GB823893A - Apparatus for use with trawling nets - Google Patents

Abstract

823,893. Trawl fishing gear. BULMAHN, A. Sept. 3, 1957 [Sept. 3, 1956], No. 27825/57. Class 48. [Also in Groups XXV and XXX] Apparatus for use when trawling comprises a centrally marked line 9 connected to symmetrical points on both sides of the trawling gear and a marker clamp 10 slidable on the line 9 and provided with a delay action device preventing the clamp from gripping the line for a predetermined period. The marker clamp 10 is attached to a float 23 which due to flow resistance drags the marker clamp 10 to the rearmost part of the line 9 and the delay action device ensures that the clamp does not grip the line until trawling has commenced. When at the end of a trawling operation the net is raised on to the trawler the position of the marker clamp 10 relative to the central mark on the line indicates whether the net had been towed with its mouth at right angles or oblique to the direction of towing. The line 9 may be attached to the headline 7 or to the otter-boards 3, 4. The clamp consists of a coil spring 12 having arms 13, 14 provided with clamping jaws 15, 16 and bent portions 17, 18 preventing escape of the line 9 when the jaws are open. The lower jaw 16 supports a cylinder 19 into which a piece of rock salt 24 is inserted and the upper jaw 15 has a small plate 22 which is adapted to enter the cylinder to abut against the rock salt. As the rock salt dissolves the plate 22 moves into the cylinder until the jaws grip the line 9. In a modified clamp the jaws are held apart by a bolt which is gradually drawn back by clockwork. In a further modified clamp one of the jaws is moved through reduction gear by a propeller driven by the water. The reduction gear may be braked by a rotating vane.