CHARLESTON, S.C. - Almost four years after the Confederate submarine H.L. Hunley was raised from the Atlantic, experts are still unsure why the first sub in history to sink an enemy warship went to the bottom.
More clues should be revealed in the coming weeks as scientists finish the excavation of the sub's interior.
"The Hunley has been very stingy with her secrets," said state Sen. Glenn McConnell, the chairman of the South Carolina Hunley Commission.
The silt and sediment that filled the sub was removed months ago, but scientists are working to remove encrusted areas inside the sub. They are looking specifically at the valves on the rear pump.
They will X-ray the valves to determine whether they are open or closed. That may tell whether the crew was attempting to pump out water that might have spilled in, Mr. McConnell said.
Experts think the crew ran out of air.
"The question is, how did they get into that shape?" Mr. McConnell said. "Did the weather get rough that night and every time they replenished air with the hatches open did they take on water?"
The hand-cranked, 40-foot Hunley became the first sub to sink an enemy warship when, on Feb. 17, 1864, it rammed a spar with a black powder charge into the Union blockade ship Housatonic.
The Hunley never returned and was located off Sullivans Island nine years ago.
In April, thousands of re-enactors took part in a funeral for the eight-man crew in what was billed as the last Confederate funeral.
Mr. McConnell said Friday that new research suggests a weather front moved through the area the night the Hunley set out on its mission.
"Was she battling to come in against roughening seas, and did she have trouble taking on air?" he asked. "It's like a giant jigsaw puzzle, and each of these little pieces starts to paint the picture."
Scientists also hope to recover additional artifacts, such as canteens or additional billfolds, that may be encrusted beneath the crew bench.
"It would seem there would be, because they only found one wallet, and it would seem that more than one person would have a wallet," Mr. McConnell said.
The Hunley, currently housed at a conservation lab at the old Charleston Naval Base, will eventually go on display in a North Charleston museum.