Pooling carrier and battleship tonnage in one treaty limit

What happens if aircraft-carrier and battleship tonnage are combined into one Washington Treaty pool?

Navies must trade flight decks against gun ships, with Britain likely demanding a larger total allowance to preserve both roles.

The counterfactual places aircraft carriers and battleships inside a single treaty tonnage pool while retaining a maximum displacement for individual ships. That arrangement makes every carrier consume capacity that could otherwise support a battleship, so national doctrine directly determines the fleet mix. As a comparatively late convert to carrier aviation, the United States might choose fewer carriers than Britain. Britain would resist the historical aggregate limit and seek enough tonnage for roughly eight carriers and sixteen other capital ships in one illustrative calculation. Applying a 5:5:3 ratio would leave Japan with a smaller but still substantial combined allowance and a difficult set of choices between flight decks and gun ships. The arithmetic is explicitly exploratory, but it reveals how treaty categories can shape doctrine by making unlike ship types compete for the same scarce resource.