Fig. 10.18 Grffl rec»rder record ot slant range from support ship PRIVATEER to BEN FRANKUN Range increases to nghL The larger (thickest) trace is the primary pulse (slant 

 range); the thinner trace is the secondary pulse which can be read to provide vehicle depth (NAVOCEANO) 



tion is fairly useless either as an accurate or 

 a repeatable system. Even when the sub- 

 mersible is bottomed and stationary, multi- 

 ple fixes on it from different positions pro- 

 duce position errors in the neighborhood of 

 200 to 300 yards (23). Since such surface 

 acoustic tracking systems require an acous- 

 tic pinger on the submersible, however, they 

 do provide a necessary safety feature desira- 

 ble for surfacing and gross positioning in the 

 event of a submerged emergency. 



Submerged Navigation 



The title of this section should not be con- 

 strued so as to infer independence from the 



surface ship, because all of the following 

 systems ultimately relate the submersible's 

 track or location to positions established by 

 and on the surface. 



The schemes and systems in this category 

 position the submersible either relative to 

 undersea objects (both passive and active) or 

 by dead reckoning. Their commonality re- 

 sides in the fact that theoretically, they do 

 not require course changes or directions 

 from the surface once a reference marker or 

 a "start" position has been established. The 

 systems fall basically under Acoustic and 

 Non-Acoustic approaches but overlapping of 

 both is so common that such a distinction is 



503 



