Ironclads such as HMS Warrior and the French Gloire and their development into predreadnoughts such as the British Royal Sovereign and Majestic classes is well documented and fascinated me. However in the period of 1860-1890 a massive number of ship types exists from Armored Frigates and Corvettes, Casemate ships, Rams, Monitors, Turret and Barbette ships and my favorite the Central Battery ships. All these ships are classes as Ironclads.
In my mind this never made all that much sense. And I will readily admit that I am in no way qualified to change things, not even having any form of college degree. However if it where up to me I would add a category of ship that fit in between the Ironclad and Predreadnought. And Here is how my system would work.
Ironclad.
Encompassing everything built from the early 1860s onwards to roughly the 1880s the Ironclad is a vessel built primarily of wood with wrought Iron armor clad to the hull. These ships feature a variety of guns, armor, propulsion and design philosophy.
Ship types such as Armored Frigates and Corvettes, casemate ships, Monitors, Central Battery ships and some Turret ships all fit this category. Generally anything with a mostly wooden hull with armor added to it can be classed as a Ironclad.
Steel Battleships.
First appearing in the 1870s with ships such as HMS Devestation a Steel battleship carries either wrought Iron or Nickel-Steel armor on a hull made primarily of Iron. Ship types such as turret ships, breastwork monitors and barbette ships fit this category and the first such ships were built congruently with Ironclads.
Many steel battleships also lack sails as a means of propulsion and feature and increased reliance on coal.
Predreanought
Mounting all their guns on either barbettes or turrets the Predreadnought first appears with the Royal Sovereign class. These ships have either Nickel-Steel, Harvey armor or Krupp cemented Steel armor. All their guns are arranged in batteries with a primary battery of heavy guns, secondary battery of intermediate guns and a tertiary battery of light quick firing guns for use against torpedo boats.