The Assistant Chief of Naval Staff initially considered one carrier each for the Home and Mediterranean fleets and a total of four modern ships. A 22,500-ton design could carry roughly fifty-two aircraft and make 30 knots, making four ships appear cheaper than five, but the calculation ignored routine absence from service. Over a twenty-four-year carrier life, two years in refit meant that one of four hulls would be unavailable through much of an eight-year cycle, leaving an effective force of only three. Retaining five ships while keeping four commissioned allowed the spare hull to rotate through refits. Under the Washington Treaty's 135,000-ton total, six 22,500-ton carriers also offered greater tactical resilience than five 27,000-ton ships if aircraft capacity and seakeeping were similar.
Notable Point · 13:20-14:50
Carrier treaty limits collided with fleet availability
A four-hull paper fleet would often yield only three available carriers because of refits, making five ships with four commissioned or six smaller treaty carriers more resilient choices.