The 1936 rules lower maximum standard displacement to 23,000 tons and retain the 6.1-inch gun ceiling, with no more than ten guns above 5.25 inches. They also distinguish conventional flight-deck carriers from ships without such a deck, leaving seaplane carriers inside the framework. A twenty-year service rule permits old carriers to be replaced rather than freezing the category indefinitely. Ark Royal shows how much capability could still fit within roughly 22,000 long tons.
Chapter · 36:12-38:22
The 1936 treaty narrows carrier size and armament
The later treaty sets a 23,000-ton limit, caps heavy guns, defines flight-deck and non-flight-deck carrier categories, and permits replacement after twenty years.