it has many scale and depth combinations readily available. However, 

 the PGR is also rather more complex than the PDR. It uses a helix 

 instead of the stylus of the PDR for recording. Although this is felt 

 to be an improvement, the helix requires a wet- chemical paper, which 

 is regarded by some as objectionable. The PGR requires further eval- 

 uation, in that it, too, is not entirely compatible with the sonar sounding 

 set. 



C. CONCLUSIONS AND RECOMMENDATIONS 



1 . Shallow water instruments 



The existing equipment for shallow survey work is considered 

 to be sufficiently accurate, but it is difficult to maintain and does not 

 perform consistently to depth specifications. The Hydrographic Office 

 is closely following the current efforts of the Coast and Geodetic Survey 

 to have an improved portable echo sounder developed by a commercial 

 firm. 



2. Deep water instruments 



The present precision deep water sounding equipment has been 

 developed piecemeal. It is recommended that this equipment be 

 redesigned into a single piece of equipment that would embody the 

 best features of the AN/UQN, PDR, and PGR. 



The present equipment, particularly as to transducer directivity, 

 is a compromise. It is recommended that a study be made of the 

 latest advances in sonar design with a view toward increasing the 

 directivity of the sound beam without sacrificing depth range or 

 stability. It has been suggested, as a possibility, that a transducer of 

 considerable size could be developed of multiple facets, each independ- 

 ently stabilized. 



The precision deep water echo sounder should be capable of sound- 

 ing to maximum ocean depths of 6,000 fathoms with a beam width 

 sufficiently narrow to provide resolution of bottom features. Such 

 resolution, which varies with the nature of the bottom and with horizon- 

 tal position uncertainty, may require beam widths as narrow as 6°, 

 or even 1° in special cases. 



3. New instruments 



A new system is required to combine depth information with 

 automatic position plotting equipment, preferably plotting depth contours 

 within the range of unrefracted sound rays. 



XI- 4 



