The Navy Oceanographic Meteorological Automatic Device (NOMAD) buoy's 6-metre (20 ft) hull was originally designed in the 1940s for the United States Navy’s offshore data collection program. The United States Navy tested marine automatic weather stations for hurricane conditions between 1956 and 1958, though radio transmission range and battery life was limited.[5] Between 1951 and 1970, a total of 21 NOMAD buoys were built and deployed at sea.[6] Since the 1970s, weather buoy use has superseded the role of weather ships, as they are cheaper to operate and maintain.[7] The earliest reported use of drifting buoys was to study the behavior of ocean currents within the Sargasso Sea in 1972 and 1973.[8] Drifting buoys have been used increasingly since 1979, and as of 2005, 1250 drifting buoys roamed the Earth's oceans.[9]