HAYES— U. S. NAVY MV TYPE OF HYDROPHONE. 



577 



Referring to Fig. 3, let (H) represent the position of the MV 

 hydrophone and (F) the ship's propeller. The sound heard by (H) 

 has traversed the path P — B — H, making an angle (f) with the sur- 

 face. If (2L) is the distance between the propeller and the hydro- 



T^R= 



\ 



is 





For creeper wafer JJ " Ci-Zi ' Ci-L fan P 



for sha/hiver no fir D " Ci-/i = CfL' fan 'P' 



anUNDING BY' ANGLE DF RErLECTIDN METHOD 



Fig. 3. 



phone, both located a distance (C) below the surface, and if the 

 sea-bottom is a horizontal plane, then the depth (D) is given by the 

 equation 



D = C — Ltan^, 



= C + Ltan(7r — ^), 

 or 



D = C + L tan <^, 



This equation will be referred to as the " sounding equation " and 

 the angle </> will be referred to as the " sounding angle." It is to be 

 noticed that the compensator scale is designed to feature d, the 

 angle the sound makes with the ship's keel extended forward, in 

 order to give directly the relative bearing of surface vessels. The 

 sounding angle <^ is the supplement of this angle. 



The range of a vessel ahead or astern can be determined roughly 

 if the depth of water is known, since the hydrophone determines the 

 angle which its reflected sound signals make with the surface. 



Referring to Fig. 4, where S^ or 5^2 represents an artificial sound- 

 source upon a vessel ahead or astern of the vessel equipped with the 

 hydrophone {H), we have 



