WO2013136041A2 - Perfectionnements apportés ou se rapportant à un cadre de drague - Google Patents

Perfectionnements apportés ou se rapportant à un cadre de drague Download PDF

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Publication number
WO2013136041A2
WO2013136041A2 PCT/GB2013/000115 GB2013000115W WO2013136041A2 WO 2013136041 A2 WO2013136041 A2 WO 2013136041A2 GB 2013000115 W GB2013000115 W GB 2013000115W WO 2013136041 A2 WO2013136041 A2 WO 2013136041A2
Authority
WO
WIPO (PCT)
Prior art keywords
raking
blade
flat
resilient material
torsional spring
Prior art date
Application number
PCT/GB2013/000115
Other languages
English (en)
Other versions
WO2013136041A3 (fr
Inventor
Richard Gidney
Original Assignee
Deeside Marine Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GBGB1204637.1A external-priority patent/GB201204637D0/en
Priority claimed from GBGB1223059.5A external-priority patent/GB201223059D0/en
Application filed by Deeside Marine Limited filed Critical Deeside Marine Limited
Publication of WO2013136041A2 publication Critical patent/WO2013136041A2/fr
Publication of WO2013136041A3 publication Critical patent/WO2013136041A3/fr

Links

Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K80/00—Harvesting oysters, mussels, sponges or the like

Definitions

  • the present invention relates to a fishing dredge and in particular to a frame for a fishing dredge.
  • Dredging is used for harvesting bivalve molluscs such as oysters, clams and scallops.
  • a traditional scallop dredge is a framed basket attached to a set of connected iron rings or wire netting called a belly or chain belly.
  • the lower edge of the frame has a raking bar, with or without teeth or swords depending upon the species of mollusc that is being caught.
  • the catch is lifted off the seabed or out of the sea by the raking bar or teeth and passes back into a basket or bag known as a belly.
  • the number of dredges may vary from a single dredge towed behind the vessel to from 5 to 20 or more dredges per side.
  • Dredges are generally attached to a towing bar and one is operated from each side of the vessel simultaneously.
  • Figure 1 shows a trawler 1 which has a tether or trawl warp 3 connected between the winch of the boat and a dredge 5 which is pulled along the sea bed 9.
  • Figure 2 shows the features of a typical dredge set up.
  • the dredges 11 are connected to the trawler via the trawl warp 3 which connects to a towing triangle 13.
  • Four chain bridles 15 extend from the towing triangle 13 and are connected to a tow bar which has a pair of bobbin wheels 17.
  • the tow bar couples the chain bridles 15 to dredges 21.
  • dredge 23 comprises a frame 25 and a net bag 26.
  • the frame is typically made from steel and has a plurality of teeth or swords 31 which extend downwards from the frame. Eyebolt 27, H-plate 29, spring 32 and paw 33 provide the mechanism by which the sword 31 engages with the sea bed in order to disturb the molluscs.
  • the molluscs are dug out from the sea bed by the sword 31, they gather along the front surface of the frame 34 and then they pass through the frame into the net 26.
  • the teeth 31 mounted on the tooth bar are fixed in position and are connected to the frame at a pivot point towards the top of the frame.
  • the tooth bar is also attached to a compression spring 32.
  • the teeth 31 are retained in the downward position in which they dig into the seabed to uncover molluscs.
  • the tooth bar moves about the pivot point to raise the tooth bar and move over the object. This prevents the tooth bar from getting stuck on the sea bed.
  • raising the tooth bar also means that the molluscs that have accumulated on the front of the tooth bar escape under the raised toothbar.
  • Dredging in general is viewed as having a significant environmental impact because it agitates the sea bed and in the process causes significant damage.
  • the act of dragging the dredges along the sea bed requires the trawler to use significant amounts of fuel to power its engines.
  • Figure 4 is a side view which shows a frame 41 having an open side 42 which is supported by a diagonal frame member.
  • the frame has a ground engaging rail 45 which is in contact with the seabed and which slides along the seabed in use.
  • Support beam 47 extends across the frame and supports the sword or tooth 49 which is attached to the support beam 47 by means of a helical winding 51 with which it is integrally formed and is an extension of the spring as shown in figure 5.
  • An abutment 53 is positioned above the helical winding and acts to retain the tooth 49, helical winding 51 and support beam 47 in position.
  • the tooth 49 extends outwards from the frame such that it can scrape the seabed in order to uncover molluscs.
  • the frame 41 In use, the frame 41 is dragged along the seabed using rails 45 and the tooth 49 digs into the seabed in order to uncover molluscs.
  • the frame 41 has eight teeth which are independently resiliently mounted on the support beam 47 such that when one of the teeth encounters a hard object such as a stone it will move backwards under tension in order to move over of the stone. As the teeth are all independently resiliently mounted the movement of one tooth over a stone does not affect the ability of the other teeth to continue the operation of digging into the seabed. Therefore even when one tooth encounters an object such as a stone and has to move, the remaining teeth can continue to collect molluscs.
  • Figure 5 shows the support 47 extending across the frame and having eight teeth extending downwards.
  • the teeth 49 are mounted in pairs such that both teeth of a pair of teeth are made from a continuous piece of stiff wire which contains two helical sections connected together by a bridge section (not shown).
  • the bridge is attached to the support beam 47 by means of a bolt 60.
  • a raking element for a fishing dredge frame comprising:
  • a length of resilient material shaped into a flat-spiral torsional spring which is connectable at a first end to a fishing dredge frame and wherein a second end thereof extends from the flat-spiral torsional spring to form a blade which digs into the sea bed, in use.
  • the flat-spiral torsional spring has a spring constant which provides sufficient resilience to the raking element for digging into the sea bed and for the blade to be resiliently displaced if the blade encounters a substantially fixed obstruction on the sea bed.
  • the resilient material has a rectangular cross section with the major axis of the cross section across the width of the resilient material.
  • the spiral section of the raking element is formed by bending the resilient material along its length with respect to its width
  • the blade section is positioned to engage a seabed across the depth of the resilient material, in use.
  • the orientation of the cross section of resilient material is displaced by approximately 90° as between the flat-spiral torsional spring and the blade.
  • the resilient material is twisted to displace the orientation of the cross section of the blade with respect to the flat-spiral torsional spring.
  • the length of resilient material has a substantially circular cross section.
  • At least part of the second end of the length of resilient material is flattened to form the blade.
  • the blade section is positioned to engage a seabed across the depth of the flattened resilient material.
  • the blade is substantially linear.
  • the blade is curved.
  • the angle at which the teeth contact the sea bed is adjustable.
  • the raking element further comprises a barrier which prevents debris from collecting in the flat-spiral torsional spring.
  • the barrier comprises a filler which is introduced into the gaps between the turns of the flat-spiral torsional spring.
  • the filler adheres to the flat-spiral torsional spring so as to minimise the effect of the filler upon the torque of the flat-spinal torsional spring.
  • the barrier comprises a cover which extends across the flat-spiral torsional spring.
  • the torque of the spring coil is in the range 450Nmm/degree to
  • the blade is between 80mm and 190mm in length.
  • raking assembly comprising a plurality of raking elements mounted thereon.
  • the raking assembly comprises mounting means and one or more spacers arranged between raking elements.
  • a frame for a fishing dredge comprising:
  • said raking element having a blade which extends beyond the seabed engaging portion of the frame; and wherein the raking element comprises a length of resilient material shaped into a flat-spiral torsional spring which is connected at a first end to the mounting means, the second end thereof extends from the flat-spiral torsional spring to form the blade which digs into the sea bed, in use.
  • the flat-spiral torsional spring has a spring constant which provides sufficient resilience to the raking element for digging into the sea bed and for the blade to be resiliently displaced if the blade encounters a substantially fixed obstruction on the sea bed.
  • the resilient materia! has a rectangular cross section with the major axis of the cross section across the width of the resilient material.
  • the spiral section of the raking element is formed by bending the resilient material along its length with respect to its width
  • the blade section is positioned to engage a seabed across the depth of the resilient material, in use.
  • the orientation of the cross section of resilient material is displaced by approximately 90° as between the flat-spiral torsional spring and the blade.
  • the resilient material is twisted to displace the orientation of the cross section of the blade with respect to the flat-spiral torsional spring.
  • the length of resilient material has a substantially circular cross section.
  • At least part of the second end of the length of resilient material is flattened to form the blade.
  • the blade section is positioned to engage a seabed across the depth of the flattened resilient material.
  • the blade is substantially linear.
  • the blade is curved.
  • the angle at which the teeth contact the sea bed is adjustable.
  • the raking element further comprises a barrier which prevents debris from collecting in the flat-spiral torsional spring.
  • the barrier comprises a filler which is introduced into the gaps between the turns of the flat-spiral torsional spring.
  • the filler adheres to the flat-spiral torsional spring so as to minimise the effect of the filler upon the torque of the flat-spinal torsional spring.
  • the barrier comprises a cover which extends across the flat-spiral torsional spring.
  • the torque of the spring coil is in the range 450Nmm/degree to
  • the blade is between 80mm and 190mm in length.
  • Figure 1 is illustrates the process of dredge fishing
  • Figure 2 illustrates a known type of fishing dredge
  • Figure 3 is a side view of a known type of fishing dredge frame and belly;
  • Figure 4 is a side view of another known type of dredge frame;
  • Figure 5 is a side view of the dredge frame of figure 4.
  • Figure 6 is a plan view of a dredge frame with a raking element in accordance with the present invention.
  • Figure 7 is a side view of the dredge frame of figure 6;
  • Figure 8 is a plan view of a raking element assembly in accordance with the present invention.
  • Figure 9 is a side view of a raking assembly in accordance with the present invention.
  • Figure 10 is a perspective view of a raking assembly in accordance with the present invention.
  • Figure 11 is a side view of a raking element in accordance with the present invention.
  • Figure 12 is a perspective view of a raking element in accordance with the present invention.
  • Figure 13 is a perspective view of a second embodiment of the present invention.
  • Figure 14 is a side view of the embodiment of figure 13;
  • Figure 15 is a plan view of the embodiment of figure 13;
  • Figure 16 is an end view of the embodiment of figure 13.
  • the present invention provides a raking element, typically used in an assembly of such elements as part of a frame for a fish dredge.
  • the apparatus of the present invention is particularly suitable for dredge fishing for scallops or other bivalve molluscs as generally described with respect to Figures 1 and 2 above.
  • the present invention provides an improved apparatus for raking or digging the seabed which retains the advantages of previous frames by reducing the drag but also improving the longevity of the blades whilst retaining an appropriate degree of resilience in the spring to allow it to be displaced when passing over a seabed obstacle.
  • Figures 6 to 12 show an embodiment of a frame, raking assembly and raking element.
  • Figure 6 shows a frame 61 , with a rake assembly 63.
  • the rake assembly comprises a plurality of spacers 65 which separate raking elements 67.
  • Figure 7 shows a side view of the frame in accordance with the present invention.
  • the first end 73 of the raking element is connected to a mounting bar 71.
  • the raking element has been bent to form a flat-spiral torsional spring 72 with a blade section 78 extending downwards beyond the seabed engaging portion of the frame 76.
  • the distance between the lowermost portion of the frame 76 and blade 78 represents the distance into the seabed to which blade may penetrate.
  • Figure 8 is a plan view of the rake assembly 63
  • Figure 9 is a front view of the rake assembly 63
  • Figure 10 is a perspective view of the same.
  • the assembly as shown comprises the mounting bar 71 with eight raking elements separated by spacers. Three spacers have been omitted from the diagram for clarity.
  • the side view of the rake element in accordance with the present invention is shown in Figure 11 and a perspective view of the same is shown in Figure 12.
  • the raking element 81 comprises a first end which forms a flat-spiral torsional spring which has a mounting bar engaging section 85 which is sized to fit within a slot on a mounting bar (not shown).
  • the flat spiral 87 is created by bending a length of resilient material, typically steel, into a spiral shape. The number of turns on the spiral and the distance between them as well as the properties of the material determine the spring constraint of the spring.
  • the resilient material's properties in this regard depend upon the material's composition, its length, width and thickness or depth.
  • the second end 91 of the length of resilient material comprises the blade, the end of which 93 experiences considerable friction in use by being dragged across a seabed.
  • the raking element contains a twisted section 89 which changes the orientation of the resilient material such that the leading edge of the blade 93 which experiences considerable abrasion during dredging has sufficient material depth to withstand seabed abrasion for considerably longer than the tines used on previous dredging frames.
  • the leading edge of the blade is formed by the shortest side of the resilient material which provides a finer cutting edge than has been previously available.
  • a further advantage of the present invention is that the geometry of the flat-spiral torsional spring takes up less space along the mounting bar than previously use helical spring tines which were wound along the length of the mounting bar. Use of the spring tines limited the number of blades that could be used and prescribed the position along the mounting bar at which they must be placed. Neither of these restrictions apply to the use of a raking element which uses a flat-spiral torsional spring.
  • Figure 13 is a perspective view of a second embodiment of the present invention.
  • the raking element is shown from the side in Figure 14, figure 15 is a plan view and figure 16 is an end view of the embodiment of figure 13.
  • the raking element 101 comprises a first end 103 which forms a flat-spiral torsional spring which has a mounting bar engaging section 105 which is sized to fit within a slot on a mounting bar (not shown).
  • the flat spiral 107 is created by bending a length of resilient material, typically steel, into a spiral shape.
  • the second end 111 of the length of resilient material comprises the blade, formed by twisting the resilient material at position 109.
  • the end 1 13 of the blade 111 experiences considerable friction in use by being dragged across a seabed.
  • the space between the turns of the coil of the flat-spiral torsional spring has a barrier 1 15 which prevents debris such as grit, sand and small stones from becoming lodged within the space between the turns of the spring.
  • the barrier is made from a silicone filler material which adheres to the coil and fills out the space between the turns, forming a solid barrier to prevent debris from becoming lodged in the turns.
  • the filler has a negligible effect upon the torque of the raking element.
  • this design has been found to reduce the failure rate of the individual raking elements by preventing the buildup of sand within the coils.
  • the raking element contains a twisted section 109 which changes the orientation of the resilient material such that the leading edge of the blade 113, which experiences considerable abrasion during dredging, has sufficient material depth to withstand seabed abrasion for considerably longer than the tines used on previous dredging frames.
  • the leading edge of the blade is formed by the shortest side of the resilient material which provides a finer cutting edge than has been previously available.
  • the raking element will have a spring torque of around 40 ⁇ mm/degree to 600Nmm/degree, a blade length 123 of 130mm, a thickness [2] of around 3mm, an outer spring diameter 117 of around 85mm and a cavity 119 which allows the raking element to fit around a 30mm bar.
  • the primary purpose of the barrier is to prevent materia) lodging between the turns of the coil and silicone filler or an elastomer with similar properties has been found to be a suitable material for this purpose.
  • this type of product has a negligible effect upon the torque of the spring and can be easily incorporated in the raking element by a heat treatment process or by direct injection. Rubber may be used in place of silicone to form the barrier.
  • the barrier comprises a cover which extends across the flat-spiral torsional spring.
  • a further advantage of the present invention is that the geometry of the flat-spiral torsional spring takes up less space along the mounting bar than previously use helical spring tines which were wound along the length of the mounting bar. Use of the spring tines limited the number of blades that could be used and prescribed the position along the mounting bar at which they must be placed. Neither of these restrictions apply to the use of a raking element which uses a flat-spiral torsional spring.
  • flat-spiral torsional spring means any suitable spring which may be incorporated as part of a raking element and has the properties required to assist the invention in achieving one or more of the advantages of the present invention such as improved wear and tear on the blade, appropriate resilience and spring constant for dredging and taking up less space on a mounting bar.
  • Such springs may also be described using other terms such as flat coil springs, brush springs, clock springs or main springs.
  • the length of resilient material has a circular cross section and the blade is formed by flattening the end of the material instead of incorporating a twist in material having a rectangular cross section.
  • a further advantage of the present invention is that the raking elements may be manufactured as separate discrete components which are easily replacable in a raking assembly on a frame. Accordingly, the raking elements may be sold separately as spare parts.

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  • Life Sciences & Earth Sciences (AREA)
  • Environmental Sciences (AREA)
  • Animal Husbandry (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Mechanical Means For Catching Fish (AREA)

Abstract

L'invention concerne un élément à ratisser et un ensemble d'éléments à ratisser qui peuvent être agencés dans un cadre pour une drague de pêche. L'élément à ratisser comporte une longueur de matériau élastique qui est façonnée en un ressort de torsion en spirale aplatie ayant un couple prédéterminé à une extrémité qui est en mesure de se raccorder au niveau d'une première extrémité sur un cadre de drague à pêche. La seconde extrémité de la longueur de matériau élastique formant une lame qui creuse dans le fond marin, lors de l'utilisation. La présente invention concerne un appareil amélioré permettant de ratisser ou de creuser le fond marin qui améliore de la durée de vie des lames tout en retenant un degré approprié d'élasticité au niveau du ressort pour lui permettre de se déplacer lors d'un passage sur un obstacle se trouvant sur le fond marin.
PCT/GB2013/000115 2012-03-16 2013-03-15 Perfectionnements apportés ou se rapportant à un cadre de drague WO2013136041A2 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GBGB1204637.1 2012-03-16
GBGB1204637.1A GB201204637D0 (en) 2012-03-16 2012-03-16 Improvements in and relating to a dredge frame
GBGB1223059.5 2012-12-20
GBGB1223059.5A GB201223059D0 (en) 2012-12-20 2012-12-20 Improvements in and relating to a dredge frame

Publications (2)

Publication Number Publication Date
WO2013136041A2 true WO2013136041A2 (fr) 2013-09-19
WO2013136041A3 WO2013136041A3 (fr) 2014-11-06

Family

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Application Number Title Priority Date Filing Date
PCT/GB2013/000115 WO2013136041A2 (fr) 2012-03-16 2013-03-15 Perfectionnements apportés ou se rapportant à un cadre de drague

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010102077A2 (fr) 2009-03-04 2010-09-10 Intelliserv International Holding, Ltd Système et procédé d'utilisation d'un raccord d'usure dans un système de forage

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0815114D0 (en) * 2008-08-19 2008-09-24 Deeside Marine Ltd Improvments in and relating to a dredge frame

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010102077A2 (fr) 2009-03-04 2010-09-10 Intelliserv International Holding, Ltd Système et procédé d'utilisation d'un raccord d'usure dans un système de forage

Also Published As

Publication number Publication date
WO2013136041A3 (fr) 2014-11-06

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