The basic method is the sacrificial anode method, which uses a sacrificial metal (such as magnesium alloy) that is highly active to oxygen and is more susceptible to oxidation and corrosion as an anode to protect the structural metal (often made of steel) of buildings or bridges. The sacrificial metal will corrode before the structural metal being protected.

Currently, the sacrificial anodes used in seawater mainly include zinc anodes and aluminum anodes. Due to the current efficiency, magnesium anodes are not recommended for use in seawater environments.

Originally, the sacrificial anodes used on ships were mainly zinc anodes. However, in recent years, due to environmental issues (zinc anodes contain cadmium) and fluctuations in raw material prices, they have been gradually replaced by aluminum alloy anodes.

Cathodic anti-corrosion loop system:

The reference electrode detects the hull potential and transmits the signal to the automatic potential controller. At this time, the automatic potential controller compares the received signal with the set potential value and tells the power supply to increase or decrease the current to the anode, so that the whole hull is protected by cathode.