It left the dock quietly and slowly in a thick fog, like a wraith, like a ghost out of the past.

The Independence was a famous ship in its day, but that was long ago. The liner made its maiden voyage from New York on a cruise to the Mediterranean 57 years ago this month.

The old ship sailed under a new name: It has been called the Oceanic since summer.

Its voyage is also a bit of a mystery. Norwegian Cruise Line, the ship's last owner, sold it last year but refused this week to say who the new owner is.

There was even a minor mystery about its destination. Earlier this week, Leon Hall, of Inchcape Shipping Services, an agent representing the ship, said the final port of call "had not been decided yet." On Friday, however, the destination was listed as Singapore.

There is a lot of speculation in maritime circles that the real destination is a scrap yard in India or Bangladesh. There is not much of a future for a 57-year-old steamship that has not sailed under its own power in seven years.

"She is one of the great ships," said William Miller, an expert on ocean liners who wrote a book about the Independence. "But she has had her day, absolutely. I would bet you 50 cents she will be sold for scrap."

Admirers of old ships have been circulating rumors and reports on the Internet about the fate of the Independence.

Some, like Eric James, a ship buff from Boston, say the ship is full of toxic material like asbestos and is being taken out of the United States illegally. They say it should be preserved as a memorial to U.S. passenger ships. But there is no formal move to preserve the ship, and once it sailed out the Golden Gate, it was probably too late.

If the Independence is scrapped, it will be a sad end for a ship that was one of the prides of the U.S. flag merchant marine. The Independence was built in Quincy, Mass., by Bethlehem Steel and launched in 1950. The Independence and its sister ship, the Constitution, cost $50 million. Each of the ships could carry 1,000 passengers - 295 in first class - and could make 23 knots.

At first, they sailed from New York to Genoa, Italy, for American Export Lines on a southerly route across the Atlantic passengers called "The Sun Lane." It was a favorite of movie stars and important people.

Former President Harry Truman and his wife sailed on the Independence at least once. But jet planes killed the transatlantic liners, and in the 1960s, the two ships were sold.

The Independence was tricked out like a 1968 hooker with a gaudy pop-art paint job - a pink sunburst rose out of the side of the ship from a pair of huge seductive-looking eyes painted just above the waterline. The theme was Go-Go cruises.

That flopped, and the ship was laid up, sold a couple of times, and finally, in 1980, the Independence began sailing around the Hawaiian Islands.

The ship sailed every Saturday for 21 years on weeklong Hawaiian cruises under the U.S. flag. For a while, the Constitution joined the Independence in Hawaii but it was withdrawn and sank on its way to the scrap yard in 1996.

The Independence carried on alone. It was a good life in Hawaii, and a popular service. As late as 2000, the Independence received the Ship of the Year award from the Steamship Historical Society of America.

But the parent company of American Hawaiian Cruises went bankrupt when tourism dropped after the 2001 terrorist attacks. The ship completed its final voyage and sailed from Honolulu, arriving in San Francisco on Nov. 8, 2001. It was the last voyage under its own power.

The ship kicked around the bay and even spent some time in the mothball fleet near Benicia. Finally, in 2004, it was laid up at Pier 70 not far from the baseball park.

Rumors flew: It was going back to sea, it was going to be a floating hotel in New Orleans, or maybe in Dubai. But nothing happened. The Independence just sat, a bit of a landmark. Not every waterfront has an old white ocean liner with two funnels as a backdrop for the edge of the bay.

"I'm going to miss it. It's a good-looking boat," said Capt. Joshua Pryor, who operates the charter boat Ruby out of a pier next to the Ramp restaurant.

Andrew Wong, who was working on the yacht Rampage at the next dock, said the Independence reminded him of home. "I used to see it when I was a kid in Hawaii," he said.

About 10 a.m. Friday, bar pilot Tom Miller, who also handled the Queen Mary 2 when it visited San Francisco last year, slowly guided the old ship out of its berth. He used two tugs - the Delta Deanna and the Delta Linda, to pull the ship out, then turned it so it was facing toward the central bay. He positioned the ship so it could be towed away by the oceangoing tug Pacific Hickory.

The tule fog lay on the bay as thick as mushroom soup, and the Independence kept appearing and disappearing. About 11:30 a.m., the old ship, its sides streaked with rust, the flowers painted around the funnels faded with age and neglect, slowly disappeared into the mist.

"It's fitting weather for a final departure," said William Miller, who had written the book on the Independence. "It's kind of poetic."

E-mail Carl Nolte at cnolte@sfchronicle.com.