The heroic rescue of 32 seamen off the Chatham, Mass., coast more than 60 years ago has been called the greatest small-boat rescue in Coast Guard history.

Today, the small boat at the center of that tale has its own determined crew of rescuers. But they’re now facing a shortfall that could once again leave their famous charge high and dry.

Retired from service for nearly half a century, the 36-foot motor lifeboat known as CG36500 sits at the mouth of Rock Harbor, inconspicuously docked at the end of a line of fishing boats. Listed on the National Register of Historic Places, the floating museum, known to few, “looks like it could fit into a bathtub,” said Casey Sherman, coauthor of “The Finest Hours,” a 2009 book about the rescue.