GB2430213A

GB2430213A - Non suction shellfish harvesting head

Info

Publication number: GB2430213A
Application number: GB0519142A
Authority: GB
Inventors: Clifford Henderson
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-09-20
Filing date: 2005-09-20
Publication date: 2007-03-21
Anticipated expiration: 2025-09-20
Also published as: GB0519142D0; GB2430213B

Abstract

As the harvesting head 1 moves, shellfish located on the seabed or within the top layer of sediment are swept up using the rotating brushes 5,6. The catch, any bi-catch and sediment etc are swept up plate 7 and onto the primary grading screen 13. The material is swept over the screen 13 by chain driven rotating brushes/ rubber fingers where the bi-catch and sediment is returned to the seabed within, and directly behind, the unit. Rotating brushes 5,6, chain gear, brushes and rubber fingers 15,16,14 are kept clear of debris through the use of water jets located beneath the top of the unit 9,10,11. Water jets 8,12 are used to assist the flow of the catch over the primary grading screen and onto the open mesh conveyor 19 for onward transport to the vessel.

Description

1 2430213 Non suction shellfish harvesting head.

This invention relates to a device, attached to a floating vessel, for harvesting shellfish located on or within the top layer of the seabed. The apparatus does not rely on the fluidisation of the seabed and results in reduced effects on the benthic communities living on and within the seabed; it also results in reduced contamination of the surrounding sea water cause by the discharge plume associated with harvesting methods which employ suction dredging.

Shellfish commonly live in varying depths of water within the upper layers of the sediment forming the seabed or live on the seabed surface. This apparatus is designed to be operated in shallow water on a seabed which may or may not be exposed at low water. Traditional modem harvesting methods in shallow waters rely on the fluidisation of the seabed where the disturbed sediment, shellfish, debris and other living creatures (the bi-catch) are pumped to the fishing vessel above, where the catch is filtered/graded out of the pumped material. The associated sediment, debris and bi-catch etc is then discharged from the vessel and usually forms a discharge plume which can spread over a wide area. The result is that the bi-catch, including the benthic communities, can become spread over a large area and potentially outwith their natural habitat which can affect their sustainability. The sediment and other detritus in the discharge plume can affect the sustainability of the other marine communities both within the sea water and in the location where the plume settles.

This apparatus addresses the negative effects of the suction dredge method by carrying out the extraction of the shellfish and sediment (when required) within the enclosed harvesting head so reducing the spread of the disturbed sediment at seabed level. The shellfish, other living animals, sediment and detritus are moved over a primary grading screen contained within the endosed harvesting head where the majority of the unwanted material is returned directly to the path of the unit as it proceeds.

The harvesting head is propelled forward by the vessel and adjustable to suit the depth of water. The apparatus is also adjustable to suit different consistencies of seabed material and location of the shellfish relative to the seabed surface. All moving parts comprising brushes and elevator are controlled by vanable speed hydraulic motors to minimise unwanted disturbance and to optimise throughput of material. Variable pressure water jets are provided to prevent the brushes becoming dogged as work proceeds and to assist movement of the catch onto the elevator, these are positioned to avoid direct water jetting of the seabed in order to minimise unnecessary disturbance of sediment. Alt motors and water jets are remotely controllable from the vessel.

The harvested material is carried to the vessel using an open grid conveyor rising between the twin hulls of the fishing vessel and from there transferred to a second conveyor where the shellfish are lifted to deck level and then passed through a machine for final grading.

Fig I shows the detail of the apparatus.

Fig 2 shows the layout of the apparatus when connected to the conveyor/vessel and undergoing the harvesting operation.

Referring to Fig I and Fig 2 the apparatus, known as the harvesting head, comprises a stainless steel enclosure I open on the underside and to the rear only. The entire apparatus including moving parts, with the exception of the brushes, is manufactured from marine grade stainless steel. The enclosure incorporates skids 2 to either side extending from the front to well beyond the rear of the enclosure I with the purpose of preventing the apparatus from digging itself into the seabed. A spreader beam 3 is fixed to the approximate mid point of the harvesting head immediately above the enclosure 1. The spreader beam is equipped with a ring at its mid point to enable a wire suspension cable 4 to be attached. The wire suspension cable is connected to a deck mounted hydraulic winch which is used to raise the equipment between the twin hulls of a fishing vessel to enable the vessel to freely relocate.

HYdraulically driven, shaft mounted nylon brushes 5, 6 are Positioned at the front, within the enclosure i.

Radiused Slots are providerj in the enclosure which the brush shafts pass through The end bearings and hydraj motors driving the brushes are mounted on a pivoted Swing plate Which enables the outer circumference of the bristles to be adjustj for height relative to the unde,ide of the skids 2. Once the height independently of the other.

desired height of the brushes is set the swing plates are clamped in place. Each brush 5, 6 can be set for A hOll tube 9 is fittecj with wafer jets angled to direct water onto the bristles so Preventing the clogging of the rotating brushes 5, 6. The wafer pressure can be varied or turned off to suit the conditions The height adjustable deflector plate 7 is set so that its lowest edge matches the height of the adjacent brush 6 relative to the Skids 2. It is held in Position by clam p bolts. The deflector plate is suppO by primary grading screen 13.

hollow tube 8 which is also fitted with water jets angled to assist the movement of material Over the The 9rading screen 13 is bofted Into Position and can be exchanged for another screen with an alternative mesh Size to suit the species of shellfish to be harvested Rotating brushes made up of nylon bristles or flat rubber fingers 14 are mounted on chains 15 driven by on the outside of the casing.

sprockets 16 which in turn are powered by hydrau motors mounted direcny on the shafts and situated Hollow tube i o is fitted with water jets angled to direct Water onto the bristles of the rotating brush 6 and the chain driven brush or rubber fingers 14 to prevent the build up of any unwanted material The water pressure can be varied or turned off to suit the Conditions Hollow tube 11 is fed with water jets angled to direct water onto the bristles of the chain driven brush or rubber angers 14 to prevent the buIld up of any unwanted material These water jets can also help to encourage unwanted material to pass through the Primary grading screen The water pressure can be varied or turned off to suit the Conditions At the end of the grading screen i is a solid transition plate 18 used to direct the harvest from the primary grading Screen to the conveyor 19. The harvest of shell fish is assisted over the transition plate with the use of the hOll tube 12ich is fed with angled waterjets The structure 17 is fed to the conveyor 19 and is fixed to each side of the enclosure I through use of the pivots 20 which accommedate any necessary change in angle between the harvesting head 1 and the Conveyor i. The structure 17 accommedates any necesry differen in wicfths between the harvesting head i and the conveyor ig.

All the various hydraulic motors housed within the apparatus i are supplied with hydraulic fluid from a vessel mounted central Pump unit feeding a manifold equipp with adjustable valves to enable the hydraulic pressur and hence motor speeds to be adjusted The water Supply for the water jets 8, 9, 10, 11, 12 is provided from a vessel mounted Pump System equlpp a with manifold and adjustal valves to enable water flows to be turned off or on or varied in pressure independently of each other Under Working conditions the apparatus Works by sweeping up material from the seabed or the top layer of sediment 23, including the shellfish sought and other species sediment etc through the rotation of brushes 5, 6 and then passes over the deflector plate 7 and onto the Primary grading screen 13. The chain driven brush system 14, 15, 16 then sweeps the material over the Primary grading screen assisted by the angled waterjets located in hollow tubes 8, 12. Water jets in hollow tubes 9, ii are us as Conditions dictate to prevent or clear buifrj up of debris on the brushes Whilst water jets in hOll tube ii can also be use to assist unwanted material to pass through the grading Screen 13. Most unwanted material passes through the Primary grading screen 13 and returns to the seabed 24 on the path taken by the harvesting head within the enclosure i or immediately to the rear of it.

Claims

Claims 1. Apparatus for harvesting shellfish located on or in within the

seabed comprising an enclosure open only at the rear and to the underside containing: a) rotating cylindrical brushes; b) chain driven rectangular brushes and/or rubber fingers; c) deflector plate; d) grading screen; e) water jetting equipment.
2. Apparatus as claimed in claim 1, characterised by being propelled over the seabed by a floating vessel above.
3. Apparatus as claimed in claim 1, characterisecj by being equipped with the means of spraying water to keep the moving parts free of debris.
4. Apparatus as claimed in claim 1, characterised by being equipped with a screen to enable material to be graded and shellfish to be extracted in the vicinity of the seabed.
5. Apparatus as claimed in claim 1, characterised by being equipped with the means of spraying water to assist with the grading of material in the vicinity of the seabed.
6. Apparatus as claimed in claim 1, characterised by being equipped with the means to replace material and bi-catches including benthic species in the vicinity from which they were extracted.
7. Apparatus as claimed in claim 1, charactenseci by being equipped with the means of spraying water to assist movement of the shellfish catch through the apparatus.
8. Apparatus as claimed in claim 1, characterpsecj by being equipped with the means of connecting it to a conveyor system for the removal of the shellfish catch to the surface.
9. Apparatus as claimed in claim 1, characterisecj by being equipped with facilities to adjust the height of the rotating brushed to suit varying seabed conditions and compensate for wear.
10. Apparatus as claimed in claim 1, characterised by being equipped with facilities to remotely adjust the speed of operation of the internal moving components.
11. Apparatus as claimed in claim 1, charactensed by being equipped with facilities to remotely turn on or off and adjust the pressure of the water within the water spraying apparatus.
12. Apparatus as claimed in claim 1, charactensed by being equipped with facilities to suspend the equipment from a vessel, and to remotely adjust for varying depths of water and prevent the apparatus from dropping into a hole, gully or other depression in the seabed, and to enable the apparatus to be raised to the vessel when underway or not involved in the harvesting operation.
13. Apparatus as claimed in claim I and claim 8, characterised by being equipped with facilities to automatically adjust the angle of connection between the apparatus and the conveyor belt to suit varying sea conditions and depths of water.
14. Apparatus for harvesting shellfish substantially as herein described above and illustrated in the accompanying drawings.