(10-17) 09:58 PDT SAN FRANCISCO — The state-of-the art Oracle Team USA catamaran racing sailboat that flipped during a bay practice run and was dragged out the Golden Gate was brought back to its San Francisco base early Wednesday.

The AC72 racing craft arrived at Pier 80 south of the Bay Bridge around 12:45 a.m., more than nine hours after it capsized off the St. Francis Yacht Club in San Francisco and was dragged upside-down out to sea by a strong ebb tide. Oracle Team USA utility boats towed the boat to shore as the U.S. Coast Guard monitored the operation.

The full extent of the damage to the $8 million carbon-fiber boat was not immediately clear. But team officials said the wing – the long, mast-like apparatus that shoots in the air to catch the wind – was destroyed.

At the team’s base of operations at Pier 80 on Wednesday, crews hauled out the bits of mangled wing sail and began examining the hull of the 72-foot-long catamaran to see what could be salvaged. Early in the day, the boat was still upside-down as crews prepared to lift it out of the water.

“We’re just looking at all the damage and getting some of the loose bits freed up so we can lift (the hull) out,” said team tactician John Kostecki as divers inspected the wreckage.

One of the boat’s hulls was entirely filled with water and the other was almost three-quarters full, he said.

“We’re happy to have the platform, but the wing sail is very damaged,” Kostecki said. “That looks like at the moment to be the biggest setback.”

The boat was hard to lasso when it capsized Tuesday because it pitched forward. Crews had to spend precious hours trying to flip the boat on its side while the boat was being sucked out to sea by a 5-knot current.

Once the crews got the boat on its side, the large, violent Pacific waves tore the wing sail apart.

“The misfortune really was that there was an outgoing sea current that swept the boat into a bigger seaway which caused a lot of damage,” Kostecki said.

“It is the first time one of these AC72s capsized,” he said. “It is kind of new territory for everybody.”

He added, “I don’t think there will be any major changes (to the design of the boat). We still don’t know what went wrong.”

The boat, with a wing height of 131 feet, is supposed to defend the America’s Cup when the competition is held on the bay next year. The 11-member racing crew was out for a practice spin Tuesday when the craft tipped over. None of the sailors was injured.

The Oracle team dispatched nine boats to salvage the AC72, which was swept more than 4 miles west of the Golden Gate.

Will Kane is a San Francisco Chronicle staff writer. E-mail: wkane@sfchronicle.com Twitter: @WillKane