1 6 THE NAVY OCEAN ENGINEERING PROGRAM 



Present side-looking sonar designs can search up to 800 ft from the 

 track of the submersible, for a total search width of 1600 ft with one 

 transducer on either side. The vehicle must travel relatively near the bot- 

 tom, and must maintain precise positioning to avoid gaps in the search 

 pattern. 



Search sonars other than the side-looking variety include improved for- 

 ward-scan sonars similar to the horizontal-obstacle sonar used on the 

 DSRV. If buried objects must be found, then a sediment probe or bottom- 

 profiling type of sonar must be used. For high-resolution acoustic search, 

 an improved short-range sonar must be considered. All of these acoustic 

 equipments require development to obtain reliable and lightweight sys- 

 tems that can be carried on deep diving vehicles. 



For the visual identification of targets, significant improvements must 

 be made in existing TV and film cameras and methods of illumination. 

 Present undersea TV or, for that matter, visual observation from a viewport 

 is usually limited by light backscatter to distances under 50 ft. Turbidity 

 can further reduce this visibility to the point where visual search is not 

 practical. Extended-range optical systems are under development to over- 

 come some of these difficulties. A variety of techniques are being con- 

 sidered, including circularly polarized hght, range gating, and even the 

 application of lasers to underwater illumination. 



DEEP OCEAN SURVEY VEHICLE (DOSV) 



The primary purpose of the DOSV program is to conduct surveying 

 operations with undersea vehicles in order to evaluate the instruments and 

 vehicles available for underwater surveys. The eventual output of the pro- 

 gram will be performance specifications for a Deep Ocean Survey Vehicle. 

 The DOSV will be designed with the survey instruments incorporated to 

 prevent later expensive modifications. The tasks performed to date have 

 encompassed those missions which a Deep Oceanographic Survey Vehicle 

 will eventually perform on a routine basis, e.g., stereo-photogrammetric and 

 sonic mapping, sub-bottom profiling, gravity and magnetic measurements, 

 measurements of sediment mass physical properties, and water properties 

 affecting sound propagation. Underwater visibility measurements and 

 bottom-sediment sound-loss studies have been conducted. Existing 

 navigation systems have to be evaluated. 



To date the following undersea vehicles have been employed for these 

 operations: ALUMINAUT, ALVIN, CUBMARINE, and STAR III. Avail- 

 able underwater navigation techniques are completely inadequate for 



