By . Mark Prigg . It was a remarkable step forward in warfare - and the first submarine in history to sink an enemy warship. The H.L Hunley, a hand-cranked submarine, was first launched in 1863 - but after sinking twice, was lost a year later for unknown reasons, killing all crew. The Hunley was eventually discovered off the Charleston coast in 1995 and raised in 2000. Scroll down for video . The Confederate submarine H.L. Hunley sits in a conservation tank at a lab in North Charleston, about to undergo a chemical bath it is hoped could reveal why it sank, killing all seven crew aboard. A drawing of H. L. Hunley, based on a photograph taken in 1863 by George S. Cook . Scientists near the city where the Civil War began are now preparing to soak the encrusted Confederate submarine in a chemical bath to reveal its hull for the first time in 150 years, seeking to solve the mystery of the demise of the first sub in history to sink an enemy warship. The hand-cranked H.L. Hunley - which rests in a 76,000-gallon conservation tank - will be treated with a solution of sodium hydroxide for about three months to loosen the encrustation coating the hull and interior of the sub. Conservationists will drain the tank each day and later, wearing protective gear, use hand tools to remove the hard sand, sediment and rust coating the sub before refilling the tank each evening. 'This is the end of the beginning' of the preservation work, said Nestor Gonzalez-Pereyra, the associate director of the Lasch Conservation Center at Clemson University's Restoration Institute. 'In a year we may be able to have the clues.' Removing the encrustation will reveal the original surface of the hull and with it any damage that could yield new clues to its sinking off Charleston, S.C., in February 1864. The war had begun with the bombardment of Fort Sumter in Charleston Harbor three years earlier. The sub and its crew of eight had set off a powder charge that sank the Union blockade ship USS Housatonic as the Confederacy tried to break a Union blockade of Charleston. The H.L. Hunley, nearly 40 feet (12 m) long, was built at Mobile, Alabama, and launched in July 1863. Hunley was designed for a crew of eight: seven to turn the hand-cranked propeller and one to steer and direct the boat. Each end was equipped with ballast tanks that could be flooded by valves or pumped dry by hand pumps. Extra ballast was added through the use of iron weights bolted to the underside of the hull. Inside the Hunley: It was designed for a crew of eight: seven to turn the hand-cranked propeller and one to steer and direct the boat. In the event the submarine needed additional buoyancy to rise in an emergency, the iron weight could be removed by unscrewing the heads of the bolts from inside the vessel. She was then shipped by rail on August 12, 1863 to Charleston, South Carolina. Originally called Fish Boat, the sub sank on August 29, 1863, during a training exercise, killing five members of her crew. However, it was found and refurbished, before she sank again on October 15, 1863, killing all eight of her second crew, including Horace Hunley himself, who was aboard at the time, even though he was not enlisted in the Confederate armed forces. In the event the submarine needed additional buoyancy to rise in an emergency, the iron weight could be removed by unscrewing the heads of the bolts from inside the vessel. After being reused again, on February 17, 1864, Hunley attacked and sank the 1240-short ton (1124 metric tons) screw sloop USS Housatonic on Union blockade duty in Charleston's outer harbor. Soon after, Hunley sank, killing all eight of her third crew - and researchers still have no idea why. But the Hunley never returned and just why remains a mystery. The wreck was discovered off the coast in 1995. Five years later, in August of 2000, cannons boomed, church bells rang and thousands watched from the harborside as the 40-foot-long sub was raised and brought by barge to the conservation lab. The silt-filled interior of the sub was later excavated and the remains of the crewmen removed. In April of 2004, thousands of men in Confederate gray and Union blue walked in a procession with the crew's coffins from Charleston's waterfront Battery to Magnolia Cemetery in what has been called the last Confederate funeral. The chemical bath will help remove salts and the encrustation on the submarine's hull. The Hunley sank a Union blockade ship off the South Carolina coast in 1864. It was discovered in 1995 and raised in 2000 and brought to the North Charleston lab. Last year, scientists announced it appears the charge that sank the Houstonic was attached to the 16-foot spar at the front of the sub. That could mean the crew was knocked unconscious by the explosion and died before awakening. A closer look at the hull may provide clues. 'Chiseling away the concretion will allow us to travel back in time, potentially helping us learn what happened to the Hunley and her crew that night,' Lt. Gov. Glenn McConnell, the chairman of the South Carolina Hunley Commission, said in a statement. H. L. Hunley, suspended from a crane during its recovery from Charleston Harbor, August 8, 2000. When the Hunley was raised, historians thought it was farther away from the Housatonic and speculated the crew ran out of air before they could crank the submarine back to the coast. Gonzalez-Pereyra said while the encrustation on the hull should be removed in a year, the sub will have to soak in the chemical bath for at least four more years to remove salts in the metal and prevent further corrosion of the sub. Eventually the Hunley will be put on display in a new museum in North Charleston not far from the conservation lab.
Sub sank a Union blockade ship off Charleston in 1864 .
Was discovered off the coast in 1995 and raised in 2000 .
Researchers have been unable to find out why it sunk with crew still aboard .
By . Mark Prigg . It was a remarkable step forward in warfare - and the first submarine in history to sink an enemy warship. The H.L Hunley, a hand-cranked submarine, was first launched in 1863 - but after sinking twice, was lost a year later for unknown reasons, killing all crew. The Hunley was eventually discovered off the Charleston coast in 1995 and raised in 2000. Scroll down for video . The Confederate submarine H.L. Hunley sits in a conservation tank at a lab in North Charleston, about to undergo a chemical bath it is hoped could reveal why it sank, killing all seven crew aboard. A drawing of H. L. Hunley, based on a photograph taken in 1863 by George S. Cook . Scientists near the city where the Civil War began are now preparing to soak the encrusted Confederate submarine in a chemical bath to reveal its hull for the first time in 150 years, seeking to solve the mystery of the demise of the first sub in history to sink an enemy warship. The hand-cranked H.L. Hunley - which rests in a 76,000-gallon conservation tank - will be treated with a solution of sodium hydroxide for about three months to loosen the encrustation coating the hull and interior of the sub. Conservationists will drain the tank each day and later, wearing protective gear, use hand tools to remove the hard sand, sediment and rust coating the sub before refilling the tank each evening. 'This is the end of the beginning' of the preservation work, said Nestor Gonzalez-Pereyra, the associate director of the Lasch Conservation Center at Clemson University's Restoration Institute. 'In a year we may be able to have the clues.' Removing the encrustation will reveal the original surface of the hull and with it any damage that could yield new clues to its sinking off Charleston, S.C., in February 1864. The war had begun with the bombardment of Fort Sumter in Charleston Harbor three years earlier. The sub and its crew of eight had set off a powder charge that sank the Union blockade ship USS Housatonic as the Confederacy tried to break a Union blockade of Charleston. The H.L. Hunley, nearly 40 feet (12 m) long, was built at Mobile, Alabama, and launched in July 1863. Hunley was designed for a crew of eight: seven to turn the hand-cranked propeller and one to steer and direct the boat. Each end was equipped with ballast tanks that could be flooded by valves or pumped dry by hand pumps. Extra ballast was added through the use of iron weights bolted to the underside of the hull. Inside the Hunley: It was designed for a crew of eight: seven to turn the hand-cranked propeller and one to steer and direct the boat. In the event the submarine needed additional buoyancy to rise in an emergency, the iron weight could be removed by unscrewing the heads of the bolts from inside the vessel. She was then shipped by rail on August 12, 1863 to Charleston, South Carolina. Originally called Fish Boat, the sub sank on August 29, 1863, during a training exercise, killing five members of her crew. However, it was found and refurbished, before she sank again on October 15, 1863, killing all eight of her second crew, including Horace Hunley himself, who was aboard at the time, even though he was not enlisted in the Confederate armed forces. In the event the submarine needed additional buoyancy to rise in an emergency, the iron weight could be removed by unscrewing the heads of the bolts from inside the vessel. After being reused again, on February 17, 1864, Hunley attacked and sank the 1240-short ton (1124 metric tons) screw sloop USS Housatonic on Union blockade duty in Charleston's outer harbor. Soon after, Hunley sank, killing all eight of her third crew - and researchers still have no idea why. But the Hunley never returned and just why remains a mystery. The wreck was discovered off the coast in 1995. Five years later, in August of 2000, cannons boomed, church bells rang and thousands watched from the harborside as the 40-foot-long sub was raised and brought by barge to the conservation lab. The silt-filled interior of the sub was later excavated and the remains of the crewmen removed. In April of 2004, thousands of men in Confederate gray and Union blue walked in a procession with the crew's coffins from Charleston's waterfront Battery to Magnolia Cemetery in what has been called the last Confederate funeral. The chemical bath will help remove salts and the encrustation on the submarine's hull. The Hunley sank a Union blockade ship off the South Carolina coast in 1864. It was discovered in 1995 and raised in 2000 and brought to the North Charleston lab. Last year, scientists announced it appears the charge that sank the Houstonic was attached to the 16-foot spar at the front of the sub. That could mean the crew was knocked unconscious by the explosion and died before awakening. A closer look at the hull may provide clues. 'Chiseling away the concretion will allow us to travel back in time, potentially helping us learn what happened to the Hunley and her crew that night,' Lt. Gov. Glenn McConnell, the chairman of the South Carolina Hunley Commission, said in a statement. H. L. Hunley, suspended from a crane during its recovery from Charleston Harbor, August 8, 2000. When the Hunley was raised, historians thought it was farther away from the Housatonic and speculated the crew ran out of air before they could crank the submarine back to the coast. Gonzalez-Pereyra said while the encrustation on the hull should be removed in a year, the sub will have to soak in the chemical bath for at least four more years to remove salts in the metal and prevent further corrosion of the sub. Eventually the Hunley will be put on display in a new museum in North Charleston not far from the conservation lab.
Charleston coast in 1995 and raised in 2000. wreck was discovered off the coast in 1995. Five on the submarine's hull. The Hunley sank a Union blockade ship off the South Carolina coast in