Conservation-restoration of the H.L. Hunley

Once the Hunley's conservation and restoration is complete it will be relocated to a new museum built in its honor on the former Navy base in North Charleston.

On February 17, 1864, the Hunley destroyed the Union sloop Housatonic outside Charleston Harbor using a spar-mounted torpedo loaded with 135 pounds of gunpowder.

Well-known author Clive Cussler and underwater archaeologist E. Lee Spence both claim to have made the original discovery.

The remains of the eight crewmen serving on the Hunley when it sank were found and buried on April 17, 2004, at the Magnolia Cemetery in Charleston.

Hunley submerged in a water tank, instead of exposing it to the oxygen-rich air, until a full conservation plan could be created.

Hunley sank in the outer harbor of Charleston, the salt water had over a hundred years to eat through the metal.

Iron artifacts from the sea in particular are susceptible to rapid deterioration when exposed to an oxygen-rich environment like air.

As the crystals grow, the surface of the metal will expand and flake away, eventually reducing the artifact to a pile of iron oxide dust.

Concretion is an encrusted layer of sand, sediment and shells that builds up slowly, when an object is submerged in water.

[6] The Hunley was removed from its watery grave at a 45-degree angle in order to keep the interior contents from shifting and falling through a weakened section of the hull.

Once the submarine was relocated to the Lasch Conservation Center, it was left in the slings at a 45-degree angle until the hull plates and keel blocks were removed, eleven tons of sediment had been cleaned out of the interior and an engineering and strength evaluation could be completed.

Once the evaluation was completed and the Hunley was deemed safe to move, it took three days in June of 2011 to turn the civil war submarine upright.

[11] Removing the concretion that has built up allows researchers to analyze why the Hunley sank and if the holes they have found in the outer hull of the submarine were from the attack on the Housatonic.

"During treatment, the Hunley will be constantly monitored and once the chemical bath is saturated with the salts it has leached from the submarine, it will be drained from the tank, neutralized, and replaced with a fresh solution.

This process, which is estimated to take approximately 5-7 years, will be repeated until the level of salt in the iron is low enough to allow the Hunley to be rescued from its delicate and dangerous state.