Figure 11-6.--Dry-cell battery circuit.

potential of metals. Some of the factors affecting the

than the metal that is less corrosion prone. In

amount of corrosion are stray currents, resistivity,

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.

11-7