The SS United States is the fastest, sleekest ocean liner ever built, a giant gem of midcentury design and engineering, and in the brief time it spent on the high seas before the great liners were finally supplanted by jet flight, it truly became what its admirers now call it: “America’s flagship.” In its glory days it seemed hard to believe it would ever end like this: Moored permanently in a berth on the Philadelphia side of the Delaware River, cold and empty. That’s where it’s been for a long 14 years while a succession of owners have tried to figure out what to do with it. There’s been talk of turning it into a casino, or a luxury dockside hotel; there’s been talk of refitting it and sending it back out on the seas. But the clock is running down, and now it looks like the end may be approaching: The current owners, Genting Hong Kong, have begun to seriously solicit bids from scrappers. The SS United States Conservancy has mounted a last-ditch effort to raise public awareness about the dire straits in which this beautiful ship now finds itself. Take a look at the trailer for “SS United States: Lady In Waiting,” a documentary produced by SSUSC board member Mark Perry, and if you’re moved to help, contact the Conservancy.