GB2129661A

GB2129661A - A trawl board

Info

Publication number: GB2129661A
Application number: GB08229511A
Authority: GB
Inventors: Thomas Horsfield; John Crawford; Robert Reginald Wall
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-10-15
Filing date: 1982-10-15
Publication date: 1984-05-23
Also published as: GB2129661B

Abstract

A trawl board for use with a trawl net has a hollow open end form with a substantially straight rear face 1 and a curved front face 2 both of which have louvres bevelled (as at 5,6,7) to facilitate passage of the board over the sea bed and the disposition and positioning of the board. A sole iron (20,21) is provided at the lower edge of the board. The louvres and open ended form of the board creates a jet effect which facilitates passage of the board through the water thus reducing the fuel consumption. It also permits a greater spread of the trawl net to be achieved and greater trawler manoeuvrability. <IMAGE>

Description

SPECIFICATION A trawl board The present invention relates to a trawl board.

A trawl board is a device mainly for holding open the neck of a trawl net during fishing bytrawling. The trawl net is usually provided with two trawl boards respectively arranged on the right and left hand sides of the trawl net. At the present time, such boards are generally rectangular in front elevation and have either a straight or a curved cross section. When the cross-section is curved, the concave curved innerface is usually parallel to the convex shaped outer face.

These boards exhibit a considerable resistance to being pulled through the water by the trawler. As a result, when the net and associated trawl boards are released into the water priorto a fishing operation, a braking force must be applied by the winch from which the trawl cable is being paid out to reduce the relative speed between the net and the trawler. If the relative speed is not reduced, the boards will not stand up and the trawl neck will not be held open. The relative speed could also be reduced by reducing the speed ofthetrawl, butthis is nota satisfactory solution.Theresistancetothetrawl boards being pulled through the water also increasesthefuel consumption ofthetrawler.

According to one aspect ofthe present invention, there is provided, a trawl board for use with a trawl net which board has a cross-section having a substantially straight rearface and a curved front face.

According to another aspect ofthe present invention, there is provided a trawl board for use with a trawl net which has louvrestherein which permit watertoflowthrough the board in use thereof.

According to a further aspect of the present invention there is provided a trawl board, for use with a trawl net, which is of hollow open ended form.

Where the board is hollow, and has a front face and a rearface both faces are louvred. Each louvre may be produced by making a cut in the corresponding face and pushing the material inwards away from the cut.

The material ofthe board may be metal such as mild steel, synthetic plastics or other suitable material. The faces of the board may be welded together or connected together by nuts and bolts. Advantageouslyfixed points for both the trawl net and line are provided on the board.

In orderthatthe invention may be more clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which Figure 1 shows a front elevational view of a trawl board according tothe invention, Figure 2 shows a rear elevational view ofthe board of Figure 1, Figure 3 shows a cross-sectional view ofthe board of Figures 1 and 2, Figure 4 shows another cross-sectional view of the board of Figures 1 and 2, Figure5 is a diagrammatic plan view showing the boards in position in a trawl net, Figure 6 is a diagrammatic side elevational view of the net of Figure 5, Figure 7 is a detail view of a towing bracketfor use with the board of Figure 1, and Figures 8b, 9,10 and 11 are detail views of parts oftheboardofFigures 1,2and3.

Referring to Figure 1, the main body of the board, which is of hollow open ended form, comprises a plain back 1 connected to a curved front 2. The back 1 and front 2 may be made of metal (such as mild steel), synthetic plastics material or other suitable material and may be connected to each other by welding nuts and bolts or any other appropriate method. eight stiffening members 3 are disposed between the back 1 and front 2 although the number of stiffening members may vary depending on the size, weight and material ofthe board. In some cases no such members at all may be required. The corners of the board are either curved (as at 4) or bevelled (as at 5,6 and 7)to facilitate the passage of the board over the sea bed and the disposition and positioning of the board.The lower edge ofthe board is provided with a complementary curved sole iron. The sole iron comprises two component parts 20 and 21 for easier replacement to caterforwear and tear.

Referring specifically to Figure 1, the curved front 2 defines a series ofthree louvres 8. Each louvre 8 is formed by making a curved cut 9 and bending the material of the front 2 about a straight line axis 10. In addition a pairoffixing loops 11 and 12 are provided.

These fixing loops receive the inverted V-shaped towing bracket 13 shown in Figure 7. This bracket 13 is provided with holes 24 to receive the shackle and two wire connected to the trawler. Alternativefixing loops 11 a and 1 2a are provided for an alternative towing bracket (not shown). A lifting bracket and ring is shown at 13a. A detailed view of loop 11 is shown in Figures 8a and 8b. Detail views of items 12a and 13a are shown in Figures 9 and 10 respectively.

Referring specifically to Figure 2, the back also defines a series of six louvres 15 arranged in two rows ofthree. Each of these louvres 15 is smaller than the louvres 8 and is produced by cutting a straight line 16 in the back 1 and then bending the material about a straight line 17. A bracket 25 is welded to the back of the board. This bracket is adapted to receive lines connecting the board to the trawl net. Bridle type towing points to the trawl net, a detail view of one of which is shown in Figure 11, are shown at 25a.

Referring to Figures 5 and 6, two ofthe trawl boards such as are described with referenceto Figures 1 to 4 are fixed between the trawling vessel 26 and trawl net 19. The method of fixing is as follows. Two lines 30,31 connect respective trawl boards to a winch on the rear of the trawlervia respective pulleys. These lines 30,31 are connected to the fronts of respective boards through their brackets 13. The backs of respective boards are connected by a sweep wire 32 to the trawl net 19. The free ends of the sweep wire 32 are connected to respective boards by means oftheir brackets 25 and a Danleno 33 and wing 34 is interposed in the wire. Floats 35 are connected to the upperfront edge of the trawl net 19 and the lower front edge of the net is connected to a ground line 36.

During a trawling operation the louvres 8 and 15 in conjunction with the open ended form of the board permit sea waterto flow th rough the board thus reducing resistance to movement of the boards through the water and creating a jet effect to the rear of the boards. Thisjet effect replaces the vacuum created with prior art boards as these boards are towed through the water and eases the passage of the boards ofthe invention through the water. This in turn enables the trawlerto move at a steady speed through the waterwith greater economy and to take up fishing more quickly than would otherwise bethe case. It is thoughtthatfuel savings of the order of 20% are attainable with the inventive boards as compared with conventional boards.In addition, the inventive boards permit a greater spread ofthe net to be achieved, allowthetrawler greater manoevrability on opening the net to commence fishing and in particular allow it to turn about and go in the opposite direction significantly quickerthan when using boards of known design.

Using a boat of some two hundred horse power, it was fond that the vessel could be turned in this way in seven minutes, whereas with an ordinary set of boards, up to thirty minutes was generally required.

In addition, whilst manoevring, it has been discovered thatthefishing gear always maintains the correct fishing position with the neck ofthe net open.

This is the case even when completing a manoevre of a complete turn about. With present boards, such a manoevre would involve a high risk of the neck of the net closing, the boards becoming entangled which would then require a delay whilst the problem was sorted out.

The required result can be achieved with a board of this design with a net of specific length and weight, with a much smaller board.

Also, the braking tension required to be applied by the net release winch on the existing boards is not required with the boards of the invention.

Itwill be appreciated that the above described invention has been described by way of example only and that many variations are possible without departing from the scope ofthe invention. For example, although open ended boards have been described they could well be closed atthe ends although such closure mighttend to reduce the jet effect of the water flowing through the board.

CLAIMS(Filed on 14/10/83).

1. Atrawl board for use with a trawl net which board has a cross-section having a substantially straight rearface and a curved front face.

2. Atrawl board for use with a trawl net which has louvres therein which permit water to flowthrough the board in use thereof.

3. Atrawl board for use with a trawl net, which is of hollow open ended form.

4. Atrawl board as claimed in claim 3, comprises front and rearfaces both of which are louvred.

5. Atrawl board as claimed in claim 4, in which the frontfaceofthe board is curved.

6. Atrawl board as claimed in claim 4 or 5, in which the rear face of the board is substantially straight.

7. Atrawl board as claimed in claim 2,4, or 6, in which each louvre is produced by making a cut in the corresponding face and pushing the material inwards away from the cut.

8. Atrawl board as claimed in claim 1,4, our 6, in which one or more stiffening members are disposed between the front and rearfaces.

9. Atrawi board as claimed in any preceding claim in which the corners thereof are curved or bevelled to facilitatethe passageofthe board overthesea bed.

10. Atrawl board as claimed in any preceding claim, in which the lower edge ofthe board is provided with a complementary curved sole iron.

11. Atrawl board as claimed in claim 10, in which the sole iron comprises two component parts for easier replacementforwear and tear.

12. Atrawl board as claimed in any preceding claim comprising atowing bracket.

13. Atrawl board as claimed in any preceding claim comprising a lifting bracket.

14. Atrawl board as claimed in any preceding claim comprising meansforconnectingthetrawl net thereto.

15. Atrawl board as claimed in claim 14, in which the meansforconnecting comprises a bracket adapted to receive lines for connecting the trawl net.

16. Atrawl board for use with a trawl netsubstantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. reducing resistance to movement of the boards through the water and creating a jet effect to the rear of the boards. Thisjet effect replaces the vacuum created with prior art boards as these boards are towed through the water and eases the passage of the boards ofthe invention through the water. This in turn enables the trawlerto move at a steady speed through the waterwith greater economy and to take up fishing more quickly than would otherwise bethe case. It is thoughtthatfuel savings of the order of 20% are attainable with the inventive boards as compared with conventional boards.In addition, the inventive boards permit a greater spread ofthe net to be achieved, allowthetrawler greater manoevrability on opening the net to commence fishing and in particular allow it to turn about and go in the opposite direction significantly quickerthan when using boards of known design. Using a boat of some two hundred horse power, it was fond that the vessel could be turned in this way in seven minutes, whereas with an ordinary set of boards, up to thirty minutes was generally required. In addition, whilst manoevring, it has been discovered thatthefishing gear always maintains the correct fishing position with the neck ofthe net open. This is the case even when completing a manoevre of a complete turn about. With present boards, such a manoevre would involve a high risk of the neck of the net closing, the boards becoming entangled which would then require a delay whilst the problem was sorted out. The required result can be achieved with a board of this design with a net of specific length and weight, with a much smaller board. Also, the braking tension required to be applied by the net release winch on the existing boards is not required with the boards of the invention. Itwill be appreciated that the above described invention has been described by way of example only and that many variations are possible without departing from the scope ofthe invention. For example, although open ended boards have been described they could well be closed atthe ends although such closure mighttend to reduce the jet effect of the water flowing through the board. CLAIMS(Filed on 14/10/83).

3. Atrawl board for use with a trawl net, which is of hollow open ended form.

12. Atrawl board as claimed in any preceding claim comprising atowing bracket.