Until the 19th century boats and ships were made of wood. With industrialization, shipbuilding was revolutionized. Consequently, iron and steel was used for shipbuilding, steam engines and propellers now propelled the ships. Experiments were carried out to find out how to protect the metal parts of the ship from corrosion. It took until the 20th century that the process of corrosion was sufficiently understood. It has been found a way to guide the corrosion impact into wearing parts and thus protect the important parts from corrosion. The sacrificial anode was born.