Machinery power density can shift a capital ship along the battlecruiser-battleship spectrum. Moving from 21 to 28 knots can transform what a fleet can do, while gaining only a few knots beyond the mid-thirties offers a smaller operational return. Designers can spend the same displacement on additional armor coverage and subdivision instead of maximum speed. The Iowa comparison illustrates a fast battleship whose machinery does not require abandoning a battleship-level protection scheme. Speed alone therefore cannot define a warship type.
Notable Point · 32:07-34:39
Machinery power density turns speed into a protection choice
The diminishing return from ever-higher speed explains why efficient machinery can free displacement for armor coverage and subdivision.