GOVERNMENT AFFAIRS BoatU.S. SPECIAL REPORT BY RYCK LYDECKER
IS COPPER BOTTOM PAINT SINKING?
Last year, Washington became the first state to ban copper bottom paint.
Now the California legislature is taking up similar restrictions
WHEN IT COMES TO PAINTING the bot- tom of a recreational vessel’s hull to discourage marine growth, boat- ers currently have a wide array of products from which to choose. And
while the choices can be a bit bewildering, beginning
January 1, 2020, boaters in the state of Washington can
scratch off their lists any paints that contain more than
0.5-percent copper. That’s because last year, in response
to concerns about contamination in Washington waters,
the state legislature outlawed copper-based antifouling paints. (Paints on the market today contain 20- to
This ban applies only to private recreational boats 65 feet and
under. That leaves commercial, government, research, and for-hire
passenger vessels — not to mention large ocean-going ships that frequent Washington waters — free to discourage marine growth with
paint that recreational boaters can’t use. And the fine, if they do, is a
maximum $10,000 per day.
Copper, the fouling control substance of choice for the past
two centuries or so, first as sheet cladding for wooden ships in the
days of “iron men” and in more recent times
mixed in bottom coatings, could be headed
the way of tributyltin (TBT). Two states
away, the California Legislature came close
to passing a similar copper-paint ban last
year. The measure, now amended to allow
use of low-leach-rate copper paints, is back
for debate in Sacramento, and likely a vote,
in this year’s session. Discouraging aquatic
critters from taking up residence on a boat’s
bottom and on its submerged running gear
is what antifouling paints are designed to do.
So let’s look at the problem with copper as
the key ingredient in those paints.
GETTING TO THE BOTTOM
Whether it’s animal fouling in the form of
the old familiar barnacle, or a relative new-
comer, the zebra mussel, or plant and slime
growth, most antifouling paints work by
dissipating metal at the hull’s surface to kill
organisms or prevent them from adhering.
Since the demise around 1988 of the all-
too-effective tin compounds that also proved
highly poisonous to underwater ecosystems,
not just to hull growth, copper became the
biocide of choice. But the metal-biocide
approach has a downside.
DID YOU KNOW: ANTIFOULING PAINTS FALL UNDER THE SAME STATE AND FEDERAL PESTICIDE
REGULATIONS THAT COVER CHEMICALS YOU USE TO FIGHT PESTS ON YOUR LAWN.