Susan Gibbs needs to find a new parking spot, fast. And not just any parking spot will do.

It needs to be big enough for an ocean liner.

It’s for a ship bigger than the Titanic, one that is nearly as long as the Chrysler Building is tall. A ship so luxurious that it was the first choice of presidents and royalty. A ship so trusted that it once carried the Mona Lisa. A vessel so fast that its mammoth propellers, churning the sea beneath its grand promenades and shipboard orchestras, were a Cold War state secret.

A ship named the United States that Ms. Gibbs has come to adore. In fact, she has dedicated her life to saving it.

Ms. Gibbs’s grandfather William Francis Gibbs was a famous ship designer, and the United States was his masterwork. But remarkably, she knew almost nothing about that until she was well into adulthood.

“This, I would not have predicted,” she said recently about being responsible for a rusty steamship.

Ms. Gibbs, 62, works in Washington at a private foundation where her primary focus is eradicating genital cutting of women. Between that and her advocacy for the ship, she noted, “People must be so confused by my social media presence.”