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Hunley hatch may open way to subs restoration

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Hunley hatch may open way to subs restoration

Postby TMSmalley » Tue Jan 09, 2007 9:17 am

By Brian Hicks -
Charleston Post & Courier

The metal has been stripped back to the 19th century, revealing sleek, Victorian curves that were hidden beneath a thick crust of sand and shell for more than a century.

If you look closely in the orange oxidation now dusting the surface of the Hunley's aft hatch, you can see distinctive little black streaks, evidence that 130 years' worth of ocean salt soaked into the metal is now, slowly, leaching out.

After six years of archaeological digs and investigative work on the Civil War submarine, scientists have begun restoring the Hunley. Before the entire sub undergoes treatment, they are testing their Navy-approved conservation technique on one of the trickiest pieces of it: a 95-pound, cast-iron hatch.

The hatch, 16.5 inches wide and nearly 21 inches long, is sitting in an alkaline solution bath, a slight electrical charge running through the water, in the middle of the Hunley lab, where scientists can monitor it daily.

The cast iron is much more fragile and difficult to preserve than the wrought iron most of the sub's hull is constructed from, so Hunley officials figure if the chemical bath can restore the hatch, it will work for the rest of the sub.

"This will tell us if the current technology will remove the salts from the crevices and seams of the submarine," Sen. Glenn McConnell, chairman of the state Hunley Commission, said Friday. "The more we see of the sub, the more I'm glad we've gone with the conservation plan we have. I don't want to disassemble this fine craftsmanship."

Paul Mardikian, the senior Hunley conservator, said he should be able to tell in six months whether the process is going to work.

Scientists had considered taking the sub apart, treating the wrought iron differently than the cast pieces, but in the end decided that would rob the Hunley of some of its historical integrity. A treatment that conceivably could speed the process along is still being tested. If the process is perfected in the next few years, it could play a part in restoring the sub.

For now, there is little to do but let the hatch soak, although the alkaline chemicals have to be changed regularly, as exposure to air dilutes them.

The work on the hatch is something of a milestone. Since the sub's recovery in 2000, scientists have refrained from removing any of the concretion stuck to its hull. The hard shell of sand has acted much like the cold water the Hunley currently soaks in, keeping it stable without actually helping or hurting it.

To ready the hatch for the alkaline bath, the concretion was chipped off it, revealing its true shape, curved with a low profile, which Mardikian compared to a World War I soldier's helmet. Mardikian says it's just further proof that Conrad Wise Chapman's 1863 painting of the sub in Mount Pleasant is the most accurate record of the Hunley. It looks exactly the way Chapman depicted it.

"The shape, the slope, it just looks like the 19th century," Mardikian said.

Plans call for the complete restoration of the Hunley, the first submarine to sink an enemy ship in battle, to be finished by 2013.

As for this first step into that process, Clemson material science professor Mike Drews says it could be up to two years before the hatch is completely restored.

Ultimately, Mardikian expects that their methodical testing, planning and worrying is going to pay off handsomely.

"You will not fall asleep looking at the sub when we finish," Mardikian said. "It's going to look fantastic."

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Tim Smalley
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