The old Revell Midway-class kit, originally released in 1954 (as the Franklin D. Roosevelt), was one of those notorious early Revell flat bottomed ships. The Forrestal, which came along in 1957, had a full hull.
One explanation for the flat bottoms was that Revell wanted kids to be able to play with the models on the floor. (Aurora did the same thing with several of its first warship kits.) I suspect another reason was that the underwater hull lines of some or all of the ships in question were still classified. (The Midway class, after all, was the most high-tech carrier design in the world in 1954. And the S.S. United States's hull form was kept secret for a long time, because she'd been built under a big government subsidy as a high-speed wartime troop carrier.)
What still doesn't make sense to me is that the flat-bottom kits also contained those sturdy "trestle"-style mounting stands (complete with screw slots, in case you wanted to screw them down to a wood base). An old Revell Missouri, FDR, or United States sitting on those trestles looks pretty silly to modern eyes. But in those days few of us noticed.
Edit two minutes later: Bill, it looks like you and I were typing at the same time.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.