potential of metals. Some of the factors affecting the
than the metal that is less corrosion prone. In
cathodic protection, the more corrosion-prone metal is
and the temperature of the seawater.
the anode ( zinc) and the less corrosion-prone metal is
Stray-current corrosion is caused by an external
the cathode (steel hull). The rate of corrosion is
current leaving the hull of a vessel and entering the
directly related to the magnitude of the potential
seawater. If the connection between the ship and
difference and is referred to as the open- or half-cell
Figure 11-6.--Dry-cell battery circuit.
Figure 11-7.--Electrochemical corrosion cell.