Patent Description:
The invention particularly, though not exclusively, relates to a mid-line, in-line or mid-water tensioner, e.g. a tensioner provided between the end of a mooring line, e.g. at a location along a length of a mooring line.

Offshore structures, such as floating structures or platforms, can be moored by mooring lines, such as mooring chains. This may include attaching at least one mooring line to the structure to be moored and directly, or indirectly, coupling each mooring line to another structure, such as an anchor or pile located on a seabed.

A tension may be applied to each of the mooring lines. A necessary tension can be applied to each mooring line, for example, by the use of a tensioning apparatus. The tensioning apparatus may be adapted for use by a winch, or the like. The application of tension may serve to moor the floating structure or platform in a desired position.

When an appropriate tension has been applied to a mooring line, a locking mechanism may be locked or engaged to maintain the mooring line in tension. Similarly, when a tension has to be removed from the mooring line, for example, when movement of the floating structure or platform is desired, the locking mechanism may be unlocked or disengaged.

The tensioning apparatus may be located on, or coupled to, the floating structure of platform. In such an arrangement, the mooring chain and/or tensioning apparatus may be prone to wear and/or failure due to out-of-plane stresses caused by movement of the floating structures or platforms relative to the mooring chain.

The tensioning apparatus may be located on, or coupled to, the mooring chain and may direct a free end of the mooring chain towards the surface to enable adjustment of the tension in the mooring line(s), e.g. by a winch located on a vessel.

During tensioning of the mooring line, bending strain can act on the mooring line due to the mooring line being pulled and/or bent around the tensioning apparatus. This can lead to increased wear and/or damage to the mooring chain and/or to the apparatus. In order to minimise the strain on the mooring line, the size of the tensioning apparatus may be increased to accommodate larger angles for guiding the mooring line towards the surface. However, this can lead to an increased cost and weight of the tensioning apparatus. Further, the increased weight of the tensioning apparatus also increases a loading upon the mooring chain, subsequently requiring an even greater tension to maintain a desired angle of inclination of the mooring chain.

Articulating tensioners and non-articulating tensioners are known.

An articulating tensioner allows a tensioner frame to adjust to any angle arrangement as the articulating frame moves to suit angles of the chain legs. However, the frame is complex and potentially heavier than a simple non-articulating tensioner.

A non-articulating tensioner is simpler and potentially lighter, but suffers a drawback as the relationship between the wheel pivot point, rear padeye, and lock are fixed, thus having a "sweet spot" for tensioning. If the tensioner is not at the designed angle, the chain can rub on either the upper or lower portion of a guide at the front. Chain rubbing may occur on the front guide/lock part of the frame. This rubbing can make the operation of the tensioning operation jerky - which is undesirable.

Another issue that all mid-line tensioners face is that such are effectively clump weights in the mooring line. Tensioners with locks pivoting in from the same side of the mooring line as the wheel, require that the lock be spaced far enough away from the wheel so that they do not clash. The necessary structure adds mass.

Even if one imagines a double stopper lock articulating from the side, it would still have a distance that it needed to ensure that the doors did not clash.

By flipping the stopper to the opposite side of the chain, the Inventors have found that one can pivot the stopper as close as one can get to the wheel, and even stop the chain link that is sitting on the wheel (provided the wheel and stopper are designed to mesh/interact inside the projected diameter of the wheel). The stopper can be very close to the wheel.

It may be an object of at least one embodiment of at least one aspect of the present invention to obviate or at least mitigate at least one problem in the prior art.

It may be an object of at least one embodiment of at least one aspect of the present invention to provide a technically simple and/or commercially more cost effective apparatus and/or method for mooring than in the prior art.

It may be an object of at least one embodiment of at least one aspect of the present invention to provide an apparatus, such as a mid-line tensioner, which may be improved over the prior art, e.g. being more compact, lighter and/or less expensive to manufacture.

<CIT> describes a mooring tensioning arrangement for a floating structure or vessel, comprising an anchor, a mooring line, a mooring tensioner and a working line, said mooring tensioner having a tensioning pulley, said mooring line being attached at a first end to said anchor and at a second end to said mooring tensioner, said working line is adapted to be attached at a first end to said floating structure or vessel and extending over said tensioning pulley, and said working line being attached to a pulling unit at a second end, said pulling unit being remotely arranged from the offshore structure; said working line having a first flight that extends between said attachment to said floating structure or vessel and said tensioning pulley. The invention is distinctive in that a second flight extends from said tensioning pulley towards said pulling unit that said second flight of said working line is substantially parallel to said first flight of said working line so that a tensioning force from said pulling unit, acting upon said mooring line, does not pull said mooring line out of a straight line between said anchor and said floating structure or vessel.

<CIT> describes a mooring apparatus comprising a guide portion for guiding a portion of a first mooring line, an arrangement for connecting or coupling the apparatus to a second mooring line, and a lock or lock means. The guide portion is moveably connected to the arrangement, and the lock is connected to, attached to or provided on the arrangement. A system for tensioning a mooring line, the system comprising the mooring apparatus and the first mooring line and/or the second mooring line. A method of tensioning a mooring line, wherein the method comprises providing the system for tensioning a mooring line, and the method further comprises applying a pulling force to a first portion of a first mooring line in a direction away from the apparatus.

<CIT> describes a chain stopper. A wire is wound around a winch on a deck of a marine structure floating on the sea surface. The wire is connected to a chain via a sheave provided on a frame fixed at the lower end of the marine structure. The sheave and a chain cover are made rotatable by a shaft supported by a frame, and a chain guide member is provided at the lower section of the cover. A locking member is provided between the cover and the guide member, the chain is locked and fixed, and its lower end is connected to an anchor on the sea bottom. According to this constitution, the wire can be operated by the winch in the same direction regardless of the direction of the chain, also the chain is not required to be hoisted onto the deck, and the device can be made small-sized.

According to the present invention there is provided an apparatus or device according to the appended claims.

According to a first aspect of the present invention there is provided an (mooring) apparatus or device for mooring a structure and/or tensioning a mooring line.

The apparatus or device may comprise a guide portion or member (or sheave) for guiding a portion of a first mooring line.

The apparatus or device may comprise a lock arrangement or means
The apparatus or device may provide a mooring line path.

The lock arrangement or means may be provided or providable on an opposite side of the mooring line path from the guide portion at least in an unlocked disposition. The lock arrangement may be adapted to be provided or providable between the guide portion and a structure to be moored, in use, at least in a locked disposition, e.g. along the mooring line path.

The lock arrangement may be provided or providable between the guide portion and a structure to be moored along a path of a mooring line, for example, along the mooring line path.

The lock arrangement may be provided or providable proximal or adjacent the guide portion.

The apparatus or device may comprise a body or "frame".

The body may comprise an arrangement for connecting or coupling, e.g. directly connecting or coupling, the apparatus or device to a second mooring line.

The apparatus or device may be adapted for use with a mooring line comprising a mooring chain.

In use, a locked link of a/the mooring chain may be provided between and/or engaged with one or both of the guide portion and the lock arrangement.

The lock arrangement may comprise a lock member or pawl.

The lock member may comprise a pin or a yoke. The guide portion may comprise a wheel having a circumferential groove or circumferential teeth.

When in a locked disposition a face, e.g. lock face, e.g. adjacent a/the locked link, of the lock member may face the arrangement for connecting the apparatus to the second mooring line.

According to aspects of the present invention, there is provided an apparatus for mooring a structure and tensioning a mooring chain according to the appended claims.

The lock arrangement may be provided or providable between the guide portion and a structure to be moored along a path of a mooring line, for example, along the mooring chain path.

When in a locked disposition a face, e.g. lock face, e.g. adjacent a/the locked
link, of the lock member may face the arrangement for connecting the apparatus to the second mooring line. A part or point, e.g. peripheral or circumferential part or point, of the guide portion may be provided between the second mooring line connection arrangement and the lock arrangement/member when in a locked disposition.

The guide portion may be circular and/or comprise a wheel.

In a locked disposition a tangent or tangential line of or extending from a portion (circumferential portion) the guide portion may pass through the lock arrangement or member and the second mooring line connection arrangement.

The tangent or tangential line may touch the guide portion at a point at or adjacent the lock arrangement or member, at least when in a locked disposition.

By this arrangement there may be provided, in use, a linear load path comprising a (linear) portion of the first mooring chain path or tensioned portion of a first mooring chain, the tangent or tangential line of the guide portion, and a (linear) portion of a second mooring line path or path of a second mooring line.

Advantageously by this arrangement no load may be taken around the guide portion or around a curved portion of the first mooring chain portion.

Tension on the first mooring chain may, therefore, be taken at or near a contact point with the guide portion and not around the guide portion.

A radius of the guide portion extending perpendicularly to a line (or the tangential line) extending between the second mooring line connection arrangement and the lock arrangement/lock member, (at least when in a locked disposition) may intersect said line at a location between the second mooring line connection arrangement and the lock arrangement/member.

In other words, the load member (stopper) is beneficially in front of the guide wheel along a tensioned/tensionable portion of the first mooring chain portion.

An advantage of having the lock arrangement in front of the guide portion may be that the guide portion is not exposed to load. Loaded wheels on fairleads are known to cause additional stresses in mooring chains. In the present invention a load is transmitted through the lock arrangement rather than through the mooring guide portion.

The lock arrangement may be provided so that a portion of the lock arrangement operates inside a projected footprint (diameter) of the movable guide portion (i.e. wheel). The lock arrangement may operate/pivot/articulate from an opposite side of the first mooring chain portion to the movable guide portion or adjacent an intended mooring line contact point with the guide portion (e.g. a tangent point of the incoming tensioning chain). This may ensure that a bulk of a load may be transmitted to the lock arrangement and not into the guide portion. Such may also allow the incoming chain direct contact with the movable guide portion on entry to create a smooth entry in most conditions. The movable guide portion (wheel), chain and lock arrangement are designed to mesh, overlap or interact, in use.

The guide portion and lock arrangement/lock member may act as or comprise a ratchet mechanism.

A tensioning side of the lock member or ratchet may extend around the guide portion. A tensionable/tensioned side of the lock member may extend away from the guide portion.

In a locked configuration, a locked link and/or a first loaded link, may be provided in a linear arrangement with the lock member and tangential line from the guide portion, e.g. along a linear load path.

The lock arrangement may comprise a counterweight, which may be formed with, connected to, or releasably connectable to the lock member.

The guide portion and lock member may be configured such that, in use, a locked link engages or abuts with the guide portion.

The locked link may (also) engage or abut with the lock arrangement/member/lock face of the lock member.

The aforementioned configuration may allow a first (axially) loaded link to be disposed, in use, to be substantially tangential to the guide portion, e.g. on a/the tangential line.

The first mooring chain path may comprise a first lockable or locked or tensioned/tensionable portion, e.g. extending (linearly) from the tangential line contact point on the guide portion, e.g. away from the mooring apparatus.

The first mooring chain path may comprise a second free, pullable or tensioning portion or end, e.g. extending from the tangential line contact point on the guide portion, e.g. at least partially around the guide portion.

When in an open or unlocked disposition, the lock member or lock face may be on an external angle of the first mooring chain path and/or on an opposite side of the mooring chain path from the guide portion.

When in a closed or locked disposition at least part of the lock member or lock face may be in or on the first mooring chain path and/or may face the second mooring line connection arrangement.

A pivot (point) of the lock arrangement or lock member may be on the exterior angle or opposite side of the first mooring chain path than the guide portion.

The apparatus or device of the present invention may provide for a lock arrangement which is significantly closer to the guide portion than in the prior art. This may result in one or more advantages, e.g. reduced length, reduced weight, and/or reduced cost of the apparatus or device.

The apparatus or device of the present invention may also provide advantage over one or more prior art apparatus in that, in use, the mooring line around the guide portion is not under tension when the structure is moored since tension is taken by the lock arrangement.

The mooring chain path may comprise or include a curved path.

The mooring chain path may comprise an included or interior angle α and an excluded or exterior angle β.

The guide portion may be provided on or within the interior angle α of the mooring path.

The lock arrangement or means may be provided on or within the exterior angle β of the mooring chain path, at least in an unlocked disposition.

The present invention may provide an advantage over the prior art in that the lock arrangement or means may be provided on or outside of the included angle of the mooring chain path, e.g. underneath or below the apparatus or device. This may be beneficial in allowing access to the lock arrangement or means.

The present invention may provide an advantage over the prior art in that, in use, the lock arrangement may grasp or tensions the first mooring chain prior to the first mooring chain extending around the guide portion. The first mooring chain may, therefore, not be under tension around the guide portion.

The apparatus or device may comprise a body or frame.

The guide portion may be movably, e.g. rotatably, mounted on (or relative to) the body.

The lock arrangement or means may comprise a lock member, e.g. having a lock face or side. In a first, unlocked, disposition the lock member may be distal or non-coincident with the mooring chain path. In a second, locked, disposition at least part of the lock member may be coincident with the mooring chain path. For example, in said second disposition, an end of the lock member may engage with the mooring line, e.g. with a link of a mooring line comprising a mooring chain.

The lock member may be connected to or provided on the body, e.g. pivotably attached to the body. A pivot point of the lock member may be on an opposite side of the mooring chain path than the guide portion.

The end of the lock member may be closer to a structure to be moored when in the second locked disposition than when in the first, unlocked, disposition.

The connection arrangement may be provided on the body.

The apparatus or device may comprise or be referenced as a "mid-line tensioner".

The guide portion may comprise a circular member or wheel. The guide portion may comprise a plurality of circumferentially disposed teeth and/or a circumferential groove or recess, which may, in use, co-act with a/the end of the lock member, for example, so as to lock a/the mooring line relative to the apparatus or device when the lock member is in the second locked disposition.

The lock arrangement may be conveniently referred to as a 'chain stopper'.

The guide portion may comprise first and second sides, which may be circular, and which may comprise respective first and second teeth, pairs of which may be circumferentially aligned, for example, face one another.

At least a portion of the mooring chain path may be provided between the first and second sides of the guide portion.

The body comprises a guide arrangement for guiding a portion of a mooring line into or out of the apparatus or device. In one implementation the guide arrangement may comprise a pair of opposing guide members. In an alternative implementation the guide arrangement may comprise an open channel for guiding and/or seating the first mooring chain.

The lock arrangement is provided between the guide portion and the guide arrangement.

In use, when tension is applied to an end of a mooring line distal a structure to be moored or on an opposite side of the apparatus or device from a structure, the lock member will tend towards or be disposed in the first, unlocked, disposition.

In use, when tension is removed from an end of a mooring line distal a structure or an opposite side of the apparatus or device from a structure, the lock member will tend towards or be disposed in the second, unlocked, disposition.

By this apparatus a (first) mooring line may be tensioned.

The lock arrangement may comprise a mooring line lock, e.g. capable of locking or retaining the first mooring chain.

In use, at least a portion of the first mooring chain may be disposed, locked and/or secured by the lock arrangement. The at least a portion of the first mooring chain may comprise a locked link. A link adjacent the locked link in a direction away from the guide portion may comprise a first loaded link.

The lock may be adapted to secure and/or lock the first mooring chain between the lock arrangement and a portion, e.g. an outer peripheral/circumferential portion, of the guide portion.

The guide portion may be rotatably connected to the body, e.g. on or around an axis.

The lock arrangement may be hingedly or pivotably connected to the body.

Beneficially least a portion of the second mooring line may be a chain, or alternatively wire, rope, or the like.

The guide portion may be a sheave or wheel and/or may be substantially circular, such as a mooring line wheel or a chain wheel which may be rotatable relative to the body, such as around a central axis of the guide portion. The guide portion may be a sprag wheel. The guide portion may be a sheave. The guide portion may be a toothed wheel, such as a cogwheel or the like.

According to an example, there is provided an (mooring) apparatus or device for mooring a structure, the apparatus or device comprising:.

The apparatus or device may provide a mooring chain path. The lock arrangement or means may be provided on an opposite side of the mooring chain path from the guide portion (at least in an unlocked disposition). The lock arrangement may be (adapted to be) provided between the guide portion and a structure to be moored, in use (at least in a locked disposition).

The guide portion may be provided on the side of or within the included angle.

According to an example, there is provided an apparatus or device for mooring a structure and/or tensioning a mooring line, the apparatus comprising:
a body or frame:.

According to an example, there is provided an apparatus or device for mooring a structure and/or tensioning a morning line, the apparatus comprising:
a body or frame:.

According to an aspect of the present invention there is provided a system for tensioning a first mooring chain, according to the appended claims.

The system may comprise a first mooring chain. The system may comprise a second mooring line or chain.

The system may comprise at least one structure, such as a floating structure, an offshore structure, a floating platform or the like.

A portion of the first mooring chain may be threaded or threadable through the apparatus or device.

A first portion or end of the first mooring chain may be configured to be connected or connectable to the structure or device.

The system may comprise a buoy. The system may comprise a floating vessel. The system may comprise a winch and/or a pulley. The winch and/or pulley may be located on or in the floating vessel. The buoy may be a submersible buoy, a semi-submersible buoy, a submerged turret production buoy, a submerged turret loading buoy or the like.

A second portion or end of the first mooring chain may be configured to be connected to the buoy and/or the floating vessel and/or the winch and/or the pulley. The winch and/or pulley may be adapted to set, adjust or increase a tension in the first mooring chain.

A first portion or end of the second mooring line may be connected to at least a portion of the apparatus. The first portion or end of the second mooring line may be connected to the body. The first portion of the second mooring line may be releasably connected to the body.

The system may comprise an anchor. The anchor may comprise an anchoring point. The anchor may be a pile, such as a suction pile or the like. The anchor may be a subsea formation. The anchor may be adapted for use on a seabed.

A second portion of the second mooring line may be connected to the anchor or to the anchoring point.

According to an aspect of the present invention there is provided a method of tensioning a first mooring chain according to the appended claims.

The pulling force may cause the apparatus or device to pull at least one other portion of the first mooring chain towards a second mooring line.

The pulling force may cause the apparatus or device to pull at least one other portion of the first mooring chain towards the apparatus.

When an appropriate or desired tension has been applied to the mooring line, the lock arrangement may be disposed in the locked position.

When an appropriate or desired tension has been applied to the mooring line, the first portion or end of the first mooring chain may be attached to a buoy, or the like.

When an appropriate tension has been applied to the mooring line, at least a portion of the first portion of the first mooring chain may be cut away and/or removed and/or secured to the apparatus or device and/or secured to the first mooring chain and/or second mooring line.

According to an aspect of the present invention there is provided a method for releasing tension in a mooring line, according to the appended claims.

The step of retaining the lock arrangement in the unlocked disposition may require removal and/or repositioning and/or insertion of at least one locking pin.

According to an example which is not part of the claimed invention, there is provided an apparatus or device for mooring a structure, the apparatus or device comprising:.

The open channel may comprise a partial-cruciform or half-cruciform shaped surface.

The open channel may comprise a first U-shaped or D-shaped surface, with a second, smaller D-shaped or U-shaped surface disposed at a mid-point of the first U-shaped or D-shaped surface.

The open channel may comprise a first cupped or cup-shaped surface, with a second, smaller cup-shaped or cupped, D-shaped or U-shaped surface disposed at a mid-point of the first cupped or cup-shaped surface.

That is, the open channel may comprise a substantially recessed or concave first portion, with a second, recessed portion disposed at a mid-point of the first portion. The open channel may comprise a substantially recessed or concave first portion, with a second, deeper recessed portion disposed at a mid-point of the first portion.

The open channel may comprise a first trough, with a second smaller trough disposed at a mid-point of a deepest portion of the first trough. The open channel may comprise a first trough, with a second smaller trough disposed at a deepest portion of the first trough.

A cross-section of the open channel may be substantially T-shaped.

The partial-cruciform or half-cruciform shaped surface may be shaped and sized to conform to at least a portion of the first mooring chain, e.g. shaped and sized to conform to a mooring line or chain.

The partial-cruciform or half-cruciform shaped surface may be configured to seat the mooring line.

A surface of the open channel, or the partial-cruciform or half-cruciform shaped surface, may be configured to inhibit pivoting of the mooring line relative to the body in a first direction perpendicular to the mooring chain path and away from the guide portion.

The open channel may be provided to allow pivoting of the mooring line relative to the body between a/the surface of the open channel and the guide portion.

The open channel may comprise sidewalls configured to inhibit pivoting of the mooring line in a third direction, the third direction being perpendicular to the mooring chain path and the first direction.

The open channel may be located or disposed at or adjacent a periphery of the body.

The open channel may be located or disposed at an entry and/or exit point of or from the apparatus.

The entry and/or exit point may be an entry and/or exit point of the mooring line, e.g. an entry and/or exit point of the mooring line relative to the body.

The open channel may be provided between the guide portion and a structure to be moored, in use.

The body may comprise a connection portion for connecting the apparatus or device to a second mooring line. The guide portion may be disposed between the connection portion and the open channel.

The connection portion may be disposed on the body such that, during tensioning of the first mooring chain and/or second mooring line, the first mooring chain moves or pivots relative to the body in response to a tilting or rotation of the body. The movement or pivoting of the first mooring chain relative to the body may be movement or pivoting between a/the surface of the open channel and the guide portion.

In use, the first mooring chain may be free to move or pivot in the open channel, relative to the body.

The connection portion may be disposed on the body such that, during tensioning of the first mooring chain and second mooring line, the body tends to tilt or rotate to align a line between a centre of the guide portion and the connection portion with the second mooring line.

The connection portion may comprise a pad-eye, shackle or clevis.

The apparatus may comprise a lock arrangement or means.

The lock arrangement or means may be adapted to engage the first mooring chain to inhibit movement of the mooring line relative to the body in a direction along the mooring chain path and allow movement of the mooring line relative to the body in an opposite direction along the mooring chain path.

The lock arrangement or means may be provided on an opposite side of the mooring chain path from the guide portion.

The lock arrangement or means may be adapted to be provided between the guide portion and a structure to be moored, in use.

The lock arrangement may be provided between the guide portion and a structure to be moored along a path of a mooring line, for example, along the mooring chain path.

The lock arrangement may be provided proximal or adjacent the guide portion.

The lock arrangement or means may be configurable to straddle the guide portion.

The lock arrangement may comprise a yoke. The yoke may be configured to straddle the guide portion. The yoke may be configured to straddle the first mooring chain.

The lock arrangement may comprise a finger. The finger may be configured to interfere with, such as abut, the guide portion. The finger may be configured to interfere with, such as abut, the first mooring chain.

The lock arrangement or means may be configurable to straddle the first mooring chain.

The lock arrangement or means may comprise a lock member. In a first, unlocked, disposition the lock member may be distal or non-coincident with the mooring chain path. In a second, locked, disposition at least part of the lock member may be coincident with the mooring chain path. For example, in said second disposition, an end of the lock member may engage with the (first) mooring line, e.g. with a link of a mooring line comprising a mooring chain.

The lock member may be connected to or provided on the body, e.g. pivotably attached to the body.

A/the end of the lock member may be closer to a structure to be moored when in the second locked disposition than when in the first, unlocked, disposition.

The lock arrangement or means may comprise a pivotable member or clacker. The lock member may be a pivotable member or clacker.

The lock arrangement or means may comprise a counterweight, e.g. removable counterweight, for biasing the lock arrangement or means or the pivotable member or clacker towards engagement with the first mooring chain.

A point of rotation of the pivotable member or clacker may be provided on the opposite side of the mooring chain path from the guide portion.

The lock arrangement or means may be adapted to hold or seat the mooring line between the guide portion and the pivotable member or clacker.

In use, at least a portion of the first mooring chain may be disposed between the lock arrangement or means and the guide portion.

The mooring chain path may comprise a curved path.

The lock arrangement or means may be provided, e.g. in a first (unlocked) disposition, on or within the exterior angle β of the mooring chain path.

The guide portion may be movably, e.g. rotatably, mounted on the body.

The guide portion may comprise a chain wheel, a sprocket or a pocket wheel. The guide portion may be substantially circular, such as a mooring line wheel or a chain wheel which is rotatable relative to the body, such as around a central axis of the guide portion. The guide portion may be a sprag wheel. The guide portion may be a sheave. The guide portion may be a toothed wheel, such as a cogwheel, or the like.

The apparatus or device may be suitable for offshore and/or subsea operations and may be submerged, in use. By this apparatus a (first) mooring line may be tensioned.

The apparatus may be known as and/or referred to as a "mid-line tensioner" and/or "inline tensioner".

The apparatus may be a mid-line tensioner.

In use, at least a portion of the first mooring chain may be disposed, locked and/or secured by the lock arrangement.

The lock may be adapted to secure and/or lock the first mooring chain between the lock arrangement and an outer peripheral/circumferential portion of body.

At least a portion of the second mooring line may be a chain, wire, rope, or the like.

According to an example which is not part of the claimed invention, there is provided an apparatus or device for mooring a structure, the apparatus or device comprising: a body and a guide portion for guiding at least a portion of a first mooring chain along a mooring chain path; a connection portion for connecting the body to a second mooring line; wherein during tensioning of the first mooring chain and the second mooring line, the apparatus or device is configured to permit movement or pivoting of the first mooring chain relative to the body into a space or gap between the guide portion and the body, in response to a tilting or rotation of the body.

According to an example which is not part of the claimed invention, there is provided an apparatus or device for mooring a structure, the apparatus or device comprising: a body and a guide portion for guiding at least a portion of a first mooring chain along a mooring chain path; a connection portion for connecting the body to a second mooring line; wherein the connection portion is disposed on the body such that, during tensioning of the first mooring chain and the second mooring line, the body tends to tilt or rotate to align a line between a centre of the guide portion and the connection portion with the second mooring line.

According to an example which is not part of the claimed invention, there is provided an apparatus or device for mooring a structure, the apparatus or device comprising: a guide portion for guiding at least a portion of a first mooring chain; a lock arrangement or means adapted to engage the first mooring chain; wherein the guide portion is adapted to engage the first mooring chain, and wherein the lock arrangement is configurable to straddle the guide portion and/or the first mooring chain.

According to an example which is not part of the claimed invention, there is provided a (mooring) system for tensioning a first mooring chain, the system comprising at least one device or apparatus according to the previous examples, the first mooring chain, and a second mooring line.

The first mooring chain may be a chain and the open channel may be shaped and sized to conform to a longitudinally cross-sectional view of the first mooring chain.

The system may moor or may comprise at least one structure, such as a floating structure, an offshore structure, a floating platform or the like.

It should be understood that the features defined above in accordance with any aspect of the present invention or below relating to any specific embodiment of the invention may be utilised, either alone or in combination with any other feature of or defined in any other aspect or embodiment, e.g. so as to form a further aspect or embodiment of the present invention. Such further combinations are not recited herein merely for reasons of brevity.

Embodiments of the present invention will now be described by way of example only, and with reference to the accompanying drawings, which are:.

Referring initially to <FIG>, there is shown a chain tensioner generally designated <NUM>, according to the prior art as disclosed in <CIT> (SINGLE BUOY MOORINGS). As shown in <FIG>, a chain tensioner <NUM> is fixedly attached with a connection side <NUM> to an upper end of chain section <NUM> via a chain link <NUM> and connector member, such as a bow shackle <NUM>. Instead of chain section <NUM>, a wire rope or other line section is utilised to connect to side <NUM> of the chain tensioner device <NUM> using a suitable connector member. During connection of the upper end of chain section <NUM> to the chain tensioner device <NUM>, the chain section <NUM> remains clamped on deck of the vessel. A working chain <NUM> having a length of for instance <NUM> metres, is on deck of a vessel movably passed through the chain tensioner <NUM> by feeding tensioning chain section <NUM> that is formed by the lower part of the working chain <NUM> via an entry side <NUM> of the chain tensioner <NUM> through a chain stopper <NUM> and along a sheave <NUM>. The chain stopper <NUM> functions as a ratchet and only allows passage of the working chain <NUM> through the tensioner housing <NUM> in the direction of the shorter tensioning chain part <NUM> that becomes longer upon pulling it in the direction indicated as T. The tensioning chain part <NUM> of the tensioning chain <NUM> is guided via the rotatable sheave <NUM> out through an opening <NUM> in the housing <NUM> of the chain tensioner <NUM>. A pulling eye <NUM> of relatively large diameter is attached to tensioner chain part <NUM> for handling by a remote operated vehicle (ROV).

Referring now to <FIG> and <FIG>, there is shown an apparatus for mooring a structure, the apparatus comprising a mooring tensioner, generally designated <NUM> according to the prior art as disclosed in <CIT> (FLINTSTONE TECHNOLOGY LIMITED).

Referring now to <FIG>, there is shown a (mooring and/or tensioning) apparatus or device, generally designated <NUM>, according to an embodiment of the present invention. Hereinafter the apparatus or device <NUM> will be referred to as apparatus <NUM>.

The lock arrangement <NUM> is providable between the guide portion <NUM> and a structure <NUM> to be moored along a path of a mooring line, i.e. along the mooring chain path <NUM>.

The lock arrangement <NUM> is provided proximal or adjacent the guide portion <NUM>.

The apparatus <NUM> provides for a lock arrangement <NUM> which is significantly closer to the guide portion <NUM> than in the prior art. This can result in one or more advantages, e.g. reduced length, reduced weight, and/or reduce the cost of the apparatus <NUM>.

The apparatus <NUM> also provides advantage over one or more prior art apparatus in that, in use, the mooring line <NUM> around the guide portion <NUM> is not under tension when the structure <NUM> is moored, since tension is taken by the lock arrangement <NUM>.

The mooring chain path <NUM> comprises a curved path. The mooring chain path <NUM> comprises an included or interior angle α, and an excluded or exterior angle β.

The guide portion <NUM> is provided on or within the interior angle α of the mooring chain path. The lock arrangement <NUM> is provided on or within the exterior angle β of the mooring chain path <NUM>, i.e. on an opposite side of the mooring chain path from the guide portion <NUM>, at least in an unlocked disposition.

The apparatus <NUM> comprises a body <NUM>. The guide portion <NUM> is movably, i.e. rotatably, mounted on the body <NUM>.

The lock arrangement <NUM> comprises a lock member <NUM> having a lock face or side <NUM>. In a first (unlocked) disposition, the lock member <NUM> is distal or non-coincident with the mooring chain path <NUM>. In a second (locked) disposition, at least part of the lock member <NUM> is coincident with the mooring chain path <NUM>. (Further details with regard to the operation of the apparatus <NUM> can be understood from <FIG> and <FIG>). For example, in said second disposition, an end <NUM> of the lock member <NUM> engages with the mooring line <NUM>, e.g. with a link <NUM> of a mooring line <NUM> comprising a mooring chain. The lock member <NUM> can be biased to the second disposition by biasing means (not shown).

The lock member <NUM> is connected to or provided on the body <NUM>, i.e. pivotably attached to the body <NUM>. A pivot <NUM> of the lock member <NUM> is on an opposite side of the mooring chain path <NUM> than the guide portion <NUM>.

The end <NUM> of the lock member <NUM> is closer to a structure <NUM> to be moored when in the second, locked, disposition than when in the first, unlocked, disposition.

The body <NUM> comprises an arrangement <NUM> for connecting or coupling the apparatus <NUM> to a second mooring line150.

The guide portion <NUM> comprises a circular member or wheel. The guide portion <NUM> comprises a plurality of circumferentially disposed teeth <NUM>, which may, in use, co-act with a/the end <NUM> of the lock member <NUM>, for example, so as to lock a/the mooring line <NUM> relative to the apparatus <NUM> when the lock member <NUM> is in the second (locked) disposition. The lock member <NUM>, therefore, acts as a pawl, which together with the toothed guide portion <NUM> can act as a ratchet type mechanism.

The lock arrangement <NUM> is conveniently referred to as a "'chain stopper".

In this embodiment the guide portion <NUM> comprises first and second sides, which are circular and comprise respective first and second teeth 155a, 155b, pairs of which are circumferentially aligned, i.e. face one another.

At least a portion of the mooring chain path <NUM> is provided between the first and second sides of the guide portion <NUM>.

The body <NUM> comprises a guide arrangement <NUM> for guiding a portion of a mooring line <NUM> into or out of the apparatus <NUM>. In this embodiment the guide arrangement <NUM> comprises a pair of opposing guide members.

The lock arrangement <NUM> is provided between the guide portion <NUM> and the guide arrangement <NUM>.

In use, when tension is applied to an end of a mooring line <NUM> distal a structure <NUM> or on an opposite side of the apparatus <NUM> from a structure <NUM>, the lock member <NUM> will tend towards or be disposed in the first (unlocked) disposition. This allows the mooring line <NUM> to be tensioned.

In use, when tension is removed from an end of a mooring line <NUM> distal a structure <NUM> or an opposite side of the apparatus <NUM> from a structure <NUM>, the lock member <NUM> will tend towards or be disposed in the second (locked) disposition. This allows the mooring line <NUM> to be locked (relative to the apparatus <NUM>).

By this apparatus <NUM> a (first) mooring line <NUM> may be tensioned. The apparatus <NUM> comprises and/or can be referred to as a "mid-line tensioner".

The lock arrangement <NUM> comprises a mooring line lock, i.e. capable of locking or retaining the first mooring chain <NUM>.

In use, at least a portion of the first mooring chain <NUM> is disposed, locked and/or secured by the lock arrangement <NUM> and the guide portion <NUM>.

The at least a portion of the first mooring chain <NUM> comprises a locked link <NUM>. A link adjacent the locked link <NUM> in a direction away from the guide portion <NUM> can be referred to as a first loaded link <NUM>. The lock member <NUM> has a lock face <NUM>.

The lock arrangement <NUM> is adapted to secure and/or lock the first mooring chain <NUM> between the lock arrangement <NUM> and an outer peripheral portion of body <NUM>.

The guide portion <NUM> is rotatably connected to the body <NUM>, e.g. on or around an axis.

The lock arrangement <NUM> and/or lock member <NUM> is hingedly or pivotably connected to the body <NUM>, beneficially on a side of the mooring chain path opposite the guide portion <NUM>.

At least a portion of the second mooring line <NUM> can be a chain, wire, rope, or the like.

The guide portion <NUM> can be a sheave or wheel, and/or can be substantially circular, such as a mooring line wheel or a chain wheel which can be rotatable relative to the body <NUM>, such as around a central axis A of the guide portion <NUM>. The guide portion <NUM> can be a sprag wheel. The guide portion <NUM> can be a sheave. The guide portion <NUM> can be a toothed wheel, such as a cogwheel, or the like.

The present invention provides an (mooring) apparatus or device <NUM> for mooring a structure <NUM>, the apparatus or device <NUM> comprising:.

The apparatus <NUM> provides mooring chain path <NUM>. The lock arrangement <NUM> is provided on an opposite side of the mooring chain path <NUM> from the guide portion <NUM>. The lock arrangement <NUM> is provided between the guide portion <NUM> and a structure <NUM> to be moored, in use.

Referring to <FIG>, the present invention provides a system <NUM> for tensioning a (first) mooring line <NUM>, the system <NUM> comprises at least one mooring apparatus <NUM> as hereinbefore described.

The system <NUM> comprises a first mooring chain <NUM>. The system <NUM> comprises a second mooring line <NUM>.

The system <NUM> moors at least one structure <NUM>, such as a floating structure, an offshore structure, a floating platform or the like.

A portion of the first mooring chain <NUM> is threaded or threadable through the apparatus <NUM>.

A first portion or end <NUM> of the first mooring chain <NUM> is configured to be connected or connectable to the structure <NUM>.

The system <NUM> can comprise a buoy (not shown). The system <NUM> comprises a floating vessel <NUM>. The system <NUM> comprises a winch and/or a pulley <NUM>. The winch and/or pulley <NUM> may be located on or in the floating vessel <NUM>. The buoy can be a submersible buoy, a semi-submersible buoy, a submerged turret production buoy, a submerged turret loading buoy or the like.

A second portion or end <NUM> of the first mooring chain <NUM> is configured to be connected to the buoy and/or the floating vessel and/or the winch and/or the pulley <NUM>. The winch and/or pulley <NUM> can be adapted to set, adjust or increase a tension in the first mooring chain <NUM>.

A first portion or end <NUM> of the second mooring line <NUM> can be connected to at least a portion of the apparatus <NUM>. The first portion or end <NUM> of the second mooring line <NUM> can be connected to the body <NUM>. The first portion of the second mooring line <NUM> can be releasably connected to the body <NUM>.

The system <NUM> comprises an anchor <NUM>. The anchor <NUM> comprises an anchoring point. The anchor <NUM> can be a pile, such as a suction pile or the like. The anchor <NUM> can be a subsea formation. The anchor <NUM> can be adapted for use on a seabed <NUM>.

A second portion <NUM> of the second mooring line <NUM> can be connected to the anchor <NUM> or to the anchoring point.

The present invention provides a method of tensioning a (first) mooring line <NUM>, wherein the method comprises:
providing a system <NUM> for tensioning a (first) mooring line <NUM> as hereinbefore described, the method (further) comprising:
applying a pulling force to a portion <NUM> of a first mooring chain <NUM> in a direction away from the apparatus <NUM>.

The pulling force can cause the apparatus <NUM> to pull at least one other portion of the first mooring chain <NUM> towards a second mooring line <NUM>.

The pulling force can cause the apparatus <NUM> to pull at least one other portion of the first mooring chain <NUM> towards the apparatus <NUM>.

When an appropriate or desired tension has been applied to the mooring chain <NUM>, the lock arrangement <NUM> can be disposed in the locked position.

When an appropriate or desired tension has been applied to the mooring line <NUM>, the portion or end <NUM> of the first mooring chain <NUM> can be attached to a buoy, or the like.

When an appropriate tension has been applied to the mooring line <NUM>, at least a portion of the first portion of the first mooring chain <NUM> can be cut away and/or removed and/or secured to the apparatus <NUM> and/or secured to the first mooring chain <NUM> and/or second mooring line <NUM>.

The present invention provides a method for releasing tension in a mooring line, the method comprising:
providing a system for tensioning a mooring line as hereinbefore described, the method (further) comprising:.

The step of retaining the lock arrangement <NUM> in the unlocked disposition can require removal and/or repositioning and/or insertion of at least one locking pin (not shown).

Referring now to <FIG> and <FIG>, there is shown a mooring and/or tensioning apparatus or device, generally designated <NUM>, according to an embodiment of the present invention. Hereinafter the apparatus or device <NUM> will be referred to as apparatus <NUM>.

The apparatus <NUM> comprises a body <NUM> and a guide portion <NUM> for guiding at least a portion of a first mooring chain <NUM> along a mooring chain path <NUM>. The body <NUM> comprises an open channel <NUM> for guiding and seating the first mooring chain <NUM>.

The open channel <NUM> comprises a partial-cruciform or half-cruciform shaped surface, as can be seen more clearly in <FIG>, which shows a front view of the body <NUM> of the mooring apparatus <NUM> of <FIG> and <FIG>. That is, a cross-section of the open channel <NUM> is substantially T-shaped, as described in more detail below.

The open channel <NUM> comprises a first U-shaped surface <NUM>, with a second, smaller U-shaped surface <NUM> disposed at a mid-point of the first U-shaped shaped surface <NUM>. In other embodiments, the open channel <NUM> comprises a first D-shaped surface, with a second, smaller D-shaped surface disposed at a mid-point of the first D-shaped shaped surface. In yet further embodiments, the open channel <NUM> corresponds to a first trough <NUM>, with a second smaller trough <NUM> disposed at a mid-point of the deepest portion of first trough <NUM>.

The surface <NUM>, <NUM> of the open channel is shaped and sized to conform to at least a portion of the first mooring chain <NUM>.

The surface <NUM>, <NUM> of the open channel <NUM> is configured to seat the mooring line <NUM>.

The surface <NUM>, <NUM> of the open channel <NUM> is configured to inhibit pivoting of the mooring line <NUM> relative to the body <NUM> in a first direction <NUM> perpendicular to the mooring chain path <NUM> and away from the guide portion <NUM>.

The open channel <NUM> is provided to allow pivoting of the mooring line <NUM> relative to the body <NUM> between a/the surface of the open channel <NUM> and the guide portion <NUM>.

The open channel <NUM> may comprise sidewalls <NUM>, <NUM> configured to inhibit pivoting of the mooring line <NUM> in a third direction <NUM>, the third direction being perpendicular to the mooring chain path <NUM> and the first direction <NUM>.

The body <NUM> comprises a connection portion <NUM> for connecting or coupling the apparatus <NUM> to a second mooring line (not shown).

The connection portion <NUM> may comprise a pad-eye, shackle or clevis. In the example embodiment of <FIG>, <FIG> and <FIG>, the connection portion <NUM> is a padeye.

The guide portion <NUM> is disposed between the connection portion <NUM> and the open channel <NUM>.

The connection portion <NUM> is disposed on the body <NUM> such that, during tensioning of the first <NUM> mooring chain and second mooring line, the first mooring chain <NUM> moves or pivots relative to the body <NUM> in response to a tilting or rotation of the body <NUM>. The movement or pivoting of the first mooring chain <NUM> relative to the body <NUM> is movement or pivoting between the surface <NUM>, <NUM> of the open channel <NUM> and the guide portion <NUM>.

In use, the first mooring chain <NUM> is free to move or pivot in the open channel <NUM>, relative to the body <NUM>.

The connection portion <NUM> is disposed on the body <NUM> such that, during tensioning of the first mooring chain and second line, the body <NUM> tends to tilt or rotate to align a line <NUM> between a centre of the guide portion and the connection portion with the second mooring line.

The apparatus <NUM> further comprises a lock arrangement or means <NUM>, wherein the lock arrangement <NUM> is provided on an opposite side of the mooring chain path <NUM> from the guide portion <NUM>, and the lock arrangement <NUM> is provided between the guide portion <NUM> and a structure to be moored, in use.

The lock arrangement <NUM> is provided between the guide portion <NUM> and a structure (not shown) to be moored along a path of a mooring line, i.e. along the mooring chain path <NUM>.

The lock arrangement <NUM> is adapted to engage the first mooring chain <NUM> to inhibit movement of the first mooring chain <NUM> relative to the body <NUM> in a direction along the mooring chain path <NUM> and allow movement of the first mooring chain <NUM> relative to the body <NUM> in an opposite direction along the mooring chain path <NUM>.

The lock arrangement <NUM> is provided, e.g. at least in an unlocked disposition, on an opposite side of the mooring chain path <NUM> from the guide portion <NUM>'.

The lock arrangement <NUM> is adapted to be provided, e.g. at least in a locked disposition, between the guide portion <NUM> and a structure to be moored, in use.

In the example embodiment of <FIG>, <FIG> and <FIG>, the lock arrangement <NUM> is configurable to straddle the guide portion <NUM>. In the example embodiment of <FIG>, <FIG> and <FIG>, the lock arrangement <NUM> is configurable to straddle the first mooring chain <NUM>.

The lock arrangement <NUM> comprises a pivotable member or clacker <NUM>, as shown in <FIG>.

The lock arrangement <NUM> comprises a counterweight <NUM> (which can be removable) for biasing the pivotable member or clacker <NUM> towards engagement with the first mooring chain <NUM>.

The lock arrangement <NUM> is adapted to hold or seat the mooring line <NUM> between the guide portion <NUM> and the pivotable member or clacker <NUM>.

In use, at least a portion of the first mooring chain <NUM> is disposed between the lock arrangement <NUM> and the guide portion <NUM>.

The apparatus <NUM> also provides advantage over one or more prior art apparatus in that, in use, the mooring line <NUM> around the guide portion <NUM> is not under tension when the structure (not shown) is moored, since tension is taken by the lock arrangement <NUM>.

The mooring chain path <NUM> comprises a curved path. The mooring chain path <NUM> comprises an included or interior angle e and an excluded or exterior angle ϕ.

The guide portion <NUM> is provided on or within the interior angle e of the mooring chain path. The lock arrangement or means <NUM> is provided, at least in an unlocked disposition, on or within the exterior angle ϕ of the mooring chain path <NUM>, i.e. on an opposite side of the mooring chain path from the guide portion <NUM>.

The apparatus <NUM> comprises a body <NUM>. The guide portion <NUM> is movably, e.g. rotatably, mounted on the body <NUM>.

The lock arrangement <NUM> comprises a lock member <NUM>, e.g. pivotable member or clacker <NUM>. In a first (unlocked) disposition, the lock member <NUM> is distal or non-coincident with the mooring chain path <NUM>. In a second (locked) disposition, at least part of the lock member <NUM> is coincident with the mooring chain path <NUM>. For example, in said second disposition, an end <NUM> of the lock member <NUM> engages with the mooring line <NUM>, e.g. with a link <NUM> of a mooring line <NUM> comprising a mooring chain. The lock member <NUM> can be biased to the second disposition by biasing means (not shown).

The lock member <NUM> is connected to or provided on the body <NUM>, e.g. pivotably attached to the body <NUM>.

The end <NUM> of the lock member <NUM> is closer to a structure (not shown) to be moored when in the second, locked, disposition than when in the first, unlocked, disposition.

The apparatus <NUM> comprises a mid-line tensioner.

The guide portion <NUM> comprises a circular member or wheel. The guide portion <NUM> comprises a plurality of circumferentially disposed teeth <NUM>, which may, in use, co-act with a/the end <NUM> of the lock member <NUM>, for example, so as to lock a/the mooring line <NUM> relative to the apparatus <NUM> when the lock member <NUM> is in the second locked disposition. The lock member <NUM>, therefore, acts as a pawl, which together with the toothed guide portion <NUM> can act as a ratchet type mechanism.

The lock arrangement <NUM> is conveniently referred to as a "chain stopper".

The lock arrangement <NUM> is provided between the guide portion <NUM> and the open channel <NUM>.

In use, when tension is applied to an end of a mooring line <NUM> distal a structure (not shown) or on an opposite side of the apparatus <NUM> from a structure, the lock member <NUM> will tend towards or be disposed in the second (locked) disposition. This allows the mooring line <NUM> to be tensioned.

In use, when tension is removed from an end of a mooring line <NUM> distal a structure (not shown) or an opposite side of the apparatus <NUM> from a structure, the lock member <NUM> will tend towards or be disposed in the first (unlocked) disposition.

By this apparatus <NUM> a (first) mooring line <NUM> may be tensioned. The apparatus <NUM> can be referred to as a "mid-line tensioner".

The lock arrangement <NUM> and/or lock member <NUM> is hingedly or pivotably connected to the body <NUM>.

The guide portion <NUM> can be a wheel and/or can be substantially circular, such as a mooring line wheel or a chain wheel which is rotatable relative to the body <NUM>, such as around a central axis of the guide portion <NUM>. The guide portion <NUM> can be a sprag wheel. The guide portion <NUM> can be a sheave. The guide portion <NUM> can be a toothed wheel, such as a cogwheel, sprocket, or the like.

The apparatus <NUM> may be suitable for offshore and/or subsea operations and may be submerged in use.

<FIG> shows a photograph of an apparatus, generally denoted <NUM>, in use. The apparatus <NUM> does not comprise an open channel for guiding and/or seating a first mooring chain <NUM>. The first mooring chain <NUM> is being pulled along a path indicated by arrow <NUM>, thus tensioning the first mooring chain <NUM> and a second mooring line <NUM>. It can be seen the first mooring chain <NUM>, which is a mooring chain, interferes with an upper portion of a closed channel <NUM>. That is, during tensioning of the first mooring chain <NUM> and second mooring line <NUM>, the apparatus <NUM> may obstruct movement of the first mooring chain <NUM> relative to the apparatus <NUM>, due to an angle at which the first mooring chain <NUM> enters the closed channel <NUM> of the apparatus <NUM>. Such interference may result in the first mooring chain <NUM> moving in a jolting manner relative to the apparatus <NUM>, and may result in damage to the first mooring chain <NUM> and/or the apparatus <NUM>. Furthermore, such behaviour may potentially lead to a jamming of the first mooring chain <NUM> in or around the apparatus <NUM>.

<FIG> shows a series of photographs of an apparatus <NUM> according to an embodiment of the present invention. In <FIG>, a first mooring chain <NUM> and a second mooring line <NUM> are under a low tension, e.g. a substantial tensioning force in a direction indicated by arrow <NUM> has not yet been applied to the first mooring chain <NUM>. The apparatus <NUM> does comprises an open channel <NUM> for guiding and/or seating a first mooring chain <NUM>.

In <FIG>, the first mooring chain <NUM> is being pulled along a path indicated by arrow <NUM>, thus tensioning the first mooring chain <NUM> and a second mooring line <NUM>. In contrast to <FIG>, it can be seen that the first mooring chain <NUM>, which is a mooring chain, does not interferes with the channel <NUM>. That is, during tensioning of the first mooring chain <NUM> and second mooring line <NUM>, due to the open channel <NUM>, the apparatus <NUM> does not obstruct movement of the first mooring chain <NUM> towards a guide portion <NUM>. <FIG> shows the first mooring chain <NUM> and the second mooring line <NUM> further tensioned relative to <FIG>. It can be seen that during tensioning of the first mooring chain <NUM> and second mooring line <NUM>, a body <NUM> of the apparatus <NUM> tends to tilt or rotate to align a line <NUM> between a centre of the guide portion and a connection portion <NUM> with the second mooring line <NUM>.

<FIG> show a further series of photographs of the mooring apparatus <NUM> in use. In <FIG>, the first mooring chain <NUM> is being pulled along a path indicated by arrow <NUM>, thus tensioning the first mooring chain <NUM> and the second mooring line <NUM>. In contrast to <FIG>, it can be seen that an angle between arrow <NUM> and a portion of the first mooring chain <NUM> is substantially lower than an angle between arrow <NUM> and a portion of the first mooring chain <NUM> in <FIG>. That is, a wrap angle around guide portion <NUM> is larger in <FIG> than in <FIG>. As a result, the first mooring chain <NUM> is lifted further into the open channel.

Referring to <FIG> there is shown an apparatus <NUM> according to an embodiment of the present invention and referred to as a compact tensioner. The apparatus <NUM> is similar to the mooring apparatus <NUM> of Figure <NUM>(a), like parts being identified by like numerals, but iterated by "<NUM>".

<FIG> shows during tensioning a relatively large vale for internal (wrap) angle α where the first mooring chain <NUM> is in contact with or touches the open channel <NUM>.

<FIG> shows during tensioning a relatively small value for the internal angle α where the first mooring chain is biased towards the guide portion <NUM> and away from the open channel <NUM>. This can reduce the opportunity for chaffing of the first mooring chain <NUM> on entry to the apparatus <NUM>.

In both of <FIG> and <FIG> the lock arrangement <NUM> is in an unlocked disposition and provided in an opposite side of the mooring chain path <NUM> than the guide portion <NUM>.

It should be noted that the lock arrangement <NUM> can be provided with a temporary (e.g. removable) or permanent counterweight.

Referring to <FIG>, the apparatus <NUM> is shown with the first mooring chain <NUM> tensioned. The lock arrangement <NUM> is in a locked disposition and at least partly provided on the mooring path <NUM> and engaged with the first mooring chain <NUM>. In particular a lock (or stopper) face of the lock arrangement <NUM> abuts a locked line.

Referring to <FIG>, once tensioned as shown in <FIG>, excess chain can be released (and allowed to drop down).

The apparatus <NUM> can invert into an in-service disposition.

It should be noted that the locked link is engaged with the guide portion <NUM> (or dynamic guide).

It should be noted that a first clouded link is in line with a idealised or virtual mooring chain path.

Referring to <FIG>, there is shown an apparatus <NUM> accordingly to an embodiment of the present invention and referred to as an "ultra-compact" tensioner. The apparatus <NUM> is similar to the apparatus <NUM> pf <FIG>, like parts being identified by the numerals, but iterated by "<NUM>".

<FIG> shown the mooring apparatus <NUM> in an in-service disposition similar to that of the apparatus <NUM> is shown in <FIG>.

It should be noted that a first loaded link is in line with an idealised virtual mooring chain path.

Referring to <FIG>, there is shown in further detail the apparatus <NUM> of <FIG>, and the positions of the locked link and first loaded link.

Referring to <FIG>, there is shown in further detail the apparatus <NUM> of <FIG> and the positions of the locked link and first loaded link.

Referring to <FIG>, there are shown first to fourth apparatus according to embodiments of the present invention.

The first to fourth apparatus are similar to the mooring apparatus of <FIG>, like parts being identified by like numerals bit iterated by "<NUM>" and suffixed "a" to "d" respectively.

Referring to <FIG> there are shown first and second combination of guide portions and lock members for use in embodiments of the present invention.

In the combination of <FIG>, the guide portion comprises a spur/toothed wheel and the lock member comprises a yoke stopper which can mesh with the spurs/teeth of the spur/toothed wheel.

In the combination of <FIG>, the guide portion comprises a groove wheel, i.e. a wheel having a circumferential groove and the lock member comprising a finger or pin type stopper which can mush with the circumferential groove. First and second outer members of the wheel are dispersed in parallel relation to one another and can comprise further teeth or spurs.

It will be appreciated that the guide portions, lock arrangement and counterweights showing in <FIG> and <FIG> can find utility in any embodiments of the present invention, e.g. the embodiments disclosed hereinbefore.

Referring to <FIG>, there is shown a series of schematic side views of an apparatus, generally described <NUM>, according to the present invention. The mooring apparatus <NUM> is similar to mooring apparatus according to embodiments of the present invention hereinbefore disclosed.

The mooring apparatus <NUM> comprises a guide portion <NUM>, a lock arrangement <NUM>, a first mooring chain path <NUM>, a second mooring chain path <NUM>, and a tangent line T from the guide portion <NUM>.

As can be seen in <FIG>, in service, i.e. after tensioning of the first mooring chain <NUM> and locking of the lock arrangement <NUM>, the tangent line T aligns with a portion of the first mooring chain path <NUM> extending upwards, i.e. to/from the structure to be moored and the second mooring chain path <NUM> extending downwards, e.g. to an anchor point. Thus a continuous load path is provided.

Referring to <FIG>, there is shown a series of schematic side views of an apparatus, generally described <NUM>. The apparatus <NUM> is similar to apparatus according to embodiments of the present invention, e.g. <FIG> hereinbefore disclosed.

The apparatus <NUM> is shown in <FIG> in the same dispositions and acting in a similar way to the apparatus <NUM> as shown in <FIG>, respectively.

It will be noted that in the apparatus <NUM> of <FIG>, the locked link <NUM> and the first loaded link <NUM> are in the mooring chain path <NUM> in service, i.e. when the first mooring chain <NUM> has been tensioned. Also the locked link <NUM> is on the guide portion <NUM>.

It will also be noted that in the apparatus <NUM> of <FIG>, only the first loaded link <NUM> is in the mooring chain path <NUM> in service, i.e. when the first mooring chain <NUM> has been tensioned. Also, the locked link <NUM> is on the guide portion <NUM>.

Claim 1:
An apparatus (<NUM>) for mooring a structure (<NUM>) and tensioning a mooring chain (<NUM>), the apparatus providing a first mooring chain path (<NUM>) and comprising:
a body (<NUM>);
a guide portion (<NUM>) for guiding a portion of a first mooring chain, the guide portion being rotationally mounted on the body;
a lock arrangement (<NUM>) comprising a lock member (<NUM>);
the body comprising an arrangement (<NUM>) for connecting the apparatus to a second mooring line (<NUM>);
the lock member being provided on an opposite side of the first mooring chain path from the guide portion when in an unlocked position, and the lock member being at least partially provided in or on the first mooring chain path when in a locked position, wherein the apparatus is adapted such that, in use a locked link of the first mooring chain is providable between and engaged with both the guide portion and the lock arrangement; characterised in that
the lock arrangement (<NUM>) is provided between the guide portion (<NUM>) and a guide arrangement (<NUM>) for guiding a portion of the first mooring chain (<NUM>) into or out of the apparatus (<NUM>).