80 THE NAVY OCEAN ENGINEERING PROGRAM 



Navy. These moors, in chronological order, have been designated as: Hard- 

 tack (1958), TOTO I (1959), Squaw (1959), TOTO II (1962), and Squaw 

 (1965). 



The Hardtack installation, in water as deep as 6000 ft, consisted of a 

 number of moors which held test ships for an underwater nuclear shot. 

 This program provided the initial concept for permanent deep sea moor- 

 ings. An experimental ship moor based on this concept was subsequently 

 evaluated in the Tongue of the Ocean, from which it received the designa- 

 tion TOTO I. The Squaw moors positioned a buoyant, but submerged, 

 model submarine huU for sonar training exercises. The Artemis and TOTO 

 II were specifically designed for positioning large ships in connection with 

 other underwater programs. 



Although each of these moors is representative of a somewhat different 

 design and installation problem, together they represent a logical sequence 

 in development of the current mooring technique. These moors will pro- 

 vide guidance for design and installation of future deep-sea ship moors. 



ACOUSTICAL OCEANOGRAPHY 



Since World War II, the Navy's underwater detection capabilities have 

 increased greatly. Increased knowledge of the effects of the ocean environ- 

 ment on underwater sound propagation, due primarily to the acoustic inves- 

 tigations of the Navy Ocean Science Program, has been an important factor 

 in the advancement of long-range sonar and underwater weapon systems. 



In addition to the direct path commonly associated with a sonar beam, 

 long-range sonars can take advantage of phenomena which exist under cer- 

 tain conditions: 



1. Surface ducts, shallow layers of warm water near the surface, which 

 carry sound waves long distances, as they are unable to penetrate the colder 

 water beneath. 



2. Convergence zones, which occur at regular intervals as the sound is 

 alternately refracted upward by penetrating colder water, and reflected 

 downward from the surface. 



3. Bottom bounce, in which mode the sound waves are bounced off the 

 bottom at an angle of incidence which projects them farther through the 

 water. 



Surface-duct transmission requires a strong, shallow thermocline, 

 convergence zone transmission requires deep water with the depth of mini- 

 mum sound velocity well clear of the bottom, and bottom bounce requires 

 that the ocean bottom be relatively flat and hard. Hence, continuous 



