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RADIO ACOUSTIC RANGING 



6565 



Of the two methods of hydrophone suspension, the first simpHfies the operation of 

 anchoring and removing the sono-radio buoy. The second method eliminates water 

 noises to a large extent, and the distances at which the installation can be used in R.A.R. 

 are comparable with those from shore stations. The second method should be used for 

 sono-radio buoys that are to be left at the same station for several months and where 

 hydrography is to be controlled at long distances from the sono-radio buoy. 



The electric cable used with the Vincent hydrophones is a single-conductor tinned 

 aircraft wire, Yu inch in diameter, preformed 49-strand (7 by 7), insulated with a 

 60 percent rubber compound, the outer diameter being Yi inch. 



Figure 138.— Vincfiit sono-radio buoy hydrophone. 



The small duralumin Vincent hydrophone is suspended directly below the buoy. 

 The housing of this unit is enclosed m a rubber sheath (K-tube unit rubber housing, 

 see 5213) and the whole is put into a cast-iron shell approximately 12 inches in length and 

 4)^ inches in diameter. The shell is a hollow cylinder rounded at one end and open at 

 the other. The hydrophone unit and rubber sheath are placed in the shell so that the 

 fiat end of the hydrophone is nearest the opening, the electric cable entering through a 

 hole in the rounded end of the shell. The suspension cable is secured to an eyebolt 

 attached to the shell. (See fig. 138.) The shell is intended to hang horizontally and 

 to afford some streamlining. It has been used successfully in strong currents. 



6565. Tests and Maintenance of Hydrophones 



Although quantitative measurements of hydrophone characteristics would be 

 valuable, they are not attempted because they would require equipment whose use is 

 not practicable on board most survey ships. However, certain tests should be made, 



