It's not as far-fetched as it sounds;
It's not as far-fetched as it sounds; throughout the interwar period, a major element of the US Navy's mobilization planning in the event of a Pacific War was converting large liners to auxiliary carriers, know as the "XCV" program. This program was a significant push for the programs to retrofit existing ships (like Leviathan) and build new, large liners (Manhattan and Washington, for example).
WPL-10 (1924) envisioned Leviathan as one of seven carrier conversions, although most of the ships included on the prospect list were also on the troopship list, so there's no guarantee any given ship would get a carrier conversion; it would depend greatly on the strategic situation, shipyard availability, etc. Leviathan, however, was one of those with an earmark for XCV conversion, largely because of her size and (after the conversion to oil burning) speed and (relative) ease of underway replenishment.
Air groups were envisioned as a standard three squadron, 54-72 aircraft group, depending on size of the baseline ship, and divided equally between fighters, scout/dive bombers, and torpedo bombers; basic planning (1929) was for the first conversion at Boston, in service and deployed to Oahu by M+120, with a second conversion at New York and arriving at Oahu by M+150; however, the need for troop transports was expected to preempt most if not all of the carrier conversions, and by the mid-1930s, conversions were expected to take at least 180 days, and might be as long as 360 days.
By 1939, conversion cost for the smaller, but more modern Manhattan and Washington were estimated at $6 million.
By 1941, the two Manhattans, the brand-new America (which essentially replaced Leviathan as the flagship of the US-flag Atlantic liners); and the interned Swedish liner Kungsholm were considered for XVC conversions; the ships' use as troopers was seen as more important, especially give the number of fast carriers (Essex and Independence classes) on the ways, and the usefulness of freighter-derived escort carriers ...
As it was, about the closest analogues to these ideas were the IJN's Junyo and Hiyo, the Italian Aquila and Sparviero, and the British Pretoria Castle; given the war records of the above in comparison to the US and British purpose-built carriers, and CVE conversions, make it clear that the concept of the converted liner had pretty much had its day by the 1940s.
Leviathan, of course, would have made an excellent "monster" trooper, along the lines of Queen Mary etc; that being said, presumbaly the British put the steel to good use in 1938 and afterwards...
Best,
