How do ocean explorers know where to look when they investigate and document the historical secrets of the deep? Well, archaeological expeditions use a myriad of modern surveying technologies. Recently, when NOAA’s Monitor National Marine Sanctuary was investigating a World War II underwater battlefield site, they called on a surveying expert with NOAA’s Coast Survey to assist.
Vitad Pradith, a physical scientist with Coast Survey’s Navigation Services Division, joined a sanctuary team for a week, to provide ocean depth information for the marine archaeology site off North Carolina’s Outer Banks. Pradith and the sanctuary scientists onboard NOAA National Marine Sanctuary Vessel SRVx combined previous depth soundings with new data acquired by sonar to facilitate safe operations of an autonomous underwater vehicle looking for wreckage in depths exceeding 300 feet.
The team also prepared to follow up on items discovered during the 2011 Battle of the Atlantic Expedition. Pradith trained sanctuary archaeologists to use a magnetometer that will detect metal even if it is buried under the sea floor. With the magnetometer, teams can go back to previous contacts to investigate “items of interest” that were barely distinguishable with sonar. This particular sensor enables scientists to visually map the magnetic fields of the contacts to help discover vessels lost in battle.
COAST SURVEY AND THE ATLANTIC COAST DURING WORLD WAR II
This isn’t the first time that Coast Survey experts are involved in World War II wrecks on the Atlantic Coast. Following the attack on Pearl Harbor, the Coast and Geodetic Survey expanded rapidly and devoted virtually all of its resources to the successful prosecution of the war effort. They provided ships, personnel and, of course, charts.
“At the beginning of WWII, the C&GS annually produced about 800,000 nautical and aeronuatical charts, and related products,” explains Albert ‘Skip’ Theberge, a noted NOAA historian. “The comparable figures for the last year of the war were approximately 23 million publications. These included the normal suite of domestic nautical and aeronautical charts, but then the agency added aeronautical charts of foreign territories, target charts for aerial bombing, and other special charts.”
Two of those special charts, produced by the U.S. Coast and Geodetic Survey in 1942, were classified “restricted” — for purposes of anti-submarine warfare — until they were declassified in 1982. Bottom characteristics were mapped by the Woods Hole Oceanographic Institution for the National Research Defense Committee and overlaid on Coast and Geodetic Survey charts. The sunken ship locations, determined by C&GS, were also noted on the charts. See:
- Cape May to Cape Hatteras, published Sept. 1942, by the U.S. Coast and Geodetic Survey, L.O. Colbert, Director (declassified 2/21/84)
- Cape Hatteras to Charleston Light, published Sept. 1942, by the U.S. Coast and Geodetic Survey, L.O. Colbert, Director (declassified 2/21/84)
Theberge points out that “because of enemy submarine attacks, the Atlantic coast was strewn with shipwrecks that constituted major hazards to navigation. They were also mistaken for potential submarines ‒ thus the need to chart their location both for navigation and defense purposes.”
“In 1943 and 1945, USC&GS surveyors used a primitive sidescan system, coupled with an early marine magnetometer, camera system, and recording fathometer for locating and identifying wrecks,” he says. “The project’s primary objective was to develop methods for anti-submarine warfare but it also served as a model for modern hydrographic search methods.”