Chapter 13 

 SEALAB II EXTERIOR LIGHTING 



R. A. Barth and P. A. Wells 



U. S. Navy Mine Defense Laboratory 



Panama City, Florida 



INTRODUCTION 



The exterior lighting provided for Sealab II was Standard Navy diving lights, Symbol 313, 

 as shown in BuShips Drawing 9000, S6405-74445, mounted on the exterior of the hull. As con- 

 structed by San Francisco Naval Shipyard, the power cables and plugs were to be led in through 

 a section of the instrumentation trunk, connected to an interlocking switch and receptacle direc- 

 tly above the instrumentation trunk. A switch and receptacle was provided for each light. Dur- 

 ing the outfitting by Naval Ordnance Test Station at Long Beach, a decision was made to alter 

 this arrangement by using Electro-Oceanic underwater connectors. The underwater connectors 

 as well as the locations of the lights were numbered 1 through 6 for identification. Considera- 

 tion was given to the use of the Burns -Sawyer Underwater Lights; however, the reports from 

 Sealab I indicated that more problems were experienced with these lights than with the Navy 

 diving lights. An oversight in selecting the Navy diving lights was in their short life, 50 hours 

 nominal. The experience of Sealab II, however, indicates that the life is much longer. 



After failure of the Navy diving lights on Sealab II, other types, such as quartz iodine and 

 mercury vapor were used with varying degrees of success. From all reports, it seems that the 

 primary failure of the quartz iodine light was due to the housing. Quartz lamps are very rugged 

 to thermal shock and are small in size and produce about 21 to 22 lumens per watt. They can 

 be operated on standard voltages and require no auxiliary equipment. The mercury vapor lamp, 

 like any discharge lamp, requires that some sort of current-limiting device be used. Ballasts 

 are used to limit the current and act as transformers to provide sufficient voltage for starting 

 and operating. This voltage may be as high as 460 volts. The efficiency of the mercury vapor 

 lamp is very high; the lumen-per-watt output ranges from 23 for the 100 watt size to 54 for the 

 1000 watt size. The mercury lamp produces a bluish-white light which is not suitable for photo- 

 graphy.. 



It would appear there is a need for improved underwater lighting. The writer suggests 

 that the following factors be considered in the development of improved underwater lighting. 



1. Diver safety, i.e., low operating voltage or good insulation 



2. Long life 



3. Efficiency 



4. Simple lamp replacement 



5. Light and portable 



6. Suitability for photography 



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