Could a huge wartime fleet be sustained?

Would the difficulty of sustaining a huge fleet make wartime expansion impossible?

No. Wartime need can justify expansion of the fleet and its supporting infrastructure, with some vessels potentially uncrewed.

States normally reduce fleets in peacetime, but a major war can reverse that contraction. Some of the additional vessels could be uncrewed. Matching a large enemy fleet would require expansion of the supporting infrastructure as well as the number of hulls. Rome's investment in infrastructure provides the historical comparison.