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: 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 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: 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: In a seismic streamer cable, stress sensors are co-located with the hydrophones in the cable. The stress sensors are responsive to mechanical stresses applied to the cable but it are substantially unresponsive to acoustic waves propagating in fluid media. The signal outputs from the stress sensors are combined with the signal outputs from the corresponding co-located hydrophones to cancel spurious signals due to bulge waves.

Abstract: A ship is provided with booms that may be extended outwardly from the ship. Arrays of geophysical devices of different genera are towed from the booms, in the water behind the ship. A UHF antenna is located on 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 oriented along a line perpendicular to the ship's track, independently of the ship's heading for the purpose of maintaining the integrity of the geometric pattern of the arrays of the towed geophysical devices.

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.

Abstract: A seismic streamer section includes a flexible tube with bulkheads at intervals therealong, end means to make electrical and mechanical connections with adjacent sections, tension lines extending from one end means to the other through the bulkheads, hydrophones in the tube between the bulkheads, an electric bundle including through conductors extending from one end means to the other through the bulkheads to various ones of the hydrophone. Each hydrophone comprises a drum shaped case with dished ends and convex sides providing standoff from the bundle and lines for piezoelectric wafers supported inside the ends. A cylindrical metal ring forms the side of the case. Stainless steel cups disposed with their bottoms adjacent and having their rims welded to the rims of the ring form the ends of the case. The piezoelectric wafers are conductively secured one each to the inner surfaces of flexible diaphragms forming the bottoms of the cups.

Abstract: A seismic streamer section includes a flexible tube with bulkheads at intervals therealong, end means to make electrical and mechanical connections with adjacent sections, tension lines extending from one end means to the other through the bulkheads, hydrophones in the tube between the bulkheads, an electric bundle including through conductors extending from one end means to the other through the bulkheads to various ones of the hydrophone. Each hydrophone comprises a drum shaped case with dished ends and convex sides providing standoff from the bundle and lines for piezoelectric wafers supported inside the ends. A cylindrical metal ring forms the side of the case. Stainless steel cups disposed with their bottoms adjacent and having their rims welded to the rims of the ring form the ends of the case. The piezoelectric wafers are conductively secured one each to the inner surfaces of flexible diaphragms forming the bottoms of the cups.

Abstract: An under-sea-water electric discharge generator includes a source of stored electrical energy connectable through solid state switch means to a cable extending to a number of pairs of electrodes to be towed under sea-water. The switch means comprises an inductor in series with five main branch circuits: a capacitor discharge branch includes a plurality of SCRs connected in series and a sub-branch of RC elements for gate control with one RC element across each but an end one of the SCRs; a reverse discharge branch includes a plurality of diode means, one across each SCR. Diodes across the gate-cathode circuit of each but said one SCR protect against reverse negative voltage during reverse discharge. Static, dynamic, and over voltage branches parallel the SCR branch with one element of each (resistor, RC element, thyrector) across each SCR.

Abstract: A hydraulic reel is used to organize the streamer harness inside a tank having a nozzle. A piston attached to the harness is inserted into one end of the streamer jacket affixed to the tank nozzle. The tank is filled with a liquiform fluid, hereinafter called oil. Pressure is applied to the tank, the piston is pushed through the jacket, towing the harness. Pressure causes some jacket expansion. Initially, with the jacket in place on the nozzle, a main pump fills the tank rapidly, almost to overflow. A metering pump then fills the tank until oil enters a gage glass, indicating a full tank. A flow meter is set to zero with gage valve closed. Oil is metered into the tank, forcing the harness into the jacket. All oil entering the tank is metered until the end bulkhead is in banding position. The metering pump is reversed to extract excess oil until the required quantity is present in the jacket, as indicated by the net meter reading.

Abstract: A pressure-sensitive improved acceleration-cancelling hydrophone assembly and transducer unit for inclusion therein, each transducer unit being made of glass and metal parts hermetically sealed together with no exposed plastic, each sealed unit containing paired piezoelectric wafers mounted inside the sealed unit in opposed relationship and electrically interconnected such that pressure forces combine in the output signal but acceleration forces cancel, and the hydrophone assembly comprising a barrel in which one or more of these transducer units are mounted in vibration-isolated relationship, the mountings engaging the transducer units at surfaces thereof which are least likely to couple vibrations to the piezoelectric wafers.