TABLE 10.2 CHARACTERISTICS OF THE STRAZA (MODEL 500) CTFM SONAR 



fectiveness is lighting. The effectiveness of 

 direct viewing is also governed by viewport 

 location, which was discussed in the preced- 

 ing chapter. Assuming 20/20 vision of all 

 observers, there is little more that can be 

 discussed other than artificial light arrange- 

 ments and characteristics with regards to 

 direct viewing. The topics of this section, 

 therefore, are limited to lighting as it affects 

 visual observations and to television as an 

 adjunct to direct viewing. 



Lighting — The varieties, characteristics and 

 manufacturers of underwater light sources 

 on present submersibles would be all but 

 impossible to list because they can and do 

 change rapidly. In some instances the lights 

 are "homemade" modifications of automobile 

 lights. The SEA OTTER operators (Fig. 10.3), 

 for example, took British "Rally Lights" 

 manufactured by CBIE and pressure-com- 



pensated their housings with air using a 

 scuba-type regulator. But for the most part 

 underwater lights are purchased from one or 

 several of the many companies supplying 

 this area. (The 1973 Undersea Technology- 

 Handbook Directory, reference (2), lists 60 

 suppliers of marine lights and beacons in the 

 U.S., though it does not distinguish which of 

 these are of the underwater variety.) 



It is difficult to discuss underwater light- 

 ing without first discussing light transmis- 

 sion in the sea. Space, however, limits the 

 discussion herein merely to a brief introduc- 

 tion. Virtually any introductory book on 

 oceanography or undersea photography will 

 provide the reader with an adequate back- 

 ground. For a complete and technically thor- 

 ough treatment of the principles involved, 

 the work of Tyler and Preisendorfer (3) is 

 recommended. 



471 



