Antifouling Revisited

29 Jan
 Anti-fouling paint chips on the ground in a tidal area on the French river Auray 

As I mentioned in my last post the environmental effects of copper-based antifouling paints are still a contentious issue. Some maintain that all this copper poses a grave threat to the environment while others brush it off as a drop in the bucket. I found convincing arguments across the board- that copper leached by boats is a naturally occurring heavy substance which quickly drops out of sight (US Naval Study), that copper is doing damage to our waters but bottom paint is not always an issue or is eclipsed by industrial pollution (UK Conservation Group and An Organic Chemistry Paper), and that bottom paint is the major contributor to toxic levels of copper which make their way up the food chain (Oops, I can’t find the link I was thinking of but this study makes much the same point).

It is difficult to sift through all this conflicting information, particularly when considering that much of it is produced by those with vested interests. To my amateur’s eye which doesn’t feel like reading the full 300 pages of scientific jargon all of these positions have their merits and they might not be as incompatible as they first appear. The ocean is vast and unlike the highly toxic chem-lab-produced TBT it is replacing the copper used in antifoulings is no different from the common element and is essential to organic life (in small concentrations). In areas with decent tidal flow a coat of antifouling on the bottom of a sailboat is a small issue, especially in the scale of industrial copper pollution. However, put hundreds of boats in a cozy bay and give half of them seasonal ablative paints designed to rapidly slough off and you soon have thousands of pounds of potentially toxic heavy metal falling over quite a small area. Thus it is no great surprise that with the relatively enclosed Baltic Sea and vast numbers of boats in inland waterways environmentally conscious Sweden and the Netherlands are on the forefront of antifouling regulation.

The problem is that as far as I know there isn’t much of an alternative, other than elbow grease. On fast-moving vessels fouling will slide off of some ultra smooth paints or it can be cleaned off with a scrubber and a reservoir of patience relative to the size of your boat (I found one study which determined if you clean your non-toxic bottom paint with a power tool every 15 days it will stay pretty clean! [NOAA]). Of course on boats which sit year-round in cold and/or filthy waters diving in to scrub the hull every two weeks is not a pleasing prospect.

Active substances in Swedish antifouling products, 2008

Even in Sweden where it is heavily regulated Copper
is the most common antifouling strategy. (Source: Kemi)

Meanwhile, all sorts of new technologies are being experimented with and some ultra-high-tech ideas show promise. One is ePaint, an antifouling uses a sun-powered chemical reaction to produce a thin layer of hydrogen peroxide(H2O2) on the boat’s hull. This acts as a biocide before dissipating into the surrounding water. A pretty impressive resume for a layer of paint! Unfortunately what I could find on this new product indicates it may work well but needs frequent reapplication and is pricey. If, like the Coast Guard who have been experimenting with it on some vessels, you can afford to regularly repaint your hull this could work well.

For the rest of us the ease and effectiveness of copper paints still proves elusive, especially for plodding boats which are painted as infrequently as possible (in other words, cruisers!). But the search goes on and it is likely to accelerate rapidly as the EU begins to more heavily regulate the use of copper antifouling.

This article was syndicated from Safe At Harbour But Meant For The Sea: DIY Sailing with Paul Calder

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