Generally, zinc blocks are embedded in the hull of seagoing ships because the hull is made of steel. In seawater, steel will have some chemical reactions to corrode the hull, and zinc is more active than iron. In seawater, zinc will react before iron, and zinc will lose electrons and be corroded, so the hull will not be protected. In this reaction, zinc will lose electrons, be corroded as anode, and iron will be protected as cathode. This is the so-called sacrificial anode cathodic protection method.