M. BATHYMETRIC MEASUREMENTS 



Echo sounders used by the Hydrographic Office have been developed 

 in the past primarily for fleet use. Thus, they have not been designed 

 to meet peculiar survey requirements. Most echo sounders lack the 

 resolution and depth capabilities desirable for efficient survey work 

 in deep water. Instruments of greater capability for deepwater work 

 have been developed by the Woods Hole Oceanographic Institution and 

 the Lamont Geological Observatory for their own use. The main fea- 

 ture of such instruments is a recorder, either the Precision Depth 

 Recorder or the Precision Graphic Recorder, which allows selection 

 from a wide range of depths at constant scale. Installation of Precision 

 Depth Recorders aboard Hydrographic Office survey vessels has been 

 a major improvement. The following are recommendations for further 

 longer- range improvements: 



1. Development of a means for combining on punched tape or cards 

 the depth with positioning information and other geophysical measure- 

 ments is recommended. Lamont Geological Observatory has success- 

 fully recorded course, speed, and some geophysical measurements on 

 one graphic recorder. However, the greatest economy in the processing 

 of survey data will come from automatic processing of such data, which 

 should begin at the collection stage with the recording of data directly 

 on punched tape or cards. 



2. It is recommended that a stabilized, narrow beam transducer, 

 which will eliminate hyperbolae, side echoes, etc., be developed for 

 detailed surveys. 



3. An underwater contouring system consisting of multiple trans- 

 ducers would increase the capabilities of survey ships by broadening 

 the strip of bottom delineations with each passage of the ship. Not 

 only would this decrease the time required for surveying a given area, 

 but it also would give details of features not easily obtained with existing 

 equipment. 



The Hydrographic Office has initiated a development characteristic 

 for the development of such a system. Current indications are that the 

 Navy intends to proceed actively on this system. It is recommended 

 that this Office continue to support and encourage this work. 



N. TIDE MEASUREMENTS 



The portable tide gauges currently in use by this Office are gener- 

 ally satisfactory; however, development of pressure gauges for tidal 



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