A sacrificial anode is a metal that has a more negative potential with respect to the structure metal to be protected. Sacrificial anodes corrode preferentially to the protected structure, providing protection to the structure.

The objective of a galvanic anode system is to deliver sufficient current to protect part of the structure for the designed life of the system.

There are three basic components of a marine sacrificial anode cathodic protection system (SACP):

1.Anode(s)
2.Connecting System, including cabling and fasteners
3.Protected Structure

Sacrificial anode materials are usually alloys of aluminum, zinc, or magnesium.

Protected structures in ships include but are not limited to: ship hull, shafts, rudders, sea chests, heat exchangers, condensers, ballast tanks, etc.