top long-term bottom paints—those appropriate for multi-season antifouling protection—included Interlux Micron 66, Pettit Trinidad SR, and Interlux Epoxycop. These extensive tests also included marine bottom paints from Awlgrip, Flexdel, and Microphase Coatings. The lineup also covered re-branded products from West Marine.

Bottom Paint Tests
Testers recently pulled the four sets of bottom paint test panels in Connecticut and Florida for inspection. Two sets (one in each locale) had been in the drink for six months, while the others had seen 18 months of sea time.

 

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Over the years—through panel tests and field trials on our own boats—we’ve witnessed an evolution in marine antifoulants. Shaped by government regulations, environmental concerns, and industry innovations, this shift started with tin-based bottom paints in the 1980s. Once hailed as the most effective marine antifoulant, tin-based biocides came under fire for the harm they caused to marine life, and they eventually gave way to copper-based paints, which at the time of their development were touted as the environmentally friendly antifoulant.

Now, we are seeing a sort of eco-dé ja vú, and concerns are being raised about the environmental impact of copper, especially in high-traffic, low-flow areas (like San Diego Bay; see page 38) where metals accumulating in the waters have raised copper counts to dangerous levels.

At the same time, newer and less harmful zinc-biocide and water-based antifoulings continue to hit the market. However, in our tests, most copper-alternative paints have not matched the protection level and duration of copper paints.

According to one industry representative, Blue Water’s Don Schnurr, the latest wave of biocides are organic and rapidly break down into other compounds without posing the accumulation problems of heavy metals.

As we watch these market shifts—from tin-based to copper and zinc paints to who knows what—Practical Sailor continues to try to sort the best from the rest through our static paint panel tests, our field reports, and our semi-annual bottom paint review.

In this report, you will find the first results from our most recently painted group of panels (sunk in summer 2008). Related stories cover the 18-month update on our other panels (pages 36-37) and a number of head-to-head boat test results (page 39). Bear in mind that these tests are subject to uncontrolled variables and that location and other factors can affect antifouling performance. We encourage readers to supplement this data with information from local boatyards or other boatowners in your area.

Deciphering the Data

Our six-month test paints—which total 72—represent a good cross-section of what’s being used in boatyards and sold in stores. The Value Guides on the following pages are divided by paint type: hard paints and copolymer/ablatives. The choice between a hard or ablative paint has less to do with effectiveness than with how the boat is used and maintained.

As the "hard paint" name implies, these tend to have a moderately smooth, hard finish that provides for reduced water drag and can stand up to hand scrubbing.

After several years of repainting with a hard coating, expect a cake-layer build-up on your hull. This eventually will have to be stripped off, and the coating started anew. This extra work of stripping every few years should be considered when you’re evaluating the costs of one paint versus another.

Ablative paints vary significantly in hardness and in the way they work, but they all slough off material over time to prevent marine growth.

If your boat moves enough to shed the majority of the bottom paint between haulouts, an ablative paint can be less costly (in money and time) to maintain than a hard paint. Usually, all it takes is a quick pressure wash before repainting.

Within these two larger paint categories are specialty paints, which include those marketed and recommended for racing or freshwater use and those that are water-based, eco-friendly, or suitable for use on aluminum hulls. We’ve included a designated column in the Value Guides that lists which, if any, specialty the paints are marketed for.

For long-distance cruising and racing where speed through the water really counts, choose one of several racing paints listed. Hard racing paints can be sanded and burnished to a very smooth finish.

Water-based paints are easy to apply and clean up and are less harsh on the environment than solvent-based paints. Eco-friendly paints have low or no metal-based biocides and low volatile organic compounds (VOCs), which are gases emitted from certain solids or liquids that can cause adverse health and environmental effects. (Eco paints are usually compatible with metal hulls as well.) Among the six-month test paints, editors tried to flag at least one Recommended paint for each specialty.

Keep in mind that the highest-rated paint might not be the best for your situation. If you are looking for long-term protection, refer to the "18-month Report" above. If you plan to haul out and repaint every year, an expensive multi-season paint will be a waste of money. Instead, check out the budget priced paints in the six-month checkup and the Value Guides on pages 34-35. Past tests have shown that Fair paints at six months often improve with age, comparatively. If you want the absolute cleanest bottom for six months, and don’t mind paying for it, then the top-rated six-month paints come into the picture.

Another key step in choosing a paint is to be sure it is compatible with the paint last applied. If you plan to haul and relaunch, be sure the paint will not lose its punch during storage.

How We Tested

Once a year, Practical Sailor testers apply paint samples to stationary panels that remain submerged in salt water year-round. This is similar to the method some paint manufacturers use for testing. We supplement our test panel results with head-to-head comparisons done on a variety of boats.

To maintain consistent results, we use a standard set of procedures and protocols each year. Testers start with brand-new polyester/fiberglass panels that are de-waxed and prepped, then taped into sections, and paint samples are applied. Panels are hung to remain completely submerged at all tide levels.

Testers follow manufacturers’ instructions for application and number of coats. Individual panels are identified by a binary code drilled into the panel. Paint performance is rated (with no reference to the name or maker) every six months.

Paints are tested in two locations: a saltwater canal in the Florida Keys (Tavernier, Fla.) and along a boatyard dock in eastern Long Island Sound (Groton, Conn.). At any given time, there are two sets of panels at each location. (Currently being tested are an older set submerged in June 2007 and a newer set submerged in June 2008.) After two years in the water, a panel set is retired.

Before we review and rate the paints, testers sluice each panel with a bucket of seawater. To get an Excellent rating, a paint must have virtually no growth. This is an absolute rating and does not vary from test to test or panel set to panel set. Good and Fair ratings are relative within each panel set. Good ratings go to those paints with a minimum of soft growth, little to no paint discoloration, and low adhesion of any soft growth. Fair ratings are assigned to paints that clearly allowed more soft growth to occur, show some discoloration, or the growth that is present is adhering solidly to the paint sample. Poor ratings, which are absolute like the Excellent ratings, are given to paint samples with hard growth.

Because Good and Fair ratings are relative, an individual paint can improve from Fair up to Good in successive ratings, depending on the overall condition of the other paints being rated. Any bottom paint that consistently gets Fair or better ratings is a viable option.

Once ratings are put on paper, editors identify overall winners, as well as the top paints in the various categories. If some similar paints scored equally in both locales, we gave the nod to the lower-priced product. Finalists at the 18-month mark also earned our recommendation at six months, unless the formulas had changed or they scored poorly at six months.

A note about prices: Editors scour the Web to find the lowest prices for the paints. (Shipping costs are not included). Prices vary without notice, so check before you buy. This year, we saw price increases for most of the test paints.

2008 Freshmen

In June 2008, we applied more than a dozen new paints and reintroduced some boatyard paints absent from recent tests. This review is our first look at those paints. The panels were pulled and rated in December 2008, after six months in the water.

The vast majority of the reintroduced products were Blue Water’s MarPro paints, which are private labeled for Donovan Marine, a wholesaler that supplies independent dealers and boatyards. Their formulas are similar, but not identical, to their sister paints, Blue Water’s consumer line, and the SeaBowld paints, made by Blue Water and retailed by Boater’s World. (We did not test the SeaBowld paints this go-around but would expect them to perform similarly to the Blue Water line.)

Some new introductions were market-targeted paints like Epaint’s copper-free Ecominder; Interlux’s California Bottomkote for California boatyards and Pacifica for the West Coast market; Caribbean-marketed paints included Pettit’s Vivid Caribe and Sea Hawk’s Islands 77. These paints earned mostly Fair ratings. Two paints, Interlux VC 17m and Trilux II, are available only in Canada.

MicroPhase Coatings’ PhaseCoat Bare Bottom had a good showing with two Good ratings. However, according to MicroPhase’s Brad Lienhart, the paint’s success in static panel tests was not duplicated in real-world use, so the company no longer markets it to boaters.

One paint, Pettit Unepoxy, surprised us by earning Poor ratings in both Florida and Connecticut. This inexpensive paint had performed well in previous tests. Pettit said that the newer formula had slightly less copper but that its tests showed no drop in performance.

A few Pettit paints included in this round of testing aren’t due to hit stores for several more months. In its effort to minimize the use of copper while still maintaining acceptable performance, Pettit’s new paints utilize the latest coatings technologies and biocides.

Its Hydrocoat ECO, which earned Good and Fair ratings at six months, is set for launch in spring 2010. It is a water-based paint that uses Econea as a biocide. Econea, a newly approved metal-free antifouling made by Janssen PMP (part of the Johnson & Johnson family), targets hard growth and does not accumulate in the marine environment as copper and other metal-based biocides do. It’s also safe for use on aluminum hulls, and makers claim it offers weight savings.

Another Econea-based Pettit paint, the copper-free Vivid ECO, is due out later this year, as is Interlux’s copper-free Econea offering, Pacifica Plus with Biolux for slime control. We plan to include both in our next round of panel testing.

Pettit’s Ultima SSA CCT, which will be rebranded and sold as West Marine CPP CCT, is set for release later this year while the West Marine product will be launched in 2010. These paints utilize Copper Composite Technology (CCT). According to Pettit, instead of using a solid copper flake, CCT is a silica crystal coated with copper. This reduces the weight of copper by 25 percent in the paint while offering the same level of protection. The single-season Ultima SSA CCT earned Fair ratings at six months. Pettit also plans to replace Unepoxy with a new CTT paint (Unepoxy CCT), later this year. Look for it in a future test lineup.

6-Month Conclusions

While the MarPro paints dominated in the ratings—each one earning at least one Excellent—we rated them as Recommended paints rather than Best Choice because of their limited availability.

Taking the top spots after six months are Blue Water’s Copper Shield 45 Hard and Copper Shield 45 Ablative, both Excellent performers and available online. Recommended hard paints include Blue Water Copper Pro SCX 67 and Sea Hawk’s Sharkskin, which both earned Good ratings. Our ablative recommended paints are Blue Water Copper Shield SCX 45 and Pettit’s Ultima Pro. Budget Buy honors go to Pettit’s Copper Guard, which sells for $85 per gallon.

In the specialty categories, the top picks for a water-based paint were two moderately priced products: Flexdel Aquagard Bottom Paint and Pettit Hydrocoat. Aquagard is rated for a single season, and we’d stick to that recommendation.

Topping the paints marketed for racing are Interlux’s multi-season Regatta Baltoplate Racing and single-season VC Offshore.

Paints designed for aluminum hulls and Recommended after six months include Pettit Vivid Free, a copper-free paint that uses zinc omadine as a biocide, and Epaint’s EP-21, which also gets our recommendation for a freshwater paint.

Boatowners looking to have a "green" bottom would do well choosing from the top copper-free (aluminum safe) or water-based paints or others with low VOCs.

Comments (1)

Are there any copper free bottom paints that can be mixed or tinted to a color approximating the "copper bottom" color that is essential for authentic restoration of classic wooden runabouts?
Gene Porter
Chair, ACBS Govt Affair Cte
gporter77@gmail.com

Posted by: Gene P | September 27, 2011 11:15 AM    Report this comment

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