GB158100A - Improvements in or relating to fish trawling gear or the like - Google Patents

Abstract

158,100. Evans, L. Oct. 31, 1919. Trawling - gear; net floats and buoys; nets. -The action of trawling apparatus is regulated by the passage of fluid to and from container elements thereon. In one form, as shown in Fig. 1, a hollow metal beam d is divided into two compartments, each of which has an air-pipe connection d<4> and water outlet d<3>, and is pivotally attached at d' to skid frames e<1>, Fig. 3. In operation, the beam is floated alongside the vessel with the cod-end b of the net a closed. Armoured air-pipes, which can be run out with the towing-ropes, connect the beam to air-compressors, and are provided with intermediate valves and pressure gauges. On opening the valves, the net is submerged, its depth being regulated by means of the gauges. A trap c<1> is fitted with a strangulation cord, which may be operated by a collapsable bellows-shaped caisson. The net is raised by supplying air to displace the water in the beam. In another form, as shown in Fig. 7, a trawl is fitted with a lifting-member h and with otter-boards i, formed as weighted caissons and provided with skids i<1>, the throat of a trap being connected to a member h and closed when the latter is inflated. Each caisson i is a hollow rigid structure, or may have a rigid inner side and a flexible outer side, and is provided with an air-pipe connection i<8>, water outlet i<9>, and longitudinal pivoted planes i<2>, each pivot i<3> having an arm i<4> connected by a link i<5> with a piston i<6> working spring-controlled in a cylinder i' connected to an air-pipe. The piston may be operated alternately by a collapsable caisson. The trawl is controlled by supplying or removing air from the elevator and caissons as described above for a beam trawl, assisted by the planes.