The alternate rules require carriers completed through 1926 to be conversions and require at least two conversions in each navy's programme through 1930. This protects capital already committed to hulls and long-lead machinery while preventing an immediate race for wholly new 33,000-ton ships. Pre-treaty experimental carriers could retire from 1930, later conversions from 1934, and new builds would remain for at least eighteen years. The timetable uses replacement policy to spread technical change across several generations instead of trying to freeze carrier development.
Notable Point · 53:40-54:49
Conversion deadlines and carrier service lives
Staged conversion requirements would preserve existing investment while delaying unrestricted purpose-built carrier construction.