Thursday, May 21, 2015

Navy divers prep for mission to raise Civil War ironclad

Lance M. Bacon, Navy Times
19 May 2015

JOINT EXPEDITIONARY BASE LITTLE CREEK-FORT STORY, Va. – A team of Navy divers spent a week in mid-May preparing for an historic salvage of a Civil War ironclad scuttled more than 150 years ago.
Mobile Diving and Salvage Company 23 will deploy to Savannah, Georgia, on June 1 to free the Confederate States Ship Georgia from her watery grave. The operation, expected to take just under two months, is to recover wreckage in five groupings; forward and aft armor casements; engine remnants such as boilers, shafts and propellers; four cannons; and live ordnance.
The number of projectiles is still under evaluation by on-site archaeologists, but most of them are believed to be lying atop the river bottom, said CWO3 Jason Potts, commander of MDSC-23. Explosive ordnance disposal divers from Mobile Unit 6 Detachment, Naval Submarine Base Kings Bay, Georgia, will place the ordnance in handling fixtures specially designed for this mission, then turn it over to Marine Corps EOD technicians.
Potts' 20-man team will then move in for artifact recovery. A specialized rigging plan and purpose-built handling fixture was developed to safely salvage each artifact. The pieces are 35 to 50 feet deep, relatively shallow for a Navy diver, but some are half buried in the muddy riverbed. That means the "bottom work" will require underwater jetting, vacuum and pumping systems. Some sections of the ship will have to be segmented because they are simply too large to handle, Potts said. Divers will use a variety of hydraulic tools to separate then lift the armor for later preservation.
The divers will submerge in two-man teams for optimal safety and efficiency. One diver will tend umbilical and tool lines while the other works the site. Each team will remain underwater approximately 90 minutes.
That may sound like an easy day. Think again. The work is physically grueling. It takes roughly twice the energy to perform a task underwater as topside, and that is before you add up to 100 pounds of weights, a muddy working surface, and opposing currents. When tools and rigging are added to the mix, exertion levels quickly compound. The jetting nozzle alone kicks out 150 psi – enough to send a diver tumbling if not for the back thrust that holds him in position. Therefore, each team will dive a few times a week but never twice in one day.
The biggest challenge is the environment, said Potts, who has more than 15 years in the diving community. The wreckage is on the edge of a shipping channel (the salvage is needed to allow an expansion of that channel). That location means divers will deal with strong currents and ever-changing debris. Navy Meteorology and Oceanography will identify periods of slack water to maximize efficiency and safety.
"You're dealing with something that's been down there for 150 years; I can't imagine that any part will be easy," said Navy Diver 2nd Class Jonny Pounders.
There is no need for an underwater elevator in such depths, so tenders topside will control all vertical movements with "mandraulics." Once lowered, visibility will be zero. It is unlikely a diver will be able to see his hand even when pressed against his faceplate, so everything will be done by feel. If a diver needs a different or replacement tool, the diving supervisor will use the bubble plume to mark the diver's location (the bubbles are slightly behind the diver's actual location), then guide him to the drop spot.
This surface-supplied diving method is common for underwater salvage, but the target ship is anything but common. Despite the pressure inherent in such a high visibility mission (leaders at the highest levels are well aware of every step taken), the divers calmly proceeded through preparatory training with calm resolve. Indeed, Potts is confident the Navy, and the nation, has the right team to retrieve the historic artifacts.
"Their proficiency has really never been higher," he said of the team, which recently returned from a six-month deployment to Central Command and Africa Command that included daily dives. "They are very well prepared for the operation, and have been progressing exceptionally well."
The Historic Target
The CSS Georgia was built in 1862 in Savanna. Confederate soldiers provided the bulk of the labor force; the Ladies Gunboat Association provided the funding. The group raised $115,000 to build a ship to protect their city.
The ironclad served its purpose, but wouldn't have been candidate for the "Battle E" ribbon had it existed at the time. The vessel leaked badly, likely a result of using unseasoned wood in her construction. According to historic accounts, the ship had a double engine with twin propellers, but was hardly maneuverable. The engines could not provide the force necessary to drive the heavy vessel against the Savanna River's swift currents. That could be why the ironclad, designed to carry 10 heavy guns, had only four heavy and two light guns at the time of her sinking.
Indeed, there are more questions than answers when it comes to CSS Georgia. What was believed to be the only existing photo of the ironclad was revealed to be a hoax in April, and original plans do not exist, so historians have little more than contradictory contemporary accounts on which to rely. But era engravings as well as eyewitness descriptions suggest the vessel was 160 feet in length with a beam of 55 feet and a 10-foot draft, with a single smokestack projecting from the top. A double layer of interlocked railroad iron weighing more than 1,500 tons was fixed atop 15 inches of solid timber and covered with cement filled with iron filings. The 24-foot iron walls rested at a 45-degree slope.
The ship was scuttled on Dec. 20, 1864, as Gen. William T. Sherman's Union troops seized the city she was built to protect. She was roughly five miles from Savannah, off Old Fort Jackson on the north edge of the Savannah Harbor navigation channel.
The wreckage, which is listed on the National Register of Historic Places, was inadvertently discovered during dredging operations in 1968. Navy divers retrieved a 64-square-foot section of the warship on Nov. 12, 2013. This enabled further analysis that green-lighted a $14 million plan by the Army Corps of Engineers to raise the wreckage so Savannah Harbor could expand.
"It's an honor to even be part of something like this," Pounders said. "It's a great honor for me personally. It's a huge part of history, it's a tragic part of history. I think it's good that we remember things like this, and that the nation, parts of the nation or whoever gets to see this, remember that these things happen, and we can always learn from something like that."

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