INTRODUCTION TO SONAR 



a time fuze. After repeated failures to force the 

 screws through the copper sheathing of the hull 

 of HMS Eagle, the submarine gave up and with- 

 drew, exploding its powder a short distance from 

 the Eagle. Although the attack was unsuccessful, 

 it caused the British to move their blockading 

 ships from the harbor to the outer bay. 



On 17 February 1864, a Confederate craft, a 

 hand-propelled submersible, carrying a crew of 

 eight men, sank a Federal corvette that was 

 blockading Charleston Harbor. The hit was ac- 

 complished by a torpedo suspended ahead of the 

 Confederate Hunley as she rammed the Union 

 frigate Housatonic, and is the first recorded 

 instance of a submarine sinking a warship. 



The submarine first became a major com- 

 ponent in naval warfare during World War I, 

 when Germany demonstrated its full potentiali- 

 ties. Wholesale sinking of Allied shipping by 

 the German U-boats almost swung the war in 

 favor of the Central Powers. Then, as now, the 

 submarine's greatest advantage was that it could 

 operate beneath the ocean surface where de- 

 tection was difficult. Sinking a submarine was 

 comparatively easy, once it was found — but 

 finding it before it could attack was another 

 matter. 



During the closing months of World War I, 

 the Allied Submarine Devices Investigation Com- 

 mittee was formed to obtain from science and 

 technology more effective underwater detection 

 equipment. The committee developed a reasonably 



accurate device for locating a submerged sub- 

 marine. This device was a trainable hydrophone, 

 which was attached to the bottom of the ASW 

 ship, and used to detect screw noises and other 

 sounds that came from a submarine. Although 

 the committee disbanded after World War I, 

 the British made improvements on the locating 

 device, during the interval between then and 

 World War II, and named it asdic after the 

 committee. 



American scientists further improved on the 

 device, calling it sonar, a name derived from the 

 underlined initials of the words sound navigation 

 andjianging. 



At the end of World War H, the United States 

 improved the snorkel (a device for bringing air 

 to the crew and engines when operating sub- 

 merged on diesels) and developed the Guppy 

 (short for greater underwater propulsion power) 

 is a conversion of the fleet-type submarine of 

 World War n fame. A Guppy submarine is shown 

 in figure 2-1. The superstructure was changed 

 by reducing the surface area, streamlining every 

 protruding object, and enclosing the periscope 

 shears in a streamlined metal fairing. Perform- 

 ance increased greatly with improved electronic 

 equipment, additional battery capacity, and the 

 addition of the snorkel. 



The world's pioneer nuclear-powered sub- 

 marine is the USS Nautilus (SS(N) 571). (See 

 fig. 2-2.) The Nautilus .commissioned in Sep- 

 tember 1954, is 320 feet in length, with a 



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71.1(346) 

 Figure 2-1.— Guppy submarine. 



10 



