American output was low in 1941, with much larger totals expected in 1942 and 1943. The approximate construction figures fall from 38-39 months before Pearl Harbor to 31-32 months for battleships, from 31-32 months to about 16 for carriers, from 14 months to 7-8 for submarines, and to about six months for destroyers. These accelerations required experience and could not be achieved instantly. The authorized fleet on paper was much larger than the force actually built and available in January 1942. The United States therefore had to buy time for promised resources to become ships in the water and reach the places where they were needed.
Chapter · 11:02-13:04
The US Navy had to buy time for promised production
American output was about to surge, but authorized ships and resources were not yet an operational fleet in January 1942.