TRAWL DOOR WITH LIFT ADJUSTING MEANS

Abstract

A trawl door used for trawl fishing, and more particularly, a trawl door adapted for stable and efficient operation. The door is equipped with moveable plate members (44) mounted on an outer panel (18) of the trawl door, hereby controlling an opening (42) in the outer panel and as a result controlling the lift of the trawl door.

Claims

1. A trawl door with lift adjusting means adapted to being remotely controlled, said trawl door comprising: an upper frame defining a top surface of the trawl door, a lower frame defining a bottom surface of the trawl door, and an intermediate frame positioned between said upper frame and said lower frame, said trawl door further comprising: a first number of longitudinal upper panels of hydrofoil construction arranged and extending between said upper frame and said intermediate frame, and a second number of longitudinal lower panels of hydrofoil construction arranged and extending between said intermediate frame and said lower frame, said trawl door having a cambered cross section and comprising a leading edge and a trailing edge, an inner trawl door side surface for facing a trawl mouth, and an opposite outer trawl door side surface, said upper frame, said intermediate frame and said first number of upper panels defining an upper trawl door section of said trawl door, and said intermediate frame, said lower frame and said second number of lower panels defining a lower trawl door section of said trawl door, said first and second number of panels each including an inner panel, which defines at least part of said inner trawl door side surface, and an outer panel, which defines at least part of said outer trawl door side surface, wherein said outer panels having an opening and a moveable plate member being connected to a driving unit and adapted to be controlled remotely when the trawl door is being towed through the water, such that said moveable member may be arranged in a first position closing said opening, and in a second position establishing an adjustable opening through said outer panel side surfaces, hereby adjusting a flow of water through said outer panels.

2. The trawl door according to claim 1, wherein said moveable plate member comprises a flap, hingedly connected to said opening for moving said flap between a first open and a second closed position.

3. The trawl door according to claim 1, wherein said moveable plate member comprises a slideable plate connected to said opening in a slideable manner between a first open position and a second closed position.

4. The trawl door according to claim 2, wherein said flap is hingedly connected to said outer panels for pivoting about an axis which extends parallel to said outer panels, said flap being pivotal towards said outer side surface and/or towards said inner panels.

5. The trawl door according to claim 4, wherein said flap is hingedly connected for opening towards said leading edge or towards said trailing edge.

6. The trawl door according to claim 2, wherein said flap is hingedly connected to said opening through an axis substantially through a centerline of said flap.

7. The trawl door according to claim 3, wherein said slideable plate is slideable connected to said outer panel on an outer side of said panel or an inner side of said panel.

8. The trawl door according to claim 7, wherein said slideable plate is slideable towards both said leading edge and said trailing edge.

9. The trawl door according to claim 1, wherein said trawl door further comprises at least one intermediate panel extending in spaced relationship between said inner and outer panel.

Description

[0044] The invention will now be explained in more detail below by means of examples of embodiments with reference to the very schematic drawing, in which:

[0045] FIG. 1 shows a perspective view of a trawl system.

[0046] FIG. 2 shows a perspective view of a prior art trawl door.

[0047] FIG. 3 shows a perspective view of an outer side of a trawl door section.

[0048] FIG. 4 shows a sectional view of a trawl door.

[0049] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout. Like elements will, thus, not be described in detail with respect to the description of each figure.

[0050] FIG. 1 illustrates the basic arrangement of a prior art trawl system. The system comprises a trawl net 38, which comprises a trawl mouth 48 facing the trawling direction.

[0051] The trawling trawl net 38 comprises towing warps 40 being connected to either side of the trawl mouth 48 and extending from the trawl net 38 to a sailing vessel, which is indicated by the arrows. In connection with the warps 40, there is arranged a pair of trawl doors 10, each trawl door being connected to the warps 40 at either side of the trawl mouth 48, such that the trawl doors 10 arrange the trawl mouth 48 with a desired opening (spread 46). Arranging the trawl doors with increasing lift, increases the spread 46, and arranging the trawl doors with a lower lift, decreases the spread 46.

[0052] FIG. 2 illustrates a perspective view of a prior art trawl door which corresponds substantially to the applicant's prior trawl door, which is described in DK178860B1.

[0053] The trawl door 10 comprises an upper trawl door section 10a and a lower trawl door section 10b. The trawl door comprises an upper frame 12, a lower frame 14, and an intermediate frame 16, which divides the trawl door 10 in two sections. Between the upper frame 12 and the intermediate frame 16, and the intermediate frame 16 and the lower frame 14, is arranged a number of longitudinal panels of hydrofoil construction, which generates the lift of the trawl door. The trawl door comprises a leading edge 32, which during fishing faces towards the sailing vessel, and a trailing edge 34, which during fishing faces towards the trawl net 38. The longitudinal panels of hydrofoil construction comprise outer panels 18 which face towards an outside of the trawl system and away from the trawl mouth, and an inner panel (not shown) which is arranged on an opposite side of the trawl door and facing the trawl mouth 48 and the trawl door arranged on the opposite side of the trawl net 38. The outer panels 18 and the inner panels 20 are spaced in parallel relationship, and a number of intermediate panels 22 is arranged in parallel relationship in-between the outer panels 18 and inner panels 20. In the example shown in FIG. 2, the trawl door 10 comprises two intermediate panels in each of the upper panel section 10a and the lower panel section 10b, respectively. The skilled person would however recognize the possibility of arranging no intermediate panels, only one intermediate panel 22, or a number of intermediate panels 22 larger than two, e.g. three or four, etc.

[0054] FIG. 3 illustrates an embodiment according to the invention and illustrates for the purpose of simplicity only the upper trawl door section. It is however evident that the description of the drawing applies to the lower trawl door section 10b.

[0055] The upper trawl door section 10a comprises the upper frame 12, the intermediate frame 16, the outer panel 18, the inner panel 20, and the intermediate panel. It is evident from the figure that the upper panel 18 is arranged towards the leading edge 32 and the intermediate panels 22, and the inner panel 22 (not shown) are arranged towards the trailing edge 34. The outer panel 18 comprises an opening 42 and a moveable plate member 44 which in the illustrated embodiment is illustrated as a slideable plate which is moved towards the trailing edge 34, such that the upper panel 18 comprises the opening. The plate member 44 is activated by an activation mechanism, such as a mechanical, pneumatic, hydraulic or electric drive which is known to the person skilled in the art. The moveable plate member 44 may be moved back towards the leading edge 32, whereby the opening 42 is closed and the outer panel 18 comprises a complete surface. As previously described, the moveable plate member 44 may be arranged as a hinged flap generating an opening towards the leading edge or the trailing edge. The hinged flap is arranged for pivoting towards the outer side or the outer panel 18 or may in a further embodiment be arranged for pivoting in both directions.

[0056] Further, as illustrated, the moveable plate member 44 is slit towards the trailing edge, but may in a further embodiment be arranged for sliding towards the leading edge, or may even be arranged for sliding in both directions, hereby being suitable for establishing an opening 42 on either side of the plate member 44. The opening 42 and the moveable plate member 44 are illustrated with equal distance to the upper frame 12 and the intermediate frame 16; however, in another embodiment, the opening 42 and moveable plate member may be arranged either closer to the upper frame 12 or closer to the intermediate frame, whereby it is possible to influence the stability of the trawl doors when they operate under various conditions.

[0057] FIG. 4 illustrates a sectional view of the upper trawl door section 10. In the figure it is clearly illustrated that the trawl door 10 comprises first pulling points 28 for connection of the towing warp 40 between the trawl door 10 and the vessel, and second pulling points 30 for connecting the towing warp 40 between the trawl door and the trawl net 38). The arrangement of the plates 18, 22, 20 of hydrofoil construction is also evident from the figure.

[0058] Contrary to the upper panel 18 and the intermediate panels 22, the lover panel is arranged as a hollow and may as disclosed in the applicant's above mentioned patent be arranged with a moveable flap which is connected to a driving unit for controlling the opening and closing of the flap, hereby controlling the lift of the trawl door. In FIG. 4, the opening in the outer panel is illustrated with a “square”, which is arranged at a rear most part of the outer panel. Test performed by the applicant show that the opening may also be arranged in the middle of the panel or towards the trailing edge.

[0059] In the following is given a list of reference signs that are used in the detailed description of the invention and the drawings referred to in the detailed description of the invention. [0060] 10 Trawl door [0061] 10a Upper trawl door section [0062] 10b Lower trawl door section [0063] 12 Upper frame [0064] 14 Lower frame [0065] 16 Intermediate frame [0066] 18 Outer panel [0067] 20 Inner panel [0068] 22 Intermediate panel [0069] 28 First pulling points [0070] 30 Second pulling points [0071] 32 Leading edge [0072] 34 Trailing edge [0073] 36 Inner trawl door side surface [0074] 38 Trawl net [0075] 40 40 Towing warp [0076] 42 Opening [0077] 44 Moveable plate member [0078] 46 Spread [0079] 48 Trawl mouth