Actually opening the Hunley for excavation was not something the archaeological team took lightly. After many months of planning, the Hunley project team came up with a plan to excavate the submarine. Scientists wanted to concentrate on the central compartment of the sub, where the 8-man crew would have been located and on January 21, 2001 the excavation of the Hunley began. The excavation plan was divided into four main stages:
Phase One: Studying the Submarine
Carlos Velazquez of Epic Scan, Ltd., working with the point-cloud data from the Cyrax Laser Scan of the submarine.
Rendering of the exterior laser scan of the H.L. Hunley.
In order to safely enter and excavate the submarine, a careful preliminary study and mapping of the H.L. Hunley had to first be completed. Using a relatively new technology called a Cyrax 3D laser scanning system (www.cyra.com) provided by Pacific Survey Supply (www.pacificsurvey.com) and Epic Scan Ltd. (www.epicscan.com), archaeologists were able to scan the entire exterior of the submarine prior to any cleaning or removal of concretion. The scan produced an exact model of the submarine accurate to within 2 millimeters. Using this digital model of the H.L. Hunley, researchers were even able to zoom in and measure the heights of barnacles on the submarine's exterior surface. This preliminary study enabled us to ascertain the proper access to conduct a safe scientific excavation without damaging the Hunley and the artifacts she holds.
Phase Two: The preliminary excavation of the stern ballast tank.
Archaeologist Shea McLean removing sediment from the ballast tank during the stern excavation.
There is an existing hole in the upper starboard side of the tank. This provided a limited, but easy access to the interior of the submarine, and also provided important data on the condition and nature of the hull plates, ballast tank, backing plates and rivets, and the location of ship machinery such as propeller shaft and steering controls. This phase and review revealed how theHunley's iron plates were fastened, and how the sedimentation occurred.
Phase Three: Removal of the plates.
Removing the first hull plate from the center section of the submarine. Over 100 rivets were drilled out to loosen this plate.
A series of hull plates, and possibly other construction features, were removed to gain sufficient access into the submarine's interior. This enabled the excavation team to retrieve the remnants of the crew and any artifacts associated with them and as well as learn more about the operation of the submarine. An important focus during the phase, and the whole excavation, was to maintain the integrity of the submarine's construction and therefore remove as few plates as possible.
Phase Four: Removal of sediments.
Archaeologist Michael Scafuri excavating mud and sediment from theHunley.
The sediments inside the central compartment and the accessible portions of the ballast tank areas were excavated by hand using a combination of trowels, metal and wood scrapers and spatulas. All sediments after screening will be collected and disposed of in a respectful and proprietary fashion.
Lt. Dixon's Gold Coin
Ezra Chamberlin's ID Tag