A third system used a combination of a buoyant and 

 a nonbuoyant cable with the shock-cord suspension system 

 (fig. 16). The buoyant cable was used to place the hydro- 

 phone farther away from the ship, to minimize the inter- 

 ference from the radiated noise of the ship. A nylon line 

 was also used for this system and was attached to the float. 

 The float had enough buoyancy to prevent the weight of the 

 nonbuoyant cable from pulling the buoyant cable under the 

 surface. The procedure used for this system is the same 

 as that for the all -nonbuoyant cable system. The results 

 obtained are similar to those of the previous system and, 

 as before, the weights involved produced quite a large stress 

 on the cable. 



A cable system that was used on the Charles H. Davis 

 (AGOR-5) (fig. 17) employed the simple float system 

 described earlier. The system consisted of a total of 1500 

 feet of buoyant cable to which was attached a 50 -foot length 

 of nonbuoyant cable with the hydrophone. A 7 -pound weight 

 was attached to the nonbuoyant cable about 5 feet from the 

 hydrophone, to sink the system to the desired depth. The 

 depth was selected by attaching the inflated hose at the 

 proper distance from the hydrophone. The 7 -pound weight 

 also presents a greater inertia to accelerating forces on 

 the system. The procedure involved releasing 500 feet of 

 cable over the side and letting it drift away while keeping 

 the remainder on the deck in a figure-8. During the run 

 the cable was payed out just fast enough to keep it slack 

 throughout the run. After the run the cable was brought 

 back in and placed in a figure-8 in preparation for the next 

 run, leaving 500 feet of cable out. 



Also used during the cruise of the Davis was a 

 small -boat system consisting of nonbuoyant cable with the 

 spar-buoy suspension system described earlier (fig. 18). 

 About 500 feet was sufficient to provide a long enough slack 

 period for an ambient-noise sample. A slack condition 

 was obtained by paying out the nonbuoyant cable slowly 

 while the spar buoy and the small boat drifted apart. 



26 



