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Magnets help reduce fouling on ships
by Claire
Ainsworth
From New Scientist magazine, vol 169 issue 2273, 13/01/2001, page
14 |
SHIPS and oil platforms could use magnets to ward off squatters. British
researchers have found that magnetic fields reduce the amount of seaweed
fouling underwater surfaces. They hope that the technique could be
used as an environmentally friendly antifouling system.
Fouling is a major problem for ships and underwater structures such
as platforms. Weeds and barnacles growing on hulls create drag and
slow shipping down, and can make recycling old platforms more costly.
Current antifouling methods involve painting surfaces with toxic paint
such as tributyltin. But these can poison other sea creatures such
as shellfish (New Scientist, 8 May 1999, p 23).
Researchers have long known that electric fields affect seaweed germination
by interfering with tiny electrical currents inside cells. But electric
fields aren't always practical for use on the water. So Jill Shaw
and her colleagues at the Glasgow Marine Technology Centre and Dove
Marine Laboratory, University of Newcastle upon Tyne wondered whether
a magnetic field might have the same effect.
To find out, Shaw sandwiched bar magnets between two glass or steel
slides, and placed them in seawater along with some spiralled wrack
seaweed embryos. She found that far fewer embryos settled on the steel
slides when the magnet was present. More embryos settled on the glass
slides, but they tended to congregate at the magnetic poles, she told
a meeting of the British Ecological Society last week.
Although the system doesn't prevent fouling completely, Shaw believes
that it could be worth incorporating magnets in steel structures.
"I don't think there's anything-unless it's as toxic as TBT-that
will be 100 per cent effective," she says.
"It sounds a good idea, but there's work to be done," says
William Perry, a naval architect at the Southampton Institute.
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