OTTER BOARD Russian patent published in 2001 - IPC

FIELD: commercial fishery. SUBSTANCE: otter board shield has two strips arranged at rear side of board in plane extending parallel to incidence and obturation ribs. Keel is formed by stringer of width at least equal to thickness of board. Stringer is arranged perpendicular to board lower plate. Keel is further formed of column with at least two detachable shoes and portions for accommodating shoes attachment units. Column is mounted perpendicular to keel stringer at maximum offset of column toward face side of board. Upper stringer is positioned at an angle of 50- 60 deg to board upper plate surface. Detachable shoes are made of difficult-to-cut and difficult-to-forge alloy. Portions for accommodating shoes attachment units on keel column are made of readily processed material. Otter board of such construction allows trawl lifting and raising speed to be increased at any trawling velocity and trawl minimum horizontal opening to be kept. EFFECT: enhanced reliability in operation and prolonged service life by improved keel wear-resistance. 2 cl, 8 dwg