摘要:
A trawl door (10) for pelagic fishing comprises an accurately shaped main deflector portion (24) provided with a leading edge lift enhancing structure constituted by a plurality of slats which form leading edge slats (20,22). At least the main deflector portion, as preferably also the slats are formed of plate metal for ease of construction. The preferred embodiment is a V-shaped trawl door made up of two sections of door.
摘要:
Netting (15) includes mesh bars (26) made from twines (11,13) which possess physical properties that vary, change or alternate along a series of collinear mesh bars (26). The non-homogeneous media obtained by arranging in this way mesh bars (26) having varying physical properties may be configured to dampen or attenuate vibrations in the netting (15) such as harmonic oscillations (resonance). Furthermore, twines (11, 13) that attenuate vibrations may be chosen that also reduce the amount of material required to make netting (15) which has strength similar to or greater than conventional machine-made netting (15). Due to reduced vibration, the improved netting (15) lasts longer than conventional machine-made netting (15), and reduces the possibility of injury to fish which escape through a trawl's mesh cell openings.
摘要:
The invention relates to an otter board (20) which may be used for generating a spreading force in connection with trawl fishing. The otter board according to the invention comprises at least two foils (1-3) which are suspended between a number of longitudinally extending ribs (5, 6, 10, 17, 26, 27) in such a way that at least one tapered channel is formed in which the flow of water is passing through the otter board. The channels are curved and formed so that water is ejected at a high speed in relation to the towing speed in a direction slightly downwards and along a respective end section of an adjacent lower or intermediate foil extending from the outlets of the channels, whereby turbulence is prevented from occurring even at high angles of attack of the otter board.
摘要:
System for towing equipment at sea, preferably in relation to seismic surveys, comprising a main vessel (7) adapted to tow equipment (8) in a given direction of movement, at least one deflector (1) on each side of the main vessel (7) adapted to, during towing, pulling at least a part of the towed equipment (8) transversally in relation to the direction movement. The system comprises at least one support vessel (9) for supplying an additional towing force in the moving direction of the vessel and/or providing the active deflector(s) with power and possibly controlling signals to through a cable (6).
摘要:
Une porte de chalut (1) comprend un panneau (2) de forme rectangulaire, de préférence angulaire, avec des demi-portes réglables pour régler la surface active de la porte de chalut. Les demi-portes réglables sont placées de chaque côté de l'axe longitudinal central du panneau (2); une demi-porte (10) plus petite est placée au milieu de la partie inférieure (6) du panneau (2) lors de son utilisation, et une demi-porte (18) deux fois plus grande environ est placée au milieu de la partie supérieure (4) du panneau (2). On obtient ainsi une porte de chalut presque universelle, qui peut être facilement réglée pour presque tous les types imaginables de pêche, étant donné que la porte de chalut (1) a une envergure maximale lorsque les demi-portes (10, 18) sont complètement fermées, et une envergure minimale lorsque les demi-portes sont complètement ouvertes.
摘要:
A commercial fishing trawl has a net and a mouth opening defined by a head line, a foot line, and side lines. The mouth opening is spread by a plurality of foil segments threaded on one or more of the head line, foot line, or side lines. Foil segments may also be threaded on tag lines or foil lines attached about the mouth opening to spread and maintain the mouth opening as the trawl is towed through the water, behind a tow vessel.
摘要:
A bridle block (17) for a deflector (1), the bridle block (17) including a stem (7) and a rocker arm (18) pivotably attached to each other on a pivot axis (19), the stem (7) having an attachment (20) for a towline (31) from a vessel (3), a forward portion (22) of the rocker arm (18) having an attachment (23) for fore bridle lines (15) of the deflector (1), and an aft portion (24) of the rocker arm (18) having an attachment (25) for aft bridle lines (16) of the deflector (1), and the bridle block (17) including a hydraulic cylinder (30) provided with at least one valve (35, 36), and the hydraulic cylinder (30) being attached to the stem (7) and the rocker arm (18) to hold the stem (7) and the rocker arm (18) in a chosen relative position, wherein the at least one valve (35, 36) is operated directly or indirectly by an electric control signal from a control unit (99), and the at least one valve (35, 36) takes an open position when a control signal is missing, so that there is an open fluid connection between the piston side (38) of a piston (37) and a reservoir (51) for hydraulic oil (58) or an open fluid connection between the piston-rod side (39) of the piston (37) and the reservoir (51). A method of using the bridle block (17) to passively guide a deflector (1) into a known angle of attack relative to water when the deflector (1) is being towed through the water is described as well.
摘要:
A flow booster (8) is disclosed, shaped as a thick hydrofoil with an internal cavity (32), being aerodynamically inefficient on its own with a bulky relative thickness larger than 24 %, and being arranged to be positioned substantially below the rear part of a trawl door (37) comprising an overlapping sequence of several very slender hydrofoils (2), in such a way that the flow booster (8) forms a structurally connected integrated part to the hydrofoil (2) and impacts the upstream flow forcing it into a velocity boosted region (28) upstream of the flow booster (8) and to the pressure side (31) of the conventional part of the trawl door (1), such that the flow is pre-accelerated prior to running through the conventional trawl door channels (29) between the hydrofoils (2). Furthermore, a trawl door (39) comprising such a flow booster (8) and some uses of such a trawl door is disclosed.
摘要:
A trawl door for pelagic fishing comprises an accurately shaped main deflector portion (24, 25) provided with a leading edge lift enhancing structure constituted by a plurality of slats (20, 22) which form leading edge slats. At least the main deflector portion, as preferably also the slats are formed of plate metal for ease of construction. The preferred embodiment is a V-shaped trawl door made up of two sections (28, 29) of door.