August 29, 2015

Scientists begin revealing hull of Confederate sub

A member of the Hunley's conservation team works to remove concretion from the vessel (Image: Clemson University)

A member of the Hunley’s conservation team works to remove concretion from the vessel (Image: Clemson University)

Scientists are now beginning to remove an encrusted layer of sediment and rust that has accumulated on the Confederate submarine H.L. Hunley.

The Hunley was the first sub to ever sink an enemy warship when it torpedoed the USS Housatonic in February 1864. However, the vessel never made it back to land after the explosion. The sunken vessel was discovered in 1995 and raised in 2000 It has since been undergoing conservation work at a North Charleston lab for the past 14 years.

The true surface of the Hunley will slowly start to be revealed as Clemson University scientists kick off a year-long effort to remove the brittle concretion masking the legendary submarine and some of her finer features.

“There is no person alive that has seen the submarine as it was when it was in use,” Warren Lasch Conservation Center director Stéphanie Cretté told South Carolina Radio Network. “By uncovering its original surface, we will get clues of what happened that night.”

In fact, removing concretion from the Hunley’s spar — an iron pole that held the torpedo in front — led researchers to form a new theory about what happened to the vessel that night. Conservators eventually discovered a copper sleeve. That sleeve matched a diagram currently housed at the National Archives, which showed the torpedo to hold 135 pounds of gunpowder. The discovery also meant the torpedo was likely still attached to the spar when it exploded against the Housatonic, researchers say. That could have been close enough for the explosion to knock the Hunley’s crew unconscious.

“This is an exciting step for everyone involved, but also has important scientific significance,” Assistant Director of the Lasch Conservation Center Nestor Gonzalez said in a statement. “Removing the encrustation will enable us to move forward with the final phases of the archaeological and conservation efforts surrounding the Hunley.”

The concretion has served as a protective cocoon, helping stop further corrosion that can be caused once saltwater-covered iron is exposed to oxygen. Once the concretion is stripped away, it will allow for the free flow of a liquid conservation treatment to reach the metal of the submarine and leach out the salts threatening her existence.

Cretté said the deconcretion project may take up to twelve months to complete.

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