Apparatus for subsea repair

Abstract

An apparatus and method is provided for subsea repair or reinforcement of nets, each net having a plurality of net segments, the apparatus including: a holder for catching a segment of the net; a guide tube for feeding a stitching line towards the holder, the stitching line being retractably fed in and out of the guide tube; a stitching device that connects the stitching line to a first segment of the net and to a second segment of the net; a cutting device for severing the stitching line; and a control module; wherein the control module actuates the stitching device to connect the stitching line to the first segment of the net, retractably feed out additional stitching line whilst the holder is relocated towards the second segment of the net, and tighten the stitching line before connecting the stitching line to the second segment of the net.

Description

Apparatus for Subsea RepairTechnical Field

[0001] This invention finds utility in the field of aquaculture and mariculture, and more particularly in inspection and repair and / or reinforcement of aquaculture nets in situ in a subsea environment.Background of Invention

[0002] As global populations continue to increase, so does the demand for sustainable sources of seafood. Since supplying demand from wild fish stocks is dependent on wild fish stock renewal and demand is outstripping supply, a number of countries have focused efforts on developing sustainable aquaculture industries, in order to supply increasing demand. Many aquaculture industries are directed largely to production of salmonids, i.e. Atlantic Salmon and Trout and are geographically concentrated in countries such as Norway, Canada, Scotland, Chile and Australia which naturally boast conditions favourable for optimal salmonid production.

[0003] Fish are farmed in aquaculture systems which anchor fish cages or sea pens offshore. Individual fish cages comprise mesh or netting to form an enclosure which keeps the farmed fish in and undesired marine species out. The mesh or netting is supported by a floating frame formed of steel or plastic and is anchored in place. Fish cages may be square or circular, anywhere from 80, 120, 160 to 240 metres in circumference and 12 to 45 metres deep. A large sea cage can contain up to 200,000 fish. Fish cages are commonly placed side by side to form an anchored aquaculture system including a floating wharf with walkways along the net boundaries. Additional nets may surround the aquaculture system to keep out predatory marine mammals which damage the netting.

[0004] Due to the inherently hostile environment in which aquaculture occurs, fish pens or cages are vulnerable to damage. Damage to the net or mesh can be caused by abrasion from net movement caused by wind, wave and currents; collision with boat propellers or debris; biting by fish or other predatory marine animals; or the like. Such damage may cause holes to form in the nets and can have adverse impactssuch as fish escapes which has significant financial repercussions as well as environmental impacts.

[0005] Regular inspection of fish cages or sea pens are therefore vital to confirm net integrity and avoid escape events. Presently, if a hole is identified in a fish cage or sea pen, one or more divers are dispatched to repair or reinforce the net underwater by hand. Using divers in such hostile environments has obvious OH&S risks, comes at significant cost and is often plagued by delays.

[0006] Accordingly, it would be desirable to provide a safer and more convenient alternative for efficient repair or reinforcement of nets in aquaculture environments.

[0007] A reference herein to a patent document or any other matter identified as prior art, is not to be taken as an admission that the document or other matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.Summary of Invention

[0008] According to an aspect of the present invention, there is provided an apparatus for subsea repair or reinforcement of nets, each net having a plurality of net segments, the apparatus including: a holder for catching a segment of the net; a guide tube for feeding a stitching line towards the holder, the stitching line being retractably fed in and out of the guide tube; a stitching device that connects the stitching line to a first segment of the net and to a second segment of the net; a cutting device for severing the stitching line; and a control module; wherein the control module actuates the stitching device to connect the stitching line to the first segment of the net, retractably feed out additional stitching line whilst the holder is relocated towards the second segment of the net, and tighten the stitching line before connecting the stitching line to the second segment of the net.

[0009] In one embodiment, the holder includes a pair of guiding arms for catching the segment of the net therebetween. Each of the pair of guiding arms may have an end proximal to a body of the apparatus and another end distal to the body of the apparatus and the pair of guiding arms are configured such that their distal ends splay outwards.

[0010] In another embodiment, the holder further includes a jaw region situated between the pair of guiding arms and the guide tube feeds the stitching line towards the jaw region. The stitching device may be positioned adjacent to the jaw region.

[0011] In some embodiments, the apparatus further includes a staple dispenser and the stitching device uses staples to connect the stitching line to segments of the net. The staples may be loaded into the staple dispenser via a staple storage and feed rail.

[0012] In some embodiments, the jaw region is configured to catch the stitching line and the net segment in its grasp such that the stitching device is positioned to dispense and crimp a staple to connect the stitching line and net segment together.

[0013] In certain embodiments, a winch and a retractable reel cooperate to retractably feed the stitching line in and out of the guide tube. The retractable reel may include a biasing member to cause stitching line that is winched back in to be fed back onto the reel.

[0014] In some embodiments, the biasing member is a torsion spring. The biasing member and the retractable reel may be coupled by a magnetic clutch.

[0015] In certain embodiments, the stitching line is retractably fed in and out of the guide tube using sufficient force to tension the stitching line so as to provide a repair or reinforcement with a design specified tension specific to the type of net undergoing repair or reinforcement.

[0016] In some embodiments, the winch includes a motor coupled to a compact gearbox to drive a capstan located inside a winch housing. An internal surface of the winch housing may have a fixed helical channel to guide the stitching line through the capstan.

[0017] In some embodiments, the net is located underwater and has intact segments and damaged segments, the damaged segments forming a hole in the net that requires repair, wherein the stitching device connects the stitching line to a first intact segment of the net that is adjacent to a damaged segment of the net, and after retractably feeding out stitching line and relocating the holder to a second intact segment of the net that is situated on the distal side of the hole, tightening thestitching line before connecting the stitching line to the second intact segment of the net.

[0018] In some embodiments, the apparatus is configured to be mounted on a vehicle or a mechanical arm that is operable underwater.

[0019] According to another aspect of the present invention, there is provided a method for repair or reinforcement of a net, the net having a plurality of net segments, the method including the following steps: providing an apparatus configured to: catching a segment of the net between a pair of guiding arms; feeding a stitching line towards a jaw region situated between the guiding arms, the stitching line being fed in and out of a guide tube by a retractable reel; connecting the stitching line to a first segment of the net; feeding out additional stitching line whilst the guiding arms are relocated towards a second segment of the net; operating a retractable reel to tighten the stitching line; connecting the stitching line to the second segment of the net; repeating the steps as many times as required to securely repair or reinforce the net; and severing the stitching line once the repair or reinforcement is complete.

[0020] In some embodiments, the stitching device dispenses a staple and connects the stitching line to segments of the net by crimping the staple to connect the stitching line and segments of the net. The staples may be fed into the staple dispenser via a staple storage and feed rail.

[0021] In certain embodiments, the stitching line is retractably fed into and out of the guide tube. Tension may be maintained on the stitching line by feeding stitching line that is winched back onto a biased reel.

[0022] In some embodiments, the tension on the stitching line is specified so as to provide the repair or reinforcement with a design specified tension specific to the type of net undergoing repair or reinforcement.

[0023] According to yet another aspect of the present invention, there is provided a non-transitory computer readable medium storing instructions for repairing or reinforcing a net, the net being located underwater and having a plurality of segments, that when executed by a processor cause it to perform the following steps: guide a pair of guiding arms for catching a segment of the net therebetween; feed a stitchingline towards a jaw region situated between the guiding arms, the stitching line being fed in and out of a guide tube by a retractable reel; connect the stitching line to a first segment of the net to be repaired or reinforced; feed out additional stitching line whilst the guiding arms are relocated towards a second segment of the net; operate a retractable reel to tighten the stitching line; connect the stitching line to a second segment of the net; repeat the steps as many times as required to securely repair or reinforce the net; and severe the stitching line once the repair or reinforcement is complete.Brief Description of Drawings

[0024] The invention will now be described in further detail by reference to the accompanying drawings. It is to be understood that the particularity of the drawings does not supersede the generality of the description of the invention.

[0025] Figure 1 A is an oblique view of the apparatus for repairing or reinforcing nets underwater according to an embodiment of the invention.

[0026] Figure 1 B is an oblique view of the apparatus for repairing or reinforcing nets underwater of Figure 1 A further including a cutting device.

[0027] Figure 1 C is an oblique view of the apparatus of Figure 1 B shown from the other side.

[0028] Figure 2 shows the apparatus of Figures 1 A, 1 B and 1 C shown mounted on a ROV according to an embodiment of the invention.

[0029] Figure 3 is a top down transverse view of the apparatus mounted on the ROV of Figure 2.

[0030] Figure 4 is an oblique view of the head of the apparatus according to an alternative embodiment of the present invention.

[0031] Figures 5A and 5B are oblique views of the head of the apparatus from different sides, additionally showing the cutting device according to an embodiment of the present invention.

[0032] Figures 6A, 6B, 6C and 6D are top down transverse views of the stitching device during consecutive steps of the crimping process, and Figure 6E is a top down transverse view of the stitching device together with the holder according to an embodiment of the present invention.

[0033] Figure 7A is a top down transverse view of the cutting device of the apparatus according to one embodiment.

[0034] Figure 7B is an oblique view of the cutting device of Figure 7A.

[0035] Figure 8A is an oblique view of the winch component of the apparatus according to one embodiment.

[0036] Figure 8B is an exploded view of the winch component of Figure 8A.

[0037] Figure 9 is a close up view of the winch housing also shown in Figures 8A and 8B showing the helical channel according to an embodiment.

[0038] Figure 10A is an oblique view of a clutch according to an embodiment.

[0039] Figure 10B is a top down transverse view of the clutch of Figure 10A.

[0040] Figure 11 is a schematic block diagram showing the control system.

[0041] Figure 12 is a flow chart for the hand control unit of Figure 11.

[0042] Figure 13 is a flow chart for the subsea control unit of Figure 11 .

[0043] Figures 14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H and 141 show a representation of the method for repairing or reinforcing a net situated underwater using the apparatus of the present invention.

[0044] A person skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. It will further be appreciated that the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description below.Rectified SheetISA / AU ( Rule 91)Detailed Description

[0045] The apparatus is configured for subsea or underwater repair and / or reinforcement of nets and mesh, such as those used to form fish cages in aquaculture operations. These aquaculture nets are designed to keep fish or other farmed marine life in, whilst keeping predators out. Accordingly, maintaining the structural integrity of the nets and attending to necessary repairs promptly is vital to their proper function.

[0046] It will be understood that a net comprises a plurality of segments forming a mesh-like structure and that a net requiring repair will typically have some intact segments and other damaged segments. The damaged segments may be frayed or torn, forming a hole in the net that brings with it a risk of fish escaping and of predators breaching the net. Both scenarios have the potential to cause substantial losses making maintaining net integrity a significant and high priority issue for aquaculture operations. In other situations, it may be desirable to reinforce a net to provide strengthening, perhaps before the net has become damaged such that a hole has been formed therein. It will be understood that the apparatus described herein may be applied to either or any similar scenario where subsea net repair or reinforcement may be required including exclusion or predator nets such as shark nets and the like.

[0047] Referring firstly to Figure 1 A, there is shown the apparatus for repairing and reinforcing nets underwater. The apparatus 100 includes a holder 115 situated towards the head 105 or forward orientated end of the apparatus, the holder being configured to catch a segment of the net (this action is shown in more detail in Figures 14A to 14C). More specifically, the holder 115 first catches a net segment, for example an intact segment of the net that is adjacent to a damaged segment. The catching function is intended to hold the apparatus 100 in position close by the net whilst it undertakes the repair or reinforcement functions described herein.

[0048] The apparatus 100 has a guide tube 120 that feeds a stitching or repair line 125 (not shown as obscured by guide tube) towards the holder 115. The stitching line 125 is fed in and out of the guide tube 120 retractably so that a requisite tension can be maintained on the line. Head 105 of apparatus 100 further includes stitching device 130 that connects the stitching line 125 to a first intact segment of the net to berepaired, and then to a second intact segment of the net, the second intact segment of the net, for example, being situated on the distal side of the hole. In this way, the stitching line 125, once in place, replaces or substitutes for the damaged segment of the net. In other examples, a hole may not necessarily exist in the net, but rather the addition of stitching line is intended to reinforce the net.

[0049] Referring now to Figure 1 B, head 105 of apparatus 100 further includes cutting device 135 to sever stitching line 125 once connected or crimped in position. This process is repeated as many times as is necessary to reliably repair the hole in the net or add the required reinforcement, as the case may be. The number of times the process will need to be repeated is contingent on the size of the hole and the number of damaged net segments that form the hole.

[0050] A control module (see Figure 3) actuates stitching or crimping device 130 to connect stitching line 125 to the first intact segment of the net to be repaired, retractably feed out additional stitching line whilst holder 115 is relocated towards a second intact segment of the net that is situated on the distal side of the hole, and to tension the stitching line before connecting it to the second intact net segment. Tensioning stitching line 125 ensures that the repaired net has a functional equivalence to the intact net prior to being damaged. Stitching line 125 is tensioned by cooperation of winch 140 and retractable reel 145 that act together to retractably feed the stitching line in and out of guide tube 120. Also shown in Figures 1 B and 1 C is linear actuator 112 for driving the crimping device 130. The linear actuator 112 is omitted from Figure 1A for simplicity.

[0051] Stitching line 125 itself comprises a material with high friction properties to enable the line to be readily fed out and retracted and make it less likely to slip once crimped to the net. Additionally, the stitching line material has a high tensile strength and is severable without fraying at the severed ends. One example of a suitable material having the requisite properties is polyurethane.

[0052] Figure 1 C shows apparatus 100 of Figure 1 from the other side and thereby shows more clearly the winch 140 and retractable reel 145 arrangement situated towards the tail 110 or backward orientated end of the apparatus. Clutch 500 couples retractable reel 145 and biasing member (see Figure 10B). The biasingmember can be a torsion or helical spring. This configuration enables any stitching line 125 that is winched back in to tension the repair, to be fed back onto reel 145, and to allow the stitching line to be fed out even whilst the biasing member is fully tensioned.

[0053] Winch 140 is mounted to motor coupled to a compact gearbox and encased in housing 150 to drive a capstan (see Figure 8B). The gearbox maybe a planetary gearbox or could be a cycloidal drive or similar alternative to reduce the speed of the input shaft. Planetary and cycloidal drives offer high torque relative to their compact size. Motor requires a high power to weight ratio and may be a brushless DC motor and preferably a stepper motor. This configuration enables the winch system to retract stitching line 125 with sufficient force to bring the net segments together with their design-specified tension, and to feed out the stitching line again with ease.

[0054] Referring now to Figure 2, there is shown the apparatus 100 mounted on a submersible remotely operated vehicle (ROV) 200 to provide mobility and operation of the apparatus according to one embodiment. More specifically, apparatus 100 is configured for mounting on an observation class ROV. This class of ROV is typically fitted with one or more cameras that transmit image data back to an operator at the surface. It will be appreciated that mounting apparatus 100 on this type of ROV 200 makes the apparatus relatively quick and easy to deploy, thereby minimising times from notification that a net repair is required and attending to the repair, as well as minimising costs. A suitable ROV will offer six degrees of freedom such that the apparatus platform is enabled for fully controlled position and attitude to facilitate repair of nets at any angle and from any direction. Generally, observation class ROVs will be tethered for provision of power and communications. Such ROVs typically operate on a tether of up to 200 metres and are operable to depths of up to 150 metres making them an ideal candidate for the intended application.

[0055] Figure 3 is a top down view of apparatus 100 mounted in position on submersible ROV 200. The locations of the ROV thrusters 210 are shown relative to the apparatus components including holder 115, cutting device 135, winch 140, retractable reel 145 and subsea control unit 170. Also shown in Figure 3 is power pod 173 for storing batteries, motor controllers and the like.

[0056] It will be appreciated that mobility and operation of the apparatus could be otherwise provided by means of mounting the apparatus on a mechanical submersible arm itself mounted on a suitable part of aquaculture system, fish pen or fish cage, or on a vessel attending the scene.

[0057] Figure 4 is an oblique view of head 105 of apparatus 100. In Figure 4, head 105 of apparatus is shown with a short segment of net 700 caught in holder 115, after a staple 175 has been crimped to secure the net and stitching line 125 together.Staple 175 is dispensed by stitching device 130 as will be described in more detail by reference to Figures 6A to 6E. Holder 115 generally comprises pair of arms 180A and 180B configured to catch an intact net segment 700 therebetween. Each of the pair of arms 180A and 180B has one end proximal to the body 190 of apparatus 100 and another end distal to the body of the apparatus and to enhance the catching functionality, the pair of arms are configured such that their distal ends splay outwards. This arm configuration facilitates catching a segment of the net 700 and guiding it towards jaw region 185 situated generally between pair of arms 180A and 180B. Jaw region 185 is configured to retain the stitching line 125 therein, e.g. arcuate to prevent slippage of the stitching line. Also shown in this oblique view is stitching line 125 being fed into jaw region 185 in which stitching device 130 resides, via guide tube 120. Guide tube 120 in Figure 4 is configured as an open channel rather than the fully enclosed tube as shown in Figures 1 A, 1 B and 1 C. However, as in the previously illustrated embodiment, purpose of guide tube 120 is simply to guide stitching line 125 between winch 140 and stitching device 130.

[0058] Guide tube 120 is configured so as to allow stitching line 125 to be pushed via action of winch 140, to reposition stitching line 125, as required. For example once stitching line 125 has been severed, or for reloading of stitching line when a replacement reel 145 is fitted in position. Guide tube 120 may be lined with a low friction material such as polytetrafluoroethylene (PTFE).

[0059] Figures 5A and 5B are oblique views of head 105 of apparatus 100 shown from different sides. These views show the relative arrangement of holder 115 including two arms 180A and 180B working in unison to provide the catching and holding function and cutting device 135 which is positioned to allow it to severstitching line 125 (not shown as obscured by guide tube 120) as it is fed towards stitching device 130 via guide tube 120.

[0060] Figures 6A, 6B, 6C and 6D are top down transverse views of stitching device 130 shown during consecutive stages of the stitching and crimping process. More particularly, Figure 6A shows net segment 700 and stitching line 125 caught in jaw region 185. Jaw region 185 is defined by two pincers 305A and 305B. In Figure 6B, pincers 305A and 305B hold staple 175 in readiness for the crimping action. Pincers 305A and 305B close over net segment 700 and stitching line 125, thereby crimping staple 175 thereby connecting the net segment and stitching line together. Pincers 305A and 305B are moved towards the closed or crimping position via linear actuator 310. As can be seen in Figure 6B, at this point, i.e. when pincers 305A and 305B are in the closed or crimping position, new staple 175 is dispensed into jaw region 185 for a subsequent crimping action. Staples 175 are dispensed and loaded into the staple dispenser via staple storage and feed rail 195 (see also Figures 1A, 1 B and 1 C).

[0061] Once the crimping action is complete and net segment 700 and stitching line 125 are connected together, as shown in Figure 6C, pincers 305A and 305B move apart via operation of linear actuator 310 in reverse, to reveal net segment 700 and stitching line 125 fixedly connected together by crimped staple 175. Figure 6D shows the connected net segment 700 and stitching line 125 released from the pincers 305A and 305B. At this point, apparatus 100 is repositioned by movement of ROV 200 to the next location where crimping or repair is required.

[0062] Referring now to Figure 6E, there is shown a top down view through a higher plane showing the stitching device 130 of Figures 6A to 6D together with holder 115 superimposed thereupon to show the relative positions of the various components.

[0063] Whilst the stitching action has been described herein and involving connecting the stitching line to a segment of the net to be repaired or reinforced using crimped staples, it will be appreciated that other means may achieve a similar aim. For example, stitching device 130 may be configured to thread the stitching line through and around net segments to provide connection of the stitching line to thenet. However, threading rather than crimping whilst providing a serviceable and alternative means of repair, may result in friction occurring between the stitching line and the net segments, which may ultimately shorten the life of the repair. Connecting the stitching or repair line to the net at multiple points using a crimped staple provides for a more sturdy and durable repair or reinforcement.

[0064] Referring now to Figures 7A and 7B, there are shown a top down transverse view and an oblique view respectively, of cutting device 135. Blade 410 is positioned within aperture 415 in cutting member 420, the aperture having a stadium or discorectangle shape. It will be appreciated that the aperture could have other suitable shapes such as a circle, oval, square or rectangle. Cutting member 420 is configured to house blade 410 within aperture 415 to protect operators from accidental injury, as well as protecting blade 415 itself from damage. Blade 410 itself is a standard format scalpel blade and can be removed and replaced by releasing single bolt 425. Blade 410 is arranged within aperture 415 to provide an edge-to-edge cutting area. This ensures that stitching line 125 is properly severed.

[0065] Cutting member 420 is operated by means of a motor located in waterproof housing 430 situated nearby to cutting member 420. A slotted link mechanism or scotch yoke 435 converts rotational motion of eccentric shaft 440 connected to motor (not shown) into linear motion of cutting member 420 via linear guide rails 445.

[0066] As previously described, stitching line 125 is fed towards holder 115. Tension is maintained on stitching line 125 throughout the repair operation by means of cooperation of winch 140 with retractable reel 145 that act together to retractably feed stitching line in and out of guide tube 120. Referring now to Figure 8A and 8B, there is shown winch component 140. Winch component 140 is includes a motor (not shown) coupled to a compact gearbox encased in housing 450 to drive a capstan or winch barrel 460. Capstan or winch barrel 460 in encased by housing 465 and upper bearing plate 470. Upper bearing plate 470 is coupled to output shaft upper bearing 475. Output shaft lower bearing 480 is coupled to output shaft 485 which is coupled to winch base plate 497 via bearing retaining ring 495. The winch component is mounted to the motor via winch base plate 497 and motor mounting plate 499.

[0067] Capstan 460 has a toothed surface (see Figure 8B) to increase the frictional force between the capstan and the stitching line, that is, to offer increasing pulling force as stitching line load increases. Moreover, compression wheels 496 mounted on compression wheel holders 498 act to compress the stitching material against the toothed barrel surface at the entry and exit point of the capstan barrel. This provides increased friction between the capstan and stitching material which is multiplied by the wrapping of material around the barrel. Use of the compression wheels, wrapping the stitching material around the capstan barrel and using teeth on the inner capstan barrel surface act together increase the pulling force of the winch component.

[0068] Furthermore, as is shown in Figure 9, internal surface of winch housing 465 may have a fixed helical channel 467 to guide the stitching line through the capstan 460 and prevent jamming.

[0069] An exemplary gear ratio for a suitable gearbox is 100: 1 . Gearbox may be a planetary gearbox providing high torque relative to its compact size. Motor 450 is preferably a stepper motor and is encased together with gearbox in a waterproof pressure housing 450. For example, a 1 .2 nm stepper motor provides high torque and precise control for feeding the stitching line 125 towards the head 105 of the apparatus 100.

[0070] Referring now to Figures 10A and 10B there is shown an oblique view of clutch 500 used to couple biasing member 525 to retractable reel 145. Allowing the stitching line to be fed in and out of guide tube 120 whilst maintaining sufficient tension on the stitching line enables the net repair to be made with a design specified tension specific to the type of net undergoing repair. The tension of the repair of reinforcement may be measured using a strain gauge, or can be unascertained by eye. That is, given that the intact net provides an adjacent grid refence, a comparison can be made by eye (generally via an in situ camera) to check the relative tension on the repair versus the original net.

[0071] Clutch 500 has a base plate 505 and an extended central shaft 510 to stabilise the stitching line storage reel 145. Bearing 515 keeps the clutch core runningtrue on the integral central shaft and prevents friction-induced binding. Reel coupling teeth 520 may have various shapes to customise for different reels 145.

[0072] Magnets 540 are integrated into interior clutch core 530 as well as exterior clutch core to couple them together. Magnetic fields of the interior and exterior clutch cores interact to transfer torque between the biasing means 525 and reel 145, forming a torque-limiting magnetic clutch. This configuration enables the stitching line to be fed out, even when the torque spring is fully tightened. Magnets 540 may be neodymium magnets. The biasing means may be a torque spring configured for multiple turns around interior clutch core 530. An O-ring groove is used to waterproof the housing and protect the clutch mechanism and in particular, biasing means 525. Furthermore, a viscous fluid may be provided within the housing to enable the clutch mechanism to provide controlled spooling.

[0073] Referring now to Figure 11 there is a show a schematic block diagram of control system 600 for controlling the apparatus. The control unit includes hand control unit (HCU) 605 for use by an operator on or near the surface of the water, and subsea unit 610 mounted on ROV 200 alongside apparatus 100. Hand control unit (HCU) 605 provides the interface via which an operator may, for example, operate the apparatus from a boat, pontoon or floating walkway positioned in the general vicinity of the net or nets to be repaired. Hand control unit (HCU) 605 is tethered to the subsea control unit 610 for provision of power and communications to apparatus 100 and ROV 200. For example, communications may be provided using RS-485 serial interface or similar.

[0074] Subsea control unit 610 includes microcontroller unit (MCU) 615 connected to ancillary power supply 620, electronic circuit 625 and driver circuit 630. For example, electronic circuit 625 may be a H-circuit connected to a linear actuator 635, e.g. a DC brushed motor, that controls the motor to go backwards or forwards to actuate stitching device 130. Driver circuit 630 is connected to a motor, e.g. stepper motor 640 that drives the stitching line feed and retract functions previously described. Microcontroller unit (MCU) 615 is further connected to a servo motor 645 for actuating cutting device 135. Power is also provided to ROV 200 via surface tethering of subsea control module 610.

[0075] Referring now to Figure 12, there is shown a flow chart showing inputs and outputs to the hand control unit 605. Some of those inputs and outputs will be signals from subsea control unit 610. Other inputs will be made by the operator, such as for example, an emergency stop signal which is transmitted to subsea controller 610.

[0076] Referring now to Figure 13 there is shown a flow chart showing inputs and outputs to the subsea control unit 610. The subsea control unit 610 receives inputs from and transits outputs to hand control unit (HCU) 605. Inputs are provided to stitching device 130, cutting device 135 and stitching line feed and retract system provided by cooperation of winch 140 and reel 145.

[0077] Referring now to Figures 14A to 141, there is illustrated the method for repairing or reinforcing a net located underwater using the described apparatus. Net 710 includes intact segments 700 and damaged segments 705. The damaged segments 705 are severed, tom or frayed and will generally form a hole in net 710 that requires repair to reinstate the integrity of the net to ensure it can fulfil its purpose.

[0078] As shown in Figure 14A, an apparatus is provided to attend to the net repair. Only head end 105 or forward orientated end of the apparatus 100 is shown in this series of Figures 14A to 14I. Apparatus 100 is configured to guide pair of arms 180A and 180B to catch an intact net segment 700 that is adjacent to a damaged net segment 705 generally between the arms.

[0079] Referring now to Figure 14B, stitching line 125 is fed towards jaw region 185 situated between arms 180A and 180B. Stitching line 125 is fed in and out via guide tube 120. The stitching line pushing and retracting function is provided by the winch 140 and retractable reel 145 arrangement previously described by reference to Figures 8A, 8B, 9, 10A and 10B.

[0080] Referring now to Figures 14C and 14D stitching device 130 is shown connecting stitching line 125 to a first intact segment 700 of the net to be repaired using staple 175. This crimping action was described in detail by reference to Figures 6A to 6E.Rectified SheetISA / AU ( Rule 91)

[0081] Referring now to Figure 14E there is shown additional stitching line 125 being fed out from guide tube 120 once the stitching line is connected to the first intact segment 700 of the net. It can also be seen that apparatus 100, or rather ROV 200 on which apparatus is mounted (see Figures 2 and 3) is manoeuvred from a first position on one side of the hole formed in the net to be repaired, towards a second position on an opposite or distal side of the hole formed in the net to be repaired. Additional stitching line 125 is fed out during this relocation of apparatus 100 towards a second intact segment of the net 710 that is situated on the distal side of the hole.

[0082] In Figure 14F, forward facing arms 180A and 180B catch a second intact segment of net 710 that is situated on the distal side of the hole. Winch 140 and retractable reel 145 (see Figures 1A, 1 B and 1 C) are actuated to tighten the stitching line 125, thereby removing the slack in the line that is shown in Figure 14F. Once the slack is removed as shown in Figure 14G using the previously described retraction function, stitching line 125 is connected to the second intact segment of the net using a staple 175 applied by stitching device 130, as previously described. Stitching line 25 is severed using cutting device 135 (shown in Figures 5A and 5B) and whose function is described by reference to Figures 7A and 7B.

[0083] Once stitching line 125 is secured at two or more points along the stitching line as shown in Figure 14H, the steps described by reference to Figures 14A to 14H are repeated as many times as required to securely repair the hole in the net.Referring now to Figure 141 there is shown a simple net repair made using apparatus 100.

[0084] The apparatus of the present invention provides a number of advantages over conventional and manual methods of repairing and / or reinforcing subsea nets. Providing an apparatus that can be mounted on an observational class ROV makes the net repair apparatus relatively quick and easy to deploy, thereby minimising times from notification that a net repair is required and attending to the repair, as well as minimising costs. The reduction in time to completion of critical net repairs greatly improves outcomes for aquaculture installations, by reducing both fish escape and impact of predators on stock levels. Ultimately this leads to improved financial returns for operators. Furthermore, by reducing reliance on divers, OH&S risks are minimisedRectified SheetISA / AU ( Rule 91)considerably in what is an inherently hostile operating environment. Costs and response times are accordingly reduced.

[0085] Where any or all of the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims), they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components.

[0086] While the invention has been described in conjunction with a limited number of embodiments, it will be appreciated by those skilled in the art that many alternative, modifications and variations in light of the foregoing description are possible. Accordingly, the present invention is intended to embrace all such alternative, modifications and variations as may fall within the spirit and scope of the invention as disclosed.

Claims

The claims defining the invention are as follows:1 . An apparatus for subsea repair or reinforcement of nets, each net having a plurality of net segments, the apparatus including: a holder for catching a segment of the net; a guide tube for feeding a stitching line towards the holder, the stitching line being retractably fed in and out of the guide tube; a stitching device that connects the stitching line to a first segment of the net and to a second segment of the net; a cutting device for severing the stitching line; and a control module; wherein the control module actuates the stitching device to connect the stitching line to the first segment of the net, retractably feed out additional stitching line whilst the holder is relocated towards the second segment of the net, and tighten the stitching line before connecting the stitching line to the second segment of the net.

2. The apparatus according to claim 1 , wherein the holder includes a pair of guiding arms for catching the segment of the net therebetween.

3. The apparatus according to claim 2, wherein each of the pair of guiding arms has an end proximal to a body of the apparatus and another end distal to the body of the apparatus and the pair of guiding arms are configured such that their distal ends splay outwards.

4. The apparatus according to claim 2 or 3, wherein the holder further includes a jaw region situated between the pair of guiding arms and the guide tube feeds the stitching line towards the jaw region.

5. The apparatus according to any one of claims 1 to 4, wherein the stitching device is positioned adjacent to the jaw region.The apparatus according to any one of claims 1 to 5, further including a staple dispenser and wherein the stitching device uses staples to connect the stitching line to segments of the net. The apparatus according to claim 6, wherein the staples are loaded into the staple dispenser via a staple storage and feed rail. The apparatus according to any one of claims 4 to 7, wherein the jaw region is configured to catch the stitching line and the net segment in its grasp such that the stitching device is positioned to dispense and crimp a staple to connect the stitching line and net segment together. The apparatus according to any one of claims 1 to 8, wherein a winch and a retractable reel cooperate to retractably feed the stitching line in and out of the guide tube. The apparatus according to claim 9, wherein the retractable reel includes a biasing member to cause stitching line that is winched back in to be fed back onto the reel. The apparatus according to claim 10, wherein the biasing member is a torsion spring. The apparatus according to claim 10 or 11 , wherein the biasing member and retractable reel are coupled by a magnetic clutch. The apparatus according to any one of claims 1 to 12, wherein the stitching line is retractably fed in and out of the guide tube using sufficient force to tension the stitching line so as to provide a repair or reinforcement with a design specified tension specific to the type of net undergoing repair or reinforcement. The apparatus according to any one of claims 9 to 13, wherein the winch includes a motor coupled to a compact gearbox to drive a capstan located inside a winch housing. The apparatus according to claim 14, wherein an internal surface of the winch housing has a fixed helical channel to guide the stitching line.The apparatus according to any one of claims 1 to 15, the net being located underwater and having intact segments and damaged segments, the damaged segments forming a hole in the net that requires repair, wherein the stitching device connects the stitching line to a first intact segment of the net that is adjacent to a damaged segment of the net, and after retractably feeding out stitching line and relocating the holder to a second intact segment of the net that is situated on the distal side of the hole, tightening the stitching line before connecting the stitching repair line to the second intact segment of the net. The apparatus according to any one of claims 1 to 16, wherein the apparatus is configured to be mounted on a vehicle or a mechanical arm that is operable underwater. A method for repair or reinforcement of a net, the net having a plurality of net segments, the method including the following steps: providing an apparatus configured to: catching a segment of the net between a pair of guiding arms; feeding a stitching line towards a jaw region situated between the guiding arms, the stitching line being fed in and out of a guide tube by a retractable reel; connecting the stitching line to a first segment of the net; feeding out additional stitching line whilst the guiding arms are relocated towards a second segment of the net; operating a retractable reel to tighten the stitching line; connecting the stitching line to the second segment of the net; repeating the steps as many times as required to securely repair or reinforce the net; and severing the stitching line once the repair or reinforcement is complete.21 The method according to claim 18, wherein the stitching device dispenses a staple and connects the stitching line to segments of the net by crimping the staple to connect the stitching line and segments of the net. The apparatus according to claim 19, wherein the staples are fed into the staple dispenser via a staple storage and feed rail. The apparatus according to any one of claims 18 to 20, wherein the stitching line is retractably fed into and out of the guide tube. The apparatus according to claim 21 , wherein tension is maintained on the stitching line by feeding stitching line that is winched back onto a biased reel. The apparatus according to claim 22, wherein the tension on the stitching line is specified so as to provide the repair with a design specified tension specific to the type of net undergoing repair or reinforcement. A non-transitory computer readable medium storing instructions for repairing or reinforcing a net, the net being located underwater and having a plurality of segments, that when executed by a processor cause it to perform the following steps: guide a pair of guiding arms for catching a segment of the net therebetween; feed a stitching line towards a jaw region situated between the guiding arms, the stitching line being fed in and out of a guide tube by a retractable reel; connect the stitching line to a first segment of the net to be repaired; feed out additional stitching line whilst the guiding arms are relocated towards a second segment of the net; operate a retractable reel to tighten the stitching line; connect the stitching line to a second segment of the net;22 repeat the steps as many times as required to securely repair or reinforce the net; and severe the stitching line once the repair or reinforcement is complete.

Images