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                                   BULLETIN
            FSB-031 - DAMAGE CAUSED BY MARINE ANTIFOULING MATERIALS
                  DATE/REV:  01MAR90 / 0 (previously FSB 4-8)
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ABSTRACT:  Describes precautions to take when using antifouling materials.

INSTRUMENT/PROGRAM AFFECTED:  All ADCPs.

DESCRIPTION:  Any object deployed within about 30 meters of the ocean surface
is subject to bio-fouling, especially in warm water.  Bio-fouling is not usu-
ally a problem in deep or cold water.  Soft-bodied organisms usually cause no
problems, but the hard shells of barnacles can cut through the urethane trans-
ducer face causing failure of the transducer or leakage into the ADCP.  There-
fore, you should take steps to prevent bio-fouling during shallow-water de-
ployments.  However, this presents other problems:

a.  Cuprous oxides - This antifouling paint can cause dezincification of
    VM-ADCP transducer assemblies.  Dezincification, once started, is a self-
    sustaining process.  Complete destruction of the transducer assembly is a
    possible outcome.

b.  Nopcocide - This antifouling grease can cause drying and cracking of the
    urethane coating on the transducers, which may eventually develop into a
    leak through the transducer head.

c.  Tributyltins (TBTs) - This class of antifoulant kills the target organisms
    and keeps the protected surface free from bio-fouling.  However, TBTs also
    kill non-target organisms.  Most government and environmental agencies
    strictly regulate or have outlawed their use.

SOLUTION/ACTION:  We strongly discourage the use of cuprous oxide and nopco-
cide.  If you have been using cuprous oxide, inspect the transducer for corro-
sion.  If you have been using nopcocide, carefully remove all traces of it
from the transducers and check for damage.  For TBTs, we suggest you check and
obey any local laws.

We are continuing to study this problem.  For now, the only safe way we know
of to prevent bio-fouling problems is to inspect and clean the transducer
faces on a regular basis (weekly) during shallow and warm water deployments.

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