In 1974, the US Navy was looking forward to smaller “Sea Control Ship” aircraft carriers packing VTOL fighters like the ill-fated Rockwell XFV-12. Smaller carriers would be cheaper than giant supercarriers, so there could be more of them, spread to the numerous hotspots of the world… or at there very least there would be some of them, as the military budget was way down. The VTOL capability of the fighters would mean the smaller decks would not be a major hinderance to flight operations.
Planners were sufficiently optimistic about the chances for VTOL fighters that companies began sketching out ideas for minimum-size carriers. Normally nobody would ever think of landing a jet fighter on something the size of a Coast Guard cutter, yet helicopters do so with some regularity; so in principle is should be possible to operate VTOL fighters from ships this size. So companies and military organizations produced artwork (it’s unclear how detailed and rigorous the actual designs were) of small ships capable of carrying one or two fighters.
One Boeing notion called for the use of a fast hydrofoil boat to carry a single fighter. In this case the fighter was a VATOL (Vertical Attitude Takeoff and Landing) design… not exactly a tailsitter, but instead operating in the same fashion as the Ryan X-13. A landing platform would be raised to the vertical (like a billboard), and the fighter, standing on its tailjets, would mosey on up to it and latch on. Aware of the difficulties encounted by similar VATOL craft in the past, specifically the trouble the pilot has in seeing where he’s going when his cockpit is pointing straight at the sky, Boeing fitted their fighter design with a cockpit that could tilt “down” 90 degrees, allowing the pilot to remain comfortably upright while the plane bent underneath him.
A US Navy concept sketch used the XFV-12, with two of these planes operating from an Advanced Marine Vehicle. This would be used to support a larger conventional carrier group, by providing a ring of interceptors and similar missions.
Of course, the whole idea fell flat. The XFV-12 proved wholly incapable of lurching itself into the sky, and the one VTOL fighter to enter US service, the AV-8 Harrier, proved to be somewhat troublesome (it’s jet exhaust would happily bore holes through the decks of most ships, for instance). By the 1980’s, the budget for the military began to go back upwards, and Cheap Small Aircraft Carriers fell out of favor.