Acoustic aids in oceanographic research

Acoustic techniques for operating various types of marine equipment and instrumentation used in the fields of geology and biology have resulted in greater operational efficiency. The user has full control of the various switching operations and a visual record is obtained which is suitable for later analysis. New types of piezo-electric transducers were developed to allow efficient operation under severe working conditions. Geological dredging, pelagic trawling in the scattering layers, and bottom dragging for lost equipment have all been improved by these techniques.