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The Sea Change - 300 Fathoms Deep, 3 Years Later

The sea change experienced in a large under-water acoustic energy source, placed on the ocean floor at a 300-fathom depth, is discussed as it is examined from the surface three years later by reactivation of an installed closed-circuit video link. The author recapitulates an earlier paper on this subject that was presented at the SPIE Seminar of February 1968 (published in the Seminar Proceedings, vol. 12, pp. 73-80), updates the background of the initial ocean emplacement, and discusses the sea changes in the submerged structure and instrumentation. He illustrates the various areas of interest by videotape recordings. Many questions have arisen concerning the effects of long-term deep submergence on various parts of the video' apparatus including the camera, camera viewport, the camera pan and tilt unit, the lighting unit, and the long cable. This paper discusses some of these questions.