Sunday, January 01, 2006

Historical Center Investigates 19th-Century Vessels - The "Hunley" and "USS Alligator"


By Max Uphaus
Naval Historical Center Public Affairs

WASHINGTON (NNS) -- This summer, scientists under the direction of Dr. Robert Neyland, head of the Naval Historical Center's (NHC) Underwater Archaeology Branch, carried out investigations of two historically significant 19th-century naval craft.

An international group of researchers working under the NHC have uncovered new operational details that may provide a clue to the loss of the world’s first successful combat submarine, H.L. Hunley, while another archaeological team conducted a survey to locate the wreck of the anti-slave trade schooner USS Alligator.

Hunley scientists made their discovery while removing the layer of concretion that covers the interior and exterior sections of the Civil War-era boat.

“As we dig inch by inch into the concretion, we get closer to the final clues that will help solve the mystery of why the Hunley disappeared,” said Sen. Glenn McConnell, chairman of the South Carolina Hunley Commission.

Once a layer of the concretion was removed, an integral series of valves and pumps, connected by a pipe running from the forward to the aft ballast tank, was exposed. The configuration suggests that the submarine’s pump system may have had a dual purpose. Scientists knew the pumps were used to control the water level in the ballast tanks, which enabled the submarine to rise or dive while in operation. The complexity of the pump system is leading scientists to believe it also served as a bilge system that would have allowed the crew to remove water from inside the submarine in the event of an emergency.

Depending on the valve setting and pump position, Hunley scientists may be able to tell if the crew was desperately trying to remove water from the crew compartment or trying to pump water out of the ballast tanks to gain buoyancy the night that it vanished Feb. 17, 1864.

“Only archaeological detective work will answer the questions of what were the Hunley crew’s actions during their last moments and...why the sub never returned from her mission,” said Neyland.

The remaining concretion still covers a majority of the pump system and has not been further removed, because it protects the submarine from corrosion as it awaits conservation treatment.

Scientists are hopeful that once they can safely excavate and x-ray this key aspect of the submarine’s internal pump mechanisms, it will reveal what the crew was doing in the last moments of their voyage.

Hunley, a Confederate boat, sank USS Housatonic off of Charleston, S.C., on the evening of Feb. 17, 1864 - the first time in history a submarine sank a surface ship. After signaling to shore that the mission had been accomplished, the submarine and its crew of eight vanished.

Lost at sea for more than a century, Hunley was located in 1995. The hand-cranked vessel was raised in 2000 and delivered to the Warren Lasch Conservation Center, where the NHC, in partnership with the South Carolina Hunley Commission, is supervising its protection and study.

In search of Alligator, NHC Underwater Archaeology (UA), together with the National Oceanic and Atmospheric Administration and the Florida Keys National Marine Sanctuary, surveyed Alligator Reef and Shoal, Fla. Alligator, launched in 1821, was one of only five Navy schooners designed to interdict slavers and pirates, which would make it a very rare and valuable discovery.

“USS Alligator is one of the Navy’s most significant shipwrecks,” commented Neyland. “Alligator’s mission was to enforce a U.S. law prohibiting the slave trade on U.S. merchant ships, and it did its mission well.”

Until recently, historians believed that the schooner’s wreck site had been identified, but in 1995 and 1996, archaeologists found discrepancies between that shipwreck and historical accounts, invalidating this idea.
Because dozens of ships foundered on the reef during the same historical period as Alligator, its accurate location has not been easy to determine.

Based on historical data, including contemporary charts and maps and the ship commander’s own estimate of the vessel’s position the day before it sank, UA plotted a high-probability search zone of one square mile. The scientists then conducted a remote-sensing survey, using a magnetometer in an attempt to detect the iron ballast that Alligator was known to be carrying when it went down.

Early in its brief but eventful career, Alligator mounted two patrols off of West Africa. “Its first mission founded a colony for former captives and slaves, which is today the nation of Liberia,” said Neyland. “The crew of Alligator boarded slave ships...and freed the captives, delivering them to the new colony.”

Alligator spent 1822 in anti-piracy operations near Cuba, where, though badly outnumbered, it won numerous victories and liberated captured American ships. The schooner ran aground in November on what is now the Alligator Reef, its crew abandoning and scuttling it on Nov. 23 to prevent pirates from salvaging it.

“Hunley and Alligator were different ships with entirely different missions,” Neyland pointed out. “However, both represent a previously forgotten part of U.S. history, which is now being revealed through science and underwater archaeology.”

Hunley - Digital image made using Vulcan laser system.

For related news, visit the Naval Historical Center Navy NewsStand page at

Links: - Hunley photo page - USS Alligator resumed history - (Article) The hunt for the Alligator - (article) - Virtual Hunley exhibit



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