By MATTHEW FRENCH
Staff Writer

When underwater explorers discovered the Confederate submarine H.L. Hunley just a few miles off the coast of Charleston in 1995, it was one of the most important maritime archaeological discoveries in history. The Hunley is the first submarine to ever sink another ship in battle.

And, after lying at the bottom of the Atlantic Ocean for 130 years, the fear that it would be damaged beyond repair proved to be unfounded. The Hunley now sits in a freshwater bath in North Charleston where scientists and academics work on a daily basis to preserve the vessel.

It has been one of the more critical historical tourist draws over the past four years since it was brought up from the ocean floor.

“Besides preserving history, this is an important part of our tourism economy,” says Dr. Robert Neyland, project director for Hunley preservation and the head underwater archaeologist for the U.S. Navy Historical Center. “The Hunley has become a very important factor in the Charleston and North Charleston area for attracting historical tourists.”

Neyland cites the case of the Swedish vessel Vasa, a 17th-century ship that was raised in the early 1960s and has been on display in Stockholm, Sweden. The Vasa has been such a popular draw that it attracts 850,000 visitors per year and accounts for 40% of the city’s tourism.

“The Hunley is a major draw to the Charleston area,” he says. “As is the USS Monitor in the Newport News, Va., area.”

In an ironic twist of historical fate, groups of scientists working on the Union ironclad Monitor and the Confederate Hunley are working together, trading techniques and information to help better preserve both vessels.

Officials from the Mariners’ Museum in Newport News, on the Southeastern coast of Virginia, which is the official repository of Monitor artifacts, have taken a page from Hunley preservationists in accelerating the removal of corrosion from the iron ship.

“We have pieces of the monitor, of the ship itself, such as the turret, engine, compressor and thousands of smaller pieces,” says Marcie Renner, chief conservator of the USS Monitor. “We’re very excited to be using some new technology that the Hunley folks are developing.”

Renner says experts at Clemson University, led by Paul Mardikian, senior conservator on the Hunley Project, and Mike Drews, the materials scientist heading the Clemson research team, have started using subcritical fluids for chloride extraction from the metal. Because of the submarine’s long submersion in seawater, the hull and all iron parts are coated in iron chlorides, which, when combined with oxygen, is one of the leading causes of rust and can lead to the rapid decay of iron. If left on its own, the hull of the boat could literally collapse and turn to iron dust.

Neyland explains that the method used to prevent this involves placing the metal object in a sealed chamber and raising both the temperature and pressure of the fluid. At a certain point where the fluid has the properties of both a liquid and gas, the chlorides and salts contained in the metal are diffused out.

“This has really raised the awareness of the scientific community of how chlorides penetrate metal over time,” he says. “Traditionally, getting chlorides out is a long process. It’s been doable with current technology, but it’s labor intensive, time intensive and costly.”

The standard method, which used electrolytic reduction to remove the chlorides, could often take years. The new method, says Renner, could reduce that time to months, or even weeks in some cases.

“With the Monitor, we are basically disassembling each piece we bring up, treating it, and re-assembling it in a new gallery,” she says.

Neyland says the new preservation method would be faster and less expensive, which will cause a trickle-down effect, all the way to the tourists venturing out to see the submarine.

“It removes the chlorides more rapidly and thoroughly,” he says. “That means it will save us time and bucks, which can be put into further restoration. That also means we can possibly get the artifacts on display more rapidly. Military icons like the Hunley and the Monitor are a very important source of national pride.”

Matthew French is a staff writer for the Business Journal. E-mail him at mfrench@crbj.com.

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