between the buoy and the 50-foot cable, and a 100-foot line, 

 also between the buoy and the 50-foot cable. The shock 

 cord is meant to isolate the hydrophone from the motion of 

 the surface waves and the line is to prevent the shock cord 

 from being extended beyond its elastic limit and possibly 

 breaking and the float being lost. The inflated buoy was 

 weighted so that most of the float was underwater, the pur- 

 pose being to reduce the effect of waves on it. The weight 

 in water of the 50-foot cable and hydrophone was adjusted 

 to about 2 or 3 pounds, so as to provide the right amount of 

 weight on the shock cord for proper operation. 



Another suspension system which was tested is 

 shown in figure 12B. It consists simply of floats attached 

 to a line which is connected at the other end to the junction 

 of a 50-foot cable and a 1000-foot length of nonbuoyant 

 cable. No shock cord was used in this system for isolation. 

 A suspension used during part of an extended cruise 

 of USNS Charles H. Davis (AGOR-5) consisted simply of an 

 inflated plastic hose, which was tied with about a 10 -foot 

 line about 300 feet from the sea end of the buoyant cable 

 when operating in deep water. No shock cord was used in 

 this suspension. The float can be attached at any place on 

 the cable, thus regulating the depth of the hydrophone. The 

 plastic hose was weighted so that most of it would be under- 

 water, but with enough buoyancy remaining so that it could 

 support the system. 



A spar buoy was used as a suspension for a system 

 to be used on a small boat for taking data several miles 

 from the mother ship. The spar buoy (see fig. 13) was a 

 hollow plastic tube about 3 inches in diameter and about 

 20 feet long. One end was sealed airtight. In the operating 

 position the lower end of the tube was left open and the tube 

 was allowed to partially fill with water. The upper part of 

 the tube contained some trapped air which provided the 

 buoyancy. * The buoy was very stable and did not appear to 

 be much affected by the wave action. It had enough buoyancy 

 to support the hydrophone and cable which were attached to 

 the bottom end. 



* The open-end spar buoy was suggested by J.J. Blanchard. 



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