A 27,000-ton fleet-carrier design could produce a capable ship, but a 135,000-ton national allowance yielded only five of them. The cumulative limit mattered more than the unit limit. Designs therefore became smaller to increase hull numbers without giving up too much air-group capacity, protection, or subdivision. The treaty barred most warships above 10,000 tons while imposing no comparable cumulative ceiling below that threshold. A carrier kept under the line could therefore be built without consuming the national carrier allowance.
Chapter · 7:42-12:26
Washington Treaty pressure for smaller carriers
The Washington Naval Treaty made cumulative carrier tonnage the main constraint while leaving sub-10,000-ton warships outside a comparable total limit.