Marine

Mystery of Civil War sub's sinking may be solved

An oil painting by Conrad Wise Chapman, "Submarine Torpedo Boat H.L. Hunley, Dec. 6, 1863"
An oil painting by Conrad Wise Chapman, "Submarine Torpedo Boat H.L. Hunley, Dec. 6, 1863"
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An oil painting by Conrad Wise Chapman, "Submarine Torpedo Boat H.L. Hunley, Dec. 6, 1863"
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An oil painting by Conrad Wise Chapman, "Submarine Torpedo Boat H.L. Hunley, Dec. 6, 1863"
A diagram of the H.L. Hunley
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A diagram of the H.L. Hunley

On Feb. 17, 1864, outside Charleston Harbor, South Carolina, a Confederate submarine known as the H.L. Hunley sank a 1,200-ton Union warship, the USS Housatonic. It was the first combat submarine to sink an enemy ship. Mysteriously, however, the sub itself then also proceeded to sink, for no obvious reason. Now, Duke University PhD grad Rachel Lance believes that she knows what happened.

The wreck of the Hunley was discovered in 1995, approximately 300 meters (984 ft) from the remains of the Housatonic, and was subsequently raised in 2000. The 40-ft (12-m) submarine was almost entirely intact, and the skeletons of all eight crew members were still located along a hand crank that was used to propel it. The men hadn't operated the bilge pumps or opened the topside air hatches, which doesn't seem to be in keeping with the theory that they died from drowning or suffocation.

Instead, Lance thinks that they were killed by the shockwave from the explosion that sank the Housatonic.

A diagram of the H.L. Hunley
A diagram of the H.L. Hunley

The Hunley didn't shoot out self-propelled torpedoes like a modern sub, but instead carried a copper keg of gunpowder on a 16-ft (4.9-m) pole out in front of itself. The idea was that it would ram ships with that keg, hitting them below the waterline. Unfortunately for the sub's crew, this placed them perilously close to the blast zone.

In pond tests, Lance exposed a floating 6.5-ft (2-m) steel model of the Hunley to proportionally-scaled pressurized-air blasts and black powder explosions. Pressure sensors inside the model indicated that in a full-scale version of the setup, the force of such explosions would be sufficient to instantly cause fatal soft tissue injuries to the crew, particularly to their brains and lungs.

Although the Hunley was apparently subjected to test blasts when it was being designed, these were much smaller than the explosion that sank the Housatonic, plus the sub was located hundreds of yards away from them.

"Blast travels really far underwater," says Lance. "If you're practicing 200 yards away, and then you triple the size of your bomb and put it 16 feet away, you have to be at least aware that there's a possibility of injury."

A paper on her research was published this week in the journal PLOS ONE. There's more information in the following video.

Source: Duke University

Confederate Sailors on HL Hunley Killed by Their Own Weapon

4 comments
Bob
While the submarine design was a stroke of genius, it is hard to imagine that they thought they would be safe from a blast that close to their own vessel. If they could have stuck the charge and then backed away a few hundred feet, it would have been a very different story. It also seems odd that it took this long to figure out how they died.
Brian M
Seems a very plausible explanation but does beg the question was this the first Kamikaze underwater mission?
dougspair
...16 feet....What were they thinking...?
JohnAyer
I think the thought is that they meant to back off and detonate the explosion when they were as far away as they could get, but they somehow triggered it when they were just starting to pull away.
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