Abstract: The modulus of stretch af a fibrous rope is reduced by impregnating a pluity of spaced-apart segments of the rope with an epoxy plastic thereby to reduce the modulus of stretch of the segment equal to zero after curing the plastic. The overall modulus of stretch of a re-manufactured rope taken as a whole is proportional to the ratio of the length of an impregnated segment relative to a unit length of the rope.

Abstract: A variable-gap, distributed-capacitance sensor provides an output signal that is a function of its instantaneous elongation. The sensor is integrally associated with a seismic isolator section for measuring the instantaneous stretch thereof.

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: 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 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: 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.