The hypothetical battleship cannot simply retain Tiger's full boiler-room arrangement. Heavier armour requires hull framing and subdivision able to carry the additional weight. That support consumes space that might otherwise be assigned to machinery. Armour and machinery must therefore be planned together in the longer hull.
Notable Point · 43:05-44:19
Battleship armour constrains boiler-room space
Supporting heavier armour requires framing and subdivision that prevent a direct copy of Tiger's five boiler rooms.