Scientists unravel old mysteries to get inside the Hunley

Tuesday, February 6, 2001

BY BRIAN HICKS
Of The Post and Courier staff

     It is one of the more delicate phases of the Hunley excavation: This week 21st-century scientists will try their hand at reverse-engineering 19th-century technology.
     It's not nearly as simple as it sounds.
     On Monday, archaeologists working on the Confederate submarine Hunley removed the centimeter-thick layer of concretion - hardened sand and silt - from one of the panels covering the submarine's central compartment.
     Beneath the submarine's crusty covering, its hull is still a stealthy, slick black.
     Dr. Bob Neyland, the project manager, said scientists are looking for clues to what, if anything, may be fastened to those panels on the inside. Anything, that is, that could hinder the team removing three panels over the crew compartment for the excavation.
     It is much easier to take something apart when you know how it was put together. The Hunley scientists don't have that luxury, though. The fact that there were no plans or drawings of the Hunley only makes it more difficult. Conflicting historical accounts don't help, either.
     Mainly, the archaeologists are looking at the sub's rivets. As they uncover the rivets that hold the half-circle plates covering the crew compartment, they are looking for clues that the sub's steering rod is attached to the panels, too.
     To remove the plates, scientists will drill out the rivets for those panels - maybe as many as 100 on each. But if the steering rod is also attached to those panels, it could force the team to rethink its strategy.
     So far, Neyland says they have yet to find any trace that anything is attached to the inside of those panels. Nothing that would prevent them from going ahead with their excavation plan.
     "All we can do now is move forward," Neyland said.
     If all goes well, Hunley officials say the scientists could begin excavation of the crew compartment within a few weeks. But scientists have to ease into the sub, because they don't want to damage it when they remove hull panels. It is slow, precise work.
     About the best clue to the submarine's construction that the team has been able to get so far has come from the hole near the sub's stern. There, it appears the iron plates that form the hull attach to ribs.
     As has been the case throughout the investigation of the lost Confederate submarine, surprises have come daily. Scientists found that the rivets were attached from the inside out, with their ends sanded, giving the submarine a smooth, more hydrodynamic hull.
     Once they drill out a rivet or two, the scientists will try microscopic X-ray technology to try and see what's behind the panels of the sand-packed vessel.
     So far, that hard-packed interior has refused to give up any of the submarine's secrets.
     "Behind lead, wet sand is probably the best thing there is to stop X-rays," Neyland said.
     The first look at a study of the sediments in the Hunley's stern hole has been encouraging for the scientists. It shows that the sub did not move from the time the hole was made in the sub. Still no word on when that hole was made - or why.
     But that study gives scientists hope that where the Hunley was found off Sullivan's Island is exactly where it had been since 1864, when it failed to return after sinking the blockade ship USS Housatonic by ramming an explosive charge into its side.
     The Hunley was recovered 4 miles off Charleston Harbor last August after being lost for more than 130 years. It was discovered in May 1995 by a dive team funded by adventure novelist Clive Cussler. The sub is now being housed in a cold-water tank at the Warren Lasch Conservation Lab in North Charleston.
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     Confederate submarine Hunley researchers spent Tuesday investigating how the 10 deadlights on top of the sub's hull were attached.
     The lights, tiny round glass portholes, are in five rows of two on the top surface. They allowed sunlight into the crew compartment. A round iron seal, held in place by rivets, kept the glass pieces in place.
     "You probably have a lot of tar and goop to hold it together," added project manager Dr. Bob Neyland.
     Some of the rivets in the sub's hull were also drilled out Tuesday as scientists begin determining how difficult it will be to enter the crew compartment. The rivets are being sorted into three different categories: soft, medium or hard.
     Neyland said that in the 19th century, rivets were traditionally made with the left-over quality iron, and by calculating the strength of the rivets, scientists will get a better idea of how soundly the sub was put together in 1863.
     Work will continue on the recovered Confederate sub this week in preparation for opening the crew compartment later this month.