page_title: Radio acoustic ranging
section_title: The cruise of the Guide
hierarchical_section_title: Radio acoustic ranging / Development history / The cruise of the Guide
caption_attribution_description: English: United States Coast and Geodetic Survey survey ship USC&amp;GS Guide
context_page_description: Radio acoustic ranging, occasionally written as "radio-acoustic ranging" and sometimes abbreviated RAR, was a method for determining a ship's precise location at sea by detonating an explosive charge underwater near the ship, detecting the arrival of the underwater sound waves at remote locations, and radioing the time of arrival of the sound waves at the remote stations to the ship, allowing the ship's crew to use true range multilateration to determine the ship's position. Developed by the United States Coast and Geodetic Survey in 1923 and 1924 for use in accurately fixing the position of survey ships during hydrographic survey operations, it was the first navigation technique in human history other than dead reckoning that did not require visual observation of a landmark, marker, light, or celestial body, and the first non-visual means to provide precise positions. First employed operationally in 1924, radio acoustic ranging remained in use until 1944, when new radio navigation techniques developed during World War II rendered it obsolete.
context_section_description: In late November 1923, with Heck aboard, Guide began a voyage from New London via Puerto Rico and the Panama Canal to San Diego, California, where she would be based in the future, with her route planned to take her over a wide variety of ocean depths so that she could continue to test her echo sounder. Guide made history during the voyage, becoming the first Coast and Geodetic Survey ship to use echo sounding to measure and record the depth of the sea at points along her course; she also measured water temperatures and took water samples so that the Scripps Institution for Biological Research (now the Scripps Institution of Oceanography) at La Jolla, California, could measure salinity levels. She also compared echo sounder soundings with those made by lead lines, discovering that using a single speed of sound through water, as had been the previous practice by those conducting echo sounding experiments, yielded acoustic depth-finding results that did not match the depths found by lead lines. Before she reached San Diego in December 1923, she had accumulated much data beneficial to the study of the movement of sound waves through water and measuring their velocity under varying conditions of salinity, density, and temperature, information essential both to depth-finding and radio acoustic ranging.
  Upon arriving in California, Heck and Guide personnel in consultation with the Scripps Institution developed formulas that allowed accurate echo sounding of depths in all but the shallowest waters and installed hydrophones at La Jolla and Oceanside, California, to allow experimentation with radio acoustic ranging. Under Heck's direction, Guide then conducted experiments off the coast of California during the early months of 1924 that demonstrated that accurate echo sounding was possible using the new formulas. Experiments with radio acoustic ranging, despite initial difficulties, demonstrated that the method also was practical, although difficulty with getting some of the explosive charges to detonate hampered some of the experimental program. In April 1924, the Coast and Geodetic Survey concluded that both echo sounding and radio acoustic ranging were fundamentally sound, with no foundational problems left to solve, and that all that remained necessary was continued development and refinement of both techniques during their operational use. Heck turned over continued development of echo sounding and radio acoustic ranging to Guide's commanding officer, Commander Robert Luce, and returned to his duties in Washington, D.C.
caption: USC&GS Guide was a survey ship in commission in the U.S. Coast and Geodetic Survey fleet from 1923 to 1941. She was the first ship to employ radio acoustic ranging operationally.
exif: {}