Ships and propulsion machinery have finite service lives that heavy use in open-ocean conditions consumes. Coastal defence ships spent less time exposed to sustained deep-sea stresses than cruising warships. Their simpler machinery, heavy armor, and large guns could therefore remain useful even as newer fleets appeared. Contemporary Type 23 hull-life work provides the comparison, showing why long-lived coastal ships were financially prudent instruments of deterrence rather than merely obsolete survivors.
Notable Point · 2:11:41-2:13:17
Why coastal warships could remain in service for decades
Limited sea time preserved hull and machinery life, allowing slow coastal ships to remain credible deterrents for unusually long periods.