TM. No. 306 



INTRODUCTION 



Since accurate tracking of test vehicles in the deep water range 

 at AUTEG will depend in part on correlating the effects of the oceano= 

 graphic environment with information obtained "by the underwater instrumenta- 

 tion^ additional data on the environmental factors involved were required. 

 To learn more about one of these factors, parachute drogues were set and 

 tracked during the period ik February to 6 March I963 in the Northeast 

 Providence Channel and selected areas of the Tongue of the Ocesinj Bahamas. 



The purpose of this program was to gather data on the water currents 

 which could be used in an attempt to answer the following questions: 



lo Can the motion of the water at the Northeast Providence Channel 

 be traced to the motion of the water in Tongue (or vice versa)? 



TongLie ? 



What is the "mixing length" of the predominant eddies in The 



3. Wliat is the general magnitude and intensity of horizontal and 

 vertical current shear in the central region of the Tongue? 



4. To what extent (and time scale) are turbulent shears (normal 

 to the bank walls) causing mixing and transport of bank water into the 

 AUTEC region? 



5. How is the wind drift pattern related to tidal data? 



Two vessels were used during the program. The OCEAN PEARL (Figure l) 

 is a privately owned ketch capable of speeds up to 9 knots under power. 

 This vessel, used by the Woods Hole Oceanographic Institution (WHOl), was 

 under the direction of Mr. John Bruce, WHOI. The H.J.W. FAY (Figure 2) 

 is a research vessel capable of speeds up to I8 knots. This vessel, on 

 contract to the Naval Underwater Ordnance Station (NUOS) from Marine 

 Acoustical Services, Inc., Miami, Florida, was under the direction of 

 Mr. Ct. S. Cook, NUOS. Both vessels were equipped with Decca Navigation 

 radar and standard ship-to-shore transceivers. Decca Hi-Fix receivers 

 were temporarily installed on each vessel and were used in combination 

 with the radars to track the drogues. Thus, if one system failed, tracking 

 could be continued with the other system alone. 



With two vessels tracking their respective drogues simultaneously at 

 various distances from each other, it was possible to make ssmoptic current 

 measurements (using drogues) for the first time in the area. In addition, 

 the program was not interrupted when one vessel had to return to port. 

 This was important, since quasi-continuous measurements were desirable in 

 order to determine meaningful flow patterns. 



