The Cressy class separates prudent design margins from hindsight masquerading as foresight. Retrofitting torpedo protection could mean adding speed-reducing bulges or rebuilding the ship's interior so extensively that a new hull would be more economical. The problem was especially severe between HMS Warrior and the First World War, when armor, engines, propellers, guns, ammunition, and fire control passed through several technological generations. A ship conceived in the 1890s could therefore remain serviceable while becoming poorly matched to a threat that barely existed when its requirements were written. The class's history centers on design uncertainty and changing threats.
Notable Point · 7:40-12:36
Why warships cannot be future-proofed against unknown threats
The Cressys illustrate why an expensive, long-lived warship can be designed sensibly yet still encounter technologies its creators could not reasonably anticipate.