Abstract: 1. Apparatus for destroying a ground mine lying proud on the ocean floor prising a self-propelled dirigible underwater vehicle carrying an explosive charge and having a catacoustic system for steering said vehicle in the azimuthal direction of a sound reflecting object, diving control surfaces carried by said vehicle, means for developing a control signal representative of the departure of the vehicle from a selected distance above the ocean floor, means responsive to said control signal for operating said diving control surfaces, and means responsive to a certain change in magnitude of said control signal within a selected time interval for releasing said explosive charge.

Abstract: 1. In a sonic echo system for classifying objects proud on the ocean floor in which a submarine vehicle moves through the ocean at a constant height above the ocean floor, scanning means for simultaneously deriving separate electric signals corresponding to the sonic reflecting values of parallel strips of the ocean floor extending athwartships of said vehicle, means for simultaneously storing said separate signals on a record medium, and means for serially reproducing the stored signals.

Abstract: 1. An apparatus for producing low frequency compressional waves under water hich comprises two circular plates spaced in opposed parallel relation, a plurality of reciprocating fluid motors arranged in parallel between said plates, an independent fluid pump hydraulically connected to each of said motors for driving the same, a by-pass valve for each motor adjustable to vary the length of the stroke of such motor, a prime mover coupled to drive all of the pumps in synchronism, whereby the motors connected thereto reciprocate in unison to move said plates toward and away from each other at a frequency corresponding to the speed of the prime mover, and means for adjusting all of the by-pass valves in assembly, whereby the amplitude of oscillation of said plates is correspondingly varied.

Abstract: 1. A towable detecting gear adapted for dragging over a water-submerged sace comprising a tail portion, a towing cable having its trailing end enclosed in a tail portion and having at least one insulated conductor, a weight member secured to said cable at the forward end of the tail portion and having sufficient negative buoyancy to drag along said submerged surface when under tow, a plurality of detecting devices disposed at intervals along the cable in said tail portion and in electrical communication with a conductor therein, said detecting devices being substantially larger in cross section than the diameter of said cable, a layer of buoyant material surrounding said cable between said devices and having a thickness such that its diameter is at least equal to the diameter of said detecting devices, and an outer covering of wear resistant flexible material enclosing said tail portion.