The new material
The hull of this type of ship is made of iron , but the superstructure is still traditionally made of wood. The reasons for switching from wood to iron were, among other things, the flourishing industrialization in England with new methods of smelting (cheaper production) and the success of the railroad .
The first big iron ships were in 1838 the Tall Ship Ironsides , with a displacement of 270 t, built at the shipyard Jackson & Jordan in Liverpool, and in the same year by the yard & Gleichmann buses constructed in Germany iron steamer named Willem I. for Dutch clients.
End of development
The development of this type of ship took place in slow steps, because even twenty years later steamers as well as sailing ships made of processed cast iron were still rare. With improved technology, the cast material in shipbuilding was replaced by rolled steel at the end of the 19th century , as the relatively brittle material made of unalloyed cast iron only allows a very limited size in shipbuilding. Steel, on the other hand, can be made much more elastic - by alloying various other metals and reducing the carbon content . This is indispensable for the construction of larger ships, as ships “twist” when moving in the water due to the movement of the waves. With a VLCC super tanker with a total length of 350 m, the torsion and connection between the bow and the stern is up to 3 m in heavy seas, i.e. around 0.85% of the total length of the ship.