Aspect. " 



We can readily give you data on the oceanic environment as it 

 affects instrument packaging and ruggedness. The vibrations, 

 humidity, voltage fluctuations, etc., which will make your design 

 problems interesting are predictable, and we know you will com- 

 pensate for them. Keep in mind, also, our management problems 

 of personnel. Skilled electronic and mechanical personnel are hard 

 enough for you gentlemen to recruit, train, and retain. The pre- 

 vailing lower pay rates, long periods away from home, and fre- 

 quently crowded living conditions aboard ship are not conducive 

 to retaining sea technicians long enough to get their "20-year 

 service pins. " Accordingly, your instruments nnust not only 

 be rugged but sophisticated, simple but flexible, precise but not 

 broad in range, and primarily they must be maintained, essential- 

 ly, by personnel with limited training. 



Paramount requirements for an oceanographic survey ship 

 assigned to ocean bottom surveys are seakeeping characteristics, 

 an accurate and reliable navigational positioning system or sys- 

 tems, and a rugged depth sounder. These requirements are funda- 

 mental. 



Depth measuring techniques have progressed steadily from the 

 hand lead, to the steam and electric sounding machine before World 

 War I, to the sonic depth sounder with the visual depth meter, to 

 the graphic depth recorder in use just prior to World War II. 

 Today we have the shoal and deep water depth recorders with the 

 Precision Depth Recorder Auxilliary which can maintain constant 

 frequency and from which recorded depths can be scanned to a 

 fathom in the deepest water. Uncertainties in water sound velo- 

 city, of course, introduce errors in excess of one fathom. 

 Developnnent is continuing on narrow beam stabilized oscillators 

 to provide vertical depths below the keel to replace the presently 

 recorded composite profile of rugged submarine topography de- 

 rived from echoes emanating from sources as divergent as 30 

 degrees on either side of the vertical. 



Progress has not been nil in the development of electronic 

 positioning equipment, but the requirements of ocean surveys 

 place a strain on present systems. 



Lioran-A and Decca are examples of pulsed hyperbolic radio 



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