A galvanic cell takes place when two or more dissimilar metals with different corrosion potentials are connected and submerged in an electrolyte. Uncontrolled corrosion is dangerous. It can sink a yacht instantly by eating away the propeller shaft and underwater metal parts of the hull. The best way to check for corrosion is to use a hull potential meter.
To combat galvanic corrosion, sacrificial anodes are often used in cathodic protection systems. Anodes need to be checked and monitored constantly for replacement when the anodes are at least 1/3 used up. The best way to prevent galvanic corrosion is to use a galvanic isolator. A galvanic isolator blocks DC current while allowing AC current to pass. To properly install the galvanic isolator, it must be connected in series with the boat’s AC ground conductor. Ensure the galvanic has proper ventilation and clearance of other devices and objects.