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Cape Hatteras. Two years later, it became NOAA's first National Marine Sanctuary. In 1998 NOAA and the Monitor National Marine Sanctuary (MNMS) submitted a long-range plan for the recovery of significant portions of the Monitor to Congress. Under the lead of MNMS Manager Dr. John Broadwater, NOAA and the US Navy began work that same year with the successful recovery of the ship's propeller. Like the vessel itself, the propeller was designed by the Swedish inventor John Ericsson-one of the two people credited with designing the first screw propeller. Ericsson held over 100 patents on USS Monitor, including everything from the ringer on the ship's bell to the rotating gun turret. It was his design that rook the US Navy
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more than 230 tons, the turret and all of its contents, including the two 11-inch Dahlgren guns, broke the surface for the first rime in 140 years. All of these artifacts are being conserved at The Mariners' Museum in Newport News, Virginia. NOAA and the Navy conducted these major recovery expePhotos of the ship ditions off a 300-foor barge with before the turret a remotely operated vehicle and a was recovered. The submersible, as well as dozens of ship rests inverted surface supplied and saturation on the seabed and divers. Separate from this massive was on top of the turret. The longitudinal feature operation, with its industrial cranes is Monitors massive armor belt. and loud thrumming of generators, to battle in 1862 against the Confederate another dive ream quietly carried out a difironclad, CSS Virginia, ushering in the age ferent, bur viral mission. A small group of of modern naval warfare. fewer than 20 people, including divers and In 2001 NOAA and the navy recov- support from NOAA, NURC, US Navy, ered Monitor's vibrating side-lever engine East Carolina University, and diving safety and the following year raised Ericsson's officers from several universities, worked most famous invention, the world's first off a 65-foor research vessel to document rotating gun turret. At a total weight of the wreck in situ. Their task was to keep an archaeological reIn August 2002, the historic gun turret from USS Monitor cord of the changes was successfully recovered from the ocean floor. (and damage) made to the wreck sire by these major artifact recoveries. This same dive ream had assisted the larger joint NOAA/US Navy expeditions since 1998 by measuring the details of the wreck and removing artifacts that might be endangered by the removal of portions of the hull. That mission 26
changed dramatically after the turret's recovery in 2002 and the completion of the final phase of the long-term recovery plan. From that date on, the NOAA divers operated independently to document the site in greater detail, using both traditional archaeological mapping techniques as well as the latest in digital photography. The 2003 field season lasted just 3 weeks in July and August of 2003, but the weather, of course, still had a major role to play. Cape Hatteras refused to give up its secrets without a fight, and the team lost half of its planned dive days due to the tempestuous offshore conditions. Because the team used conventional scuba equipment rather than saturation diving, they faced certain limitations. At a depth of more than 230 feet, Monitor divers can only spend 25 minutes on the bottom before having to make their slow ascent to the surface. During their ascent, divers must spend at least 80 minutes decompressing before they can safely head to the surface. NOAA created a breathing gas mix of 18% oxygen, 50% helium, and 32% nitrogen, called trimix, specifically for Monitor divers. Though this system has an impressive safety record, the 25 minutes it allows on the wreck is not a lot of time to work on an archaeological site. To deal with such tight time restrictions, the dive team used digital photography and video documentation to make make the most of their short visits to the bottom. Once on the sea floor, it proves extremely difficult for divers to comprehend the entire site. Most dives leave them with just enough time to swim to their specific area on the wreck, gatl1er the data, and start their ascent. This makes it very difficult for archaeologists to understand what's occurring at the site overall. To combat this, MNMS created a technique to produce digital mosaics of the entire length of the wreck site. We established a baseline parallel to the length of the Monitor's armor belt but offset by 15 feet. A diver with a digital camera was then sent along the line while maintaining a constant depth and rook a series of photographs from bow ro stern. On the surface, the photographs were stitched together with computer software. Using this technique, both rhe port and starboard sides of the SEA HISTORY 108, AUTUMN 2004