project was conducted by the Bureau of Ships and the Bureau of 

 Commercial Fisheries at Miami, Florida. Mr. R. F. Sand, Mr. 

 F. H. Stephens, Jr., and a small group of Bureau of Ships techni- 

 cal personnel continuously observed the performance of experi- 

 mental midwater trawls to a maximum depth of 60 fathoms. Opera- 

 tions were conducted aboard the Fish and Wildlife Service's ship 

 Oregon in the Bimini area. The optical characteristics of these 

 waters would be classified as "good"; they provided light transmis - 

 sion on the order of 80 percent on this occasion. Horizontal view- 

 ing distances as great as 120 feet produced useful information on 

 net and rigging performance, as well as the antics of marine life 

 entering or avoiding the trawl. The underwater television (UW- 

 TV) camera used was the first Image Multiplier Orthicon (IMO) 

 camera expressly designed for this environment. Bureau of 

 Ships model CXRL. The camera was controlled in depth and 

 attitude by our "UW-TV Glider, " a towed, remote-controlled 

 vehicle. 



Relatively little technological improvement that effects the 

 maximum range of underwater vision has been accomplished 

 since that time. Currently, low light level IMO cameras, having 

 useful performance characteristics at illumination levels on the 

 order of one nnillionth of a candle per square foot, should 

 provide comparable viewing distances in clear water to depths on 

 the order of 200 fathoms. Increased light sensitivity has rela- 

 tively little influence on the viewing distance due to the character- 

 istic turbidity of the clearest of natural waters. Improved light 

 sensitivity increases the depth attainment with natural illumina- 

 tion. We have recorded useful, detailed, pictorial information 

 from an UW-TV camera of the low light level IMO type at a depth 

 of 150 fathoms in North Atlantic waters. Natural illumination 

 between the hours of 1000 and 1500 provided viewing distances 

 up to 100 feet. 



On the occasion of the 150 fathom surveillance project, the 

 application of artificial illumination by the best practical techni- 

 que possible reduced the viewing distance by a factor of 66 per- 

 cent due to the "blinding" effect of scattered light. 



In all related instances the UW-TV picture quality obtained 

 provided true halftone detail sufficient to establish shape and 



textural information. By reducing the information requirement to 

 outline information or object detection, maximum ranges will be 

 increased on the order of 33 percent. 



You will note that the information provided consists of speci- 

 fics rather than broad statements. Due to great variations in the 

 optical characteristics of natural waters, theoretical essays on the 



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