Sunday, January 01, 2006

Scientists Discover New Stealth Feature on H.L. Hunley


Navy Newsstand
By Raegan Quinn
June 21, 2005

Official U.S. Navy file photo of scientists at theWarren Lash Conservation Center examining aCivil War-era wallet found during excavation ofthe Confederate submarine H.L. Hunley. Recentlythe scientists discovered a "stealth" feature of thesubmarine that some say was 50 years ahead of its time.

CHARLESTON, S.C. (NNS) -- Conservators of the Civil War submarine H. L. Hunley, working with the Naval Historical Center (NHC), discovered a previously unknown stealth feature called a deadlight while removing the concretion on one of the 10 glass ports, June 15.

The deadlight, which served like skylights that run along the top of the submarine, served as both a stealth and safety feature on Hunley, by stopping light from getting out and water from getting into the submarine.

"The Hunley truly is a technological marvel. Every aspect of the submarine's design is thought out to maximize her ability as a stealth and functional weapon," said Sen. Glenn McConnell, chairman of the Hunley Commission. "She is literally 50 years ahead of her time."

The skylight is covered by a hinged iron plate, or deadlight. A pin could be removed from one hinge, allowing the iron plate to drop down and let light in to the otherwise dark vessel. To cover the skylight, a crew member would push the iron plate up and re-insert the pin. When the deadlight was closed, it would block light from exiting the submarine through the skylight, increasing the Hunley's ability to approach her target unnoticed.

The deadlights also served as an important safety feature of the sub's construction. During combat, if the glass of the skylight was broken, it could cause a dangerous flow of water into the submarine. Scientists think the two hinges holding the iron plate in place may have been fitted with rubber gaskets, which would make the skylight watertight when the iron plate was closed. If the glass on the skylight was damaged, the crew could lock the iron plates in place and stop water from overtaking the sub.

Hunley scientists discovered the deadlight was in the shut position and the skylight remained covered.

"Every discovery is a clue that we will ultimately use to solve the mystery of the Hunley's disappearance. In the crew's last moments, they chose to leave this skylight closed, perhaps because they believed they would be returning home and wanted to remain undetected," McConnell said. "This is another piece of the puzzle that will lead us to the ultimate answer."

Scientists will continue work on de-concreting the remaining deadlights as they prepare the submarine for its conservation treatment.

On the evening of Feb. 17, 1864, H.L. Hunley became the world's first successful combat submarine by sinking USS Housatonic. After signaling to shore that the mission had been accomplished, the submarine and her crew of eight vanished.

Lost at sea for more than a century, Hunley was located in 1995 by author Clive Cussler's National Underwater and Marine Agency (NUMA). The hand-crank-propelled vessel was raised in 2000 and delivered to the Warren Lasch Conservation Center, where an international team of scientists under the Naval Historical Center are at work conserving the vessel and piecing together clues to solve the mystery of her disappearance.

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



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