GB862299A - Trawling device - Google Patents

Abstract

862,299. Fishing trawl gear. PULSIFER, O. B. July 25, 1958 [Jan. 27, 1958], No. 24038/58. Class 48. Apparatus for controlling the depth at which a fishing net is trawled comprises a draw-bar 10 rotatably secured to a main frame 23A, 23B and adapted to be connected between a towing cable and the net, a pair of hydrofoils 22A, 22B rigidly attached to the main frame, a pair of horizontal stabilizing planes 14A, 14B for laterally stabilizing the hydrofoils, a pair of elevator control planes 25A, 25B pivotally mounted on the main frame and hydrostatic control means adapted to control the elevator control planes 25A, 25B. The hydrofoils 22A, 22B are secured to a tube 24 which passes through a nylon bearing in the forward part of the draw-bar 10. The hydrostatic control means comprises a cylinder 11 connected by a pipe 20 to a pressure air tank 29 in the hydrofoil 22B and containing a rubber bladder 40, Fig. 3, which presses against a piston 41 adapted to actuate a crank 32 connected to a pivot rod 13. Rods 28A, 28B extend from the pivot rod 13 to the pivoted elevator planes 25A, 25B. When the apparatus is placed in the water the air pressure within the cylinder moves the piston outwardly so that the elevator planes assume a position tending to draw the apparatus downwardly, but when the apparatus reaches a predetermined depth the water pressure acting on the piston pushes it inwardly to cause the elevator planes to assume a neutral position. Further descent causes the elevator planes to urge the apparatus upwardly. The horizontal stabilizing planes 14A, 14B are pivotally mounted to the hydrofoils 22A, 22B and are actuated by a pendulum 35.