Carrier tonnage limits turn ship size into an availability problem

Aggregate tonnage, rather than the maximum size of one ship, is the central constraint on interwar carrier fleets. The Washington Naval Treaty allotted Britain and the United States 135,000 tons each, Japan 81,000, and France and Italy 60,000 apiece. A navy could build a formidable 27,000-ton carrier, but five such ships would consume the entire British or American allowance. Maintenance and training cycles would then leave only about two normally available, or three to four if wartime demands forced deferred upkeep. Smaller carriers become attractive because hull numbers determine how many stations and tasks the navy can cover at once.