PHILADELPHIA — Even now, 55 years to the week after it became the fastest vessel ever to cross the Atlantic, the rusty old ship seems to strain at her lines.

The United States was the world's sleekest, safest ocean liner, a symbol of American supremacy, and — odd as it seems — a Cold War weapon.

But it has been 37 years since the ship's last voyage and a decade since it was moored to a pier on the Delaware River. Its owners wonder what to do with it. The liner's fans wonder how to save it.

Despite longstanding hopes for its revival — a return to sea, or conversion to a floating hotel or museum — America's former "ship of state" seems to be running out of time and luck.

Norwegian Cruise Line bought the United States in 2003, saying it hoped to make it the fourth ship in the line's U.S.-flagged fleet. But losses in the line's Hawai'i cruise business recently forced it to announce plans to reduce that fleet from three ships to two.

That has dimmed hopes the line will undertake the vast cost — perhaps $500 million, as much as building a new liner — of refitting the United States.

"She was this huge expression of American pride," says Susan Gibbs, granddaughter of the ship's architect and president of the United States Conservancy (www.ssunitedstates conservancy.org), a group that seeks to preserve it. "Now she's this forlorn ghost ship."

Outside, the ship's paint is faded and peeling. Inside, it has been gutted — stripped to the bulkheads by asbestos-removal crews. The four mighty propellers lie on deck. The shuffleboard court is cracked. The badminton court is gone.

Inside, the decks are littered with paint chips and bird carcasses. Since a few hawks moved in, even the pigeons have jumped ship.

Joe Rota was the ship's photographer. He was awed when he first came aboard in 1955, and awed again last month on a visit to see what had become of the vessel.

"It's all gone," he says — the stateroom where he met Harry Truman, the first-class observation lounge where he photographed Prince Rainier of Monaco, the ballroom where he saw movie stars, including Judy Garland and Burt Lancaster, in the flesh. "All gone."

UNSINKABLE — AND UNCATCHABLE

The United States was a sensational amalgam of postwar luxury and Cold War function — "Fastest, Toughest, Most Beautiful," according to a Newsweek story in 1952.

The U.S. government, which wanted a way to ferry troops to Europe on short notice, picked up two-thirds of the $70 million cost. In 48 hours, the ship could be converted to accommodate as many as 14,000 troops, then steam 10,000 miles without refueling.

It was fireproof; virtually the only wood aboard was in the galley butcher blocks and the grand piano. (Steinway refused to make one of aluminum.) Even the sculpture in the first-class dining room was made of a fireproof material known as "foam glass."

It was overbuilt — with two engine rooms, in case one was torpedoed — and watertight compartments, like a warship. "We always said she could have hit the iceberg that sank the Titanic and stayed afloat," Rota says.

Above all, the ship was fast, a function of four steam turbines and a lightweight aluminum superstructure.

The ship's top speed was legendary, in part because it was a state secret; the Pentagon didn't want the Soviets to know.

Even toy models of the ship stopped at the waterline, because the hull's sleek underwater shape was something of a military secret.

During sea trials, engineers later reported, the ship ran at 38 knots. For a few minutes it held steady at 43 knots — about 50 mph.

On the maiden voyage from New York, which began July 3, 1952, the United States cruised at only 35 knots and still smashed the Queen Mary's 14-year-old record for the Atlantic crossing by 10 hours. When the captain wanted to make up time, Rota recalls, "you could see the wake out to the horizon."

The ship's reign ended with the cooling of the Cold War — it never was used as a troop ship — and the dominance of the jetliner.

OVERTAKEN BY JETS

Beginning in the late '50s, travelers could cross the Atlantic in six hours instead of four days, and ocean liners turned to leisure cruising in warm climates.

Now the ship's speed was irrelevant; its enclosed pools, promenades and dining rooms, perfect for the chilly North Atlantic, were liabilities; the utilitarian interior decor, useful aboard a ship that could end up carrying troops, seemed Spartan compared to other liners' paneled, padded elegance.

In 1969, the United States was mothballed at Newport News, Va. In 1984, many of its furnishings and fittings were auctioned.

NCL, which spends more than $1,000 a day to maintain the ship, says the hull is sound; that it can be rebuilt to comply with international safety standards taking effect in 2010; and that it hopes to one day return the ship to sea.

A tour of the ship, however, makes it seem unlikely that NCL, which lost $130.9 million last year, will put the United States back into service anytime soon.

Compared with contemporary liners built specifically for the cruise trade, the old ship's stairways are cramped, the windows small, the interior spaces narrow.

The ship has been stripped of every period surface, decoration and furnishing of nostalgic appeal.

A retrofit might destroy the ship's classic lines.

It would need extra decks, with more spacious staterooms featuring balconies and picture windows. It could wind up looking like a floating high-rise condo.

Neither NCL nor the ship's admirers are eager to acknowledge what increasingly seems its possible fate — to be run up on a beach somewhere in the Third World and cut up for scrap.

Standing on the dock after his visit last month, Joe Rota admitted the contrast between the ship's appearance 50 years ago — "not a rust spot, not a flake of paint out of place" — and now.

"But it's only cosmetic," he added. "She could be sandblasted. She could be back to sea in no time."