Abstract: A hydrophone is provided for use with a hydrophone array enclosed in a streamer cable that is deployed in a body of water. The active transducer elements of the hydrophone are electrically isolated from the sealed metal case in which they are mounted. The signal input and output terminals are protected from short-circuiting due to water invasion of a faulty streamer cable jacket.

Abstract: Each unit of an array of submerged oceanographic devices is provided with a depth gauge of the air bubbler type. A typical depth gauge consists of a tube or air line that has one end fluidly coupled to a manifold; the other end of the air line is open. The open end of the air line is secured adjacent a corresponding submerged device. A small flow of air is established from the manifold, through the air line, to bubble out the open end into the water. A pressure transducer is fluidly coupled to the air line and senses the backpressure due to the hydrostatic water head existing above the submerged device. Means are provided for inhibiting pneumatic cross feed in the manifold between the respective air lines.

Abstract: A hydrophone having a self-contained means for warning an operator that the hydrophone has reached or exceeded a safe design depth limit. The active elements of the hydrophone are bender-type piezoelectric wafers. An internal stop is provided such that in the presence of a hydrostatic pressure that exceeds a safe design limit, the wafers bottom out against the stop. The stop short-circuits the electrical output signals of the wafers, warning the operator that the hydrophone is in danger of destruction.

Abstract: In a tubular pressure transducer element, the axial stress imparted to the element is reduced relative to the radial stress by inserting a rigid core inside the tubular element. The reduction in stress is proportional to the ratio between the area of the full diameter of the tubular element and the area of the annulus represented by the wall thickness of the tubular element.

Abstract: A method for extrapolating the far field signature of a seismic sound source array from near field measurements, by taking into consideration, the instantaneous firing and environmental parameters that exist locally for each individual sound source in the array.

Abstract: A ship is provided with booms that may be extended outwardly from the ship. Geophysical devices of different genera are towed from the booms, in the water behind the ship. A UHF antenna is located at the outboard tip of each boom. A line joining the two antennas defines a long reference base line for determining the absolute heading of the ship with respect to a meridian and to locate the absolute positions of selected towed geophysical devices with respect to two-dimensional space. The booms may be automatically oriented along a line perpendicular to the ship's track, independently of the ship's heading.