GB2305895A

GB2305895A - Multi-hull vessel for servicing mollusc cultivations or fish cages

Info

Publication number: GB2305895A
Application number: GB9620631A
Authority: GB
Inventors: Hamish Adams
Original assignee: ADAMS EQUIPMENT Ltd
Current assignee: ADAMS EQUIPMENT Ltd
Priority date: 1995-10-03
Filing date: 1996-10-03
Publication date: 1997-04-23
Anticipated expiration: 2016-10-03
Also published as: GB9620631D0; GB9520153D0; GB2305895B

Abstract

A self-propelled vessel 31 for servicing mollusc cultivations or fish cages has an access bridge 43 (17)(fig.2) supported between two floatation pontoons each provided with an outboard motor 44,45, the vessel also having a variable height chair 46 movably supported on rails 52. In use, the access bridge may straddle a mussel cultivation (comprising cultivation ropes 38 suspended from head ropes 32 supported by barrels 33 and connected to a buoy 35 via a bridle 34) or overhang a fish cage (11)(fig.3). The mussel cultivation may provide a wave barrier and the floatation barrels 33 may be attached to the head ropes by means of a barrel seat arrangement (58)(fig.4). In an alternative form (fig. 2) the vessel has angled bows provided with solid rubber or air-filled fenders (20). The bridge may comprise a steel grillage and removable guard rails.

Description

Fish Farming The present invention relates to fish farming, cultivation of molluscs and wave barriers.

In long line mussel cultivation one head rope or two heads ropes suspended about one metre apart are supported below the surface of the water using floatation barrels. The complete head rope is provided with sufficient floatation and is moored and kept in tension on the surface by high power sea-bed anchors at each end of the line. Side anchors may be positioned at right angles along the line's length for additional security. Pegged cultivation ropes are suspended from the head rope at approximately 0.5 metre intervals and typically produce about 50kg per rope of harvestable mussels per growing cycle. The mussels are harvested using a boat, each cultivation rope being lifted in turn and taken on board.

A multi head rope system is similar save that more than two long line head ropes are arranged adjacent to each other. An ordinary boat can be positioned alongside the outer ropes but access to the inner ropes for servicing and harvesting is difficult, if not impossible.

According to a first aspect, the present invention provides a service vessel incorporating an access bridge supported between at least two spaced floatation pontoons.

The vessel may be self propelling; it may have a propulsion unit associated with each pontoon.

Access to the water level from the access bridge may be achieved via one or more access platforms. The access platform may take the form of an access chair which may be suspended from the bridge and may be moveable along the access bridge. The height of the access platform relative to the access bridge, and hence relative to the water level, may be variable.

Lifting gear and/or lifting supports may be provided for handling loads at the vessel and/or transferring loads between the vessel and the shore or another vessel.

According to a second aspect, the present invention provides a method of servicing a cultivation of molluscs from an access bridge supported between at least two spaced floatation pontoons of a service vessel.

The span of the access bridge is preferably sufficient to allow the vessel to straddle the cultivation of molluscs.

The vessel may be manoeuvred into position using a powered vessel and then pulled along a hauling rope.

Such hauling may be mechanical or manual.

The vessel may be used at a multi head-rope mussel system and the outer head ropes may be used as hauling ropes.

Circular plastic fish cages which are commonly used for fish farming have a floating collar made of high density polyethylene tube. This collar is inherently flexible which gives the circular cage durability in rough sea conditions. However, this flexibility results in any access walkway which is supported on top of the tube being susceptible to flexing and being unstable to walk on. The floating collar has a low buoyancy; any access walkway that it supports is positioned close to the surface of the water and is susceptible to becoming awash with water and to being slippery to walk on. The low buoyancy of the floating collar also prevents it being used as a support whilst working, for example to support loads of fish feed or nets, as such loads would cause the floating collar to sink locally.Furthermore, it is difficult to moor a small boat alongside the circular floating collar as there are no straight edges. The collar's mooring points which are spaced around its perimeter can chaff and damage an approaching boat and the mooring lines can obstruct a propeller drive of any vessel coming close to the cage.

Net handling on a plastic cage is also problematic. It is difficult for a number of operators to stand on the collar without their weight and the weight of the net raised out of the water causing buoyancy problems at the cage and severe distortion on the net support rail.

According to a third aspect, the present invention provides a method of servicing a fish cage from an access bridge supported between at least two spaced floatation pontoons of a service vessel.

An operator may manoeuvre the vessel such that a front of each pontoon lies against a floatation collar of a fish cage without the vessel being washed away by tidal or sea conditions. The floatation collar may be substantially circular. The operator may then position himself or herself on the access bridge adjacent to the fish. cage; feeding, harvesting, grading, mortality removal and other day to day operations may be performed from this safe working deck.

The bow of each pontoon is preferably angled and fendered to reduce the risk of damage to the cage collar. Each bow may have an angled or arcuate end profile to co-operate with portions of a perimeter of a circular floatation collar.

With the vessel in position at a fish cage, the access bridge preferably overhangs a portion of the cage. The access bridge is preferably at a sufficient height and may be positioned towards the front of the pontoons such that it clasps or embraces a circular floatation collar with the access bridge positioned over the collar net rail.

The access bridge may be provided in the form of grillage and preferably has associated safety railing.

Rail portions towards the front of the access bridge may be removable to facilitate access to the fish cage, for example, when hoisting nets on board. The vessel preferably has in-built reserve buoyancy such that it can safely support heavy loads.

According to a fourth aspect, the present invention provides a mollusc cultivation system comprising at least three substantially parallel head ropes each head rope having cultivation ropes spaced along its length.

According to a fifth aspect, the present invention provides floatation barrel attachment means comprising a first attachment portion adapted for attachment to a band passing around a perimeter of the floatation barrel and a second attachment portion, spaced from the fir$t attachment portion and adapted to be attached to a rope.

The first attachment portion preferably comprises a frame, which may have two spaced openings, which may be adapted to co-operate with respective end portions of the band passing around the perimeter of the barrel for securing the band at the first attachment portion.

The second attachment portion preferably co-operates with an elongate portion of the rope and may be adapted to be attached to the rope at each end of the elongate portion. The second attachment portion may be provided as an elongate bar which may be adapted to lie along a portion of the rope. The elongate bar may have rope stabilising means at each of its ends.

The floatation barrel attachment means may comprise a frame, which may be substantially I-shaped and which preferably has a pair of spaced first attachment portions, each of which may be adapted to be attached to a respective band passing around a perimeter of the barrel and preferably also has a pair of spaced second attachment portions each of which may be adapted to be attached to a respective rope.

According to a sixth aspect, the present invention provides a wave barrier comprising a plurality of weighted lines spaced along and supported from a head rope.

The barrier may comprise two or more spaced head ropes, each of which supports a plurality of spaced, weighted lines. Preferably, the weighted lines of one head rope are offset with respect to the weighted lines of the other head rope. The barrier may comprise three, four, five, six, seven, eight, nine, ten or more head ropes.

The head ropes may be substantially parallel to each other.

The head ropes may be supported by buoyancy aides which may be sealed barrel drums. The head ropes are preferably tethered together and the barrier is preferably anchored in place.

The weighted lines suspended from the head ropes may absorb and/or diffuse tidal energy. The lines may be adapted to have molluscs, for example, mussels, cultivated on them. The weight of the molluscs may provide part of or all of the weight for the weighted lines. The bulk and nature of the molluscs growing at the weighted lines may facilitate absorbtion and/or diffusion of wave energy.

According to a sixth aspect, the present invention provides a wave barrier comprising a multi head rope long line mussel cultivation system.

The mussel cultivation may typically be lOOm, 200m, 300m, 40Om, 50Om in length or longer.

One or more aspects of the invention may be combined in a single embodiment.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings of which: Fig.l is a perspective view of a first vessel in accordance with the invention; Fig.2 is a perspective view of a second vessel in accordance with the invention; Fig.3 is a plan view of the vessel of Fig.2 positioned at a circular fish cage; and Fig.4 is a perspective view of floatation barrel attachment means.

The vessel 31 of Fig.l is particularly suited for servicing and harvesting a multi head rope mussel cultivation system.

The multi head rope system has, in the illustrated example, eight head ropes 32 supported by barrels 33.

Every second barrel adjoins its next rope alternatively left and right hand.

End bridles 34 (only one of which is shown) are fitted at each end of the rope system with steel bracing to keep the ropes 32 parallel and correctly spaced and to hold the barrels 33 apart. The bridle 34 is tied in to a large surface buoy 35, in this case, a 680kg surface mooring buoy. This is necessary to counteract the downward forces from a 250kg mooring anchor 36. Side moorings 37, in this case 150kg side moorings, are fitted at regular intervals along the system; at these positions, chain joiners join the adjacent barrels 33 together to hold these barrels in position and to transmit the side mooring loads across the system to the opposite anchor.

Cultivation ropes 38 (only some of which are shown) are hung at 0.5 metre intervals along the head ropes 32.

This provides a large array of cultivation ropes set out in a relatively small area. Nevertheless, due to the relatively low density of cultivation ropes across the system, the water change throughout the cultivation area is unrestricted and there is ample feeding nutrient in the water column within the growing area.

The vessel 31 allows easy access to each of the head ropes and to each of the cultivation ropes 38. The vessel comprises a pair of spaced, fabricated steel floatation pontoons 41, 42 which have a length x of 7 metres. The floatation pontoons 41,42 may be constructed from a fabrication steel deck section with plastic floatation blocks. The span y between the floatation pontoons 41,42 is sufficient to clear the total width of the multi head rope system such that the vessel 31 straddles the array of head ropes. An access bridge 43 having a pressed non-skid decking is supported between the floatation pontoons 41,42. A support rail 52 provides additional structural supports.

Each floatation pontoon 41,42 has an associated outboard motor 44,45 so that the vessel 31 can be powered independently in to position. The vessel 31 can then be propelled along the long-line system either by using the outboard motors 44,45 or by hauling on the outer head ropes.

The height h of the access bridge above the water level is approximately 1.1 metres which is sufficient to clear the floatation barrels 33, the end bridle 34 and the end mooring buoy 35.

A support platform in the form of a rolling access chair 46 provides access to the water level from the access bridge 43. The rolling access chair 45 comprises a small platform 47 with supporting steelwork 48 incorporating a ladder 49 leading from the access bridge 43 and hand rails 50. The height of the platform 47 relative to the water level can be varied and a roller system 51 cooperates with the support rail 52 to allow the access chair 46 to move laterally relative to the vessel 31 to access all positions across the head-rope system. Additional access chairs may be provided if desired, for example, to allow more than one operator to work at the same time.

The operator can stand safely on the access chair 46 at the surface of the water to access the cultivation ropes 38, for example to tie, untie or remove them.

When the vessel 31 is moved along the rope system the access chair 46 can be moved laterally as necessary to avoid the floatation barrels 33.

A runway beam 53 is supported approximately 3 metres above the access bridge 43 on supports 54, 55, 56 which are placed mid-span and at ends of the access bridge 43. The runway beam 53 extends 1.5 metres beyond each floatation pontoon 41, 42 to allow loads, for example cultivation ropes or a basket containing multiple cultivation ropes to be lifted out of the water between the floatation pontoons 41, 42 by means of a suitable hoist block 57 and transported on the runway beam 53 to a harvesting tub in a work boat position below the end of the beam 53.

The multi-head rope mussel cultivation system of Fig.1 is also particularly suited for use as a tidal barrier, for the absorbtion and/or diffusion of tidal energy.

The head ropes 32 have cultivation ropes 38 strung substantially perpendicular from the head ropes, for the cultivation of mussels. The mussels cultivated on the ropes 38 provide a barrier which absorbs and/or diffuses the tidal energy of the waves passing through the mussel cultivation system. The mussel cultivation system therefore has a supplementary use as a tidal wave barrier which may be positioned as required, for example, in coastal defence, or taking the place of a harbour wall, or to protect fish cages, after a time when the mussels have been cultivated.

The vessel 10 of Fig.2 is adapted for servicing a fish tank 11 having a circular floatation collar 12.

The vessel 10 is of welded steel construction and has a pair of spaced floatation pontoons 13, 14 connected by stiffeners 15 with cross bracing 16 and an access bridge 17 supported between the two pontoons 13, 14.

Each floatation pontoon 13, 14 has multiple watertight bulkheads to ensure floatation in the case of a breached compartment.

The overall width of the vessel 10 is approximately 14 metres. Each floatation pontoon 13, 14 is 7.5 metres long at its longest point, 2 metres wide and 1 metre deep. The access bridge 17 is 2 metres wide and is arranged with its underside 18 1 metre above the top surface of the floatation pontoons such that when the vessel 10 is in the water the underside 18 of the access bridge is approximately 1.5 metres above the water level 19. This provides sufficient clearance below the bridge to clear a cage guard rail. The vessel is adapted to suit a 60 metre circumference collar which necessitates a 10 metre span access bridge. The dimensions of the vessel 10 can be adapted to suit other collar sizes.

The bow of each pontoon 13, 14 is angled at a 55- angle a to provide a tangential contact with the floatation collar 12 of the fish cage. The bows are fitted with solid rubber or air filled fenders 20 to avoid sharp contact points against the floatation collar 12. The fenders 20 are substantially vertical above and below the water line 19 to allow the vessel 10 to range up and down at å different speed to that of the fish cage 11.

A respective outboard engine 21,22 is fitted to the stern of each floatation pontoon 13, 14 in a twin engine configuration to facilitate manoeuvring of the vessel 10 to and between the fish cages by a helmsman at a helmsman's position 29. The risk of the engine propellers fouling on the network of mooring ropes which hold the fish cage in place is very small as the mooring ropes are only near the surface of the water 19 for a distance of about 2-3 metres from the cage and the outboard engines 21,22 are always spaced from the cage by the length of the floatation pontoons, in this case, by approximately 7 metres.

The access bridge 17 and cross supporting grillage are constructed of structural steel and the access bridge 17 has a pressed steel, non-skid deck surface. Guard rails 23 are provided all around the access bridge 17 and around stairways 24 leading from the floatation pontoons 13, 14 to the access bridge 17. At least one section 25 of a front rail can be removed for access purposes.

A number of mooring bollards 26 are provided on each floatation pontoon 13, 14.

When the vessel 10 is being used for feeding, a sufficient quantity of feed can be loaded on each pontoon 13, 14 to allow the operator to feed a number of cages without needing to return to either a feed store or shore base to collect supplies. Up to one tonne of feed can be loaded on to each floatation pontoon 13, 14 in a pallet at respective pallet locations 27, 28.

The vessel 10 is also provided with a number of attachment points 30 for fish lifts.

As can be seen from Fig.3, the access bridge 17 can be arranged to overhang the fish cage 11; this greatly facilitates servicing of the cage from the bridge 17.

A single vessel may comprise a combination of features described in relation to Fig.l, Fig.2 and Fig. 3.

The barrel seat device (58) of figure 4 is particularly adapted for retaining a floatation barrel (33).

The barrel (33) has two attachment bands (59) fitted to it which incorporate fixing keys (60) for attaching the barrel/band assembly to first attachment portions (61) of the barrel seat device (58). The fixing keys (60) co-operate with windows (62) in the first attachment portions (61) by inserting the fixing keys (60) of the barrel/band assembly into the corresponding windows (62). Each band is fixed to the barrel seat device (58) via fixing means, for example, a retaining bolt (not shown) which passes through holes (64) in fixing keys (60) so as to hold the barrel band assembly in position with fixing keys (60) inserted in the windows (62).

This assembly, which consists of the barrel (33) attached to barrel seat device (58) can then be further attached to ropes (32), for example, in a head rope system. This may provide support and increase the resistance of the head rope systems to wave energy, and provide buoyancy for the head rope system. The assembly is attached via a second securing means (63), which consists of elongate tubes (64) connected to a cross piece tube (65) such that the elongate tubes (64) lie substantially parallel and adjacent to the head ropes (32). Stabilising means in the form of cross pieces (66) provided at each end of the elongate tubes (64) increase the stability of the arrangement by providing two spaced contacts between each rope (32) and the barrel seat (58). The second attachment portions (63) are then fixed to the head ropes (32) by securing means (67) on the elongate tubes (64), which may be in the form of U-shaped bolts or rope lashing.

Preferably, at least two spaced securing means are used to secure each of the elongate tubes (64) to the ropes (32).

Claims

ClAIMS

1 A service vessel incorporating an access bridge supported between at least two spaced floatation pontoons.

2 A service vessel in accordance with claim 1 in which the service vessel is self propelling.

3 A service vessel in accordance with claim 1 or claim 2 in which the service vessel has a propulsion unit associated with each pontoon.

4 A service vessel in accordance with any preceding claim in which at least one access platform is provided to facilitate access to the water level from the access bridge.

5 A service vessel in accordance with claim 4 in which the at least one access platform takes the form of a movable access chair.

6 A service vessel in accordance with any preceding claim in which the service vessel is provided with lifting gear.

7 A service vessel in accordance with claim 6 in which the lifting gear is adapted for handling loads at the service vessel and for transferring loads between the service vessel and an external source.

8 A service vessel in accordance with any preceding claim in which the bow of each pontoon of the service vessel is angled and permanently fendered.

9 A service vessel in accordance with any preceding claim in which the bow of each pontoon of the service vessel has an arcuate, permanently fendered end profile.

10 A service vessel in accordance with any preceding claim in which the access bridge is provided in the form of grill age and has associated safety railing.

11 A service vessel in accordance with claim 10 in which portions of the safety railing are removable.

12 A method of servicing a cultivation of molluscs from an access bridge supported between at least two spaced floatation pontoons of a service vessel.

13 A method of servicing a cultivation of molluscs in accordance with claim 12 in which the service vessel is manoeuvred into a position straddling the cultivation of molluscs.

14 A method of servicing a cultivation of molluscs in accordance with claim 12 or claim 13 in which the service vessel is hauled along head ropes of the mollusc cultivation.

15 A method of servicing a fish cage from an access bridge supported between at least two spaced floatation pontoons of a service vessel.

16 A method of servicing a fish cage in accordance with claim 15 in which the service vessel is manoeuvred into a position whereby pontoon bows of the vessel lie against a floatation collar of the fish cage.

17 A method of servicing a fish cage in accordance with claim 15 or claim 16 in which at least a portion of the access bridge overhangs the fish cage.

18 ' A mollusc cultivation system comprising at least three substantially parallel head ropes, each head rope having cultivation ropes spaced along its length.

19 A floatation barrel attachment means comprising a first attachment portion adapted for attachment to a band passing around a perimeter of the floatation barrel and a second attachment portion, spaced from the first attachment portion and adapted to be attached to a rope.

20 A floatation barrel attachment means in accordance with claim 19 in which the first attachment portion comprises a frame having two spaced openings each adapted to co-operate with respective end portions of the band passing around the perimeter of the barrel for securing the band at the first attachment portion.

21 A floatation barrel attachment means in accordance with claim 19 or claim 20 in which the second attachment portion is adapted to co-operate with an elongate portion of the rope and is adapted to be attached to the rope towards each end of the elongate portion.

22 A floatation barrel attachment means in accordance with claim 21 in which the second attachment portion is provided as an elongate bar adapted to lie along a portion of the rope, the elongate bar having rope stabilising means at each end of its ends.

23 A floatation barrel attachment means in accordance with any one of claims 19-22 in which the floatation barrel attachment means comprises a frame having a pair of spaced first attachment portions, each adapted to be attached to a respective band passing around a perimeter of the barrel and a pair of spaced second attachment portions each adapted to be attached to a respective rope.

24 A floatation barrel attachment means in accordance with claim 23 in which the frame is substantially I-shaped.

25 A floatation barrel attachment means in accordance with any one of claims 19-24, in which the second attachment portion is adapted to be secured to the rope by means of at least one U-shaped bolt.

26 A floatation barrel attachment means in accordance with any one of claims 19-25 in which the second attachment portion is adapted to be secured to the rope by means of rope lashing.

27 A wave barrier comprising a plurality of weighted lines spaced along and supported from a head rope.

28 A wave barrier in accordance with claim 27 in which the wave barrier comprises at least two spaced head ropes which each support a plurality of spaced, weighted lines, and in which the weighted lines of one head rope are laterally offset with respect to the weighted lines of the next adjacent head rope.

29 A wave barrier in accordance with claim 27 or claim 28 in which the at least two head ropes are substantially parallel and are supported by buoyancy aides.

30 A wave barrier in accordance with claim 29 in which the buoyancy aides are sealed drum barrels, in which the head ropes are tethered together and in which the barrier is anchored in place.

31 A wave barrier in accordance with any one of claims 27-30 in which the weighted lines are adapted for the cultivation of mussels and in which the weight of the mussels provides at least part of the weight for the weighted lines.

32 A wave barrier in accordance with claim 31 in which the mussels growing on the weighted lines facilitate the absorption and diffusion of wave energy.

33 A wave barrier comprising a multi-head rope long line mussel cultivation.

34 A wave barrier in accordance with claim 33 in which the mussel cultivation is at least 100 metres in length.

35 A service vessel substantially as described herein with reference to one or more of the accompanying drawings.

36 A wave barrier substantially as described herein with reference to one or more of the accompanying drawings.

37 A floatation barrel attachment means substantially as described herein with reference to one or more of the accompanying drawings.

38 A method of servicing a cultivation of molluscs substantially as described herein.

39 A method of servicing a fish cage substantially as described herein.