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www.sea-technology.com November 2015 / st 25 R ecently declassifed Navy archives show that the seabed- mapping side scan sonar used today in ocean surveys and undersea surveillance was frst conceived and devel- oped in the 1950s by scientists and engineers at the U.S. Mine Defense Laboratory (now the Naval Surface Warfare Center Panama City Division), Westinghouse Electric Corp. (now Northrop Grumman Corp.), and the Clevite Corp. In a 1954 U.S. Navy technical report, the inventor, Dr. Julius Hagemann, outlined the "Short-Range High-Defnition Mine Location Sonar" that would eventually become the C-MK-1 mine classifcation sonar system, more commonly known as "SHADOWGRAPH". Five years prior, in an effort to coordinate the develop- ment of mine location methods, the Navy's Bureau of Ships established an initiative at the Panama City Station to re- view and evaluate current capabilities, and to develop and test detectors for all types of sea mines. Until this point in time, the focus was on cutting mine tethers or infuencing them to explode in place by "sweeping" the waters with towed gear. The need for adequate mine "hunting" systems was driven largely by the increas- ing sophistication of the threats, which could be equipped with arming delays, ship counters (allowing a preset number of ships to pass overhead prior to detonation), and trigger mechanisms that were impervious to sweeping methods. Ju- lius Hagemann led the research and authored the technical portion of the 1950 U.S. Navy report "Review and Evaluation of Existing Mine Location Devic- es," which articulated the challenges in long- range detection, clas- sifcation, localization (DCL), and corroborative identifcation of bottom mines. The existent technology was primarily comprised of for- ward-looking and sector-scanning sonars. The report con- cluded that identifcation of bottom objects as to size and/ or shape was not possible with the present equipment and that "hope can be held that a sonar gear exhibiting a suf- fciently high picture defnition can be established through which the problem could be solved for mines on a hard and littered bottom." Hagemann was uniquely qualifed to provide the techni- cal leadership for developing such gear. Born in 1901 in the Silesia province of the German Empire, he was an of- fcer in the German Navy and an inventor of mine warfare technologies. After World War II, he and his family were relocated to the United States under Operation Paperclip, SHADOWGRAPH Side Scan Sonar Pioneering Technology Marks Beginning of Modern Naval Mine Hunting By Dr. Daniel D. Sternlicht • Dr. Kerry W. Commander • Jacqui L. Barker (Photo Credit: U.S. Navy) Vintage photograph of the SHADOWGRAPH sonar/vehicle and the inventor, Dr. Julius Hagemann. Note the curved array of the rear sonar section and the marker ejection manifold of the middle section. The bot- tom 2015 photograph shows one of the last surviving vehicle and winch assemblies, located at the Museum of Man In The Sea in Panama City, Florida.