TECHNICAL FIELD

The present invention relates to a method of inspecting and/or maintaining a marine vessel, particularly, but not exclusively, isolating an aperture associated with a hull thereof; and associated apparatus.

BACKGROUND

Marine vessels, such as ships, floating platforms, FPSOs and the like, often have apertures in their hulls, such as inlets/outlets. For example, water intakes, which may be for ballast, cooling, such as engine cooling, or for other processes on the vessel or associated with the vessel. The aperture is often in or through the hull in order to allow passage (e.g. of water) into and/or out of the vessel.

Floating offshore installations (FOIs) include oil drilling platforms and similar structures which are intended for permanent or semipermanent deployment at a fixed location in the sea. Like ships, FOIs and also other wholly or partially submersible structures are critically dependent for safe operation on the pressure integrity of their hull or outer shell. However, both ships and FOIs typically have many fluid penetrations of the hull below the waterline for intakes/outlets through which volumes of water can flow for engine cooling, ballasting, and other purposes via large diameter pipes and valve gear (i.e. valves and associated apparatus) within the hull. In ships, these pipes normally terminate in compartments known as seachests which form recesses in the hull with inlets thereto protected by gratings installed flush with the hull surface.

The interior surfaces of the seachests, other hull fluid penetrations and their connected pipework and valve gear where fitted define flooded cavities in fluid communication with the sea, so their interior (wetted) surfaces are protected where possible by specialised surface coatings to combat corrosion. Nevertheless, the walls of the pipework, seachests and other parts of these flooded cavities remain vulnerable to a range of failure conditions including corrosion, erosion or obstruction by particulates, mechanical failure of stressed or moving parts, and colonisation by marine organisms which can completely block pipework if allowed to proliferate.

Provided the region to be inspected is close to the exterior surface of the hull, visual inspection may be carried out by means of a diver. Means may be provided whereby a diver may more easily manipulate heavy gratings or other closures from outside the vessel, as taught for example by J P5O-155795U and JP50-155796U. The diver may then enter the seachest and visually inspect or photograph any valve gear which is visible through the suction and discharge openings.

It may be an object of one or more aspects, examples, embodiments, or claims of the present disclosure to at least mitigate or ameliorate one or more problems associated with the prior art.

SUMMARY

According to an aspect of the invention, there is provided an isolation method. The method may comprise a method of isolating an opening. Isolating the opening may comprise sealing the opening. Sealing the opening may comprise sealing the opening closed. Sealing the opening closed may comprise temporarily sealing the opening closed, such as for a performance of an inspection and/or maintenance and/or repair operation. Sealing the opening closed may comprise sealing the opening closed to prevent ingress of fluid, such as water, into or through the opening. Sealing the opening closed may comprise sealing the opening closed to seal an internal side of the opening from an external side of the opening.

The opening may comprise an aperture, such as an inlet (and/or outlet). The opening may be to a cavity, chamber, or compartment of a marine structure. The opening may comprise a blind opening, such as defined by an enclosed recess in a hull.

Alternatively, the opening may comprise a through-opening. For example the opening may be an aperture in or through the hull of the structure. The vessel may comprise a marine vessel, such as one or more of: a ship, FOI; wholly or partially submersible structure; Floating Production, Storage and Offloading unit (FPSO); Mobile Offshore Drilling Unit; or Accommodation Vessel. The opening may be to or of a sea chest. It will be appreciated that the inlet may comprise an outlet. For example, the inlet, aperture or opening, in the hull may be for a passage of fluid (e.g. of water) through the hull - such as out of and/or into the hull. The aperture may be for at least selectively providing for fluid communication between a first and a second side of the hull, such as an inside and an outside of the hull. Additionally, or alternatively, the aperture may be for access, such as for operational and/or inspection and/or repair processes. The method may comprise sealing the opening with an isolation apparatus. The isolation apparatus may comprise a sealing apparatus.

The method may comprise utilising at least one connection point. The connection point can be used to connect a positioning line relative to the opening. The connection point may be defined by a portion of the vessel. The method may comprise defining or providing the at least one connection point relative to the opening. In at least one example, the method may comprise providing the positioning line between the connection point and the isolation apparatus such that the isolation apparatus can be manoeuvred into a desired position relative to the opening.

The method may comprise providing the positioning line between the connection point and the isolation apparatus. The method may comprise tensioning the positioning line such that the isolation apparatus is pulled towards the connection point.

In at least one example, the method comprises providing the positioning line between the connection point and the isolation apparatus; then tensioning the positioning line so as to pull the isolation apparatus towards the connection point; and further tensioning the positioning line so as to pull the isolation apparatus to isolate the opening. The method may be performed entirely diverlessly, with no personnel required in or under the water at any stage of the method, including connecting the positioning line to the connection point and pulling the isolation apparatus onto and/or into the opening.

The method may comprise tensioning the positioning line using a line tensioner. The line tensioner may comprise one or more of: a winch, a powered pulley, a reel, a motor. The winch may comprise a min-winch, such as smaller winch relative to a surface winch or derrick, the surface winch or derrick being for lifting heavier loads onto or off the vessel. The method may comprise controlling the positioning of the isolation apparatus from surface. It will be appreciated that the positioning line tensioner may be located anywhere at or along the positioning line. For example, the positioning line tensioner may be located at the connection point. Additionally, or alternatively, the line tensioner may be located at or on the isolation apparatus. In at least some examples, the line tensioner may be located remotely from the isolation apparatus. For example, the isolation apparatus may be movably connected to or with the positioning line, such as via a pulley, guide or retainer. The method may comprise attaching the positioning line to the connection point. The method may comprise mechanically attaching the positioning line to the connection point. Additionally, or alternatively, the method may comprise magnetically attaching the positioning line to the connection point. The method may comprise releasably attaching the positioning line at or proximal to the opening. The connection point may effectively define an anchor point for the positioning line, once attached.

The method may comprise positioning the isolation apparatus over and/or in the opening using one or more positioning lines. The positioning line may provide guidance for the isolation apparatus to align the isolation apparatus with the opening. In at least some examples, the method comprises tensioning the positioning line. The method may comprise tensioning the positioning line/s to pull the isolation apparatus towards the opening. The method may comprise tensioning the positioning line/s to pull the isolation apparatus onto and/or against and/or into the opening. The method may comprise tensioning the positioning line/s to pull the isolation apparatus over and/or into the opening to seal the opening.

The method may comprise tensioning the positioning line/s with the winch/es. The method may comprise tensioning the positioning line/s with a winch to pull the isolation apparatus towards the opening. The method may comprise tensioning each positioning line with a respective winch associated with each positioning line. The method may comprise tensioning a plurality of positioning lines to a similar tension.

The attachment of the isolation apparatus with the line tensioner may comprise an interim attachment. For example, a mechanical attachment with the winch may comprise an interim attachment; and a creation of hydrostatic pressure differential, such as by draining fluid from one side of the isolation apparatus (e.g. in/from the opening) may comprise a final attachment.

The method may comprise the tensioning of (multiple) lines to pull the blanking plate against the hull. The method may comprise locating the winches on the blanking plate itself. Additionally or alternatively, pulleys are located on the blanking plate and the winch/es are located elsewhere (e.g. on ROV and/or on deck/vessel). The method may comprise the locating and attachment of the anchoring points for the tensioning lines; and/or the release of the blanking plate. Additionally, or alternatively, one or more sensors, such as tension sensors may be provided. The positioning line/s 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 100kg. The level of tension may be adjusted or selected in advance of and/or during deployment. For example, a minimum tension of at least 250kg for each positioning line may be selected for a particular isolation apparatus, such as a blanking plate of a particular size, shape, or mass. For example, the selected line tension may be around 50kg, around 100kg, around 150kg, around 250kg, around 400kg or at least around 500kg, depending on specific application.

The method may comprise sealing over the opening. For example, the method may comprise sealing against one or more surface/s around the opening. The method may comprise forming a seal around the opening, to Additionally, or alternatively, the method may comprise sealing in or within the opening. For example, the method may comprise inserting at least a portion of the isolation apparatus into the opening. The method may comprise forming a circumferential seal within the opening. The method may comprise plugging the opening. In at least some examples, the method may comprise both sealing around an exterior of the opening, such as on the hull around the opening; and within the opening, such as with a plug or bung. In at least some examples, the isolation apparatus may comprise one or more of: a seal, a cofferdam, a cover, a plug, a bung, a patch.

The method may comprise sealing within the passage. For example, the opening may comprise an opening into a defined passage, such as a pipe, duct, caisson, or the like. The method may comprise circumferentially sealing within the opening and/or passage.

The method may comprise activating the seal. For example, the method may comprise reconfiguring the seal from a first configuration to a second configuration, the first configuration comprising a non-sealing configuration, such as a transit configuration, and the second configuration comprising a sealing configuration. Reconfiguring the seal may comprise re-shaping the seal, such as deforming the seal. For example, particularly where the seal is a circumferential seal within an opening or passage, such as an annular seal, reconfiguring the seal may comprise expanding the seal from a first, smaller diameter to a second, larger diameter. The method may comprise transporting the isolation apparatus through a body of water, such as adjacent the vessel, typically in which the vessel floats and/or is submerged. The method may comprise an in-water method. For example, the method may comprise a wet isolation method, whereby the vessel remains in-situ or at sea (e.g. not dry-docked). The method may comprise positioning the isolation apparatus over and/or in the opening. The method may comprise positioning the isolation apparatus to cover and/or block the opening. The method may comprise covering the opening with the isolation apparatus to seal the opening.

The method may comprise maintaining tension in the positioning line so as to maintain the seal/s (e.g. between the isolation apparatus and the vessel/hull/opening).

In at least some examples, the method may comprise locking the positioning line/s. The method may comprise locking the line tensioner associated with the positioning line so as to effectively lock the positioning line. The method may comprise locking the positioning line/s when the isolation apparatus has isolated the opening, such as after the isolation apparatus has been positioned over and/or in the opening by tensioning the positioning line/s. The method may comprise locking the positioning line/s to maintain tension in the positioning line/s. The method may comprise locking the positioning line/s to mitigate against a power failure or interruption. The power failure or interruption may be a possible future failure or interruption and/or an actual, occurring failure or interruption. For example, the method may comprise activating the lock in advance of and/or in response to a power failure or interruption.

The method may comprise releasing the isolation apparatus. The method may comprise removing the apparatus from the opening. The method may comprise releasing the positioning line/s. Releasing the positioning line/s may comprise releasing a connection or connector associated with an end of the positioning line, such as at or near the opening. Additionally or alternatively, the method may comprise releasing the apparatus by unlocking the positioning line/s. The method may comprise loosening the positioning line/s.

The method may comprise a diverless method. The method may be performed without a presence of a diver. The method may be entirely performed without any requirement for a diver. The transportation of the isolation apparatus through the body of water may be performed without a diver. The positioning of the isolation apparatus over and/or in the opening may be performed without a diver. The method may comprise an unmanned method. The method may comprise a remotely-controlled method. The method may comprise control from a remote location, such as from on-board the vessel or from a second vessel (e.g. a maintenance boat or the like), such as adjacent the vessel with the opening to be isolated.

In at least one example, the method may comprise a method of isolating a sea chest of a marine vessel, the method comprising: sealing an opening to the sea chest with the isolation apparatus; wherein the isolation apparatus is both transported through the body of water adjacent the vessel and positioned to cover the opening using a diverless operation.

The method may comprise creating or adapting the opening/s. For example, the method may comprise creating or enlarging an opening. In at least some examples, the opening may be associated with a damaged or degraded hull.

Transporting the isolation apparatus through the body of water may comprise lowering the isolation apparatus, such as from at or near surface. For example, the isolation apparatus may be lowered from a topside of the vessel, such as from a rigging, derrick, crane, surface winch or deck of the vessel. Alternatively, the isolation apparatus may be lowered from another vessel, such as a boat or the like adjacent the vessel with the opening to be isolated.

The isolation apparatus may be lowered at least partially under gravity. For example, the isolation apparatus may comprise a negative buoyancy. The isolation apparatus may be sufficiently negatively buoyant so as to maintain a tension in an elongate member, such as a support line. The elongate member may comprise one or more of wire/s, rope/s, cable/s or the like. The method may comprise suspending the isolation apparatus, such as suspending the isolation apparatus in the body of water with the elongate member at a depth corresponding to the intake. The method may comprise lowering the isolation apparatus using free suspension, with the isolation apparatus being propelled downwards under its own gravity, without requiring additional pulling or pushing force/s.

Transporting the isolation apparatus through the body of water may comprise raising the isolation apparatus. The method may comprise raising the isolation apparatus through the body of water, such as to surface, after completion of the isolation operation or completion of associated operation/s. The method may comprise pulling or reeling in the elongate member to at least partially raise the isolation apparatus, such as to raise to at or near the surface.

The method may comprise controlling a position, such as a depth, of the isolation apparatus in the body of water. The method may comprise controlling the position of the isolation apparatus by controlling the elongate member, such as by monitoring and controlling a payout length of the elongate member. The method may comprise progressively paying out a sufficient length of the elongate member such as to allow the isolation apparatus to descend to a depth corresponding approximately to a depth of the opening. For example, the method may comprise controlling a winch or the like so as to progressively lower the isolation apparatus to a depth approximately corresponding to a depth of the opening. The method may comprise controlling a payout length to be slightly longer than that required to position the isolation apparatus at the depth corresponding to the opening. The method may comprise maintaining the depth of the isolation apparatus. The method may comprise maintaining the depth of the isolation apparatus by controlling the payout length of the elongate member. The method may comprise arresting payout of the elongate member so as to maintain the depth of the isolation apparatus. Additionally, or alternatively, the method may comprise allowing a margin or play in the depth of the isolation apparatus, such as by not rigidly fixing the elongate member when the isolation apparatus reaches the depth corresponding approximately to the opening. The method may comprise providing an excess of elongate member payout length.

The method may comprise adjusting or fine-tuning the depth of the isolation apparatus to correspond to that exactly suitable for isolating the opening. The method may comprise using the ROV to position the isolation apparatus at an exact correct depth. The exact correct depth may have a smaller error margin than the approximate depth corresponding to that of the opening. The method may comprise providing the isolation apparatus and/or the ROV and/or the connection therebetween with a scope for adapting the depth of the isolation apparatus to match that of the opening. For example, the method may comprise providing the connected ROV and isolation apparatus with an ability for at least some self-alignment with the opening. The method may comprise transporting and positioning the isolation apparatus using a combination of general lowering under suspension and tensioning of the positioning line/s. Additionally or alternatively, the method may comprise transporting and positioning the isolation apparatus using a combination of general lowering under suspension without an ROV and fine positioning with a ROV connected to the isolation apparatus.

The method may comprise attaching the positioning line/s with a ROV to the connection point/s. Additionally or alternatively, the method may comprise connecting a Remotely Operated Vehicle (ROV) to the isolation apparatus. Connecting the ROV to the isolation apparatus may comprise attaching the ROV to the isolation apparatus. The method may comprise attaching the ROV to the isolation apparatus by one or more of: an inter-engaging coupling means; gripping; magnetic coupling means; a fastener/s. The method may comprise connecting the ROV to the isolation apparatus whilst both are in the water. The method may comprise connecting the ROV to the isolation apparatus when the isolation apparatus and ROV are both at a depth of at least: respectively 1 metre; 2metres, 5metres, 10 metres. The method may comprise connecting the ROV to the isolation apparatus after the isolation apparatus has been lowered to the approximate depth of the opening. Alternatively, the method may comprise connecting the ROV to the isolation apparatus at or near the surface of the body of water.

The method may comprise connecting the ROV to the isolation apparatus by manoeuvring the ROV, such as by manoeuvring the ROV apparatus such that an engagement member of the ROV apparatus engages a corresponding engagement member of the isolation apparatus. The method may comprise only mechanically connecting the ROV to the isolation apparatus, such as without electrical or optical connections or the like. The engagement member/s may be configured to allow manipulation of the isolation apparatus by the ROV, once connected.

The method may comprise controlling the line tensioner/s and/or the ROV based upon visual feedback, such as from one or more cameras of the ROV. In at least some examples, the method may comprise controlling the isolation apparatus and/or the ROV with at least some autonomy, such as where the ROV performs at least portions of one or more manoeuvres or operations autonomously. The method may comprise utilising the positioning line/s to manoeuvre the isolation apparatus. Additionally, or alternatively, the method may comprise utilising the ROV to manoeuvre the isolation apparatus via the ROV’s connection to the isolation apparatus. The method may comprise remotely controlling the line tensioner/s and/or the ROV to remotely control the isolation apparatus and/or the attachment of the connector/s of the positioning line/s and/or the release mechanism.

The method may comprise controlling an orientation of the isolation apparatus. The method may comprise controlling a general orientation of the isolation apparatus. The method may comprise controlling a general orientation of the isolation apparatus using the plurality of positioning lines. The method may comprise controlling the general orientation of the isolation apparatus by providing the isolation apparatus with a particular centre of gravity. The method may comprise providing the isolation apparatus with a balanced buoyancy corresponding to a desired orientation of the isolation apparatus.

In at least some examples, the desired orientation of the isolation apparatus may be generally vertical, such that the isolation apparatus is generally oriented for covering a generally vertical opening, such as in a wall of a generally vertical hull. According to at least some example methods, the buoyancy of the isolation apparatus may be adjusted and/or predefined so as to correspond to the desired orientation. For example, where the opening to be isolated is at an angle of inclination to the vertical, the isolation apparatus may be configured to have a buoyancy whereby the isolation apparatus is predisposed or biased to adopt at least a similar approximate angle of inclination to the vertical.

The method may comprise adjusting or fine-tuning the orientation of the isolation apparatus to correspond to that exactly suitable for isolating the opening. The method may comprise using the ROV to position the isolation apparatus at an exact correct orientation. The exact correct orientation may have a smaller error margin than the approximate angle of inclination corresponding to that of the opening. The method may comprise providing the isolation apparatus and/or the ROV and/or the connection therebetween with a scope for adapting the orientation of the isolation apparatus to match that of the opening. For example, the method may comprise providing the connected ROV and isolation apparatus with an ability for at least some self-alignment with the opening. The method may comprise blocking the opening. The method may comprise blocking the opening by the sealingly covering opening with the isolation apparatus. The method may comprise blocking the opening by positioning the isolation apparatus over the opening. The method may comprise positioning a blocking member of the isolation apparatus over the opening by remotely controlling the isolation apparatus’ position with the positioning line/s and/or the ROV. The method may comprise pressing the isolation apparatus against the opening. For example, the method may comprise propelling the isolation apparatus against the opening using the tensioning of the positioning line/s and/or the ROV. The method may comprise attaching the isolation apparatus to the vessel. The method may comprise utilising one or more attachment means of the isolation apparatus to attach the isolation apparatus. The attachment means may comprise one or more of: magnet/s; fluid pressure; underpressure; hydrostatic pressure; a pressure differential across the isolation apparatus. The method may comprise temporarily attaching the isolation apparatus to the vessel. The method may comprise attaching the isolation apparatus to the vessel with a final attachment. Optionally, the method may comprise attaching the isolation apparatus to the vessel with an interim attachment, prior to the final attachment. The method may comprise temporarily attaching the isolation apparatus to the vessel in a process involving at least two steps: the first step comprising the interim attachment; and the second step comprising the final attachment. The final attachment may be for performing operations, such as with the opening sealingly blocked. At least the first step may be performed using the interim attachment means. The interim attachment means may comprise a lesser attachment force than the final attachment means. The interim attachment means may comprise the tensioning of the positioning line/s with the line tensioner/s. Additionally, or alternatively, the interim and/or final attachment means may comprise a magnetic attraction force, such as provided between one or more magnetic member/s of the isolation apparatus and a portion of the vessel, such as a portion of one or more of: the hull; the opening; a coaming; an opening grating. The interim attachment means may provide an additional attachment force to supplement the final attachment means. The interim and/or final attachment means may comprise a fluid pressure. In at least some examples, the final attachment means comprises a hydrostatic fluid pressure provided by the body of water acting on an exterior portion of the isolation apparatus, the exterior portion of the isolation apparatus being located on, or defined by, a portion/s of the isolation apparatus away from the sealing member of the isolation apparatus. The method may comprise reducing a pressure on an interior side of the opening. For example, the method may comprise at least partially draining the sea chest inwards of the opening. At least partially draining the sea chest may generate a relative underpressure in the sea chest, such that a hydrostatic pressure of the body of water exterior of the isolation apparatus biases the isolation apparatus against the opening, thereby activating and/or maintaining a seal/s of the isolation apparatus. The method may comprise monitoring sealing during the draining of the sea chest, such as to monitor the integrity of the seal during draining. For example, the method may comprise at least partially draining, pausing, or monitoring for a period of time to assess whether there is any ingress of water into the sea chest via the opening/s. Such ingress may be indicative of inadequate sealing. Accordingly, the method may comprise re-positioning the isolation apparatus, with the ROV, to adjust the seal/s.

The method may comprise providing a double seal of the opening. The method may comprise providing a double seal with the isolation apparatus. The isolation apparatus may comprise at least a pair of sealing portions, the pair of sealing portions being radially arranged, that is to say a first sealing portion of the pair being located inside a second sealing portion. The sealing portion may extend around a perimeter of the isolation apparatus and/or the opening. Each of the sealing portions may be configured to extend around a perimeter of the opening. The method may comprise providing at least a pair of seals each extending around perimeter portions of the opening. The method may comprise positioning the first sealing portion of the isolation apparatus against a corresponding portion of the opening. The corresponding portion of the opening may comprise a portion associated with a perimeter of a grating, grille, or the like of the opening. The method may comprise positioning the second sealing portion of the isolation apparatus against another corresponding portion of the opening. The another corresponding portion of the opening may comprise a coaming, projection, rim, or the like. For example, the method may comprise providing the second seal between the isolation apparatus and the coaming of the opening.

The method may comprise blocking the opening to enable operations within the sea chest. The operations may comprise isolating the sea chest. The operations may comprise at least partially draining the sea chest. The operations may comprise draining the sea chest to below a level of an opening or intake line, such as where a device may be inspected and/or replaced. The method may comprise inspecting and/or maintaining a device associated with the sea chest. The device may comprise a valve, such as associated with an intake from the sea chest. The method may comprise inspecting and/or maintaining the device from within the marine vessel. The method may comprise disconnecting the device whilst the sea chest is isolated by the isolation apparatus/es. The method may comprise removing or breaking an intake seal, such as of a valve device, associated with the sea chest. Removing or breaking the intake seal may be enabled in situ, with the marine vessel in water, by the seal, or double seal, provided by the isolation apparatus/es. Accordingly, the method may comprise providing access to portions of the sea chest from within the marine vessel, the isolation apparatus/es providing a barrier to ingress of water from the body of water during such access. The access may enable the inspection and/or maintenance of the sea chest and/or associated apparatus. In at least some examples, such maintenance comprises the replacement of the intake valve associated with the sea chest.

The method may comprise cleaning the opening. The method may comprise cleaning the opening with a diverless operation. The method may comprise cleaning the opening before the positioning line/s is/are attached. The method may comprise cleaning the opening with the ROV. The method may comprise cleaning the opening with the ROV before the ROV is connected to the isolation apparatus. The method may comprise cleaning the opening with one or more of: mechanical cleaning; cavitation blasting; jetting; brushing. The method may comprise cleaning an external portion of the opening to enable the isolation apparatus to attach to the external portion of the opening. The method may comprise cleaning the opening before the isolation apparatus is attached to the opening.

In at least some examples, the method may comprise not connecting the isolation apparatus to the ROV throughout the entire duration of the deployment. For example, the isolation apparatus may be propelled or transited through the water and positioned relative to the opening using the positioning line/s and optionally gravity/buoyancy and/or optionally a suspension or tow line. In examples where the method comprises connecting the isolation apparatus to the ROV, the method may comprise disconnecting the isolation apparatus from the ROV (or vice versa). The method may comprise disconnecting the isolation apparatus from the ROV after the isolation apparatus is attached to the opening. The method may comprise disconnecting the isolation apparatus from the ROV after the isolation apparatus is preliminarily attached to the opening. The method may comprise disconnecting the isolation apparatus from the ROV after the isolation apparatus is finally attached to the opening. The method may comprise deploying a plurality of isolation apparatuses.

The method may comprise positioning each of the plurality of isolation apparatuses with the ROV. The method may comprise positioning each of the plurality of isolation apparatuses with a same ROV, such as using a single ROV for all of the plurality of isolation apparatuses. The method may comprise sequentially positioning each of the plurality of isolation apparatuses. Alternatively, the method may comprise using a plurality of ROVs. Each of the plurality of isolation apparatuses may be lowered from surface on a respective elongate member.

The method may comprise reconnecting the ROV to the isolation apparatus (or vice versa).

The method may comprise detaching the isolation apparatus from the opening. The method may comprise releasing at least the final attachment means. Detaching the isolation apparatus may comprise releasing the final attachment means to an interim released configuration of the isolation apparatus, such as with the isolation apparatus attached with the interim attachment means, but not the final attachment means. Detaching the isolation apparatus may comprise detaching or at least reducing the attachment means. Detaching the isolation apparatus may comprise removing or reducing a pressure differential across the isolation apparatus. The method may comprise filling or re-filling the sea chest to increase pressure on an internal side of the opening and isolation apparatus. The method may comprise providing a fluid path for water from the body of water to pass into the sea chest. The method may comprise providing the fluid path at or through the isolation apparatus. The method may comprise opening an opening in the or an (e.g. another) isolation apparatus to provide at least one fluid path for water from the body of water through at least one opening into the sea chest. The opening may comprise a valve, such as a bleed valve. The method may comprise opening and/or further opening the opening with the ROV. Additionally, or alternatively the method may comprise filling the sea chest from within the vessel, such as by using a discharge outlet into the sea chest to pump out fluid from the marine vessel.

In at least some examples, the method may comprise opening the opening with the ROV whilst the ROV is disconnected from the isolation apparatus. For example, the method may comprise sequentially: positioning the isolation apparatus with the ROV, attaching the isolation apparatus to the opening, disconnecting the ROV from the isolation apparatus; performing operations with the isolation apparatus attached to the opening; opening the opening with the ROV; reconnecting the ROV to the isolation apparatus. The method may comprise opening the opening with the ROV’s engagement member. In other examples, the method may comprise opening the opening with the ROV whilst the ROV is connected to the isolation apparatus. The ROV may comprise an opening engagement member in addition to the engagement member for connecting to the isolation apparatus.

The method may comprise isolating a plurality of sea chests. The method may comprise sequentially isolating the plurality of sea chests. The method may comprise isolating the plurality of sea chests with a single ROV. Alternatively the method may comprise operating a plurality of ROVs to isolate the plurality of sea chests. The method may comprise isolating the plurality of sea chests with a single isolation apparatus, such as sequentially isolating each of the sea chests after the previous sea chest has been isolated and then re-filled and the single isolation apparatus detached. Similarly, where one or more of the plurality of sea chests comprises multiple openings to the sea chest, then the method may comprise isolating each of the sea chests with a single set of isolation apparatuses. Accordingly, the method may comprise sequentially or progressively isolating a plurality of sea chest openings with a single isolation apparatus. The method may comprise isolating the plurality of sea chest openings with the single isolation apparatus without retrieving the isolation apparatus entirely to surface between the respective isolations of the plurality of sea chest openings. The plurality of sea chests may be provided on a single marine vessel. Additionally, or alternatively, the plurality of sea chests may be provided on a plurality of marine vessels, such as a plurality of marine vessels located or moored in close proximity to each other.

The method may comprise a remote inspection method. The method may comprise an unmanned inspection method. The method may comprise a diverless remote maintenance method. It may be an advantage of the present invention that the method is equivalent or at least substantially equivalent, such as in quality and/or scope, to the method that would be achieved with a diver. The method may comprise not removing or detaching or reconfiguring a device/s associated with the marine vessel. For example, the method may comprise isolating the sea chest without removing or detaching or reconfiguring the coaming and/or grille and/or grating associated with the opening/s to the sea chest.

It may be an advantage of the present invention that the method has one or more of: enhanced safety; and/or reduced cost in preparation and/or inspection; and/or be a faster method which may increase system availability and/or require fewer personnel and/or reduce downtime; compared to conventional methods.

The method may comprise providing access and/or inspection via large diameter pipes and valve gear (i.e. valves and associated apparatus) within the hull, which may terminate in the sea chest/s. The functional status of any valve gear associated with the sea chest can be ascertained by closing selected ones of the valves and measuring the pressure drop across them. However, this gives only a momentary indication of the functional condition of the valve, and does not provide any warning of the extent of internal corrosion or other mechanical damage which could be expected to lead to failure in the months or years following the test. For example, FOIs are usually inspected at intervals of up to 3 years and so it is important that the inspection identifies incipient failure conditions that may lead to failure during the 3-year period following the test. For this reason, visual inspection of valves and other vulnerable regions within the flooded cavities may be strongly preferred. Such visual inspection may be enabled by the presently-disclosed methods, without requiring any diver/s.

The extent to which visual inspection is possible may be however limited by the extreme difficulty of access to the flooded cavities. Pipework can be very large (up to 1 metre diameter or even more) and so removal of valve gear and sections of pipework is often impractical, particularly since access to the dry side of the walls of the flooded cavities is very restricted in the confined spaces of the hull or shell of a ship or FOI. Despite the large size of much of the pipework, it may be extremely difficult to access by remotely operated vehicles (ROVs), not least because a failed or trapped ROV would become an obstruction. ROVs are not conventionally used for anything that penetrates hull cavities, such as sea chest intakes.

According to an aspect, there is provided an isolation apparatus. The isolation apparatus may be for performing the method of any aspect, example, claim or embodiment disclosed herein. The isolation apparatus may comprise the line tensioner. The line tensioner may comprise a winch. The isolation apparatus may comprise a plurality of line tensioners for tensioning the plurality of positioning lines to pull the isolation apparatus onto and/or into the opening. In at least some examples, the apparatus comprises a blanking plate with a plurality of winches mounted thereto. The winches may each comprise a respective positioning line for attaching the blanking plate to and/or in the opening. The apparatus may comprise a quick release connector at the opposite end of each positioning line from the respective winch.

The isolation apparatus may be configured to attach a hull, such as at or near an opening in the hull. The isolation apparatus may be configured to attach to a sea chest opening. The isolation apparatus may comprise an engagement member for engagement with or by a ROV engagement member. The isolation apparatus engagement member may be configured to allow gripping and/or manipulation of the isolation apparatus by the ROV.

The isolation apparatus may comprise a sealing portion for sealingly engaging the opening. The isolation apparatus may comprise at least a pair of sealing portions for sealingly engaging the opening. The pair of sealing portions may be radially arranged, that is to say a first sealing portion of the pair being located inside a second sealing portion. The sealing portion may extend around a perimeter of the isolation apparatus. Each of the sealing portions may be configured to extend around a perimeter of the opening. The first sealing portion of the isolation apparatus may be configured to seal against a corresponding first portion of the opening. The first corresponding portion of the opening may comprise a portion associated with a perimeter of a grating, grille, or the like of the opening. The second sealing portion of the isolation apparatus may be configured to seal against a second corresponding portion of the opening. The second corresponding portion of the opening may comprise a coaming, projection, rim, or the like. For example, the method may comprise providing the second seal between the isolation apparatus and the coaming of the opening.

The sealing portion/s of the isolation apparatus may be resilient. In at least some examples, one or more sealing portion/s of the isolation apparatus are deformable to adapt to the corresponding portion/s of the opening against which the isolation apparatus is to seal. The sealing portion/s may be sufficiently deformable so as to accommodate a range of openings. For example, the first and/or second sealing portion/s may be sufficiently deformable to accommodate a variation in heights of coaming or projection/s adjacent a grating or grille of an intake. The portion/s may be elastically deformable. In at least some examples one or more of the sealing portion/s comprises a neoprene® or the like.

The isolation apparatus may comprise a valve. The valve may comprise a bleed valve. The valve may comprise a one-way valve. Additionally or alternatively, the valve may comprise a remotely-controllable valve. The isolation apparatus may be configured to selectively provide a fluid path for water from the body of water to pass into the sea chest. The isolation apparatus may comprise the fluid path at or through the isolation apparatus, such as via an opening in the isolation apparatus. The isolation apparatus may be configured to provide at least one fluid path for water from the body of water through at least one sea chest opening into the sea chest. The opening may be selectively openable and/or selectively closable. The opening may be configured to be cycled between open and closed configurations. Alternatively, the opening may be configured for single operation, such as for selectively opening from an initially closed configuration. The opening may be then reconfigured, such as at surface, following completion of the inspection and/or maintenance method, or between deployments of a plurality of isolation apparatuses. The opening may comprise a valve, such as a bleed valve. The opening may be configured to be opened and/or further opened with the ROV. The opening may be configured to be closed with the ROV.

The isolation apparatus may comprise a blanking plate. The blanking plate may comprise the two sealing portions on a single side of the blanking plate, the single side being for engagement with the intake. An opposite side of the blanking plate may comprise the engagement member/s for connection to the ROV. The opposite side of the blanking plate may comprise an external side, away from the sea chest opening in use. The opposite side of the blanking plate may comprise access for opening and/or closing the opening. For example, the opposite side of the blanking plate may comprise an actuator for engagement and operation by an ROV.

The isolation apparatus may be configured to be oriented correctly by the positioning line/s. Additionally or alternatively, isolation apparatus may be configured to be at least partially self-orienting. The isolation apparatus may comprise a particular, predefined centre of gravity so as to provide the isolation apparatus with a desired orientation. The isolation apparatus may comprise a balanced buoyancy corresponding to the desired orientation of the isolation apparatus. The isolation apparatus may comprise a negative buoyancy. For example, the isolation apparatus may comprise a negative buoyancy so as to allow the isolation apparatus to be lowered through the body of water under gravity.

The isolation apparatus may comprise attachment means, such as one or more connectors, anchors, fasteners, or the like, such as for attaching the apparatus via the positioning line/s. Additionally or alternatively, the apparatus may comprise one or more magnets for attachment to the marine vessel, such as to a metal opening, coaming, grating or the like.

The isolation apparatus may comprise a suspension point attachment member, such as a fastener or the like for attachment to an elongate member for suspension of the isolation apparatus. Accordingly, the isolation apparatus may be suspended via an elongate member, such as a support line.

According to a further aspect, there is provided a system comprising a plurality of the isolation apparatus of any other aspect, example, claim or embodiment. The system may be configured to sealingly block or isolate a plurality of openings. The system may be configured to sealingly block or isolate a plurality of openings simultaneously and/or sequentially. The system may be configured to isolate a plurality of sea chests. The system may comprise a ROV. The system may comprise a lifting apparatus, such as a surface winch or the like. The system may comprise an elongate member.

According to an aspect, there is provided a system comprising a controller, the system arranged to perform a method according to any aspect, claim, embodiment, or example of this disclosure.

According to an aspect, there is provided computer software which, when executed by a processing means, is arranged to perform a method according to any aspect, claim, embodiment, or example of this disclosure. The computer software may be stored on a computer readable medium. The computer software may be tangibly stored on a computer readable medium. The computer readable medium may be non-transitory.

Any controller or controllers described herein may suitably comprise a control unit or computational device having one or more electronic processors. Thus, the system may comprise a single control unit or electronic controller or alternatively different functions of the controller may be embodied in, or hosted in, different control units or controllers. As used herein the term “controller” or “control unit” will be understood to include both a single control unit or controller and a plurality of control units or controllers collectively operating to provide any stated control functionality. To configure a controller, a suitable set of instructions may be provided which, when executed, cause said control unit or computational device to implement the control techniques specified herein. The set of instructions may suitably be embedded in said one or more electronic processors. Alternatively, the set of instructions may be provided as software saved on one or more memory associated with said controller to be executed on said computational device. A first controller may be implemented in software run on one or more processors. One or more other controllers may be implemented in software run on one or more processors, optionally the same one or more processors as the first controller. Other suitable arrangements may also be used.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples, and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

The invention includes one or more corresponding aspects, embodiments or features in isolation or in various combinations whether or not specifically stated (including claimed) in that combination or in isolation. For example, it will readily be appreciated that features recited as optional with respect to the first aspect may be additionally applicable with respect to the other aspects without the need to explicitly and unnecessarily list those various combinations and permutations here (e.g. the apparatus or device of one aspect may comprise features of any other aspect). Optional features as recited in respect of a method may be additionally applicable to an apparatus or device; and vice versa. The apparatus or device of one aspect, example, embodiment or claim may be configured to perform a feature of a method of any aspect, example, embodiment or claim. In addition, corresponding means for performing one or more of the discussed functions are also within the present disclosure. It will also be appreciated that features associated with one of the isolation apparatus and the line tensioner may also be associated with the other of the line tensioner and the isolation apparatus. For example, where examples or features are disclosed in combination with the isolation apparatus, it will be appreciated that those features may apply equally to the line tensioner, and vice versa, as appropriate. In at least some examples, the position of the line tensioner may be inverted (e.g. the line tensioner may be provided at, nearer, or past the opening and/or connection point such that the line tensioner shortens the length of line at the opening/hull end of the positioning line).

In addition, corresponding means for performing one or more of the discussed functions are also within the present disclosure.

The above summary is intended to be merely exemplary and non-limiting.

Various respective aspects and features of the present disclosure are defined in the appended claims.

It will be appreciated that one or more embodiments/aspects may be useful in at least isolating an opening, such as sealing an aperture in a hull.

It may be an aim of certain embodiments of the present disclosure to solve, mitigate or obviate, at least partly, at least one of the problems and/or disadvantages associated with the prior art. Certain embodiments may aim to provide at least one of the advantages described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Figure 1 shows a schematic diagram of a method according to a first example;

Figures 2(a) to 2(c) show a depiction of cleaning an opening in the hull of a marine vessel;

Figures 3(a) to 3(c) show a depiction of attaching positioning lines to the hull of a marine vessel; Figures 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;

Figures 5(a) to 5(c) show a depiction of using the isolation apparatus to seal the opening in the marine vessel;

Figures 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;

Figures 6(a) and 6(b) show a front and rear view of an isolation apparatus;

Figure 6(c) shows a side view of a mini-winch located towards a corner of the isolation apparatus of Figure 6(a);

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

Figure 7 shows a depiction of the isolation apparatus of Figure 6 suspended above sea level from a winch on a marine vessel;

Figures 8(a) and (b) show a depiction of lowering the isolation apparatus of Figure 6 from above sea-level, to an opening in the hull of a marine vessel; Figure 8(c) shows a depiction of an isolation apparatus of Figure 6 whilst being attached to an opening;

Figure 9 shows an arrangement wherein multiple isolation apparatuses are attached to multiple openings;

Figure 10 shows an example of a connector with quick release mechanism, for attaching each positioning line at or near the opening - as shown sequentially in Figures 10a through 10e; and

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

DETAILED DESCRIPTION

Referring first to Figure 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.

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).

Figures 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.

Referring now to Figure 2, Figure 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.

As shown in Figures 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.

As shown in Figure 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 Figures 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 Figure 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.

Referring now to Figures 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 Figure 4(c).

Once the isolation apparatus 20 has been lowered to the appropriate depth, the positioning lines 11 are tensioned (further). Although not visible in Figure 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.

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.

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 100kg. The level of tension may be adjusted or selected in advance of and/or during deployment. For example, a minimum tension of at least 250kg 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.

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 opening12 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 Figure 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 Figures 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).

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

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 Figure 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. 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.

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.

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.

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 Figure 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.

Referring now to Figures 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. Figure 6(a) depicts a face of the apparatus 20. It will be appreciated that the view shown in Figure 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. Figure 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 Figure 6b). Figure 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. Figure 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 Figure 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. Figure 6d shows cross-sectional view A-A, illustrating two of the winches 60 with respective positioning lines 11. lt will be appreciated that the blanking plate’s seal 58 provides a continuous encircling seal around an entire periphery of the opening 12.

T urning now to Figure 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 Figures 10 or 11. Figure 7 also shows an enlarged view of the blanking plate 20, as discussed with reference to Figure 6.

Figures 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 Figure 8b, with the blanking plate 20 over the opening 12 in the hull 14.

Figure 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. Figure 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.

In at least some embodiments; and as explicitly shown in Figure 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.

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, Figure 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.

Referring now to Figure 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 Figure 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 Figures 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 Figure 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 Figures 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 Figure 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 Figure 11j, 11k, and 111. Figure 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.

As shown in Figure 11a, the four positioning lines 111 have each been attached using a tool 82 and connector 80 as shown in Figure 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 Figure 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 Figures 11b and 11c. Figures 11d, 11e and 11f show the blanking plate 120 attached over the opening 112. Here, each positioning line is tensioned individually to around 250kg, 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 Figure 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. Figures 11g through 111 show a release of the blanking plate 120 using the quick release mechanisms 90 associated with the connectors 80. As shown in Figure 11g, here a remotely-operated tool 98, such as operated using a ROV, pulls the quick release member 86, as shown in Figure 11 h. With the quick release member 86 shown fully extracted from the quick release mechanism 90 in Figure 11i. Once all of the connectors 80 have been released, such as further illustrated in Figures 11j and 11k, the blanking plate 120 is fully released; and can be removed from the opening, as shown in Figure 111.

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.

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.

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.

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.

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.

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 contact - with 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.