Standard displacement excluded fuel and reserve water

For surface ships, standard displacement included armament, ammunition, equipment, provisions, and crew water but excluded fuel and reserve boiler feed water. Submarines received wider exclusions covering fuel, lubricating oil, fresh water, and ballast water. The treaty defined a ton as 2,240 pounds, or 1,016 kilograms. These rules rewarded long-range designs because much of the liquid load needed for endurance did not consume the nominal treaty allowance. Reserve water could also occupy space through which an incoming weapon would otherwise pass, giving the load a potential protective effect. The treaty's legal vocabulary therefore shaped both published tonnage and practical naval architecture.