[Ruy Dias de Bivar]

My reading of history says the ships had copper sheathing, not Iron.

[outofsalt]

"By the mid-19th century steam engines had been fitted in some wooden ships of the line. But the Royal Navy was shocked when, in 1858, the French started building La Gloire. This was the first armour-hulled ship. However, because French industry could not make an iron hull, the Gloire had to be built of wood protected by 11 cm (4.5 in) of iron. Iron cladding the wooden British fleet was the simplest way of responding to this French challenge. However, Sir John Pakingham, the First Lord of the Admiralty, supported the idea of a completely iron hull. So, the Warrior was ordered in June 1859."

Iron rusted so copper sheathing the iron was tried, however galvanic interaction between the metals was even worse. They then tried wooden planking between the iron and the copper. The link above is very informative.