Page 147 control and signal building 26 



Table 5. — Statistics of typical hydrographic survey projects using buoy control 



Sounding lines (statute miles). 



Fixed positions- _, (number). 



Area (square statute miles) . 



Control buoy stations, including sono-radio 



(number) . 



R. A.R. stations do 



Taut-wire traverse (statute miles) . 



Serial temperature stations (number) . 



Trinitrotoluene (TNT) (pounds) . 



Fuse - (feet) . 



Bombs, various sizes (number) . 



Total working days do 



Days to establish control do 



Mileage of survey vessel (nautical miles) 



(1) 



Gulf of 



Mexico, 



1938 



L5, 260 

 20, 310 

 10, 331 



252 



819 

 119 



154 



24 



19, 372 



(2) 



Gulf of 



Mexico, 



1939 



17, 621 

 13, 015 

 36, 758 



138 



32 



278 



44 



2, 263 



(0 



1,607 



136 



15 



24, 400 



(3) 



Pacific 



Coast, 



1933 



13, 407 



4, 248 

 15, 874 



50 



(0 



0) 



2,083 



298 



28 



18, 906 



(4) 



Atlantic 



Coast, 



1939. 



10, 496 



7, 503 



8, 562 



84 



24 



271 



135 



3,511 



4, 170 



5,506 



101 



18 



16, 481 



(5) 



Gulf of 



Maine, 



1940 



15, 334 



10, 992 



8,901 



53 



22 



96 



138 



5, 200 



5,300 



8,904 



107 



18 



20, 564 



' Data not available. 



Column ;.— Statistics of a project of offshore surveys off the Texas Coast from April 18 to November 11, 1938. The surveys were 

 plotted on six 1:40,000 scale sheets and two 1:80,000 scale sheets and were controlled almost entirely by three-point sextant fixes and 

 dead reckoning from buoys established in a scheme similar to that described in 2562. 



Columv 2.— A season's project of offshore surveys off the Texas and Louisiana Coasts from April 25 to November 13, 1939. The 

 season's hydrography was plotted on three 1:20,000 scale sheets, four 1:40,000 scale sheets, two 1:80,000 scale sheets, and one 1:240,000 

 scalesheet. The surveys were controlled by three-point sextant fixes and R.A.R. methods from a combination of the schemes described 

 in 2562 and 2573. 



Column 3.— The surveys of this project ofl the coast of Southern California were plotted on three 1:20,000 scale sheets, six 1:40,000 

 scale sheets, and three 1:120,000 scale sheets during the period between December 5, 1932, and January 30, 1934. The control was by 

 R. A.R. methods using seven shorestations, supplemented by three-pointfixeswhereshore signals were visible. The R.A.R. stations 

 were established along the shore in a manner similar to that described in 2572. 



Column i.— The statistics in this column are from an oflshore survey of Nantucket Shoals and the adjacent continental slope plotted 

 on one 1:60,000 scale sheet and two 1:120,000 scale sheets. The surveys, between May 2 and September 25, 1939, were controlled exclu- 

 sively by R.A.R. methods, the buoys being established in a scheme similar to that described in 2573. 



Column 6. — An offshore project in the Gulf of Maine controlled entirely by R.A.R. methods and plotted on two 1:120,000 scale 

 sheets. The surveys were started on April 12, 1940, and the season's work ended on September 12. The control was established by 

 the method described in 2574, from stations located by taut-wire traverse just beyond the inshore shoals. 



26. R.A.R. STATIONS 



In addition to sono-radio buoys (see 284 and sections 64 and 65), R.A.R. shore 

 stations and ship stations may be. used to receive subaqueous sound and transmit the 

 instant of its arrival to the survey ship. Sono-radio buoy stations are in general use 

 for R.A.R. control, but it may be that shore stations can be advantageously substituted 

 for them in some areas. 



261. R.A.R. Shore Stations 



During the early use of R.A.R., shore stations were used exclusively for receiving- 

 stations, but the completely automatic sono-radio buoy is now used exclusively on the 

 Atlantic and Gulf Coasts and probably has replaced the shore station almost entirely. 

 On the Pacific Coast and in Alaska, where deep water approaches the shore and strong 

 currents make the use of sono-radio buoys difficult, shore stations may still be useful.. 

 The general arrangement of an R.A.R. shore station is shown in figure 42. 



2611. Selection of Shore Station Sites 



R.A.R. shore stations for hydrographic control should be established along a coast 

 as outlined in 2572. On the open coast ideal sites are rarely available where needed 

 and often a site lacking one or more of the requirements must be accepted. The re- 



