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PROBLEM 



Investigate and report on factors in physical oceanogi-aphy which pertain to 

 underwater sound, including physical properties such as sound velocity, thermal 

 structure, and water motion. Specifically, determine the type of shallow-water 

 flowmeter best suited for measuring low level, steady-state currents in the 

 presence of orbital velocity motion due to surface waves. 



RESULT 



No known commercial meters are available for accurate measurements of 

 this type. The electromagnetic method is believed to be inherently the best 

 approach to the problem. 



RECOMMENDATIONS 



1. Investigate new configurations using ac fields that will 



(a) provide minimum hydrodynamic interference, 



(b) measure flow over large distances. 



2. Experimentally determine the directional response of the "tube" configuration. 



3. Consider using the earth's field type flowmeter, but only if a feature for zeroing 

 is employed. 



REVERSE SIDE BLANK 



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