ICCP system

An ICCP (impressed current cathodic protection) system protects a steel hull from corrosion by driving a controlled protective current from inert hull-mounted anodes, supplied by a transformer-rectifier referenced to fixed silver/silver-chloride electrodes. Unlike sacrificial galvanic anodes, the current is regulated to hold the steel at a protective potential, typically near minus 800 to minus 900 mV versus Ag/AgCl, as fouling, speed, and salinity change. ICCP suits large hulls because a handful of anodes replaces many sacrificial blocks and cuts drag and replacement docking. It is paired with an anti-fouling and barrier coating; over-protection can cause cathodic disbondment of the paint and hydrogen evolution at the steel.