TM Wo. 306 



SUMMARY 



The Naval Underwater Ordnance Station is responsible for the design, 

 installation, test, and evaluation of an underwater weapons tracking range 

 for the Atlantic Undersea Test and Evaluation Center (AUTEC). As this 

 work requires a knowledge of the environmental factors affecting deep 

 water tracking, a program was established to gather additional data on 

 the water currents in the Northeast Providence Channel and selected areas 

 in the Tongue of the Ocean, Bahamas. 



Water current measurements were taken during February and March I963 

 by tracking parachute drogues along five transects in the areas selected. 

 The drogues were placed at various positions and depths (from surface to 

 1500 meters) along each transect, and were tracked for periods of one to 

 four days . Although it had been planned to track each drogue for a longer 

 period of time (three to five days), the weather (high winds) proved to 

 be a limiting factor. 



A total of 27 drogues (all identical in construction) were tracked, 

 and over 5OO position fixes were taken. When the surface floats were 

 recovered, a tension was noted on the suspension wire prior to cutting. 

 This indicated that the parachute was still open and that the run was 

 successful. 



Two vessels were used to track the drogues which made it possible 

 to: m.ake a greater number of observations during the time allocated for 

 the program; obtain the first synoptic, drogue water current measurements 

 taken in the area; and acquire the quasi-continuous measurements of the 

 currents that were desired in order to determine meaningful flow patterns. 



Decca Hi-Fix (a short range, high precision, position-fixing system) 

 was used to determine the positions of the surface floats relative to 

 known landmarks at various intervals along the drogue tracks. Standard 

 navigation radar fixes were taken simultaneously with the Hi-Fix readings 

 to provide back up information, and to position the surface floats if the 

 Hi-Fix system failed or the range was too great. However, the Decca Hi-Fix 

 position fixes were quite adequate for tracking the drogues throughout the 

 areas covered. 



Although information on the water characteristics at the time and 

 place each measurement was taken would be valuable, no effort was made 

 to assess these characteristics since the time involved would interfere 

 with the planned program, and hydrographic station data are available 

 for the areas of interest. These data cover all months over a period of 

 years and could be used in conjunction with the water current data obtained 

 to provide a more complete analysis. 



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