Anti-fouling Paint: Fights Barnacles and Slime
© John Crandall May 28, 2007
Over time a ship's hull in the water can become
overgrown with barnacles, seaweed, and other marine
organisms. This is called a fouled hull.
Fouled hulls are bad because they cause the once
smooth surface of the ship's hull to be rough. This
rough surface causes drag as the ship moves through
the water. This drag casuses reduced top speed, and a
need for more power to perform the same as a ship with
a clean hull.
This fact that marine life see ship's hulls as a place
to make their home has long been a problem to
mariners. Antifouling goes back at least as far as the
Pheonicians who attached copper bars to the hulls of
their ships. Copper, as it breaks down in contact with
water produces a chemical which is deadly to barnacles
and similar organisms. Copper based powders were later
added to marine paints to have a similar biocide
effect. Of course, the 20th century saw advanced
chemical biocides which were very effective at killing
the unwanted organisms. Unfortunately, over time these
deadly chemicals built up in coastal waters, and began
to kill off oyster beds, and other desirablke life.
This had the effect of having most of these "advanced"
biocides banned by law, and put men back to using
copper based powders in paint.
Scientists are scrambling for a new way to deal with
this problem. Organic and earth friendly methods are
being tried. The United States Navy is using powdered
chemicals delivered by small tubes surrounding the
ship's hull beneath the waterline through tiny holes.
As water touches the chemical concoction natural
biocides are produced that not only keep the hulls
clean, but are also biodegradeable and earth friendly.
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