AU2019264576A1 - A barrier - Google Patents

Abstract

A selective barrier 1 for an aquatic environment. A first run 5 of one or more flexible pulling elements 7 spans a horizontal distance. Barrier members 13 are connected to the first run. Spacers 15 space the barrier members. 5,7 3 1 5 A 1913 5-13 -- 3 SB FIGURE 1 5,7 15 15 31 29 7 9,11 21 2 FIGURE 2 FIGURE 3

Description

A BARRIER

FIELD

The invention relates to barriers for aquatic environments.

BACKGROUND

Barriers are used in aquatic environments to divide one area of water from another. Selective barriers have openings dimensioned to enable water and smaller items and species to pass from one side to the other of the barrier but block larger items and/or species. By way of example, selective barriers might be used to exclude large sharks from a bathing area or to contain large fish in the context of aquaculture.

Aquatic, and in particular marine, environments are harsh. Aquatic barriers are frequently subject to waves or other powerful environmental factors, are often subject to corrosion, and are sometimes the targets of vandals. Build-up on barriers, and in particular selective barriers, also presents problems. The build-up can include accumulated rubbish and aquatic growth.

Existing forms of aquatic barriers include steel panels, of vertical bars, mounted between suitable supports, e.g. between the pylons of a pier. Other arrangements entail flexible plastic meshes.

It is not uncommon to deploy divers to maintain such barriers, e.g. to clean the barriers of accumulated build-up. This work is slow, expensive and potentially dangerous (e.g. potentially dangerous if a diver becomes entangled with the barrier and/or any rubbish accumulated thereon). In the context of flowing water, opaque water and/or adverse weather conditions, subsurface maintenance may not be practical.

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The removed build-up typically falls to the bottom and/or washes ashore. At both locations, the build-up can be unsightly and otherwise problematic. A rotting carpet of debris can smother or otherwise kill off life, such as seagrasses, on the seabed. Debris washed ashore can lead to foul odour. The build-up can include shellfish, the shells of which are broken as they are removed. These broken shells can be very sharp and pose a hazard to bathers. The removal of build-up can also spread invasive plant and animal species.

With the foregoing in mind, preferred variants of the invention aim to provide improvements in and for barriers for aquatic environments, or at least to provide alternatives for those concerned with such barriers.

SUMMARY

One aspect of the invention provides a selective barrier, for an aquatic environment, comprising a first run of one or more flexible pulling elements spanning a horizontal distance;

barrier members connected to the first run; and spacers spacing the barrier members.

The barrier members may be upright, e.g. substantially vertical. Preferably the spacers are sleeves sleeving respective portions of the first run. Most preferably at least most of the spacers each have a density in the range of 800 kg/m³ to 1200 kg/m³ inclusive. Optionally at least most of the spacers are formed of plastic, e.g. high-density polyethylene (HDPE).

The selective barrier may comprise two stop portions bracketing the barrier members and the spacers to substantially prevent the barrier members and the spacers moving along the first run. Optionally at least one of the stop portions grips one of the one or more flexible pulling elements.

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Preferably at least most of the barrier members are rigid barrier members.

Another aspect of the invention provides a selective barrier, for an aquatic environment, comprising a first run of one or more flexible pulling elements spanning a horizontal distance; 5 and barrier members connected to the first run;

wherein at least most of the barrier members are rigid barrier members.

Preferably at least most of the barrier members each have a density in the range of 800 kg/m³ to 1200 kg/m³ inclusive. Most preferably at least most of the barrier members are formed of plastic, e.g. HDPE.

The selective barrier may comprise a second run of one or more flexible pulling elements spanning a horizontal distance. The barrier members may be connected to the second run. Preferably the second run is a lower run releasable to enable the selective barrier to rise from an upright barricading configuration to a recumbent maintenance configuration.

Another aspect of the invention provides a barrier, for an aquatic environment, mounted to rise from an upright barricading configuration to a recumbent maintenance configuration.

The barrier may be a selective barrier.

The barrier preferably comprises a first run of one or more flexible pulling elements spanning a horizontal distance; and

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2019264576 13 Nov 2019 a second run of one or more flexible pulling elements spanning a horizontal distance;

wherein the second run is a lower run when the barrier is in the upright barricading configuration; and releasable to enable the barrier to rise to the recumbent maintenance configuration.

Preferably the barrier comprises an arrangement about which the flexible pulling element connected to the second run is upwardly turned to enable release from above.

Preferably the first run is mounted above a waterline.

Another aspect of the invention provides a selective barrier, for an aquatic environment, mounted to rise from a barricading configuration to a maintenance configuration.

Another aspect of the invention provides a method, of maintaining a barrier for an 15 aquatic environment, comprising raising the barrier from a barricading configuration to a maintenance configuration;

operating on the barrier; and lowering the barrier to the barricading configuration.

The barricading configuration may be an upright barricading configuration. The maintenance configuration may be a recumbent maintenance configuration.

The raising may comprise horizontally urging one or more floats under the barrier to support the barrier, or more preferably to support the barrier above water.

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2019264576 13 Nov 2019

The urging may be pulling or towing.

The operating on preferably comprises removing debris from the barrier.

The method may comprise arranging a debris-collector under the barrier to collect the debris. The debris-collector may comprise permeable fabric. A frame may be provided to support the fabric. Preferably the debris-collector comprises the one or more floats.

The operating on may comprise pressure cleaning.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is an elevation of an aquatic barrier;

Figure 2 is an enlargement of detail A in Figure 1;

Figure 3 is an elevation of an end of another aquatic barrier;

Figure 4 is a plan view of a boom;

Figure 5 is a vertical cross-section view illustrating the barrier of Figure 3 at four of its operating positions;

Figure 6 is a plan view of a debris trap; and

Figure 7 is a cross-section view of the debris trap of Figure 6 collecting debris from the barrier of Figure 3.

DESCRIPTION OF EMBODIMENTS

Figure 1 illustrates a barrier 1 mounted between a pair of end supports 3. In this case, the end supports are pylons of a pier anchored into the seabed SB. Variants of the barrier 1 might be mounted between other forms of end support, e.g.

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2019264576 13 Nov 2019 between natural formations, between dedicated pylons (or other dedicated formations) or between formations suspended from a floating structure.

Barrier 1 includes a top run of flexible pulling element 7. In this example, the flexible pulling element 7 takes the form of rigid 1x19 10 mm 316 stainless steel rigging wire. Rope, chain and other grades of cable are other potential examples of flexible pulling element.

The top run 5 consists of a single length of the cable 7 although, in other variants, two lengths of cable might be joined end-to-end along the run to form a single flexible pulling arrangement.

The barrier 1 further includes a lower run 9 of flexible pulling element 11. In this example, the runs 5, 9 are formed of separate cables 7, 11. In another variant of the barrier 1, the runs 5, 9 might be formed of a single cable looped around suitable turning points connected to one of the end supports 3. Optionally the lower pulling arrangement may be weaker than the upper cable, to save cost. By way of example, the cable 11 might take the form of 8 mm plasma or Dyneema™.

Each of the runs 5, 9 spans a horizontal distance corresponding to the horizontal distance between the end supports 3. The runs 5, 9 are substantially horizontal and mutually parallel. In other variants of the barrier 1, this may not be so. By way of example, the run 9 might parallel the inclined seabed SB (whilst still spanning the horizontal distance between the inputs 3).

The runs 5, 7 are preferably tensioned and most preferably include one or more adjusters (e.g. turnbuckles) to facilitate periodic retensioning.

Barrier members 13 are spaced, in this case substantially equispaced, along the run 5. The barrier members 13 are rigid although, in other variants of the barrier 1, more flexible members might be suspended between the runs 5, 9. Amongst other advantages, the rigidity reduces the prospects of marine animals, e.g. dolphins, becoming entangled. The members 13 are preferably bars (i.e. elongate members

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2019264576 13 Nov 2019 each having a substantially uniform cross-section over at least most of its length), such as round bars or square bars. This simple form lends itself to low-cost production methods such as extrusion or a series of straight cuts from a larger block of material.

The barrier members 13 are formed of HDPE. HDPE is a relatively low-cost material and is resistant to biofouling. Another advantage of HDPE is a density similar to the density of water so that the barrier 1 is approximately neutrally buoyant. This reduces the load on the runs 5, 9 and assists with the maintenance operation described below. Of course, other materials having a density similar to 10 the density of water (say, in the range of 800 kg/m³ to 1200 kg/m³ inclusive), or indeed other materials more generally, may be used. Engineering plastics are preferred.

A variety of approaches for mounting the barrier members 13 on, and spacing the barrier members 13 along, the run 5 are contemplated. By way of example, each 15 barrier member 13 might be bracketed by a dedicated pair of swages.

Alternatively, each barrier member 13 might have a dedicated clamping arrangement for gripping the run 5.

Preferably each barrier member 13 is penetrated by a respective bore for each of the top and bottom runs by which the barrier members 13 can be threaded onto 20 those runs. The bores are preferably formed via a material-removal operation such as drilling. Other options are possible. By way of example, the bores might be defined by suitable pins within an injection mould tool.

In the barrier 1, the members 13 are spaced along the run 5 by spacers 15 and along the run 9 by spacers 17. Preferably the spacers 15, 17 take the form of tubular sleeves for sleeving the flexible pulling elements 7. In this case, the spacers 15 are 25 mm OD cylindrical tubes. Other shapes and sizes, and indeed other forms of spacers more generally, are possible. The spacers are preferably formed of plastic, most preferably engineering plastic such as HDPE.

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Relative to other potential materials, HDPE has the following advantageous properties:

• light weight and floats slightly in the water;

• low co-efficient of friction;

• high surface release properties;

• high chemical resistance;

• excellent impact resistance;

• excellent abrasion resistance;

• self-lubricating;

• does not absorb water;

• does not need painting or antifouling, which reduces pollutants into the water;

• easily machined on-site with relatively low environmental impact;

• an extremely low 'Eco Indicator 95' of 2.8 mpt.

Each spacer has a length corresponding to the preferred separation of the barrier members 13 and is larger than the cable-carrying bores of the barrier members 13 so as to abut the side faces of those members.

The spacers 17 are simple cylindrical tubes. The spacers 15 incorporate drainage holes 18 but are otherwise substantially identical to the spacers 17.

In this particular variant, the upper run 5 is mounted above a waterline WL. In the context of a tidal environment, WL may correspond to high tide. The drainage holes reduce the volume of water trapped within the spacers 15, thereby slowing the corrosion of the cables 7. For a similar reason, the upper bore of each member 13 may have a chamfered lower face to promote free draining, whereas the corresponding lower bore may be a simple, straight, cylindrical bore.

According to a preferred variant, the barrier members 13 have mutually different lengths selected to follow what is beneath, e.g. to follow the seabed. For this

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2019264576 13 Nov 2019 purpose, the members 13 might be cut to length, e.g. cut to length on-site during installation of the barrier.

Some variants of the barrier 1 may carry floats such as the 8 PVC deep sea floats 19. The floats may be threaded over the spacers 15.

Preferably the members 13, 15, 17 are restrained from movement along the runs 5, 9. This may entail stoppers bracketing the members, e.g. a dedicated stopper gripping the flexible pulling element at each end of a run. A swage, such as the swage 21 of Figure 3, is an example of a stopper.

Preferred variants of the barrier 1 are configured to enable the barrier to rise, e.g.

to rise to or above the surface, for maintenance. Figure 3 illustrates a preferred approach to this configuration. According to this preferred approach, the other end of the barrier 1 has a similar configuration.

The flexible pulling element 7 of the run 5 is fixed to the eyelet of a band 23 embracing the pylon 3. Lower down the pylon 3 is a corresponding band 25, the eyelet of which carries a shackle about which the flexible pulling arrangement (or more specifically cable 11 in this case) of the lower run 9 is upwardly turned to facilitate access to the flexible pulling arrangement from above.

The upward run of the cable 11 is shackled to the eyelet of the band 3 via an adjustable tensioner 29, such as a turnbuckle, and a releasable connector 31.

A preferred approach to raising the barrier entails utilising a float in the form of a floating boom such as the floating boom 33 (Figure 4). The floating boom 33 takes the form of an air-filled HDPE cylinder which is 6 m long in this case. Other constructions are possible. By way of example, the boom might be a steel structure having floats spaced along its length.

Tow points 35, in the form of eyelets in this case, are mounted along the length of the boom. In this case there are four equispaced mounting points. A set of three

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2019264576 13 Nov 2019 ties 37 is also mounted along the boom 33. The ties are equispaced from each other and interleaved with the tow points 35.

Figure 5 illustrates a barrier rising from an upright barricading position A, through intermediary positions B and C, en route to a recumbent maintenance position D.

In the recumbent maintenance position the barrier 1, or more specifically the barrier members 13 in this case, are more or less horizontal, say within 20 degrees of horizontal. Preferably the barrier 1 is in the vicinity of the waterline WL to facilitate operations such as pressure cleaning by a human aboard a small boat adjacent the barrier 1.

A preferred raising sequence entails positioning the boom 33 (labelled as boom 33A in Figure 5) along the barrier 1. The boom 33 is tied to the barrier members 13 with ties 37. In this example, each tie 37 takes the form of a short length of cable having a simple fitting, e.g. a snap hook, at its end so that the cable can be looped around the barrier member 13 and then fastened back on itself.

Tow lines are run from the tow points 35 to a suitable tow vehicle, typically a boat, and the releasable connection 31 and the corresponding connection at the other end of the barrier are released to enable the run 9 to move relative to the end points 3. The upward run of cable 11 may include a portion extending beyond the connection 31, or an extension element might be added prior to the release of the connection element 31, so that a portion remains grippable from above, ready for when it is time to lower the barrier.

The tow vehicle is operated to tow the boom 33A (to the right as drawn in Figure 5) to urge the barrier 1 through the intermediate positions B and C. As noted, the barrier 1 is not far from neutrally buoyant, whereby raising the barrier through these intermediate positions does not require a great deal of power.

The tow vehicle thus horizontally urges the boom 33 to raise the barrier 1. There are other ways in which the boom might be horizontally urged, e.g. the barrier

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2019264576 13 Nov 2019 might be pushed or might be pulled using something other than tow vehicle, e.g.

using a winch. There are other ways in which the barrier 1 might be raised.

The barrier members 13 to which the boom 3 is tied function as guides guiding the boom to slide in a direction at least approximately perpendicular to the axis about which the barrier turns (about the run 5 in this case), and at least approximately parallel to a plane of the barrier 1. Other guide arrangements are possible. Some variants of the method may proceed without, or without utilising, such guide arrangements. By way of example, in the context of a barrier having extensive biofouling, it may not be practical for the ties 37 to slide along the barrier members 10 13 (because they would catch on the build-up). In this case, positioning the floating support may entail some manhandling of the barrier and/or float. Potentially the ties could be disconnected and then reconnected to help pass any particularly problematic portions of build-up.

The extent to which the ties 37 can slide along the barrier members 13 is limited by the bottom rung 9. The ties 37 have a length that enables the boom 33 to move beyond that run towards the ends of the barrier members 13. For this purpose, the ties 3 may have differing lengths selected to complement the differing lengths of the barrier members 13 beyond the tie-stopping run of cable. Alternatively, some free length of the barrier members may be left to simply overhang the boom 33 and/or the boom 33 might be manipulated into a position that is not limited by the ties 37.

Preferably the method is performed when the turning axis (e.g. the axis of run 5 in this case) is above, preferably a short distance above, the waterline WL. In tidal environments, the method may entail scheduling based on the tides.

The boom 33 (labelled 33D in Figure 5) holds the portions, of the barrier 1 spaced from the turning axis, above the waterline WL whereat the barrier is presented for convenient access for cleaning without the need for a scuba diver. Preferred variants of the cleaning operation can improve the appearance and extend the service life of the barrier. Preferred variants of the method enable accurate visual

P1592AUAU inspection. Marine engineers aboard a boat can see for themselves what is happening without having to rely on photographs and/or verbal feedback from divers. To lower the barrier 1, the described process can essentially be reversed.

Figure 6 illustrates a preferred form of debris-collector 39 for trapping debris cleaned from the barrier 1. When required, the collector can be used to limit the damage caused by falling debris and fragments of plants (etc) released during cleaning.

The debris-collector incorporates the boom 33, a second floating boom 41 and a pair of support arms 43 which together form a rectangular frame 45. The collector 39 further includes permeable fabric 47 supported by the frame 45.

If space permits, the debris-collector 39 can be positioned adjacent the barrier 1 prior to initiating the described barrier-raising sequence, to drag the collector 39 in under the barrier to the position illustrated in Figure 7, whereat the collector is positioned to collect debris cleaned from the barrier 1.

Alternatively, components 41,43, 47 may be installed after the barrier has been raised.

Preferably the fabric 47 is fastened to the frame 45 via a simple releasable fastening arrangement, e.g. the fabric 47 might take the form of geotextile mesh (or other penetrable material) that is impaled upon spikes about the frame, whereby, after the cleaning operation, the fabric 47 can be lifted from the spikes and thereby released from the frame 45 and gathered up and removed to carry away the debris. Most preferably, a drawstring encircles the fabric 47 such that the string and the fabric together constitute a drawstring bag for carrying the debris.

Preferred variants of the barrier 1 are well adapted to part-by-part replacement to extend the service life of the barrier. It is contemplated that the lower run of cable may need to be replaced more often than the upper run. To replace the lower cable, the barrier 1 can be lifted, the old cable cut and removed, and then a new

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2019264576 13 Nov 2019 cable threaded through the various components. Optionally the leading end of the new cable may be threaded through so as to follow closely behind the trailing end of the withdrawing old cable, so that at most only a small number of spacers are loose at any one time. This part-by-part replacement may reduce the lifetime cost of the barrier relative to other constructions such as meshes that must be replaced once the lower reaches are degraded, even if the upper portions of the mesh remain intact.

Preferred variants of the barrier 1 are also well adapted for reconfiguration, e.g. to suit a shifting seabed. Advantageously, the bands 23, 25 may be shifted up and 10 down as required. Of course, other forms of vertically relocatable mounting points are possible. Optionally the barrier may be installed with additional barrier-member length above the water level, whereby the lower ends of the barrier 13 can be trimmed, and the barrier as a whole lowered, from time to time to more closely follow the changing underlying terrain, e.g. shifting seabed.

Optionally, the lower ends of the barrier members 13 might be embedded in the underlying sand (or other floor material). Raising the barrier may entail moving the sand (or other floor material), e.g. may entail dredging.

The invention is not limited to the described examples. Rather, the invention is defined by the claims. By way of example, whilst a barrier having two runs of cable 20 has been described, other variants may have barrier members hanging or floating from a single run of cable. Conversely, other variants of the barrier may have more than two runs of cable, e.g. three or more runs of cable may be advantageous in the context of barriers vertically spanning water more than 2.5 m deep.

The term 'comprises' and its grammatical variants has a meaning that is determined by the context in which it appears. Accordingly, the term should not be interpreted exhaustively unless the context dictates so.

Claims (27)

1. A selective barrier, for an aquatic environment, comprising a first run of one or more flexible pulling elements spanning a horizontal distance;

barrier members connected to the first run; and

5 spacers spacing the barrier members.

2. The selective barrier of claim 1 wherein the spacers are sleeves sleeving respective portions of the first run.

3. The selective barrier of claim 1 or 2 wherein at least most of the spacers each have a density in the range of 800 kg/m³ to 1200 kg/m³ inclusive.

10

4. The selective barrier of claim 1 or 2 wherein at least most of the spacers are formed of HDPE.

5. The selective barrier of any one of claims 1 to 4 comprising two stop portions bracketing the barrier members and the spacers to substantially prevent the barrier members and the spacers moving along the first run.

15

6. The selective barrier of claim 5 wherein at least one of the stop portions grips one of the one or more flexible pulling elements.

7. The selective barrier of any one of claims 1 to 6 wherein at least most of the barrier members are rigid barrier members.

8. A selective barrier, for an aquatic environment, comprising

20 a first run of one or more flexible pulling elements spanning a horizontal distance; and barrier members connected to the first run;

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2019264576 13 Nov 2019 wherein at least most of the barrier members are rigid barrier members.

9. The selective barrier of any one of claims 1 to 8 wherein at least most of the barrier members each have a density in the range of 800 kg/m³ to 1200 kg/m³ inclusive.

5 10. The selective barrier of any one of claims 1 to 8 wherein at least most of the barrier members are formed of HDPE.

11. The selective barrier of any one of claims 1 to 10 comprising a second run of one or more flexible pulling elements spanning a horizontal distance;

wherein the barrier members are connected to the second run.

10 12. The selective barrier of claim 11 wherein the second run is a lower run releasable to enable the selective barrier to rise from an upright barricading configuration to a recumbent maintenance configuration.

13. A barrier, for an aquatic environment, mounted to rise from an upright barricading configuration to a recumbent maintenance configuration.

15 14. The barrier of claim 13 being a selective barrier.

15. The barrier of claim 13 or 14 comprising a first run of one or more flexible pulling elements spanning a horizontal distance; and a second run of one or more flexible pulling elements spanning a horizontal

20 distance;

wherein the second run is a lower run when the barrier is in the upright barricading configuration; and

P1592AUAU releasable to enable the barrier to rise to the recumbent maintenance configuration.

16. The barrier of claim 12 or 15 comprising an arrangement about which the flexible pulling element connected to the second run is upwardly turned to enable release from above.

17. The barrier of any one of claims 1 to 12, 15 and 16 wherein the first run is mounted above a waterline.

18. A selective barrier, for an aquatic environment, mounted to rise from a barricading configuration to a maintenance configuration.

19. A method, of maintaining a barrier for an aquatic environment, comprising raising the barrier from a barricading configuration to a maintenance configuration;

operating on the barrier; and lowering the barrier to the barricading configuration.

20. The method of claim 19 wherein the barricading configuration is an upright barricading configuration; and the maintenance configuration is a recumbent maintenance configuration.

21. The method of claim 20 wherein the raising comprises horizontally urging one or more floats under the barrier to support the barrier.

22. The method of claim 20 wherein the raising comprises horizontally urging one or more floats under the barrier to support the barrier above water.

23. The method of claim 21 or 22 wherein the urging is pulling.

24.

The method of claim 21 or 22 wherein the urging is towing.

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25. The method of any one of claims 21 to 24 wherein the operating on comprises removing debris from the barrier.

26. The method of claim 25 comprising arranging a debris-collector under the barrier to collect the debris.

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27. The method of claim 26 wherein the debris-collector comprises permeable fabric and a frame supporting the fabric.

28. The method of claim 26 or 27 wherein the debris-collector comprises the one or more floats.

29. The method of claim 19 or 20 wherein the operating on comprises

10 removing debris from the barrier.

30. The method of any one of claims 19 to 29 wherein the operating on comprises pressure cleaning.