GB2093322A - Fishing dredge - Google Patents

Abstract

A toothed bar 5, for disturbing shellfish from the sea bed for collection in net or chain belly 4, is secured to frame 2 by means of resiliently deformable blocks 6 which allow the toothed bar to undergo resilient movement to ride over obstacles on the sea bed. The lower end of each block 6 to which the toothed bar 5 is secured, is encased in a metal cap 22 to reduce wear. The block 6 is held between metal plates the rear one of which is curved outwardly at its bottom end to allow the required degree of rearward flexure of the block. <IMAGE>

Description

SPECIFICATION Fishing dredge This invention relates to fishing dredges and in particular to such dredges for catching scallops and other shellfish.

According to this invention there is provided a fishing dredge comprising a frame for connection to a towing warp for towing the dredge in a predetermined direction relative to the frame and for supporting a net with its mouth open transverse to said predetermined direction so as to receive and collect shellfish when the dredge is towed in said predetermined direction, a toothed bar secured to the frame by means of resiliently deformable members such that the toothed bar is resiliently held in a position for disturbing the sea bed in front of the net mouth during towing of the dredge and can undergo resilient movement to clear obstacles.

Preferably the resiliently deformable members comprise blocks of rubber or resilient plastics material.

Embodiments of this invention will now be described by way of example with reference to the accompanying drawing in which: Fig. 1 is a schematic side view of a scallop fishing dredge embodying this invention; Fig. 2 is a plan view of part of the dredge shown in Fig. 1; Fig. 3 is a further side view showing part of the dredge shown in Fig. 1; Fig. 4 is an end view of part of the dredge shown in Fig. 1; Fig. 5 is a perspective view of a part of the dredge shown in Fig. 1; and Figs. 6 and 7 are views, corresponding to Figs.

1 and 5, of modified forms of the dredge.

Referring to the drawings, a scallop fishing dredge comprises a frame 2 having a shackle 3 for connection to a towing warp W. A collecting net 4 is secured to the frame so that the mouth of the net is held open and extends across the path of travel of the dredge so that the net receives and collects shellfish during towing of the dredge. A toothed bar 5 is secured to the frame 2 across and in front of the open mouth of the net 4 whose upper part extends forwardly of the toothed bar.

The teeth of the toothed bar serve to disturb the sea bed so that shellfish rise into the path of the open mouth of the net.

Difficulty arises if the toothed bar 5 snags on an obstacle such as a large stone and cannot be freed. It may then be necessary to cut the warp W and abandon the dredge.

To reduce the risk of this happening the toothed bar 5 is secured to the frame 2 by means of resiliently deformable members in the form of rubber blocks 6. These enable the toothed bar to undergo resilient movement to clear obstacles due to resilient deformation of the blocks 6.

Referring particularly to Fig. 5, each block 6 has three bores 7, 8 and 9 (each of which may be provided with a reinforcing metal liner) two of which (7, 8) serve to secure the block by means of bolts 10, 11 to a metal plate 12 welded at 1 3 (Fig.

5) to an arm 14 of the frame 2. The block 6 is reinforced in its fastening to the plate 12 by means of an outer metal plate 1 5 through which the bolts 10, 11 also pass. The lower end of the plate 1 5 is curved outwardly from the block 6 as shown to provide the required degree of freedom for flexture of the block to the rear when the bolted bar rides over obstacles. The metal plate 1 5 could also be made vertically variable in position (by providing additional bolt-holes) on the block 6 so that the degree of flexure of the block 6 could be varied in accordance with requirements.

Chain belly rail supports 16 (Fig. 3) are welded to the frame 2 and at 17 (Fig. 5) to the plate 12 and serve to support a chain belly rail 1 8 running across the dredge and to which is secured the underside of the net 4 which is usually in the form of a metal ring mesh calied a chain belly.

A portion of the block 6 protrudes below the metal plates 12, 1 5 and the bore 9 extends through this portion. The toothed bar 5 is secured to each of the blocks 6 by means of bolts 19 passing through the bores 9 and a blade portion 20 of the toothed bar to which teeth 21 are fixed.

A rectangular cross-section metal cap 22 is mounted on the end of the block G and has apertures 23 to receive the bolt 1 9. The cap 22 serves to reduce wear of the block 6.

In use the ability of the block 6 to deform resiliently provides resilient movement of the toothed bar to enable the latter to clear obstacles on the sea bed.

Since the blocks 6 to a large extent provide independent relative movement of the two ends of the toothed bar, for obstacles which are positioned off-centre of the bar 5, the dredge 1 presents better characteristics in terms of clearing obstacles and maintaining optimum engagement of the bar with the sea bed than if the toothed bar were only movable about an axis disposed rigidly with respect to the frame.

Referring now in particular to Fig. 6, this shoves how "set" can be introduced into the dredge as shown in Fig. 1. The dimension X indicated in Fig. 6 is the amount of "set" introduced and has the effect of angling forward the toothed bar 5.

This is considered desirable under certain circumstances and is regarded as improving the action of the dredge.

Referring to Fig. 7 a modified form of the arrangement shown in Fig. 5 comprises several features of difference one or more of which may be adopted. The bores 7', 23" are now positioned equidistantly from the ends of the block 6 and the bore 8' is central between the bores 7' and 23'. In this way the block 6 can be turned upside down if its bottom end should become worn beyond tolerable limits. Also the shift in position of the bores 7', 8' makes it preferable to offset (as shown) the positions 13', 1 7' of attachment of the plate 12 to the frame.

A further modification resides in the possible provision of a spring steel plate 24 between the block 6 and the plate 1 2 and blade portion 20.

This enables the cap 22 to be dispensed with and provides reinforcementfor the block 6. Such a spring steel plate may also be provided at the other side of the block 6 between the latter and the plate 1 5. It is even possible that the block 6 be replaced by a laminated core comprising such spring steel plates although problems due to corrosion might restrict the usefulness of this possibility. However the useful working life of such an arrangement might be extended by coating the core and/or individual steel plates (particularly their major faces) with a resiliently deformable plastics coating.

Claims (12)

1. A fishing dredge comprising a frame for connection to a towing warp for towing the dredge in a predetermined direction relative to the frame and for supporting a net with its mouth open transverse to said predetermined direction so as to receive and collect shellfish when the dredge is towed in said predetermined direction, a toothed bar secured to the frame by means of resiliently deformable members such that the toothed bar is resiliently held in a position for disturbing the sea bed in front of the net mouth during towing of the dredge and can undergo resilient movement to clear obstacles.

2. A fishing dredge according to claim 1 wherein the resiliently deformable members comprise blocks of rubber or resilient plastics material.

3. A fishing dredge according to claim 2 wherein the toothed bar is secured to one end portion of each said block, the other end Dortion serving for securing to the frame.

4. A fishing dredge according to claim 3 wherein said one end portion is held in a metal cap to which the toothed bar is also secured.

5. A fishing dredge according to claim 3 or claim 4 wherein said one end portion extends over a shorter length than said other end pOrtiOn.

6. A fishing dredge according to any one of claims 3 to 5 wherein said other end portion of each said block is held between two metal plates one of which serves to secure the block to the frame.

7. A fishing dredge according to claim 6 wherein the other of said plates is curved outwardly from the block at the end of the plate adjacent said one end portion so as to provide a required degree of flexure of the block rearwardly of the dredge when in use.

8. A fishing dredge according to any one of claims 2 to 7 wherein said blocks are secured to the toothed bar and to the frame by means of bolts extending through bores in the blocks.

9. A fishing dredge according to claim 8 wherein the bores have metal liners.

10. A fishing dredge according to any one of the preceding claims wherein the resiliently deformable members can be removed and reversed in direction between the frame and the toothed bar.

11. A fishing dredge according to any one of the preceding claims wherein said resiliently deformable members include one or more spring metal plates.

12. A fishing dredge substantially as described herein with reference to the accompanying drawings.