Cathodic protection (ICCP)

Impressed current cathodic protection drives a controlled protective current onto the hull from inert anodes fed by a rectifier, holding the steel at a potential where corrosion is suppressed, in contrast to sacrificial anodes that corrode preferentially. Reference cells monitor the hull potential and the controller adjusts the output to hold it in the protective range as speed and water resistivity change. The system supplements rather than replaces coatings, since the coating carries most of the protection and the current only treats breaks in it. The IMO guidance is Resolution A.798(19).