HMS Warrior's selective armour scheme

The term ironclad did not mean that a vessel was uniformly covered in iron. Warrior's protection concentrated on the central fighting and machinery spaces, using interlocking iron plates backed by eighteen inches of teak, while the ends were left unarmoured. The protected box could preserve buoyancy even if the unarmoured extremities took on water. The same principle appears in the armoured hangars of the Midway, Taihō, and Illustrious classes and in battleship deck protection, where the thickest armour likewise covers central vital spaces. The design demonstrates the enduring naval trade-off between comprehensive protection, displacement, stability, and safeguarding the spaces most important to survival and combat power.