Jun 13, 2011, 6:38 AM
Post #2 of 2
From Roger Marshall:
Re: [ms] Copper Antifouling Paint - California Senate Bill 623
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Having checked into bottom paints and seen the results over many years, I'll add my two cents worth. Different boats need different paints. Racing sailboats that move at higher speeds need a harder bottom paint which usually has less copper. Conventional slow speed boats can use a rosin based paint. Most boats use an ablative paint.
Ablative paints wear away as the boat moves and the new surface exposes more copper. However, slime build up can cut down on any paint's effectiveness, so most manufacturers use Irgarol or Biolux to prevent slime build up.
The California problem according to people (paint manufacturers) who have looked at the problem carefully, occurs mostly in San Diego harbor where boats are cleaned by divers. Each time a boat is cleaned a cloud of copper residue sinks to the bottom. In San Diego the tides don't scour the ocean bed like they do in say, Narragansett Bay, and the residues build up in the bottom sediment.
Copper occurs naturally in seawater - in fact, I once saw an estimate that said, all boats add less than 1% copper to the amount already in the ocean. It is used for water pipes in most homes. In fact, I remember Steve Schultz, former president of Interlux and now with Boero, telling me that the company used scrap water pipes to make the copper compound in their paints until China started buying most of the US scrap metals. Copper bottom paint is only toxic in high concentrations and that occurs within a few millimeters of the hull paint.
Where copper is banned, manufacturers will use other less effective (and possibly more hazardous), chemicals. I'd say beware of what you legislate away.
Here is an article published by IBI Magazine from November 17, 2006 titled ‘Copper is low-risk to marine life, new antifouling study reveals’ that disputes the copper threat: http://www.ibinews.com/ibinews/newsdesk/20061017110702ibinews.html