Barnacles Consume Test Panels at 18 Months

Posted by Darrell Nicholson at 11:16AM - Comments: (8)

The Econea-based Interlux Micron CF, fifth panel from left, shown at 18 months, was one of our cleanest panels just six months earlier.

Our semi-annual inspection of bottom paint panels always yields a few surprises, but during the nearly ten years I’ve been barnacle-counter-in-chief, I haven’t been more surprised than I was last month. The panels we inspected last month were painted and immersed in the summer of 2013. My inspection in January marked the eighteenth months of continuous immersion for approximately 60 paints that were undergoing testing. During a normal year, I would expect roughly 12-15 of those panels to still be fighting barnacles, but that’s not what I found.

Every single panel was toast. The worst panels were unrecognizable, with a thick carpet of barnacles and soft growth covering the painted area (slightly less than one square foot). The best panels had thin coatings of slime, and about 10 percent of the panel was covered in barnacles and other hard growth. (Any hard growth qualifies as a failure in our test.)

Let’s be clear. The conditions of our panel test are far more rigorous than the conditions your own boat will face, for several reasons:

  1. Our panels do not move, making it much easier for barnacles to become established.
  2. We keep our panels in warm, shallow, nutrient-rich Sarasota Bay, Florida. If barnacles were hosting a convention, they’d have it in Sarasota Bay.
  3. Except for a rinse every six months, we don’t clean our panels of slime or soft growth. Hard paints, in particular, can benefit from regular cleaning after the first year. (Start with a soft cloth and progress to a 3M scrub-pad as growth becomes more tenacious. Vigorous scrubbing will scrub away your protection. If you need a scraper, a haulout is long overdue.)

Although our test conditions are admittedly more strenuous than most boats will encounter, the fact remains: paints that during prior tests were barnacle-free at the 18-month interval had conspicuously failed this time around. Why?

Tweaks to the formulas could be a factor. A few of these paints have had their formulas changed slightly—either to meet new environmental restrictions on volatile organic compounds or to compensate for the rising cost of copper—but the majority were the same formulas we have been testing for years.

My guess is that conditions were simply more challenging than ever before, with warmer water temperatures and higher nutrient levels. Although we don’t track temperature, salinity, etc. from year to year, environmental factors have almost certainly played a role in past tests, though not to this degree.

The white, copper-free, Epaint ZO (second from left) was almost spotless at 12 months. (The tester's thumb is used to indicate which panel is being photographed.)

At 18 months the EPaint ZO had succumbed completely to soft and hard growth. The Econea-based paints showed a similar pattern of full protection to no protection at all.

The widespread failure among all paints was the headline event this year, but of almost equal importance were the results of new bottom paints containing Econea. Developed by a division of Janssen Pharmaceuticals, Econea is the latest chemical additive introduced as a substitute to copper biocide, which has come under scrutiny by the state and federal environmental agencies.

Along with a few copper-free single season paints for aluminum hulls, the Econea panels were the worst of the lot. This was not a huge surprise. With rare exception (Epaint in 2009), no copper-free paint has made it past the 18-month mark in our tests. The shocking part was the manner in which they failed—suddenly and completely. The potency of these paints doesn’t fade away; it stops, just like that. The best Econea paints that were still working great at 12 months (some didn't make it that far), were completely carpeted at 18 months. The copper paints by comparison, saw more gradual declines in protection.

What does this mean for sailors? If you are inclined (or forced because of local legislation) to use an Econea-based antifouling paint, you can probably expect 12 months of protection—if you choose the right paint. But when that paint fails, it will likely fail all at once; there will be little, if any lingering protection to get you through the next six months or so, as is often the case with copper paints.

To be fair, I wouldn’t say these results suggest that everyone should steer clear of Econea paints. Copper is clearly a safer bet, but as I pointed out, our panel tests are one bit of information to be used to guide your decision. Reducing the amount of biocide introduced to the ocean is a noble cause, and for a sailor who repaints every year after winter haulout, 12 months protection is just fine. And it could also be that an Econea-based paint will provide longer protection in your home waters, which are almost surely less fertile for barnacles. A more accurate assessment can only come through some real-world testing on actual boats in various regions.

The makers of Econea paints insist that they have seen very impressive results in the field, and the fact that more brands of Econea-based paints continue to appear on the market suggests that they do work better than our tests indicate. However, until we start applying these paints some of our test boat hulls (we will be doing this in the spring), and putting them to real world trials, we’ll not be able to verify these claims. So far, we are unimpressed.

If you have been using an Econea-based paint, I’d be very interested in hearing your experience. Please comment below or write to me at

To find out which paints—copper and non-copper— fared best in our most recent antifouling tests, check out the April issue of Practical Sailor, which will be available online March 15. Or if you are buying right now, our recent results from March of 2014, which analyzes the best bottom paints by region, will serve as an excellent guide.

Comments (8)

Similar to Cartagena,we have found in CA, in the 6 years we have been south of Mexico, that only copper based paints last over a year, and even the best Pettit Trinidad SR, has to have an occasional barnacle scraped off, usually near the waterline, or somewhere there is a scratch on the paint, but we are getting 4 years between haulouts and repaints. There is a carpet like mat in some estuaries that grows fast, but fortunately comes off easily. Prop is a mess after 3 months.

Posted by: William N | March 10, 2015 4:33 PM    Report this comment

No copper, no stopper.

Solomons, MD

Posted by: Glenwood C | March 4, 2015 11:20 AM    Report this comment

With the cost of bottom paint going higher and higher what does PS think of alternating the paint coat formulas within the same manufacturer family. For example (while using PS 2014 recommendations) first coat with Copper Shield 45 Hard and second coat with Copper Pro SCX 67 Hard. In this example it would save $120 and I'm wondering if it would make a "significant" difference?

Posted by: MIKE H | February 28, 2015 12:41 PM    Report this comment

We strongly support your caveat that results will differ in various locales. In our experience the speed at which bottoms foul is dramatically different from place to place. In Cartagena, Colombia, to cite the most extreme example we've seen, there's no way any paint (not even those with tin) lasts more than a month without getting barnacles. And the idea of not using a scraper in that environment is laughable.

We scrape our bottom every month or so after the first six months, no matter where we are. Three coats of bottom paint last us about 3 years with that regimen.

Posted by: Robert O | February 26, 2015 12:16 PM    Report this comment

Have you done any work on Econea-based paints in freshwater?

Posted by: Lewis S | February 25, 2015 3:20 PM    Report this comment

Have you done any work on Econea-based paints in freshwater?

Posted by: Lewis S | February 25, 2015 3:19 PM    Report this comment

Hi Doug,
The April issue will feature the complete ratings for these paints and all of the others we tested, offering rating based on relative performance, a best of the worst, so to speak. The March 2014 issue is still an excellent guide if you need that information right away, since the only real change in the lineup are the new Econea paints. If you are looking for an Econea paint, then check the October 2014 issue, which has the 12-month rating, when these paints were on the last few months of life.

Posted by: DARRELL N | February 25, 2015 12:48 PM    Report this comment

I am wondering if you would be so kind as to identify ALL of the strips in these pictures? We can see differences even though you call them all 'failed', so I would like to know which are which.
And, I was wondering if any of these have used the CopperCoat product?
If not, why not?
Thank you,
Doug Sabbag

Posted by: DougSabbag | February 25, 2015 12:00 PM    Report this comment

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