An apparatus for carrying by a diver while underwater that provides information useful for enabling the diver to expeditiously and safely work on submerged vessels without the danger of tapping into an explosive gas. The invention is particularly useful for finding liquid/gas boundary in a submerged vessel or the pressure of liquid or gas behind the wall of a vessel. A transmitting transducer provides a low frequency acoustic tone burst that is transmitted toward the hull of the ship. The reflected signal from the inner surface of the hull is received by a hydrophone and processed. Electronic circuit means, responsive to the received signal, processes the signal and computes the location of a liquid/gas interface or the presence of liquid or gas behind the hull. A display provides indications of the computed values.
An acoustic data acquisition system for shipboard use is disclosed that allows for underwater acoustic data measurements at preselected submerged marine structural coordinates using a free swimming, quiet dynamically positionable remotely operated vehicle (ROV). Moreover, the disclosure provides a method of performing acoustic data acquisition with an ROV by first inputting the marine structural features by use of a computer aided design subsystem, determining the required trajectory path and hovering coordinates for data measurements, next, establishing the acoustic telemetry system for the remotely operated vehicle's control system to operate within and make an absolute positional fix to the marine structure's coordinates then, establish the ambient acoustic conditions of the worksite. The system is monitored and controlled from a computer based system. The system includes an ROV subsystem that operates in conjunction with a computer based long baseline underwater telemetry and positioning control subsystem, an acoustic transducer array attached to the ROV and a real time data-coordinate storage subsystem. A particular type of transducer suitable for use with this vehicle is a passive acoustic transducer array (hydrophones) that measures low level sound pressures and phase data that provides a detailed description of the sound power field emitted over the surface of the marine structure. Applications include oil/gas pipeline leak detection and location of malfunctioning underwater marine equipment.
