INSPECTION AND/OR MAINTENANCE METHOD AND ASSOCIATED APPARATUS

Abstract

An isolation method, and apparatus, for isolating and temporarily sealing closed an opening of a marine vessel to prevent ingress of fluid into or through the opening, sealing an internal side of the opening from an external side of the opening. A positioning line is provided between a connection point and the sealing apparatus, with the positioning line being tensioned to pull the sealing apparatus towards the opening. The method is performed entirely diverlessly, with no personnel required in or under the water at any stage of the method, including during connecting the positioning line to the connection point and pulling the sealing apparatus onto and/or into the opening.

Claims

1. An isolation method for isolating and temporarily sealing closed an opening of a marine vessel to prevent ingress of fluid into or through the opening, sealing an internal side of the opening from an external side of the opening, the isolation method comprising sealing the opening with a sealing apparatus, wherein the method comprises: connecting the sealing apparatus to at least one connection point associated with the opening of the marine vessel, the connection point being used to connect a positioning line relative to the opening; providing the positioning line between the connection point and the sealing apparatus; tensioning the positioning line such that the sealing apparatus is pulled towards the connection point to maneuver the sealing apparatus into a desired position relative to the opening; and sealing closed the opening with the sealing apparatus; wherein the method is performed entirely diverlessly, with no personnel required in or under the water at any stage of the method, including connecting the positioning line relative to the connection point and pulling the sealing apparatus onto and/or into the opening.

2. The method of claim 1, wherein the opening is an aperture in or through the hull of the marine vessel; and the marine vessel comprises at least one of: a ship; a Floating Offshore Installation (FOI); a wholly or partially submersible structure; a Floating Production, Storage and Offloading unit (FPSO); a Mobile Offshore Drilling Unit; or an Accommodation Vessel.

3. The method of claim 1, wherein the method comprises further tensioning the positioning line so as to pull the sealing apparatus onto or into the opening to provide the closed seal.

4. The method of claim 1, wherein the method comprises tensioning the positioning line using a line tensioner located at or on the sealing apparatus, the line tensioner comprising one or more of: a winch, a powered pulley, a reel, and a motor; and the method comprises controlling the positioning of the sealing apparatus remotely, from surface.

5. The method of claim 1, wherein the method comprises releasably mechanically attaching the positioning line to the connection point, the connection point being at or proximal to the opening and effectively defining an anchor point for the positioning line, once attached; and cleaning the opening with a diverless operation before the positioning line is attached.

6. The method of claim 1, wherein the method comprises providing a plurality of positioning lines between a plurality of connection points associated with a single opening; and the sealing apparatus comprises a plurality of line tensioners in the form of a plurality of winches; and the method comprises tensioning each positioning line with a respective winch associated with each positioning line; and tensioning each of the plurality of positioning lines to a similar tension.

7. The method of claim 1, wherein the method comprises providing an interim attachment of the sealing apparatus mechanically with the tensioning of a line tensioner; and providing a final attachment of the sealing apparatus by creation of a hydrostatic pressure differential by draining fluid from one side of the sealing apparatus.

8. The method of claim 1, wherein the sealing apparatus comprises one or more sensors; and the method comprises tensioning the positioning line to a tension of at least 100 kg.

9. (canceled)

10. The method of claim 1, wherein the method comprises maintaining tension in the positioning line so as to maintain the seal closed; and locking the positioning line to mitigate against a power failure or interruption; the method comprising activating a lock in advance of and/or in response to a power failure or interruption.

11. (canceled)

12. The method of claim 1, wherein the method comprises releasing the sealing apparatus and removing the sealing apparatus from the opening after completion of an operation/inspection; the method comprising releasing the positioning line by releasing a connection associated with an end of the positioning line at the connection point; and loosening the positioning line; wherein the releasing is performed before or after the loosening.

13. The method of claim 1, wherein the method comprises transporting the sealing apparatus through a body of water by lowering the sealing apparatus from at or near surface, at least partially under gravity with a sufficiently negatively buoyant sealing apparatus suspended from a support line so as to maintain a tension in the support line; and the method comprises controlling the position of the sealing apparatus by monitoring and controlling a payout length of the support line, progressively paying out a sufficient length of the support line so as to allow the sealing apparatus to descend to a depth corresponding approximately to a depth of the opening.

14. The method of claim 1, wherein the method comprises attaching the positioning line to the connection point using a Remotely Operated Vehicle (ROV); attaching the ROV to the sealing apparatus; and the method further comprises using the ROV to position the sealing apparatus at a correct depth corresponding to that of the opening.

15. (canceled)

16. The method of claim 14, wherein the method comprises transporting and positioning the sealing apparatus using a combination of general lowering under suspension without a ROV and then fine positioning with the ROV connected to the sealing apparatus; and only mechanically connecting the ROV to the sealing apparatus, without electrical or optical connections.

17. (canceled)

18. The method of claim 14, wherein the method comprises remotely controlling a line tensioner and/or the ROV to remotely control the sealing apparatus and/or attachment of connector/s of the positioning line and/or a release mechanism.

19. The method of claim 14, wherein the method comprises sequentially: positioning the sealing apparatus with the ROV; attaching the sealing apparatus to the opening; disconnecting the ROV from the sealing apparatus; performing operations with the sealing apparatus attached to the opening; opening the opening with the ROV; and reconnecting the ROV to the sealing apparatus.

20. The method of claim 14, wherein the method comprises isolating a plurality of sea chests sequentially with a single ROV.

21. The method of claim 1, wherein the method comprises sealing over the opening by sealing against one or more surface/s around the opening, forming a seal around the opening; and/or the method comprises sealing in or within the opening by inserting at least a portion of the sealing apparatus into the opening.

22. (canceled)

23. A sealing apparatus for performing the method of claim 1, the sealing apparatus comprising: a sealing portion for sealingly engaging the opening, with the sealing apparatus being configured to attach to a hull, at or near the opening in the hull; and a plurality of line tensioners, the line tensioners being configured to tension a plurality of positioning lines to pull the sealing apparatus onto and/or into the opening.

24. The sealing apparatus of claim 23, wherein the sealing apparatus comprises a blanking plate with a plurality of winches mounted thereto, the winches each comprising a respective positioning line for attaching the blanking plate to and/or in the opening; and the apparatus comprises a quick release connector at the opposite end of each positioning line from the respective winch.

25. The sealing apparatus of claim 23, wherein the sealing apparatus comprises: an engagement member for engagement with or by a ROV engagement member, the sealing apparatus engagement member being configured to allow gripping and/or manipulation of the sealing apparatus by the ROV; and a valve; wherein the sealing apparatus is powered and controlled with power and control lines running via an umbilical/s to surface.

26. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:

[0080] FIG. 1 shows a schematic diagram of a method according to a first example;

[0081] FIGS. 2(a) to 2(c) show a depiction of cleaning an opening in the hull of a marine vessel;

[0082] FIGS. 3(a) to 3(c) show a depiction of attaching positioning lines to the hull of a marine vessel;

[0083] FIGS. 4(a) to 4(c) show a depiction of lowering an isolation apparatus with the positioning lines attached thereto in order to seal an opening in the hull of a marine vessel;

[0084] FIGS. 5(a) to 5(c) show a depiction of using the isolation apparatus to seal the opening in the marine vessel;

[0085] FIGS. 5(d) to 5(f) show a depiction of lowering the isolation apparatus to allow shortened lengths of positioning lines to be used to attach the isolation apparatus over the opening in the marine vessel;

[0086] FIGS. 6(a) and 6(b) show a front and rear view of an isolation apparatus;

[0087] FIG. 6(c) shows a side view of a mini-winch located towards a corner of the isolation apparatus of FIG. 6(a);

[0088] FIG. 6(d) shows a cross-sectional view A-A from FIG. 6(b), illustrating two of the winches with respective positioning lines.

[0089] FIG. 7 shows a depiction of the isolation apparatus of FIG. 6 suspended above sea level from a winch on a marine vessel;

[0090] FIGS. 8(a) and (b) show a depiction of lowering the isolation apparatus of FIG. 6 from above sea-level, to an opening in the hull of a marine vessel;

[0091] FIG. 8(c) shows a depiction of an isolation apparatus of FIG. 6 whilst being attached to an opening;

[0092] FIG. 9 shows an arrangement wherein multiple isolation apparatuses are attached to multiple openings;

[0093] FIG. 10 shows an example of a connector with quick release mechanism, for attaching each positioning line at or near the openingas shown sequentially in FIGS. 10a through 10e; and

[0094] FIG. 11 shows another example of an isolation apparatus, with FIG. 11a showing the (dummy, practice) opening with the positioning lines; and then FIGS. 11(b) through 11(f) depicting the isolation apparatus being sealingly pulled onto the opening; and FIGS. 11g through 111 show a release of the isolation apparatus using quick release mechanisms associated with connectors.

DETAILED DESCRIPTION

[0095] Referring first to FIG. 1, there is shown a general method 2 of isolating an opening according to the present disclosure. The method comprises a step 2 of attaching one or more positioning line(s), which are connected or connectable to an isolation apparatus, at or near the opening in the hull of a marine vessel. The method then comprises positioning 6 the isolation apparatus such that it covers the opening. Optionally, the method involves cleaning 8 the opening prior to positioning the isolation apparatus. As shown, the cleaning 8 may even occur prior to attaching the positioning lines(s) at or near said opening.

[0096] In at least some examples, the opening comprises an inlet and/or outlet of a sea chest, with the method comprising inspection of a sea chest or devices associated with sea chests, such as intake valves or the like. Conventional sea chest inspections are however dangerous for divers and limited in scope, as well as being expensive and difficult to carry out in bad weather. Accordingly, the present disclosure here relates to diverless 9 methods, including those disclosed in WO/2020/161479, the contents of which are incorporated herein by reference. Accordingly it may be an object of at least some examples of this disclosure to inspect and/or maintain/service a hull opening (e.g. to repair or replace sea chest isolation valves) without divers. Benefits can include one or more of: Enhanced Safety; Reduced Cost; Reduced POB; Improved Budget Certainty (e.g. lower weather dependency).

[0097] FIGS. 2 to 5 depict steps according to a method in accordance with an embodiment of the present invention. A marine vessel 10 comprising an opening 12 to a sea chest in the hull 14 of the vessel 10 is shown. The steps of the exemplary method may be sequential or non-sequential.

[0098] Referring now to FIG. 2, FIG. 2(a) shows an example of cleaning 8 an opening 12 in a sea chest in the hull 14 of the marine vessel 10. An ROV 16 equipped with an attachment 18 suitable for cleaning, e.g. a cavitation blaster, approaches an opening 12 in a hull 14 of a marine vessel 10. The ROV 16 is directed to clean the opening 12 and surrounding surfaces, including coamings, gratings and the like. Cleaning 8 the opening 12 and surrounding areas enables an improved seal between an isolation apparatus and the opening 12. The ROV 16 may comprise a camera (not shown) wherein an operator can inspect the cleaning 8.

[0099] As shown in FIGS. 2(b) and 2(c), the positioning line(s) 11 are lowered from a winch 13 on the surface of the marine vessel 10 into the water column. Generally, positioning lines 11 are elongate members, for example, wire, cable or rope. Embodiments of the present invention may comprise one or more positioning line 11. Normally, more than one positioning line 11 is present, and preferably there is a positioning line 11 suitable for attaching to each corner of an isolation apparatus. Accordingly the plurality of positioning lines can be used to orientate the isolation apparatus 20 correctly. The positioning lines 11 are lowered using a winch 13 located on a surface of the vessel 10 to a pre-determined position in the water column, approximately the same depth as the opening 12 in the hull 14 of the marine vessel 10. The winch 13 may be a powered winch. In alternative embodiments, positioning lines 11 may not be lowered by a winch 13. For example, the positioning lines 11 may be lowered into the water column by manually being fed out from the surface of the marine vessel 10 by an operator.

[0100] As shown in FIG. 3(a), the ROV 16 can be used to position and attach the lower end of the positioning line 11 to the hull 14. For example, the ROV 16 may grip the end of the positioning lines 11 using a gripper 15. The ROV can then be directed to attach the positioning lines 11 around the periphery of the opening 12 in the hull 14. Other means to connect the positioning lines 11, such as with the ROV, would be apparent to those skilled in the art. As previously mentioned, the steps of the method depicted in FIGS. 2 to 5 are not necessarily sequential, and the positioning lines 11 may be connected to the ROV 16 for example, at or near the sea surface, or on the surface of the marine vessel 10 before being lowered to the approximate depth of the opening 12. As shown here, the positioning lines 11 are attached using quick release connectors, such as illustrated in FIG. 10. In other examples, the positioning lines may be attached to the hull 14 using a magnet, which is attracted to the metallic surface of the hull 14. Other means of attaching the lines 11 to the hull 14 are possible. For example, the positioning lines 11 may be attached to the hull 14 by engaging with lugs (not shown) in/on the hull. Once the positioning lines 11 are positioned and attached to the hull 14, the ROV can release its grip of the positioning lines 11.

[0101] Referring now to FIGS. 4(a) to 4(c), there is shown the isolation apparatus 20, in the form of a blanking plate, suspended from the winch 13. The isolation apparatus 20 is suspended using a support line 19 to suspend from the deck/surface (e.g. the winch 13). The isolation apparatus 20 is lowered subsea with the corners of the isolation apparatus 20 attached to the opposite ends of the respective positioning lines 11 from the ends connected at or near the opening 12. It will be appreciated that the apparatus 20 may be lowered under gravity, utilising its slightly negative buoyancy. For example, the support line 19 may be paid out to a length corresponding approximately to the depth of the opening 12. Additionally, or alternatively, the positioning lines 11 may be actively tensioned (e.g. to pull the isolation apparatus 20 downwards towards the correct depth). The positioning lines 11 may provide an advantage of restricting the movement of the apparatus 20 subsea, and also guiding the apparatus 20 to the desired depth subsea, which is approximately the depth corresponding to the opening in the hull, as shown in FIG. 4(c).

[0102] Once the isolation apparatus 20 has been lowered to the appropriate depth, the positioning lines 11 are tensioned (further). Although not visible in FIG. 4, in the example shown each positioning line 11 is tensioned by its own respective winch, or mini-winch. Here, each positioning line 11 is associated with a respective mini-winch located on the isolation apparatus 20 itself. By tensioning the positioning lines 11, the apparatus 20 is aligned with the opening 12. The ROV 16 may be present during the lowering operation and may comprise, for example, a camera (not shown) such that an operator, for example at surface (e.g. on deck of vessel 10), may observe the alignment of the isolation apparatus 20. In embodiments, the isolation apparatus may comprise a camera such that the positioning of the apparatus 20 can be observed. The alignment of the apparatus 20 with the opening 12 may be controlled using feedback from any of the aforementioned cameras. Additionally, or alternatively, one or more sensors, such as tension sensors may be provided.

[0103] When the isolation apparatus 20 is in the preferred position over the opening 12, the positioning lines 11 can be tensioned further, resulting in the isolation apparatus 20 being pulled onto the opening 12. forming a seal over the opening 12. In the example shown here, each individual mini-winch on the isolation apparatus 20 is individually controllable, such that each positioning line 11 is individually controllable.

[0104] The positioning line/s 11 may be tensioned to a particular tension, such as a predefined minimum tension. For example, the/each positioning line may be tensioned to a tension of at least 100 kg. The level of tension may be adjusted or selected in advance of and/or during deployment. For example, a minimum tension of at least 250 kg for each positioning line may be selected for a particular isolation apparatus 20, such as a blanking plate of a particular size, shape or mass.

[0105] In at least some embodiments, multiple (e.g. all of the) positioning lines 11 that are present can be tensioned simultaneously. This may be achieved by coordinated and/or synchronous operation of the respective mini-winches associated with each positioning line 11. This may be advantageous if the isolation apparatus is in the preferred position for sealing the opening 12. In other embodiments, individual positioning lines 11 can be tensioned independently from the remaining positioning lines 11. This may be advantageous in situations where the isolation apparatus 20 is not immediately aligned in the preferred position for sealing the opening 12 and so further adjustment of the alignment of the positioning lines 11 may be required. In the example shown here, initial operation of the mini-winches is synchronous such that all positioning lines 11 are tensioned during initial phases of tensioning, such as shown in FIG. 4. Thereafter, operation of each mini-winch can be independent and/or asynchronous during final phases of tensioning, for positioning the isolation apparatus 20, such as shown in FIGS. 5a and 5b. With the positioning line/s 11 fully tensioned, to a predetermined and/or satisfactory tension (e.g. as verified by one or more sensor/s and/or observation, such as via a camera), the isolation apparatus 20 is attached in at least an interim attachment. It will be appreciated that in other examples than that shown, a single line tensioner, such as a single winch mounted on the isolation apparatus 20, may tension multiple positioning lines 11. For example, a single mini-winch may be controlled to tension multiple positioning lines 11 of a similar or identical length. Accordingly, a single winch can be used to spool in a similar length of each positioning line, such as to ensure a similar shortening and tensioning of each positioning line such that the isolation apparatus 20 is positioned correctly at or over the opening 12 using a reduced number of winches (even merely a single winch).

[0106] It will be appreciated that the isolation apparatus 20 can be positioned with other arrangements or configurations of positioning line/s. For example, in FIGS. 5d, 5e and 5f is shown sequentially an alternative interim attachment process to that shown in FIG. 2b through to FIG. 5c. Here, the starting lengths of the multiple individual positioning lines 11 as shown in FIG. 5d is considerably shorter than those shown in FIG. 2b. In the transition from FIG. 5d to FIG. 5e, the ROV 16 is used to attach the positioning lines 11 in a process similar to that shown sequentially from FIG. 3a through to FIG. 3c.

[0107] In the examples shown here, the integrity of the seal of the isolation apparatus 20 over the opening 12 can be achieved or increased by utilising a pressure differential across the isolation apparatus 20. For example, by reducing pressure within the hull 14, for example by draining the sea chest (e.g. with pumps internal to the marine vessel), such as shown in FIG. 5c, the isolation apparatus 20 may be pulled onto the opening 12. Accordingly, the blanking plate is pressed tightly onto the opening 12, with the hydrostatic pressure of the body of water forcing the isolation apparatus 20 against the perimeter of the drained opening 12. It will be appreciated that the isolation apparatus 20 may comprise a valve to at least assist in managing a pressure differential across the isolation apparatus 20.

[0108] In at least some embodiments, the isolation apparatus 20 comprises one or more mechanical locks which can mitigate the positioning lines 11 loosening, such as to prevent or at least impede the positioning lines 11 from slipping or moving during tensioning and/or once the isolation apparatus is in the preferred position (e.g. due to mitigate against a loss of power if using a powered mini-winch). An advantage of these embodiments may be that the isolation apparatus 20 is not inadvertently moved resulting in the seal it forms with the opening 12 being released. In embodiments having both a mechanical winch lock and tensioned positioning lines 11, the isolation apparatus 20 may be maintained in its position if there is a leak or pressurisation in the sea chest. The mechanical lock may be remotely operable. Additionally, or alternatively, the mechanical lock may be automatic. In at last some examples, the mechanical lock comprises a ratchet mechanism, the ratchet allowing tensioning of the positioning line (e.g. by allowing the mini-winch to pull in the positioning line), whilst preventing loosening of the positioning line.

[0109] With the blanking plate so secured to sealingly block the opening 12, operations can be performed within the sea chest. Upon completion of the necessary operations, when it is desired to remove the isolation apparatus 20, the apparatus 20 can be released by reducing the tension of the positioning lines 11, and/or by increasing the hydrostatic pressure in the hull 14, for example, by pumping sea water into the sea chest using a pump (not shown). With the removal of a pressure differential across the isolation apparatus 20, the isolation apparatus is only loosely held against the opening 12. The surface winch 13 and/or the ROV can be operated to mechanically pull the isolation apparatus 20 away from the opening 12. It will be appreciated that the apparatus 20 can be returned to its starting position and may be reused to seal other openings in the hull 14. It will also be appreciated that the isolation apparatus may be re-used to seal another (or re-seal the same) opening in the hull, without returning the isolation apparatus 20 to surface.

[0110] As shown here, the isolation apparatus comprises a remotely-controlled valve. The remotely-controlled valve is effectively a bleed valve, allowing balancing of a pressure differential across the isolation apparatus 20 when it is desired to release or remove the isolation apparatus 20 from the opening 12.

[0111] In at least some embodiments, the isolation apparatus 20 may be provided with a release mechanism for removing the apparatus 20 from the opening 12. In at least some examples, the release mechanism can enable release and removal of the isolation apparatus 20 from the opening 20 without the need to re-pressurise the hull 14 and/or reduce the tension of the positioning lines 11. An advantage of these embodiments can that the apparatus 20 may be removed quicker than with the aforementioned removal techniques. Similarly, such release mechanisms can facilitate the use of automatic mechanical locking mechanisms (e.g. ratchets) since release can be achieved without re-extending the length of the positioning line/s between the mini-winch/es and the attachment point/s. Additionally, or alternatively, the release mechanism may enable release and optionally removal of the isolation apparatus 20 from the opening 12 In the embodiment shown, the release mechanism is a quick release mechanism in the form of a three-ring release system, roughly similar to that used by in skydiving parachutes. The release mechanism may be provided on one, or where more than one positioning line 11 is used, on multiple or all positioning lines 11. As shown here, each positioning line 11 is provided with a quick release mechanism, such as those shown in FIG. 10. The release of the apparatus 20 could be activated by an operator on the surface of the vessel 10, such as by activating or even directly pulling, on one or more quick release lines. In other embodiments, the release mechanism can be activated using an ROV 16. In use, the release mechanism is a quick release mechanism, activated by pulling on a release member. The tension required to pull the release member is significantly less than the tension supported by the three-ring system for the positioning line.

[0112] Referring now to FIGS. 6(a) and (b), there is shown an isolation apparatus 20 in the form of a blanking plate in accordance with an embodiment of the present invention. Blanking plates are known in the art and any conventional blanking plate can be used in embodiments of the present invention. FIG. 6(a) depicts a face of the apparatus 20. It will be appreciated that the view shown in FIG. 6a is schematic, with the seal 58 generally not visible through the back of the blanking plate 20. It will also be appreciated that the entire central portion of the blanking plate 20 is continuous, to provide a continuous barrier within the bounds of the peripheral seal 58. Each of the four mini-winches 60 of the blanking plate 20 are powered and controlled with power and control lines running via umbilicals to surface from a junction connector 61. In other embodiments it will be appreciated that other power and/or control arrangements may be provided. For example, local power source/s may be provided, such as a battery/cell on the blanking plate 20 as such and/or an associate ROV 16 or the like. Likewise, control may be without requiring umbilical, such as with wireless and/or autonomous or semi-autonomous control. FIG. 6(b) shows the opposing face of the blanking plate 20, which is able to engage with a surface of the hull 14 to form a seal over the opening 12 (not shown in FIG. 6b). FIG. 6(c) shows an enlarged view of a cross-section of the blanking plate 20, shown in use, sealingly attached to a coaming 56 associated with the opening 12. FIG. 6c also shows a side view of one of the four mini-winches 60 located towards each of the four corners of the blanking plate 20. As shown in FIG. 6c, the positioning line 11 is tensioned between the mini-winch 60 and a connection point associated with the opening-being a lug 70 as shown here. In this example, the blanking plate 20 also comprises guide members 62 for guiding the positioning lines between the winches 60 and the connection points, thereby mitigating the positioning lines undesirably rubbing against an edge of the blanking plate, or otherwise becoming entangled or misdirected. In the example shown here, the blanking plate 20 comprises a neoprene seal 58 for sealing directly against the coaming 56. FIG. 6d shows cross-sectional view A-A, illustrating two of the winches 60 with respective positioning lines 11. It will be appreciated that the blanking plate's seal 58 provides a continuous encircling seal around an entire periphery of the opening 12.

[0113] Turning now to FIG. 7, which shows a view of vessel 10 and surface winch 13, with the isolation apparatus 20 suspended from the winch 13 above sea-level 17 by a support line 19. Positioning lines 11 are shown connected to the apparatus 20 and the lines 11 extend below sea-level 17 to a depth of the opening 12 in the hull 14 of the vessel 10. The positioning lines 11 have already been attached to the hull 14 using means such as those illustrated in FIG. 10 or 11. FIG. 7 also shows an enlarged view of the blanking plate 20, as discussed with reference to FIG. 6.

[0114] FIGS. 8(a) and (b) depict the apparatus 20 as it is lowered from the winch 13 along positioning lines 11 through the water column to the desired position of FIG. 8b, with the blanking plate 20 over the opening 12 in the hull 14.

[0115] FIG. 8(c) shows an enlarged view of the isolation apparatus 20 ready for tensioning to pull over one of four openings 12. Positioning lines 11 are arranged such that there is a positioning line attached to each corner of the apparatus 20. The opposing end of each positioning line 11 is attached to the hull 14 around the periphery of a selected opening 12. FIG. 8(c) shows the positioning line 11 attached at the corresponding corner of the opening 12 to the isolation apparatus 20. It should be appreciated that the positioning line 11 may be attached around the periphery of the opening 12 at additional or alternative locations.

[0116] In at least some embodiments; and as explicitly shown in FIG. 8(c), the isolation apparatus 20 comprises a support line(s) 19. The support line(s) 19 assist in supporting the weight of the apparatus 20 whilst suspended from the surface winch and also as the apparatus is lowered through the water column. The number of support line(s) 19 used can vary according to various factors: for example, the size of the isolation apparatus 20, its weight and other like factors, the shape of the hull, the presence or otherwise of a ROV for assisting with interim attachment.

[0117] It will be appreciated that selected ones of the aforementioned processes can be replicated or duplicated as appropriate for additional openings or additional sea chests. For example, FIG. 9 depicts an embodiment where a hull 14 has multiple openings 12, and an isolation apparatus 20 is deployed over each respective opening 12. It will also be appreciated than it at least some examples, the seal may be achieved by pulling a seal, such as a cylindrical plug into the opening-using the same positioning lines as shown, with the plug portion of the isolation apparatus 20 extending into the opening; or using one or more positioning lines located within the opening 12.

[0118] Referring now to FIG. 10, there is shown an example of a connector 80 with quick release mechanism 90, for attaching each positioning line 11 at or near the opening 12. The connector 80 is supported on a connection tool 82 with a hoop, supporting a loop 84 of the positioning line 11. The hoop is placed in position, shown in FIG. 10a around a lug 70 associated with a coaming of a sea chest opening 12. It will be appreciated that each of the four positioning lines 11 shown in earlier figures has a respective tool 82 associated with it, for attaching to respective lugs corresponding to each positioning line 11. As shown in the transition between FIGS. 10a and 10b, the tool 82 is the activated to release the loop 84. The loop 84 is under tension such that the loop 84 instantly tightens around the lug 70, as shown in FIG. 10c. The tool 80 can then be removed (either actively or passively, such as allowed to hang loosely). With the positioning line 11 attached as shown in FIGS. 10c and 10d, the isolation apparatus 20 can be pulled on to the opening 12 by tensioning the positioning line 11, with the loops 84 of positioning lines 11 around the lugs 70 providing anchor points for the isolation apparatus 20 relative to the opening 12, as also illustrated in FIG. 10e. After completion of the operation, or whenever it is desired to release and/or remove the isolation apparatus 20, a quick release member 86 of each connector 80 can be activated. The quick release member 86 is a longitudinal member which can typically be pulled-remotely via a release line/s from surface and/or locally such as using the ROV 16. With the quick release member 86 activated, the three-ring mechanism is released using minimal tension in the positioning line 11, such that the positioning line is released from the lug 70, as shown in FIGS. 11j, 11k, and 11l.

[0119] FIG. 11 shows an example of an isolation apparatus in the form a remotely-powered blanking plate 120. The plate 120 has four mini-winches 160 located at each corner of the blanking plate 120. Here a dummy opening 112 is used in a practice setting, but it will be appreciated that a similar apparatus and method is applicable to an opening in a vessel hull. Positioning lines 111 are connected directly between drums 162 of the mini-winches 160 and the lugs 70 associated with the opening 112. In the example shown, the mini-winches 160 are powered and controlled from surface using umbilicals associated with the support line. It will be appreciated that the winches can be hydraulically and/or electrically powered or controlled. Accordingly, each mini-winch 160 and also a central bleed valve 150 can be remotely controlled, such as by an operator at surface.

[0120] As shown in FIG. 11a, the four positioning lines 111 have each been attached using a tool 82 and connector 80 as shown in FIG. 10 (here, with four tools 82 and four connectors 80). The positioning lines 111 are attached at their opposite ends to the winches 160, as shown in FIG. 11b. The winches 160 are activated to pull each of the positioning lines 111, thus reeling the blanking plate 120 towards the opening 112, as shown in the transition between FIGS. 11b and 11c. FIGS. 11d, 11e and 11f show the blanking plate 120 attached over the opening 112. Here, each positioning line is tensioned individually to around 250 kg, with the amount of portion of positioning line 111 between each mini-winch 160 and the associated lug 70 being visually controlled by a camera. For example, a lateral view in FIG. 11e shows a tight fit between the seal 158 of the blanking plate 120 and the corresponding surface around the opening 112. Here, once satisfactorily tensioned, the mini-winches 160 are mechanically locked in place, thereby preventing rotation of the winch drum. Accordingly, power is no longer needed to be supplied via the umbilicals to the blanking plate 120 in order to maintain tension in the positioning lines 111. Although not shown here, it will be appreciated that in use on an opening in a hull vessel, full sealing and effective activation of the blanking plate's double seals can be achieved by creating a pressure differential across the blanking plate 120. Typically this can be achieved using a pump within the vessel to drain the internal side of the blanking plate 120. Additionally, or alternatively, a pump can be associated with the blanking plate 120, such as with the blanking plate's valve 150, to extract fluid through the blanking plate 120 to drain the opening 112 there behind. The pump can be locally, such as on the blanking plate 120 as such; and/or remotely, such as connected via an umbilical line from surface to the blanking plate 120.

[0121] FIGS. 11g through 11l show a release of the blanking plate 120 using the quick release mechanisms 90 associated with the connectors 80. As shown in FIG. 11g, here a remotely-operated tool 98, such as operated using a ROV, pulls the quick release member 86, as shown in FIG. 11h. With the quick release member 86 shown fully extracted from the quick release mechanism 90 in FIG. 11i. Once all of the connectors 80 have been released, such as further illustrated in FIGS. 11j and 11k, the blanking plate 120 is fully released; and can be removed from the opening, as shown in FIG. 11l.

[0122] It will be appreciated that at least some of these processes may be at least computer-assisted. It will be appreciated that embodiments of the present invention can be realised in the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the present invention. Accordingly, embodiments provide a program comprising code for implementing a system or method as disclosed in any aspect, example, claim or embodiment of this disclosure, and a machine-readable storage storing such a program. Still further, embodiments of the present disclosure may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same.

[0123] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The applicant indicates that aspects of the present disclosure may consist of any such individual feature or combination of features. It should be understood that the embodiments described herein are merely exemplary and that various modifications may be made thereto without departing from the scope of the disclosure. For example, it will be appreciated that although shown here with generally square or circular shapes, other shapes of openings can also be isolated, such as by using a rectangular isolation apparatus to isolate a rectangular opening or a circular isolation apparatus to isolate a circular opening. It will be appreciated that the isolation apparatus may be customised or bespoke manufactured prior to deployment in order to fit one or more particular hulls or openings.

[0124] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0125] The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.

[0126] The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims.

[0127] The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. It should be understood that the embodiments described herein are merely exemplary and that various modifications may be made thereto without departing from the scope or spirit of the invention. For example, it will be appreciated that although shown here with winches at the at the first contact points of the positioning lines on the isolation apparatus, in other embodiments guides, pulleys, runners or the like may provide such first points of contactwith the winch, or other line tensioner, being located elsewhere, such as centrally on the isolation apparatus, or even remotely such as being tensioned by a ROV or a tensioner associated with a ROV or even a tensioner at surface.