College of Engineering, Computing and Applied Sciences; Research

High-tech history: 160 years after making history, the H.L. Hunley submarine foretells the future of technology


It was one of the Civil War’s most technologically advanced weapons. The H.L. Hunley was a 40-foot submarine built out of iron and powered by a hand-cranked screw propeller.  

The Confederate vessel secured its place in history on Feb. 17, 1864, when it set off 135 pounds of black powder along the hull of the USS Housatonic and became the first submarine to sink an enemy ship in battle. The Hunley and its eight crew members were lost to the waters off the coast of Sullivan’s Island that cold night, and five from the Housatonic were also killed.  

On the 160th anniversary of those events in 2024, the sub that transformed naval warfare is back at the forefront of technological innovation, but in a way that none of its 19th-century creators could have predicted. 

The H.L. Hunley has been the center of a multi-agency, conservation-and-education effort since it was raised from the depths in August 2000 and moved to the Warren Lasch Conservation Center in North Charleston.  

Clemson University conservation scientists, archaeologists, conservators, and historic preservationists are playing a central role by leading the scientific work that is telling the story of the Hunley and its crew while conserving the vessel and its artifacts for posterity. 

A long white room with lab tables illuminated by florescent lights with a female student wearing a lab coat seated and bent over a table while a male student in a lab coat walks in the background.
Students Patricia Ploehn (left) and Melissa Allen use cutting-edge technology to study the H.L. Hunley submarine, which is housed at the the Warren Lasch Conservation Center in North Charleston. There, researchers have unique access to state-of-the-art technology, including scanning-electron microscope, Fourier-transform infrared spectroscopy, X-radiography and 3D laser scanners, which they use to inform conservation and preservation research.

Stéphanie Cretté, the center’s director, said its affiliation with the University gives researchers unique access to state-of-the-art technology, including scanning-electron microscope, Fourier-transform infrared spectroscopy, X-radiography and 3D laser scanners. 

With their expertise and sophisticated equipment, the center’s researchers have pioneered new conservation methods, including a subcritical technique to desalinate metal, especially iron.  

“The cherry on top is that we are in Charleston, where history and preservation developed early on, so we have a good network of collaborators,” Cretté said. “Our technologically advanced facilities and partnerships with multiple agencies are what make us unique.” 

When a submarine sinks and is found

For 131 years after the Housatonic‘s sinking, the Hunley‘s whereabouts remained a mystery. Its location was verified in 1995, when a team led by author and explorer Clive Cussler found the sub buried under silt in about 30 feet of water four miles off Sullivan’s Island. 

The Hunley, secure at the center 24 years after its raising, is again submerged. But this time it’s in a tank of sodium hydroxide, a solution that pulls salt and chlorides out of the iron.  

A man wearing a mask and a blue uniform and blue ball cap turned backward is holding a tool beside the metal shell of a recovered submarine, the H.L. Hunley

While the solution does its job, researchers are branching out beyond the Hunley to apply their expertise to other artifacts. They include a 4,000-year-old Native American dugout canoe and the International African-American Museum collection. 

Those efforts and future collaborations will give Clemson researchers plenty to do long after their work with Hunley is completed. But researchers said their job with the sub is far from over. 

Michael Scafuri, senior archaeologist, likened the Clemson team’s work to crime-scene investigation. 

“We process a site or scene and collect evidence and try and see what it tells us,” he said. “What we’re trying to do is get as close as we can to understanding this event in the past. We’re trying to understand what these people did and why they did it, their motivations and what came out of it.” 

 Johanna Rivera, senior conservator, has been working to protect the Hunley’s artifacts. They include, for example, the silver suspenders, gold pocket watch and binoculars believed to have belonged to its captain, George E. Dixon. 

“We are trying to bring things back to their state before the sinking event– bringing objects back to life, if you will,” Rivera said. “That challenge– to try and work with the material and to try to reverse time a little bit– is the best part about my job.” 

An aerial view of the H.L. Hunley submarine surrounded by framing and covered in rust while people in blue uniforms work on it.
This 2015 photo of the Hunley shows restoration efforts in action. In 1995, the sub was found buried under silt in about 30 feet of water four miles off Sullivan’s Island. The Hunley is now secure at the secure at the Warren Lasch Conservation Center in North Charleston, 24 years after its raising and 160 years after it sunk. Today, it is again submerged.The submarine is housed in a tank of sodium hydroxide, a solution that pulls salt and chlorides out of the iron.

History and stories of people recovered

Nicholas DeLong, a maritime archaeologist, has focused on personal artifacts, specifically the crew’s shoes, as well as clothing, textiles, and buttons. 

“What they were wearing can tell us about the crew members themselves and how that plays into the bigger, overarching time period of the Civil War in Charleston,” DeLong said. “What they were wearing can also tell us a little bit about how they perceived their actions, what kind of unit they were, their cohesion.” 

To understand cohesion in efforts to restore the Hunley, one need look no further than Clemson’s partnership with Friends of the Hunley. 

The University and the nonprofit share the Warren Lasch Conservation Center. Friends of the Hunley runs an exhibit that tells the sub’s story and displays some of its restored artifacts. The nonprofit offers weekend tours that allow the public a glimpse of the sub in its tank. 

“Collaborations with partners such as Clemson University are critical to illuminating an important piece of our nation’s rich naval heritage,” said Kellen Butler, president and executive director of Friends of the Hunley. “We look forward to continuing to work with Clemson to conserve the Hunley and its artifacts for future generations.” 

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