ANODES.-- The anodes (fig. 11-6) are constructed
Table 11-2.--Anode Locations on the Underwater Hull
of two platinum-mated tantalum rods mounted in an
insulating glass-reinforced polyester holder. Anodes
are bolted to the outside of the ship's hull. The dc flows
into the seawater through the platinum surface of the
tantalum rods. The platinum surface of the anode
corrodes very slowly. The replacement period for
anodes is usually 10 years or longer. Anodes are
available in three sizes--2 feet (40 amperes), 4 feet (75
amperes), and 8 feet ( 150 amperes).
When installed (table 11-2), anodes should be
placed to maintain a uniform potential throughout the
underwater hull. The following is a list of anode
locations:
REFERENCE ELECTRODE.-- The reference
electrode (fig. 11-7) is a silver/silver chloride type
constructed of a silver mesh screen that has been treated
with silver chloride. The reference electrode is bolted
to the exterior hull of the ship and is insulated from the
ship by a polyvinyl chloride holder. A stuffing tube is
used to pass the cable from the electrode through the hull
to the controller. The controller measures the potential
of the hull versus the reference electrode, and signals
the power supply to increase or decrease current output
Figure 11-7.--Reference electrode assembly.
11-9
