SS Republic Operational Overview
The archaeological excavation of the SS Republic®* began in November 2003 after a thorough pre-disturbance survey which included the production of a photomosaic of the site and discovery of the ship's bell confirming the identity of the shipwreck. The excavation was concluded with success in early 2005, after the retrieval of nearly 14,000 artifacts and over 51,000 gold and silver coins, supported by extensive documentation and recording of the entire process.
The operation was the first of its kind ever performed at 1,700 feet (518 meters) below the ocean’s surface, accomplished entirely through the use of advanced robotics and cutting-edge technologies. And with its successful completion, Odyssey Marine Exploration achieved its foremost objective of testing, improving and perfecting methods and procedures vital to the emerging field of deep-ocean archaeology.
The search for the wreck of SS Republic included an exhaustive search operation using advanced side-scan sonar and magnetometer technology that covered over 1,000 square miles during 2002 and 2003 alone. Computer models combined with information from newspapers and survivors’ reports, ships' logs and other information about currents and the storm were used in an attempt establish the search area. Possible sinking locations reflected information derived from different combinations of surface current speed, effect of winds upon the ship's movement after the engine failed, and effects of wind and current upon the movement of the ship's boats and raft after the sinking ship was abandoned. The discovery of the shipwreck site very close to the location where one of the lifeboats was picked up was the result of thorough analysis of these various sources by Odyssey's in-house research staff.
A total of 24 targets were located in 2002 and 2003 and then inspected with a Remotely Operated Vehicle (ROV). During the summer of 2003 the company’s 112-foot research vessel R/V Odyssey discovered a promising target. The side-scan sonar image revealed two paddle-wheels, the walking beam engine towering above the seabed, two boilers and a decayed wooden hull. These features and their dimensions very closely matched those of the SS Republic as documented historically. After an inspection ROV provided a visual survey of the site, Odyssey filed an ‘Admiralty arrest’ claim to protect the site.
Conducting archaeology in deep water requires the same rigorous standards as those employed in terrestrial and shallow water sites. The significant difference is the cost of the operation and the requirement for specialized equipment. At a depth well beyond a range practical and safe for human divers, the archaeological excavation of the SS Republic called for adaptations and innovations in the use of Remotely-Operated Vehicles (ROVs) combined with advanced electronic survey/navigation systems, video and still photography and data logging programs to record and process information.
This technology has developed to the extent that an archaeologist sitting on a research ship on the surface of the ocean has a better view of the site than a diver would have from the faceplate of a diving helmet or mask. Additionally, advancements in the development of hydraulic ROV manipulator arms has resulted in systems that replicate the precise movements of human hands, wrists, arms and elbows. The ROV, in effect, performs as the eyes and hands of the archaeologist working on deep-water sites.
A primary archaeological objective of the Republic project was to verify the documentary record of storm damage to the ship as chronicled in historical reports derived largely from the survivors’ accounts. These documented narratives speak of the ship’s paddle boxes and bulwarks washing away, cargo being thrown overboard, and the deck house floating away in the last moments before the ship finally sank. An essential goal was to retrieve where possible, a selection of diagnostic artifacts useful for comprehensive interpretation of the material culture aboard the ship. Study of the cargo and the ship would also further knowledge about life in immediate post-Civil War America and would contribute to current data and understanding of 19th century paddle-wheel vessel design and construction.
To conduct the excavation, Odyssey mobilized its 251-foot long, motor vessel Odyssey Explorer. Re-fitted to serve as the archaeological platform for the operation, the ship was equipped with an ROV system and with specialized components and technological systems to support archaeology, data logging, and first-aid conservation of recovered artifacts.
The eight-ton ROV (nicknamed ZEUS) was configured for conducting survey measurement, photography, manipulation and excavation of sustained duration at depths over 6,000 feet (1828 meters). For manipulation, the ROV’s manipulator arm feature permits its two manipulator arms fitted on the front of the vehicle to duplicate in sea-bed operations the movements performed by the operator aboard the Odyssey Explorer working hundreds, even thousands of feet above the site.
The archaeological investigation and excavation of the SS Republic was conducted in two phases: Phase One, the pre-disturbance survey, and Phase Two, the excavation. The pre-disturbance survey included creating photomosaics of the wreck site and the debris field derived from thousands of images captured by cameras mounted on the ROV—a process more technically complex in the deep ocean than on shallow water sites. The photomosaics proved an invaluable tool in understanding the archaeology of the site, setting the basis of a site plan, and for planning the excavation strategies. The final photomosaic of the SS Republic contained approximately 2,500 high-resolution images each digitally stitched together resulting in a large panoramic view of the entire wreck site.
The initial ROV surveys conducted during Phase One determined that the surface features of the site consisted of a wreck lying relatively upright with the metal framework of both paddle-wheels slightly canted outwards. The bow area was fairly flat, with no structures rising more than three of four feet feet (one meter) from the seabed. Further evidence at the site suggests the vessel may have landed on the seabed on her starboard bow. Lying off the port bow partially buried was the ship’s bell which was subsequently recovered to positively identify the shipwreck as that of the SS Republic.
Scattered around the bow area were broken and displaced sections of hull timbers and framing as well as remains of the ship’s deck planking. Overall, the wreck was observed to be in a poor state of preservation, affected by the topography of the seabed, exposure to the elements, accretion and scouring by the strong current and the movement of sediments.
Retrieval of delicate artifacts on the Republic project was achieved with the use of a soft silicone rubber limpet suction device, a tool often employed on Odyssey’s deep-ocean shipwreck projects. Fitted to the port manipulator arm of ZEUS and powered by the venturi pump, the limpet suction attachment permits fragile objects—some as small as buttons and coins—to be recovered from the ocean floor without damage or marking. The majority of artifacts were recovered when the ROV was either sitting down on the seabed in ‘archaeological sterile’ areas, which would not disturb any artifacts or hull remains, or within areas of dense wreckage hovering above the site to protects its remains.
Artifacts, structural remains, and other objects of interest collected from the site were placed in numbered plastic containers of an appropriate size to securely house the materials recovered. All containers were designed to cope with the effects of varying pressure, depth, and temperature to ensure the contents safe journey to the surface. When filled, the artifact containers were placed in a large rubber-lined metal lifting basket on the seabed, subdivided to store several plastic containers. Each container and division location was numbered, video recorded and entered into Odyssey’s DataLog™ system.
Once the artifacts were lifted to the surface, the artifacts' dimensions and level of preservation were manually recorded on finds sheets and then logged onto a spreadsheet for tracking. Prior to first-aid conservation, the artifacts were photographed on board the recovery vessel, and a separate photo log and file were created. With the sub-sea and surface recording systems, plus a separate inventory and management database maintained by the conservator, Odyssey was able track the history of all the artifacts from their first observation on the seafloor to Odyssey's land-based conservation facility.
Lessons learned from the SS Republic excavation have allowed the Odyssey team to further improve their techniques and equipment as they investigate more sites—working within a rigorous operational model that serves as our paradigm for all shipwreck projects.
*®SS Republic is a registered trademark of Odyssey Marine Exploration, Inc.
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