cle's underwater course. Mr. John Barringer 

 quite succinctly outlined a few of the prob- 

 lems with this approach that PC-3B 

 (CUBMARINE) encountered off Spain in the 

 1966 H-bomb search (20). 



"An infltituble buoy about three feet 

 in diameter was attached to the sub- 

 marine by a length of polypropylene 

 line. As the sub pulled this buoy 

 around, range and bearing from the 

 ship to the buoy could be determined, 

 and a rough estimate of CUBMA- 

 RINE's location made. Various factors 

 contributed to the inaccurticy of this 

 system. The length of line from the 

 submarine to the buoy was roughly 

 twice the depth of the sub. (Should the 

 line foul on some underivater projec- 

 tion, enough line ivas desirerl to allow 

 CUBMARINE to surface ivithout hav- 

 ing to pull the buoy under. The sub^s 

 power is not sufficient to pull the buoy 

 under and hold it there. Also, surface 

 action of the sea naturally moves the 

 buoy up and down, and if the line 

 were taut, CUBMARINE would be 

 moved up and down with it.) Action of 

 the wind, sea, and current greatly 

 affected the position of the buoy. It 

 was sometimes a very unreliable indi- 

 cator of the submariners course. For 

 example, when CUBMARINE executed 

 a 180 degree turn, the buoy ivould 

 travel for a time in the opposite direc- 

 tion the submarine was going, a poten- 

 tially htizarilous situation. Once when 

 working with the MSO (minesweeper), 

 sonar contact with the submarine hail 

 been lost just about the time she had 

 made a turn. The MSO continued to 

 steer a course which tvould normally 

 have been a safe folloiving one. At this 

 crucial time communication with 

 CUBMARINE was also temporarily 

 disrupted. Suddenly, the buoy stopped 

 its forwartl progress, turned, and 

 heatled directly for the ship. The ship 

 veered sharply, but not in time. The 

 buoy line fouled in her screw, €ind 

 CUBMARINE was unceremoniously 

 yanked from the bottom. Fortunately, 

 the line parted long before she could 

 he reeled up into the screw." 



While the marker buoy may seem to pos- 

 sess a capricious will of its own, it is used 

 nonetheless on quite a few vehicles in shal- 

 low water operations. 



Active Sonar Ranging: 



Essentially a steel bubble, the submersible 

 is an excellent reflector of sound. One ap- 

 proach, therefore, that would seem an excel- 

 lent candidate tracking system is that of 

 pinging* off the submersible's hull from the 

 surface and calculating a range and bearing 

 to the submersible. But several factors in- 

 hibit application of this system. First, when 

 the submersible operates on or close to the 

 bottom, the echo from the bottom is as 

 strong as that from the vehicle itself, and the 

 return ping from the vehicle usually is indis- 

 tinguishable from the bottom. Secondly, if a 

 ridge or other large object comes between 

 the surface ship and the submersible, con- 

 tact is lost. These two considerations and the 

 fact that the best of these systems resides in 

 the domain of the military have resulted in 

 very little use of active sonar ranging. 



The only reported application of this sys- 

 tem is, again, by Barringer (20) with CUB- 

 MARINE in the Spanish bomb hunt. 



'"The method employed to track 

 CUBMARINE when she tvas submerged 

 wfts one fabricated of necessity and 

 ivas far from adequftte for the tfisk. It 

 was relatively successful for vectoring 

 CUBMARINE into the area of a posi- 

 tive sonar contact, but tvas of little 

 value in making a geographical plot 

 of her progress. An MSO, ivith its UQS- 

 1 sonar, acted as control ship for each 

 of CUBMARINE s dives. The ship 

 would seftrch the bottom with her 

 sonar, and when a target was located 

 CUBMARINE would dive. The soniir 

 operator would acquire the submarine 

 as she dived, and would give the pilot 

 courses to steer until the target "blip^'' 

 and CUBMARINE's "'blip'' merged on 

 the son€ir screen. 



Sometimes this procedure tvould put 

 CUBMARINE tvithin a feiv feet of the 

 target. More often, however, the target 

 W€is not within her range of visibility 

 (usually 15-20 feet). Then she tvould 

 search in an outtvanlly spiraling pat- 



497 



