NORTH CHARLESTON (AP).- The first submarine in history to sink an enemy warship is upright for the first time in almost 150 years, revealing a side of its hull not seen since it sank off the South Carolina coast during the Civil War.

Workers at a conservation lab finished the painstaking, two-day job of rotating the hand-cranked H.L. Hunley upright late Thursday.

The Hunley was resting on its side at a 45-degree angle on the bottom of the Atlantic when it was raised in August 2000 and scientists had kept it in slings in that position in the lab for the past 11 years.

But they needed to turn it upright to continue with the job of conservation.

Scientists hope the hidden side of the sub will provide clues as to why the Hunley sank with its eight-member crew in February, 1864, after sending the Union blockade ship Houstonic to the bottom.

While there was no immediate clue from a first look at the hidden hull but "we are seeing some tantalizing clues on that side," Hunley archaeologist Maria Jacobsen said Friday.

Scientists knew there were large hull breaches on the starboard side that remained out of view all these years. Jacobsen said the area around the holes is smooth, as the sediment that has hardened on the hull was blasted away. It's not clear whether the breaches are manmade — caused by an explosion or the like — or simply caused by nature.

She said it likely could have been scoured away by water and tides.

"We may be dealing with nature here. How can these massive hull breaches occur?" she asked.

"Nothing jumps out at me" from seeing the starboard side, said state Sen. Glenn McConnell, the chairman of the South Carolina Hunley Commission. "But we will be examining it for any clue that might be there to help us solve the mystery."

There are various theories why the sub sank. It could have been damaged by fire from the Housatonic or the sub's crew was knocked out by the concussion from the blast that sank that ship. Or it could have been damaged by another Union vessel rescuing the Housatonic.

Studies show the crew died of a lack of oxygen and didn't drown. The remains of the crew, who were buried in 2004, were found at their stations and there seemed no rush to the escape hatch.

McConnell said seeing the submarine upright brings it alive.

"Instead of looking like an artifact, it now looks like a stealth weapon," he said.

"It's as if you are looking at the submarine for the first time," agreed conservator Paul Mardikian. "Before it was more like a mass of inert metal. Now it looks like something that had a life."

The next step in conserving the Hunley comes next week when it will be lowered onto keel blocks to hold it upright. It will probably be a month before a truss and the slings that suspended the sub from it will be removed, providing an even better view of the submarine.

The delicate process of righting the sub involved rotating it between 800 and 1,000 millimeters. A team of workers adjusted the slings by 2 millimeter increments during the two days the job took.

"It went better than it had any right to do," said Mike Drews, the director of the conservation center. "Knowing there were unknowns, we always erred on the side of caution."



Copyright 2011 The Associated Press.