Prior to the advent of sidescan sonar, wire-drag surveying was the only method for searching large areas for obstructions and lost vessels and aircraft. Between 1906 and 1916, Heck expanded the capability of wire-drag systems from a relatively limited area to sweeps covering channels in width. The wire-drag technique was a major contribution to hydrographic surveying during much of the rest of the 20th century. So valuable was wire-drag surveying in the United States that for decades the U.S. Coast and Geodetic Survey, and later the National Oceanic and Atmospheric Administration, fielded a pair of sister ships of identical design specifically to work together on such surveys. USC&GS "Marindin" and USC&GS "Ogden" conducted wire-drag surveys together from 1919 to 1942, USC&GS "Hilgard" (ASV 82) and USC&GS "Wainwright" (ASV 83) took over from 1942 to 1967, and USC&GS "Rude" (ASV 90) (later NOAAS "Rude" (S 590)) and USC&GS "Heck" (ASV 91) (later NOAAS "Heck" (S 591)) worked together on wire-drag operations from 1967.