On Friday, scientists announced one of the final steps that should help explain what happened after the hand-cranked sub and its eight-man crew rammed a spar with a powder charge into the Union blockade ship Housatonic off Charleston in February 1864.
Early next year the 23-ton sub will be delicately rotated to an upright position, exposing sections of hull not examined in almost 150 years.
When the Hunley sank, it was buried in sand listing 45 degrees to starboard. It was kept that way as slings were put beneath it and it was raised and brought to a conservation lab in North Charleston a decade ago.
Sunday marks the 10th anniversary of the raising of the Hunley, discovered five years earlier by shipwreck hunter Clive Cussler.
As thousands watched from boats and the shoreline, the Hunley was brought from the depths and back to the lab by barge. Thousands turned out again in April 2004 when the crew was buried in what has been called the last Confederate funeral.
Rotating the sub will allow scientists to, for the first time, completely examine the Hunley's hull.
It's a delicate operation, involving replacing the existing slings before the sub is turned upright. The pressure on the straps will be monitored electronically and a laser will monitor to make sure the surface doesn't get warped.
The Hunley is "a ghost of an iron object," said senior conservator Paul Mardikian, adding, it has "hundreds of different parts and everything has to move together."
The clues indicate the crew died of anoxia, a lack of oxygen which can overtake a person very quickly, and didn't drown. The remains showed they were at their crank stations and there was no rush for an escape hatch.
The Hunley could now be displayed in a museum by 2015, estimates Sen. Glenn McConnell, the chairman of the South Carolina Hunley Commission.
Conservation of such artifacts often takes years, underwater archaeologists say.