These ships were called ironclads.
Ironclad
They were actually called blockade runners.
privately owned warships
The old wooden ship you are referring to is the USS Merrimack, which was scuttled by the Union Navy and later raised by the Confederates. They converted it into an ironclad warship, renaming it the CSS Virginia. This ship famously faced off against the USS Monitor in the first battle between ironclad warships during the Civil War.
The battle between the USS Monitor and the CSS Virginia changed the way warships were built. The two ships were both ironclad warships.
Boats covered in iron are commonly referred to as ironclads.
Ironclads.
During the 1800's wooden warships plated with iron were called "iron-clads." By 1904 during the Russo-Japanese War, Russian sailors still called their all steel built battleships "iron-clads."
A fleet.
the hull
triremes
A convoy
(Two iron covered ships) fought during the Battle of Hampton Roads on March 9, 1862.
Privateer
The iron "beak" that was used on Roman and all other ancient warships, was called a "rostrum" by the Romans. The speakers' platform in the Roman forum was called the "rostra" (plural) because it was traditionally decorated with the beaks captured from enemy ships.
Monitor is the iron clad fighting for the Union. Virginia is the iron clad fighting for the Confederacy. Both ships were equaly matched resulting in a stalemate.
Armada, as in "The Spanish armada".