Armour plate and optics as a reserve of industrial capacity

Armour-plate manufacture is harder to recreate quickly than ordinary shipyard work. Interwar construction cuts could leave shipyards recoverable while specialist armour production withered beyond rapid repair. Stored plate would preserve the output of a scarce industrial process as well as the material itself. Older rangefinders may be less advanced than later systems, yet still equip small ships whose alternative is no fire-control system at all. Radios make the opposite case: their rapid interwar development means that warehousing old sets preserves obsolescence rather than a scarce industrial bottleneck.