It sounds pretty simple: raise the H.L. Hunley a few feet off the ground, tilt it upright and set it down.
But it’s a little more complicated than that.
This week scientists at the Warren Lasch Conservation Center will begin work on a Hunley rotation plan that is more than a year in the making – a complex engineering procedure designed to move the fragile iron sub without damaging it.
Start to finish, it should take a little more than a week.
When the work is done, archaeologists will be able to examine areas of the sub’s hull hidden for more than a decade by its original lifting straps. And that could reveal clues as to why the Hunley sank in 1864 just after it became the first submarine to sink an enemy ship in battle.
“We will see what no one has seen since the crew did on the night it disappeared,” said Sen. Glenn McConnell, chairman of the state Hunley Commission. “You’ll be able to see the Hunley unobstructed. It’ll be a sight to behold.”
When the Hunley was raised from the Atlantic in August 2000, it was brought up at a 45-degree angle – which is how it was found lying 5 feet beneath the ocean floor.
Scientists wanted to keep it at that attitude to keep from shifting the placement of artifacts inside the sub, and because no one knew how weak the iron hull was after more than a century in saltwater.
Since then, the sub has been excavated and had several hull plates, keel blocks and other pieces removed. It has changed the structural integrity of the sub, and made this job more complex.
“There is no recipe for rotating Civil War submarines,” said Paul Mardikian, senior conservator on the project. “This is just as complicated, or maybe even more complicated than raising it from the ocean floor.”
Of course, there is a recipe now – one that Hunley scientists and Clemson University professors have worked on for years. Scientists developed a 3-D model of the sub, studied weight distribution and stress factors. They looked at several ways to do it, and computer modeling showed that not all of them worked.
On Wednesday, workers will raise the sub – still in the truss used to pull it from the ocean – 3 feet off the floor of its holding tank. That’s the first step.
Then a track and keel blocks, built and donated by Detyens Shipyard, will be put under the sub. The 30 padded lift straps holding the 40-foot hull will be replaced by 15 new straps that will allow workers to slowly rotate the sub clockwise, an inch at a time, until it is upright. Lasers will make sure the Hunley does not warp in the move.
Ultimately the Hunley will be lowered onto the track and held in place with lateral supports.
Archaeologists hope an unimpeded view of the sub’s starboard side will offer some hints about its fate on the night of Feb. 17, 1864, when it sank the USS Housatonic off Sullivan’s Island.
At the very least, this is the next step in a long restoration process. Once the Hunley is free of its lifting straps, conservators can begin a year-long process of removing the concreted sand and shell from its hull. After that, the sub will begin a multi-year bath in caustic solutions to finish restoring the 148-year-old sub.