272 



MARINE PRODUCTS OF COMMERCE 



Thus, it is now as easy for a fisherman or mariner to "get the lay" of the ocean 

 floor as it is for him to read a newspaper; he merely looks into a window to see 

 the contour and depth. Moreover, he needs no special training to use this depth 

 recorder to locate fishing banks and schools of fish. 



(Courtesy Bendix Aviation Corp.) 



Fig. 13-30. Composite chart made from actual recordings by fishermen showing variovis 

 conditions indicated by a supersonic depth recorder. 



Because these instruments completely eliminate the old time-consuming method 

 of taking soundings by hand, more often than not inaccurate, especially in rough 

 weather, they are widely used today. 



{Courtesy Bendix Aviation Corp.) 



Fig. 13-31. Cutaway view showing installations of supersonic depth recorder in 

 wheel house and location of transducer, which sends and receives supersonic signals 

 in hull. The transducer can be mounted inboard through a sea chest or externally. 



Sonar— Submarine Radar. Sonar can be used not only by mariners in avoiding 

 submerged reefs, wrecks, and mines, but also by fishermen in locating fishing 

 banks and bodies (schools) of fish and even in distinguishing the species by their 

 grunting, purring, croaking, or drumming sounds. Although submarine sound- 

 detecting devices are not entirely new, developments during the past decade 

 have finally led to its practical use today in safer navigation and as a possible aid 

 to more productive fishing. 



