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Hunley Update - Finally! - copyright 2003 Charleston Post & Courier

Place for general submarine conversation

Postby TMSmalley » Thu Jul 17, 2003 7:23 am

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The Hunley sits in the center of the drained conservation tank at the former Charleston Naval Base. More photos at the Post & Courier site - Post & Courier 7/13/03 Hunley story

Preservation team in uncharted waters
BY BRIAN HICKS
Of The Post and Courier Staff
When a group of dreamers and engineers built the H.L. Hunley in 1863, they were pushing the technology of the day beyond its limits. Now the people working to restore the world's first attack submarine are doing much the same thing.

As scientists prepare for the painstaking task of preserving the Confederate sub, they are being forced to invent new ways to gauge corrosion and preserve metal, all the while compiling handy research that could help make bridges and ships safer and keep cars from rusting as quickly.

In essence, the Hunley is fostering the science that ultimately will save it.

"In my opinion, it's a blessing the Hunley remained hidden for as long as it did," said state Sen. Glenn McConnell, the chairman of the Hunley Commission. "It was ahead of its time, and it waited to resurface until technology caught up with it again."

Had the Hunley been recovered just 30 years ago, contemporary conservation techniques most likely would not have been enough to preserve it. While most officials are confident that the sub now can be restored to an amazing degree, science still hasn't caught up enough to completely tackle the complex and unique problems of restoring a 140-year-old iron submarine.

Conservators with the Hunley project and materials science experts from Clemson University are working on new ways to stabilize the submarine and cure the unforgiving effects of nature that have been eating away at the sub's hull for more than a century.

In the next few months, these scientists will prepare for a process that could last several years. Archaeologists will excavate the last remaining crevices of the sub, its ballast tanks, and project officials will decide exactly how to extract the salt and chlorine from the metal, hoping to slow natural corrosion.

The problem is complex, but the goal is simple: They want to make sure the Hunley is around in another 140 years.

The challenge is that all metal is not created equal.

The Hunley appears to be made primarily from two distinctly different kinds of iron, wrought and cast. There were good reasons for this: Some parts of the sub were pound-ed into shape, and others were forged to serve as a particular part. Some shapes require a little more finesse than a hammer provides.


The two types of metal traditionally aren't conserved the same way because they corrode differently, and therein lies the problem. Unless the scientists can come up with a new method for conservation that can benefit both metals, they might have to take the sub almost completely apart to restore it.

Putting it back together again is a slightly scary prospect to some.

"We're trying to figure out how to conserve the whole boat without having to take it apart," McConnell said. "We don't want to do that until and unless we have to."

To excavate the sub, scientists so far have removed five hull plates, and they took off the sub's spar before it was recovered off Sullivan's Island in August 2000. The Hunley team would like to avoid disassembling the sub more, not because they couldn't put it back together again, but because they prefer to avoid any risk to what is perhaps the most complete shipwreck ever recovered.

That may be unavoidable, though, as the two differing types of metal are so co-mingled on the sub. For instance, it appears the propeller blades are bolted to the prop shaft, and they could be made of different substances.

To figure out the scope of this challenge, a team led by senior conservator Paul Mardikian and Mike Drews, a Clemson materials science professor, has surveyed the sub with a fancy looking ray gun that shoots fluorescent X-rays. The gun identifies whatever material it scans, solving one of Mardikian's first hurdles: He has to know what he's conserving to conserve it.


Unfortunately, it gets much more complicated. One of the questions that Drews has been looking at is how much corrosion there is between the seams of overlapping metal of the hull plates. There is a concern among some that the sub may have to be taken apart just to make sure the metal in those seams gets the same treatment as the rest of the sub.

The entire maritime archaeology community, including the Virginia team working on the USS Monitor, awaits the study's results.


BETTER NOW THAN THEN

Had the Hunley been recovered 30 years ago, it might not be around in its present condition. The history of maritime salvage operations in the past reads like a horror novel.

In the 1960s, the state of Mississippi partially bankrolled an expedition to recover the USS Cairo, a Civil War-era Navy gunboat that was instrumental in the Union's Western campaign. The Cairo was raised with seven loops of 3-inch cable around its wooden hull. During the lift, the 175-foot ship split open under its own weight, sending artifacts spilling into the river.

Perhaps even worse, workers later cut the ship into three pieces to salvage what they could, then left those pieces on a dock where the brutal Gulf Coast sun finished off two-thirds of the ship.

In the 1980s, Great Britain raised and tried to preserve the Holland 1, the first sub built for the Royal Navy. Lost while it was being towed in 1913, the Holland 1 was discovered in the 1980s, raised and carried ashore in Portsmouth.

The sub, which was cut into three pieces during the lift, had the barnacles scrubbed off it, and workers slapped a fresh coat of paint on it. Within years, rust and the salt buried in its hide began to eat the reassembled ship alive. It cost millions to preserve what was left.

The fate of the Hunley will be different. Conservation science has come a long way since the 1980s, and the Hunley project has pulled in resources from around the world to make sure the sub gets the best care. The lab already has such a reputation that other museums are sending maritime artifacts for care at the Warren Lasch Conservation Center on the old Charleston Naval Base.

Despite a reputation that is already solid, the project is pushing science in several areas. At the lab, scientists are trying to adapt the X-ray gun that identifies metal to measure chlorine and salt deposits in the hull. Not only would that help gauge the level of conservation needed, but also Drews said if the experimental technology works it will have major implications for construction.

"The corrosion studies we are conducting on the submarine could have ripple effects that extend far pass the confines of the Hunley conservation project." he said.

For instance, the guns, which are used industrially by petroleum organizations to test their pipelines, could be modified to inspect bridge pilings, trusses and supports. They even could be used to look for weak spots in ship's hulls. That would be a big change in the way things are done now.

"The only way we have to measure corrosion now is destructive," Drews said.

He also is working with Hunley project folks to come up with the best method to stabilize the Hunley's hull as much as possible. After the salt is removed and the metal is restored as best it can be -- the march of nature can never be stopped completely -- there probably will be some sort of sealant. But unlike the Holland 1, they won't be flat-blacking it with spray bombs anytime soon.

Ultimately, McConnell says the restoration process the Hunley undergoes will become a major part of the eventual sub museum. Through three centuries, during its construction, its recovery and its preservation, the H.L. Hunley has been pushing science into undiscovered realms.

"The science of preservation is part of this story, probably a full exhibit," McConnell said. "It's just another fascinating part of the story."




Edited By TMSmalley on 1058441178
Tim Smalley
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