Sunday, January 01, 2006

Sunken mystery

By Bill Bleyer
January 03, 2005

In the coming months, scientists studying the H.L. Hunley hope to learn why the Confederate sub sank after destroying an enemy ship.

Sometime this year, scientists who have been excavating, preserving and studying the Hunley and its contents hope to have the answer.

After working in a 60,000-square-foot laboratory in North Charleston since the submarine was raised nearly 30 feet from the ocean floor in 2000, Maria Jacobsen, the project's senior archaeologist, is confident of learning the full story.

The reason is the Hunley, filled with remarkably preserved artifacts and even human remains, "is as close to a true time capsule as you can get in archaeology."

There are multiple theories for the Hunley's demise. The torpedo the 40-foot-long Hunley carried on a spar attached to its bow might have damaged the submarine when it sank the USS Housatonic, a Union ship blockading the Confederate port.

Or as the crew cranked the shaft to turn the propeller, they may have used up the fresh air, passing out and drowning when the sub subsequently sank.

Another Union warship, the Canandaigua, coming to the aid of the Housatonic, might have swamped the Hunley if its hatches were open.

Or rough seas may have swamped the Hunley.

"My theory," said Glenn McConnell, chairman of South Carolina's Hunley Commission, which has overseen the raising and preservation of the vessel, "is the water did get rough and she took on some water and she was using more oxygen than she was bringing in through the snorkels and they blacked out.

"While Jacobsen -- who will make the call, with input from scientists around the world -- doesn't want to get ahead of the science, the lab work has allowed her to draw some conclusions.

"Whatever happened appears to have happened quite quickly," she said. "They were collapsed more or less where they sat. You didn't see the guys trying to move toward the conning towers to exit. So either something happened very fast or they were not able to move."

She postulates that either the crew became unconscious from lack of oxygen or the submarine flooded so rapidly that no one could move.

Whatever caused the sinking, Jacobsen said, "there was water in the submarine quite early on. What we found was that these fellows were drowned, the bodies floated, they decomposed and slowly sank."

Once the Hunley was placed in a saltwater tank at the lab at a former Navy base, six hull plates were removed and the silt that almost filled the interior was removed in layers so human remains and artifacts could be recovered.

A forensic investigation combined with document research led to the identification of the eight men and even reconstruction of what their faces could have looked like.

Then most of the remains were buried in Charleston in April.

The 3,000 items removed from the interior were photographed and 3-D laser mapping technologies were used -- for the first time in an archaeological project, Jacobsen noted -- to create an image of the interior at the time of the sinking.

The objects were turned over to a conservation team headed by Paul Mardikian, the senior conservator at the lab who previously worked on artifacts from the Titanic.

He showed a shoe being preserved during a recent tour.

It had been cleaned mechanically and chemically and then was being freeze-dried at about minus 43 degrees to remove moisture that could cause the leather to crack.

To study the sub and its artifacts, 900 X-ray photographs have been taken and stored in a computer. The X-rays revealed that because of the lack of oxygen to foster decomposition, the crewmen's brain tissue remained inside their skulls and their bones inside their shoes.

With the excavation completed in the fall, the research is shifting to the sediment to determine how the submarine filled with silt.

The last step before the Hunley goes on permanent display in a new museum planned for the North Charleston riverfront will be examination of the hull.

"Every surface is covered with a corrosion product, the concretion," Jacobsen said. After that is removed and while the salt in the metal is removed to prevent disintegration, "we'll have to study the hull damage that is visible and determine how did it occur."

The scientists will pay particular attention to the valves in the ballast tank pumping system, which is more complex than anticipated.

They knew the pumps were used to control the water level in the ballast tanks, which enabled the submarine to rise or dive. But the same system may have served as a bilge pump to allow the crew to remove water from inside the submarine in an emergency.

"Looking at those valves, we'll begin to understand the final moments of the Hunley," McConnell said.



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