New clue? Hunley crew wasn't using air circulation system the night Confederate submarine sank ship, then vanished

Rendering shows snorkels above conning tower (Friends of the Hunley)

A new finding by those conserving the Confederate submarine Hunley revives the question of whether the eight-man crew ran out of oxygen after sinking a Federal vessel in Charleston Harbor.

A Friends of the Hunley press release this week said Clemson University researchers determined the doomed sub’s air circulation system was not in use when it made the historic February 1864 attack on the USS Housatonic.

During ongoing conservation, scientists and researchers found that a rubber hose connecting snorkel tubes to hand-pumped bellows was “intentionally disconnected and tucked underneath the crew bench.” The reason remains unknown.

The snorkel-bellows system was intended to pump out carbon dioxide and allow the replenishment of good air from the surface. The snorkel tubes were in a lowered position and not engaged during the attack, researchers said.

Set of bellows before, after conservation (Friends of the Hunley)

“The air circulation system is certainly one of many important clues to consider when trying to piece together the events of that night.” Clemson archaeologist Michael Scafuri said, according to the press release. “Still, this finding alone does not mean the Hunley crew perished from lack of oxygen.”

The Hunley could hold enough oxygen for the crew to survive for roughly two hours. There were two ways to replenish the supply.

“One was to use the air circulation system, which was designed to be stealth and allow them to discreetly get fresh air,” the release said. “The only other alternative was to come to the surface and open the hatches, a potentially dangerous move if enemy ships were nearby.”

Rubber hose was part of air circulation system 

Scientists say it is possible the builders were unable to perfect the air circulation design or when the system was not in use, the crew dismantled it to make more room in the cramped crew compartment.

The Friends group said the Hunley crew may have opted to stay well below the surface after sinking the Housatonic so as to escape detection. "If they miscalculated the timing or thought it was too dangerous to come back up to open the hatches for air, they may have slowly run out of oxygen to breathe."

On Feb. 17, 1864, the Hunley left its base on Sullivan’s Island, S.C., and placed its torpedo into the Housatonic, one of many blockade vessels on the edge of the harbor. Those on board desperately opened fire on the attackers. Five U.S. sailors were killed in the explosion and a chaotic scene ensued as other Federal ships came to the rescue. The Hunley vanished, and there have been many theories – but no proof -- of what happened to it.

Snorkel box before and after conservation (Friends of the Hunley)

Conserved snorkel tubes (Friends of the Hunley)

A 2017 archaeological report issued by the U.S. Navy, South Carolina Hunley Commission and Friends of the Hunley looked at theories on what might have happened. Among those are that a Federal vessel hit the sub, the Hunley submerged and eventually lost oxygen, a “lucky shot” brought torrents of water through a conning tower or the hull was breached. Since then, researchers found a broken intake pipe, indicating water may have flooded into the tiny war machine.

The organizations cautioned that it could have been a combination of factors that caused the disappearance.

But researcher Rachel Lance told CNN in 2017 that the crew died from blast injuries.

Shock waves from the torpedo detonation would have instantly killed those aboard the Hunley, she said. Such strong pressure would rupture lungs and damage neurons and blood vessels, she argued.

And she discounted the theory of suffocation.

Rachel Lance

After the Hunley was raised in 2000, conservators found the men were still at their stations, indicating there was no rush to escape or movement to bring air into the boat. There were no obvious physical injuries.

“The crew had about a 30-minute air supply before they would have had painful and uncomfortable symptoms from carbon dioxide,” Lance said. “They made no efforts to try to save themselves or bring air into the boat.”

The U.S. Navy and the Friends of the Hunley pushed back.

A week after the findings of her team were released, the Friends of the Hunley issued a press release that said Lance’s work is “unsubstantiated.”

“While the likely cause of the submarine’s demise has not been concluded, the scenario of a concussive wave killing the Hunley crew has been deemed not likely by those working on the actual submarine and who have access to this key data,” the organization said.

The Navy has questioned why World War II submariners survived close depth charges while the Hunley crew did not survive the torpedo blast. Lance said modern hull armor is much thicker and would have provided more protection.

Lance told a 2017 audience that the watch of sub commander Lt. George Dixon provides further evidence of the effects of a traumatic blast. The hands stopped at 8:23 p.m, the estimated time the torpedo went off.

Bellows before conservation (Friends of the Hunley)