Schlosser 



UNDERWATER SOUND PROPAGATION AND ATTENUATION 

 STUDIES 



One of the more challenging applications of instrumenting the 

 DEEPSTAR vehicle was that of the Underwater Sound Propagation 

 and Attenuation Studies^' ^^' ^*. The scientific payload of 350 pounds 

 was not approached, but the mass of the external instrumentation 

 presented shipboard-handling problems and the internal sphere 

 arrangement utilized all available space. Fig. 9 shows coring tubes 

 and probes to measure compressional wave velocity and absorption. 

 Fig. 10 shows equipment for generating shear waves by firing dyna- 

 mite caps, and geophones for observing them. To provide significant 

 data, DEEPSTAR made an early-miorning dive at a specified site 

 using instrumentation shown in Fig. 9. An afternoon dive was made 

 at the same location following an at-sea instrumentation change as 

 shown in Fig. 10. Sea-state conditions limited diving operations in 

 some instances, causing handling problems when geophones and dyna- 

 mite caps occasionally became entangled during launching operations. 



PHYSICAL OCEANOGRAPHY 



Physical Oceanography studies called for specialized equip- 

 ments capable of reliable performance at the 4000-foot operating 

 depth of DEEPSTAR. The need to obtain water samples at the sea 

 floor and at approximately 1 -f oot increments dictated that the design 

 of water samplers be compatible with DEEPSTAR 's maneuverability. 

 Deep-sea solenoids developed at NEL performed reliably throughout 

 the program. Fig. 11 illustrates the external instrumentation con- 

 figuration used for this specific mission"''^ . The measurement of 

 current flow at the sea floor in "virgin water" (without interference 

 of the vehicle hull) was accomplished by means of depositing the 

 large bale attached to the current meter on the sea floor and backing 

 off a distance of 10 to IZ feet for observation and recording. The 

 signal was carried from the meter to DEEPSTAR by a retractible 

 communication cord, similar to that used on telephones, which 

 allowed minimal wire length and precluded entanglement during 

 meter recovery. Temperature probes to be ennbedded in the sea 

 floor were carried in a "cocked" position (see Fig. 12) so that the 

 probes could be actuated by the scientist without disturbing the water 

 sampling. The underwater separation bolt provided an extremely 

 sinnple device for actuating the probes. A dye marker was also used 

 for current data. Dye, intermixed with sand and encased in "baggies", 

 was released into the current upon rupture of the "baggies" by the 

 point of the temperature probe. 



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