Researchers say they may be close to solving the mystery of what happened to the Confederate submarine H.L. Hunley before it sank off Charleston on February 17, 1864.
The Hunley made history as the first submarine vessel to sink an enemy warship in any conflict when it ignited a torpedo next to the U.S.S. Housatonic as the Union vessel blockaded the Charleston Harbor. However, it never returned from the mission and was not seen again until its wreckage was discovered on the ocean floor in 1995. It was raised in 2000 and delivered to Clemson University’s Warren Lasch Conservation Lab in North Charleston for study.
In a new report, scientists say they’ve learned the Hunley apparently was less than 20 feet away from the Housatonic when the crew set off the fateful torpedo. For years, historians thought the Hunley was much farther away when the explosion occurred.
“Now we know precisely how far away the submarine and the crew were when the torpedo exploded,” said senior archaeologist Maria Jacobsen, “Actually, with this particular configuration, they would have been above it and quite close.”
The reason for the change in thought lies with the Hunley’s spar— an iron pole that held the torpedo in front. As conservators slowly removed rock, sand and silt – often referred to as concretion – that accumulated on the vessel while she rested on the ocean floor, they eventually discovered a copper sleeve. That sleeve matched a diagram currently housed at the National Archives, which showed the torpedo to hold 135 pounds of gunpowder.
The conventional wisdom had been the Hunley rammed the spar torpedo into her target and then backed away, causing the torpedo to slip off the spar. A rope from the torpedo to the submarine would spool out and detonate once the submarine was at a safe distance. However, the new find means the torpedo would still have been at the end of the 16-foot spar when it exploded.
Now that researchers know the correct distance, Jacobsen said they will be able to more accurately simulate what happened. “Were the crew incapacitated to such an extent that they were knocked unconscious? Were they dead? How did the hull withstand this shockwave?” she asked, “But, at this point, it’s speculation. What we want to say is that we finally have the data set to move forward.”
The theory of an incapacitating shockwave could also explain why the bodies of the sub’s eight-man crew were found at their stations and why there appeared to have been no attempt to escape the vessel before it sank.
While the idea of sitting 16 feet away from a 135-pound bomb exploding sounds like a suicide mission, Jacobsen said it was an effort to inflict more damage on the Union vessel. Four months earlier, Confederate engineers had used a semi-submersible in an attack the U.S.S. New Ironsides in October 1863. That attack failed to sink the Union vessel, mostly because the torpedo was not powerful enough and was placed on the ship’s side rather than its slender underbelly.
Jacobsen said archaeologists will now carefully remove 136 years of ocean accumulation on the Hunley’s outer hull to see if there was any damage from the explosion. That could also give a better indication of what happened that historic night in February 1864.