Monday, April 11, 2016

3D sonar imaging will help confirm identity of Rebel blockade runner off N.C.

(Courtesy N.C. Office of State Archaeology)

A 3D sonar imaging device will aid divers next week as they continue to explore what’s believed to be the largely intact remains of the Civil War blockade runner Agnes E. Fry.

The North Carolina Office of State Archaeology on Monday said the Charlotte Fire Department offered the use of the technology for the investigation just off Oak Island, south of Wilmington.

Deputy state archaeologist Bill Ray Morris, in a statement, said the remains of the iron-hulled steamer match up with the Scotland-made Agnes E. Fry, one of three blockade runners that sank in the area.

“Fry was 236 feet long, and the vessel remains we have are 225 feet in length. The other runners, Georgianna McCaw and Spunkie are both considerably shorter and a much earlier design than Fry,” said Morris. “The boiler type, as well as the hull design of the wreck, are both indicative of a more modern vessel than either McCaw or Spunkie. The difference in the lengths has to do with the damage to the bow and stern.”

The wreck was first studied in late February with side-scan sonar images during remote sensing operations. Both engines and the paddlewheel shaft are missing, matching salvage records. Divers noted the missing pieces during a March 22 dive.

"Every piece of evidence we have examined to date, from sonar images to primary documentation, points directly to this shipwreck being Agnes E. Fry," said Gordon Watts of the Institute for International Maritime Research. "We look forward to working with the Charlotte team to confirm our suspicions." 

The Llama resembled the Agnes E. Fry (NCOSA)

Fire officials in Charlotte arranged for Nautilus Marine Group International, the company that provides sonar systems to its dive team, to bring the latest version of a sector-scanning imaging sonar to confirm the vessel’s identity

"This instrument will allow us to make a complete, multi-dimensional map of the site in a matter of days," Morris said in the statement. "Unlike usual methods, imaging sonar does not require good visibility and is considerably faster than on-site mapping. Visibility underwater on the site is so murky that it rarely exceeds 18 inches."

The Agnes E. Fry made several successful runs for the Confederacy before it ran aground near Wilmington in the closing months of the war.

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