[image-1]For the first time since the disappearance of the H.L. Hunley, experts are closer than ever before to seeing the Confederate submarine as it originally appeared in 1864.

Following a lengthy and ongoing effort to restore and preserve the first successful combat submarine, a team at Clemson University’s Warren Lasch Conservation Center revealed the inner workings of the Hunley on Wednesday. Soaking the vessel in low concentrations of sodium hydroxide has allowed researchers to slowly break away the tough layers of sand, sediments, and corrosion that accumulated on the Hunley over the 136 years that it spent submerged off the coast of Charleston. This effort has revealed the structural features of the Civil War submarine and provided experts with a better view of the interior of the vessel.
[embed-2] “The hull is exposed in its entirety on the exterior, so they’re going to be able to see the submarine as it was originally constructed. It looks like a submarine now as opposed to a corroded artifact,” said Clemson archeologist Michael Scafuri, who has been working on the Hunley since 2000. “The design of the submarine will be visible. The features that were hidden before are now exposed. Basically, it looks like a submarine now more than ever.”

Among the most significant discoveries is the tooth of crewmember Frank Collins, which had detached after his death and lodged in a layer of corrosion inside the submarine. Collins’ remains were buried in 2004 along with his seven fellow crewmates. The discovery was not a total surprise as researchers noticed several teeth missing from Collins’ remains at the time of the burial.

[image-2]While the ultimate goal at the Warren Lasch Conservation Center is to restore the Hunley to its original state and display the submarine to the public, there remains a considerable amount of mystery surrounding the sinking of the vessel following an attack on the Union ship USS Housatonic.

“There’s still a lot of things we don’t understand about how the submarine worked and about what happened the night of the attack on Feb. 17, 1864. We’re still trying to answer a lot of the questions that we have,” says Scafuri. “To be here and to be a part of it is exciting for me because I have a chance to solve these mysteries that have been lingering for so many years.”

In 2016, researchers from Duke University and the Naval Surface Warfare Center examined one leading theory regarding the cause of death for the Hunley crew — suffocation. Published in Forensic Science International, the study attempted to estimate the amount of oxygen available to the eight-man crew packed inside the Hunley’s roughly 4-foot-tall hull.

Researchers say that the Hunley had sunk twice on two failed training missions before the final attack on the Housatonic. Former crewman Williams Alexander wrote that the bellows designed to circulate air within the submarine never functioned properly and crews relied on opening the tower hatches of the Hunley every 20 minutes to obtain fresh air.  [content-1] The Hunley’s eight-man crew stood between 5-foot-5 and 6-foot-1, with seven men responsible for operating the hand crank that powered the vessel and the eighth man serving as the commander and navigator. Based on the size of the Hunley and the physical exertion of its crew, researchers estimate that the crew would have had between 35-47 minutes once fully submerged before losing consciousness from lack of oxygen. But in analyzing the oxygen supply aboard the ship, researchers also considered the increase of carbon dioxide within the Hunley, which would have become apparent to the crew long before they lost consciousness.

An estimated 17-24 minutes would have passed before the crew began to experience the effects of hypercapnia from elevated consumption of carbon dioxide, which would have resulted in extreme physical discomfort. Considering that the crewmembers were found seated at their original stations within the submarine, these experts suggest that it is unlikely that asphyxiation was what led to the sinking of the Hunley.

“Even with conservative calculations, the entire crew would have been experiencing noticeable hyperventilation, gasping for breath, choking, symptoms of panic, and possibly physical pain a minimum of 10 minutes before any risk of loss of consciousness,” the researchers wrote. “It is not plausible that the crew would have ignored these strong symptoms and not attempted to open the hatches.”