GB2561001A

GB2561001A - Overboarding quadrant

Info

Publication number: GB2561001A
Application number: GB1705266.3A
Authority: GB
Inventors: John Sims Colin; Andrew Mackie Alan
Original assignee: Maats Tech Ltd
Current assignee: Maats Tech Ltd
Priority date: 2017-03-31
Filing date: 2017-03-31
Publication date: 2018-10-03
Also published as: WO2018178622A1; GB201705266D0

Abstract

An overboarding quadrant 116 comprises a support for lifting and lowering a flexible elongate submersible element (110, Fig 5), such as a cable, the support defining an arcuate guide path 125 for guiding the flexible elongate submersible element. The arcuate guide path includes an axially-extending guide element 136 having a plurality of spaced-apart rotatable support elements 124, the rotatable support elements being movable inwardly to in use more uniformly distribute a pressure applied to the flexible elongate submersible element. The rotatable supports are movable outwardly to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path. The rotatable supports may be spring mounted, or may be compressible themselves and mounted on a fixed axis (Fig 14). A radial guide 150 may also be provided. The quadrant can be used for overboarding a cable from a vessel preventing or limiting damage to the cable.

Description

(54) Title of the Invention: Overboarding quadrant Abstract Title: Overboarding quadrant (57) An overboarding quadrant 116 comprises a support for lifting and lowering a flexible elongate submersible element (110, Fig 5), such as a cable, the support defining an arcuate guide path 125 for guiding the flexible elongate submersible element. The arcuate guide path includes an axially-extending guide element 136 having a plurality of spaced-apart rotatable support elements 124, the rotatable support elements being movable inwardly to in use more uniformly distribute a pressure applied to the flexible elongate submersible element. The rotatable supports are movable outwardly to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path. The rotatable supports may be spring mounted, or may be compressible themselves and mounted on a fixed axis (Fig 14). A radial guide 150 may also be provided. The quadrant can be used for overboarding a cable from a vessel preventing or limiting damage to the cable.

At least one drawing originally filed was informal and the print reproduced here is taken from a later filed formal copy.

03 18 θ/7θθθθ\\θ

03 18

2/10

03 18

I

4/10

Figure 5

6/10

Figure 7

7/10

Figure 8

126 $*gttre g

8/10

³l6

33₂

416 ^Sute j j ^10

Figiir_e j 2

616

Figure j₃ io/io

Overboarding Quadrant

The present invention relates to an overboarding quadrant, in particular but not necessarily exclusively for use in repairing and then overboarding an elongate flexible element, such as a cable, without the cable having a bend radius less than a minimum bend radius of the cable. The present invention further relates to a method of overboarding an elongate flexible element without causing damage thereto.

Flexible elongate submersible elements, such as cables or flexible pipelines, are used in many underwater environments in order to provide a connection between two structures, at least one of which is usually not on land. For example, submersible cables may be commonly used to connect offshore wind turbines to each other, a further offshore structure or the land. They may similarly be used for offshore oil and gas rigs. Submersible cables and pipelines can also be used to connect land based locations that are separated by water.

Damage may occur to these flexible elongate submersible elements, particularly sheathed cables, in use and so repairs may need to be carried out. These repairs may take the form of cutting the existing damaged cable whilst under the water and then bringing onto a port or starboard side of the stern of a cable repair vessel the cut end of the undamaged length of cable. This undamaged length of cable is then passed along cable support elements along one side of a portion of the length of the vessel before the cable is curved back on itself such that the cut end of the cable is facing the direction of the stem of the vessel. A cable overboarding quadrant, typically a semi-circular shaped frame with a radius greater than a minimum bend radius of the cable, is typically used to guide the cable as it is curved. This guiding takes the form of running the cable around an outer surface of the quadrant. This prevents or limits the cable from having a bend radius less than the minimum allowable bend radius of the cable which prevents or limits the cable from being damaged. The cut end of the cable is then connected to a second cable which has already been connected to the destination of the original, damaged cable.

The now repaired and preferably undamaged cable is then required to be drawn further onto the deck to release a tie-off tension, and winched or hoisted off the deck in preparation for lowering to the ground or bed beneath the water.

Referring to Figures 1 to 4 there is shown a process, in accordance with the state of the art, of returning a cable 10 to the water 12 from a cable repair vessel 14. The cable 10 is attached to the cable overboarding quadrant 16, typically with the use of straps or ties. The cable overboarding quadrant 16 is then typically winched up the deck and hoisted upwards, before then being moved to the edge of the stem 18 of the vessel along runners. A crane 20 then lifts and pivots upwards the quadrant, such that the cable 10 sits on top of at least part of the cable overboarding quadrant 16. The cable overboarding quadrant 16, with the cable 10 still atop, is then lowered by the crane 20 into the water and then following that to the bed, sea floor or ground 22 beneath the water. The straps are then cut by a remotely operated vehicle and the cable overboarding quadrant 16 is rotated by the crane 20 or auxiliary winch or similar, such that the cable 10 is disengaged from the cable overboarding quadrant and falls to the ground.

However, damage can occur to a sheathing of the cable 10 whilst it is being guided around the cable overboarding quadrant 16. If the frictional engagement between the cable 10 and the cable overboarding quadrant 16 is too high, then the cable 10 will be subjected to potential damage from rubbing or simply not move; if rollers 24 are then used to alleviate this issue, the high point contact when significant strain or tension is imparted to the cable 10 can rupture or otherwise damage the sheathing and/or internal cabling housed therein.

The present invention seeks to provide a solution to these problems.

According to a first aspect of the present invention, there is provided an overboarding quadrant comprising: a support for lifting and lowering a flexible elongate submersible element, the support defining an arcuate guide path for guiding the flexible elongate submersible element, the arcuate guide path including an axially-extending guide element having an axial guide surface and a plurality of spaced-apart rotatable support elements, an outer surface of the rotatable support elements being movable inwardly to in use more uniformly distribute a pressure applied to the flexible elongate submersible element thereon, and movable outwardly to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path.

In the field of submersible cable laying, a quadrant is a device traditionally shaped as a semi-circle, generally between a quarter and a half of a circle, for guiding a cable without compromising or reaching its minimum bending radius. Reducing the frictional engagement between the flexible elongate submersible element and the arcuate guide path of the cable overboarding quadrant prevents or limits the flexible elongate submersible element from being damaged whilst it is being guided around and moved along the axial guide path.

Retracting the support elements enables a more uniform distribution of pressure applied to an exterior surface of the flexible elongate submersible element. An outer sheathing or coating of the flexible elongate submersible element is thus prevented or limited from being damaged through excessive point-pressure contact. This reduction in point pressure takes place due to the axial guide surface providing a greater area for supporting the weight of the flexible elongate submersible element.

Preferably, the arcuate guide path further includes a radially-extending guide element along at least a majority of a longitudinal extent thereof which extends with at least a majority of the axially-extending guide element.

A radially-extending guide element, may prevent or limit dislodgement of the in use flexible elongate submersible element from the cable overboarding quadrant whilst the cable overboarding quadrant is being pivoted, lifted and lowered by a crane at or adjacent to the deck of the ship. The radially-extending guide element may thus provide a barrier or guide wall at least along one side or perimeter edge of the axial guide surface, typically perpendicularly or substantially perpendicularly thereto.

Preferably, the rotatable support elements are radially spring biased. Advantageously, the rotatable support elements may be mounted on leaf springs to in use move radially or substantially radially inwardly and outwardly.

Radially spring biasing the rotatable support elements allows the rotatable support elements to automatically move inwardly when a sufficient force is applied to them and then automatically move outwardly when the force is removed or reduced. This allows for the rotatable support elements to move beneath the axial guide surface when the weight of the in use flexible elongate submersible element is applied or when greater tension is other applied, such as release of any tie-offs. This may occur when the cable overboarding quadrant is vertically pivoted. When a tension on the cable is reduced or a pressure on the quadrant is decreased, the rotatable support elements are able to move radially outwardly so that they are able to be used to reduce the frictional engagement of the cable when guided around the cable overboarding quadrant. Leaf springs provide the advantage of simpler manufacture and improved longevity compared to other types of spring.

Beneficially, the axial guide surface may be a continuous surface with a plurality of spaced apart apertures.

Providing a continuous, preferably fixed, surface which is only broken by spaced apart apertures ensures that the weight of the in use flexible elongate submersible element is able to be distributed across an area which is as great as possible. This results in the stress that the flexible elongate submersible element is subject to being as low as possible and so the probability of damage to the flexible elongate submersible element thus being reduced.

In a preferable embodiment, the axial guide surface may be a discontinuous surface.

Providing a discontinuous surface, such as a series of plates separated by gaps to accommodate the retractable support elements, provides the advantage that the axial guide surface is simpler to manufacture. The discontinuity may also provide a greater space or gap for the rotatable support elements to protrude through. A larger diameter rotatable support element, such as a roller, can thus be accommodated to present a greater engagement area with the flexible elongate submersible element. An improvement in reducing the frictional engagement between the flexible elongate submersible element and the axial guide surface is thus realised.

Optionally, the radial guide element may have first and second guide elements which are spaced from one another by the axial guide surface.

The provision of two radial guide elements opposing each other across the axial guide surface may ensure that the in use flexible elongate submersible element is unable to fall or become unintentionally dislodged from the axial guide surface in either lateral direction of the axial guide surface.

Beneficially, the arcuate guide path may be semi-circular.

A semi-circular shape allows for the weight of the flexible elongate submersible element to be optimally distributed across the frame.

Alternatively, a plurality of arms, which may be pivotable in a radial direction of the support, are preferably attached to the support. Additionally, each said rotatable support element may be mounted on a respective said arm. Preferably, a coil spring may be interposed between a lower surface of each arm and the support. Alternatively, an armleaf spring or upright leaf spring may be provided between a lower surface of each said arm and the support.

In the former case, mounting each of the rotatable support elements on a pivotable arm with a spring between the arm and the support provides similar advantages to the aforementioned leaf spring. An additional advantage occurs in that the resistance to radially inward and outward motion can be more easily tuned than when compared with a leaf spring. Such tuning can be achieved by providing more or less resistant coil springs. However, in the latter case, providing the pivotable arm and the support with an arm- or upright-leaf spring therebetween, rather than a coil spring, provides a potentially simpler manufacturing technique and a reduced likelihood of in use fracture or breakage. A buckling or upright spring leaf may also have a different forcedisplacement curve that may have advantages.

Beneficially, the rotatable support elements may be rollers.

The provision of rollers, which typically only rotate about one axis, provides the advantage that the in use flexible elongate submersible element is less likely to be moved transversally off the axial guide surface than if the rotatable support elements had multiple axes of rotation, such as in the use of captive ball bearings.

In an alternative embodiment, the rollers may be diablo rollers. Diablo rollers, that is rollers which have a central nadir or reduced diameter or waist in an outer surface, provide the advantage of greater lateral support, that is in the axial direction of the frame, to an in use flexible elongate submersible element than a roller without a central nadir.

Preferably, the rotatable support elements may be elastically deformable when subjected 5 to a predetermined force. Elastically deformable rotational support elements allow for inward motion without the requirement of springs. This may increase the longevity of the overboarding quadrant.

Advantageously, each rotatable support element includes a plurality of openings in end faces thereof to enable elastic deformation.

Advantageously, the radially-extending guide element may have a plurality of spacedapart guide-rotatable elements to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path.

The presence of the guide-rotatable elements provides the advantage of reduced frictional engagement between an in use cable and the radially-extending guide element.

This reduces the amount of stress that the in use flexible elongate submersible element is subjected to and so reduces the probability of damage occurring to the in use flexible elongate submersible element.

Additionally, the guide-rotatable elements may be rollers.

The provision of rollers, which typically only rotate about one axis, prevents or limits the in use flexible elongate submersible element from moving axially off the axial guide surface when compared to a rotatable support element with multiple axes of rotation.

Preferably, the support is a frame.

According to a second aspect of the present invention, there is provided a flexibleelongate-element overboarding device comprising: a support for lifting and lowering a flexible elongate submersible element, the support defining an arcuate guide path for guiding the flexible elongate submersible element, the arcuate guide path including an axially-extending guide element having an axial guide surface and a plurality of spacedapart rotatable support elements, the support elements being movable inwardly to in use more uniformly distribute a pressure applied to the flexible elongate submersible element thereon, and movable outwardly to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path.

Advantageously, the movable support element may be a low-friction plate having a coefficient of friction which is less than that of the axial guide surface.

Beneficially, the support elements may automatically move inwardly on application of a predetermined force.

Optionally, the said predetermined force is in the order of tonnes, and may be greater than or equal to 10 tonnes.

According to a third aspect of the present invention, there is provided a vessel-mounted overboarding quadrant system, the system compromising: a vessel; a support on which at least a portion of a flexible elongate submersible element is receivable; a lifting device for lifting and lowering the support into and out of water; the support defining an arcuate guide path for guiding the flexible elongate submersible element thereon; the arcuate guide path including an axially-extending guide element; the axially-extending guide element having an axial guide surface and a plurality of spaced-apart rotatable support elements; the rotatable support elements being movable inwardly to in use more uniformly distribute a pressure applied to the flexible elongate submersible element thereon, and movable outwardly to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path.

According to a fourth aspect of the present invention, there is provided a method of overboarding a flexible elongate submersible element from a vessel whilst preventing or limiting damage to a flexible elongate submersible element, the method comprising; a support being positioned on a vessel, the support defining an arcuate guide path having a plurality of rotatable support elements, the arcuate guide path being in a plane parallel to a plane of a deck of the vessel; moving the flexible elongate submersible element at or adjacent to and around the arcuate guide path, the rotatable support elements reducing frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path; moving the support such that the arcuate guide path is at an angle to a plane of a deck of the vessel; the plurality of rotatable support elements moving inwardly to more uniformly distribute a pressure applied to the flexible elongate submersible element thereon; and overboarding the support with the flexible elongate submersible element following the arcuate guide path.

The invention will now be more particularly described, with reference to the accompanying drawings, in which:

Figure 1 shows a plan schematic of a vessel having an overboarding quadrant, in accordance with the state of the art;

Figure 2 shows a perspective representation of the overboarding quadrant on a deck of a vessel, again in accordance with the state of the art;

Figure 3 shows a perspective representation of the overboarding quadrant of 10 Figure 2 being lifted from a deck of a vessel.

Figure 4 shows an elevational view from aft of the overboarding quadrant being lowered to a sea floor from a vessel.

Figure 5 is a front representation of a first embodiment of an overboarding quadrant, in accordance with the first aspect of the present invention with an in use cable shown in dotted line;

Figure 6 shows an enlargement of box A of Figure 5;

Figure 7 shows an isometric representation of the overboarding quadrant of Figure 5;

Figure 8 shows a radial cross-section in the direction of axis X shown in Figures 20 5 and 7 of the overboarding quadrant of Figure 5, with a cable, pipeline or other flexible elongate submersible element thereon by way of example;

Figure 9 shows an enlarged longitudinal cross-sectional portion of a second embodiment of an overboarding quadrant, in accordance with the first aspect of the present invention;

Figure 10 is another enlarged longitudinal cross-sectional portion of a third embodiment of an overboarding quadrant, in accordance with the first aspect of the present invention;

Figure 11 is yet another enlarged longitudinal cross-sectional portion of a fourth 5 embodiment of an overboarding quadrant, again in accordance with the first aspect of the present invention;

Figure 12 shows a further enlarged longitudinal cross-sectional portion of a fifth embodiment of an overboarding quadrant, still in accordance with the first aspect of the present invention;

Figure 13 shows another enlarged longitudinal cross-sectional portion of a sixth embodiment of an overboarding quadrant, again still in accordance with the first aspect of the present invention; and

Figure 14 shows an axial end on view of a second embodiment of a roller forming part of a seventh embodiment of an overboarding quadrant, in accordance with the first aspect of the present invention.

Referring firstly to Figures 5 to 8 of the drawings, there is shown a first embodiment of an overboarding quadrant 116 for use in inspecting, repairing and/or maintaining and then overboarding a cable, pipeline or other flexible elongate, typically submersible, element 110, whilst preventing or limiting damage occurring to the flexible elongate submersible element 110. The overboarding quadrant 116 preferably has a semi-circular support, in this case being a frame 126, the curved exterior perimeter of which defines an arcuate cable guide path 125.

Although the overboarding quadrant may preferably have a semi-circular frame, other circular or non-circular shaped supports may be considered, and these may be a framework or solid elements such as plates. For example, the frame or support may be multi-faceted, and thus considered polygonal rather than part-circular. Furthermore, the frame or other suitable support may be arcuate, such as part-oval, part-elliptic, or partparabolic, whilst not having a uniform or substantially uniform radius across its circumference or perimeter working face. As such, although the term ‘overboarding quadrant’ and ‘cable overboarding quadrant’ are well known and well understood in the field of the invention, being cable, pipeline and flexible elongate element laying, repair, maintenance and inspection, the term ‘quadrant’ used herein and throughout is not intended to be the strict dictionary definition of a part-circle or quarter circle. As explained above, other frame shapes may be considered and are intended to be encompassed within the meaning of the term ‘quadrant’ used herein and associated with the known devices within the field.

The frame 126 preferably comprises an elongate base portion 128. A hub 130 is positioned at the centre of the elongate base portion 128 and may preferably be semi10 circular in shape. An axial axis X extends in a direction which is or is substantially perpendicular to the direction of the longitudinal extent of the flexible elongate element 110. A radial plane R extends in a direction outwardly from a centre of the elongate base portion 128 and intersects with the flexible elongate element 110.

Spaced equiangularly and radially projecting from the hub 130 are shown seven guide supports 132, of which two form the elongate base portion 128. An axially-extending guide element 134, which may also be referred to as a lateral guide element, forms part of the arcuate guide path 125 and preferably extends in an arc from one end of the elongate base portion 128 to the other. The axially-extending guide element however, may not fully extend between each end of the elongate base portion 128.

The axially-extending guide element 134 comprises an axial guide surface 136, which is supported by the plurality of guide supports 132. Between neighbouring points of contact of the guide supports 132 and the axial guide surface 136, there are two spacedapart apertures 138 in the axial guide surface 136, which otherwise is a continuous surface. The axial guide surface 136 may preferably be a semi-circle although other arcuate shapes may be used, as explained above with reference to the frame 126. Although the axial guide surface 136 is described as a continuous surface with apertures 138, it is appreciated that it may not be a continuous surface, for example it may be a discontinuous surface formed from spaced-apart plates which are supported by the guide supports.

The frame 126 further comprises a plurality of struts 140, each strut 140 being supported between adjacent guide supports 132. Each strut 140 is radially proximal to the hub 130 as compared to the axial guide surface 136. A strut support 142 projects radially from the hub 130 and engages each strut 140.

Positioned centrally on each strut 140 at a surface opposing the axial guide surface 136 is a leaf spring 144. Each leaf spring 144 takes the form of a spring-base element 146, which engages the strut 140, and a lever element 148 which is mounted on the springbase element 146. A centre of the lever element 148 is mounted onto the spring base element 146 such that the lever element 148 is parallel or substantially parallel with a longitudinal extent of each strut 140, and the lever element 148 is cantilevered in two directions away from the spring base element 146. Each unsupported end of the lever element 148 is preferably at or adjacent to an aperture 138.

Mounted on each unsupported end of each leaf spring 144 is a rotatable support element 124 which preferably takes the form of a roller and forms part of the axially-extending guide element 134. By being mounted on the unsupported end of the leaf springs 144 the rotatable support elements 124 are spring biased and may be here radially spring biased. The rotatable support elements 124 may more preferably take the form of a diablo roller, being a roller which has a central nadir or waisted portion in an outer surface. The diablo roller provides the advantage of providing greater lateral support, that is in the axial direction of the frame 126, to an in use flexible elongate submersible element 110, such as the cable 110, than a roller without a central nadir. The rotatable support elements 124 may however take the form of other components capable of rotating, for example ball bearings or rollers with uniform diameters along at least a majority of their axial extents. Each rotatable support element 124 has an axis of rotation which is parallel or substantially parallel to the axial axis X.

Each rotatable support element 124 may protrude through its associated aperture 138, when the leaf spring 144 is in a relaxed state, and thereby a portion of the rotatable support element 124 may be either side of the axial guide surface 136. This protrusion of the rotatable support element 124 allows for an in use flexible elongate element 110 to be more easily guided around the axial guide surface 136. The rotatable support elements 124 allow for the frictional engagement between the flexible elongate element 110 and the axial guide surface 136 to be reduced or eliminated.

The frame 126 further comprises at least one radially-extending guide element 150 which is fixed to an axial edge of the axial guide surface 136, the radially-extending guide element 150 taking the form of a radial guide arch 152 which matches or substantially matches the curvature and extent of the axial guide surface 136. The radially-extending guide element 150 may further comprise a plurality of radial supports 154 which interengage the axial guide surface 136 and the radial guide arch 152, and a plurality of guide-rotatable elements 156 which extend between or substantially between the axial guide surface 136 and the radial guide arch 152. The radial guide arch 152 may preferably be semi-circular with a radius which is greater than that of the axial guide surface 136 which the radial guide arch 152 is fixed to. The guide-rotatable elements 156 have an axis of rotation which is parallel with a radial direction of radially-extending guide element 150. The guide-rotatable elements 156 reduce the frictional engagement between an in use flexible elongate element 110 and the radiallyextending guide element 150.

Alternatively or in addition to the guide-rotatable elements 156, the radially-extending guide element 150 may include a low-friction layer or skin.

Preferably, an attachment structure 158 is provided on the overboarding quadrant 116. The attachment structure 158 may preferably be fixed to the overboarding quadrant 116. However, alternatively, the attachment structure may be releasable from the overboarding quadrant and thus be usable for other overboarding quadrants or other similarly sized structures.

The attachment structure 158 preferably has two parallel hoisting supports 160 which are set back in an axial direction from the elongate base portion 128 and are positioned either side of a centre of the elongate base portion 128. The provision of two hoisting supports provides the advantage of preventing or limiting the rotation of the overboarding quadrant during lifting as compared to a single hoisting support. However, there may only be a single hoisting support provided to reduce the weight of the attachment structure. There may also be more than two hoisting supports such as three or more hoisting supports which may provide further stability. Furthermore, the hoisting supports may not be parallel and the longitudinal extent of each hoisting support may be at a non-zero angle to one another. Additionally, the hoisting supports may in fact be at or adjacent to the elongate base portion, instead of being set back from the elongate base portion.

The hoisting supports 160 may preferably be proximal to an edge of the overboarding quadrant 116 which has the radially extending guide portion 150. However, the hoisting supports may alternatively be proximal to the opposite edge of the overboarding quadrant. Interengaging each hoisting support 160 and the elongate base portion 128 is a hoisting support strut 162. The hoisting supports 160 project perpendicularly to the elongate base portion 128 and parallel to a guide support 132 which engages an apex of the hub 130 and an apex of the axial guide surface 136, and or a central radial guide support 132. Further hoisting support stmts 162 interengage the proximal most guide supports 132 and the hoisting supports 160. The hoisting supports 160 extend beyond the radial extent of the axial guide surface 136, where the hoisting supports 160 then extend angularly in a direction towards the overboarding quadrant 116.

A stmt 164 which is perpendicular to the hoisting supports 160 interengages the ends of the two hoisting supports 160 distal to the elongate base portion 128. Positioned at or adjacent to each of the ends of the two hoisting supports 160 distal to the elongate base portion 128 is an attachment portion 166. The attachment portion 166 may take the form of an aperture, hook or rod which is for the attachment to a crane. Although the attachment portions are described as being preferably positioned at or adjacent to the attachment structure, the attachment portions may in fact be positioned directly onto the frame.

The frame 126, the axially-extending guide element 134, the radially-extending guide element 150 and the leaf springs 144 may be formed from iron or steel, preferably suitably corrosion treated.

In use, the overboarding quadrant 116 is positioned on a vessel, preferably on a stern deck of the vessel. The overboarding quadrant 116 is initially positioned such that a radial plane of the frame 126 is parallel to a plane of the deck of the vessel and preferably an apex of the axial guide surface 136 is distal to the stem of the vessel. The overboarding quadrant 116 is also positioned away from an edge of the stern. Similar positioning of an overboarding quadrant in accordance with the prior art is shown in Figure 1 and Figure 2. An end of an in use flexible elongate element 110 is brought up from the water and onto the stem deck where it is guided around the axial guide surface 136 and rests on the radially-extending guide element 150. The remainder of the flexible elongate element 110 extends from the stem deck into the water. As the in use flexible elongate element 110 is guided around the axial guide surface 136, the flexible elongate element 110 engages with the portions of the rotatable support elements 124 which protrude through the apertures 138 and the rotatable support elements 124 can rotate with the movement of the flexible elongate submersible element 110. This thereby reduces any potential frictional engagement between the in use flexible elongate element 110 and the axial guide surface 136. The in use flexible elongate submersible element may additionally engage the plurality of guide-rotatable elements 156 which similarly can rotate and thereby reduce the frictional engagement between the in use flexible elongate element 110 and the radially-extending guide element 150.

The end of the initial flexible elongate element 110 is then typically attached to the end of a flexible elongate submersible element which extends to the stern and then into the water. The completed flexible elongate submersible element 110 is then tied to the overboarding quadrant 116 with the use of straps or ties, whilst still permitting longitudinal motion of the flexible elongate element 110.

The overboarding quadrant 116, with the completed and/or repaired in use flexible elongate submersible element 110 extending from the water, guided around the axial guide surface 136 and then extending back into the water, is then typically moved on runners or winched and hoisted towards a stem edge of the vessel, once any ties or tieoffs have been removed. A hook or other engagement means of a crane, winch or hoist, then engages the attachment portions 166. The lifting device guides the overboarding quadrant 116 over the stern edge of the vessel.

During this lifting, the radially-extending guide element 150 prevents the flexible elongate element 110 from falling and thereby retains the flexible elongate element 110 in position at or adjacent to the axial guide surface 136. The weight of the flexible elongate element 110 now acts with greater force upon the plurality of rotatable support elements 124, causing automatic depression via the leaf springs 144, upon which the rotatable support elements 124 are mounted. This weight which causes the depression may be in the order of tonnes, and for example, may be preferably greater than or equal to ten tonnes. The rotatable support elements 124, and therefore an outer surface of each rotatable support element, are thereby caused to move inwards, in this case radially or substantially radially, and the flexible elongate element 110 thus comes into contact with and engages the axial guide surface 136. The force, due to the flexible elongate submersible element’s own weight and any other load attached to the assembly, is thereby more uniformly distributed acting on the flexible elongate submersible element 110 along the length of the flexible elongate submersible element 110, rather than the force solely acting through the points of contact between the flexible elongate element 110 and the rotatable support elements 124. This thereby reduces local maximums of stress acting on the flexible elongate submersible element 110 and therefore prevents or limits damage occurring to the flexible elongate element 110 or sheathing on the flexible elongate submersible element 110 due to the force of its own weight.

The overboarding quadrant 116, with the flexible elongate element 110 engaging the axial guide surface 136 is lowered into the water and is then lowered to or near to the sea floor or ground beneath the water. The straps or ties attaching the flexible elongate element 110 to the overboarding quadrant 116 are, at that point, typically cut by a remotely operated vehicle. The overboarding quadrant 116 is next rotated through manipulation by the crane such that the flexible elongate element 110 falls from the axial guide surface 136 to the ground beneath the water. The overboarding quadrant 116, without the flexible elongate element 110, is subsequently raised upwards through the water and positioned onto the vessel.

Referring to Figure 9, there is shown a second embodiment of an overboarding quadrant 216 wherein the spring-base element 246 of each leaf spring 244 is fixed at or adjacent to a guide support 232 and at or adjacent to the end of the two struts 240 adjacent to the guide support 232 instead of being positioned centrally on a strut. Other aspects of this embodiment are similar or identical to those of that described above, and therefore further detailed description has been omitted for the sake of brevity. Elements which are similar or identical to those of the first embodiment are indicated by their reference numeral in Figures 5 to 8 with one hundred added for ease of reference.

The spring-base element 246 of each leaf spring 244 is fixed at or adjacent to a guide support 232. The lever element 248 of each leaf spring 244 is cantilevered in two directions away from the spring base element 246 parallel or substantially parallel to a longitudinal extent of each strut 240 adjacent to the associated guide support 232. Each unsupported end of the lever element 248 is preferably adjacent to each aperture 238 which is proximal to the associated guide support 232 and a rotatable support element 224 is mounted on each unsupported end of the lever element 248 such that a portion of the rotatable support element 224 may protrude through each aperture 238. As similar to previously described, in use when the overboarding quadrant 216 is pivoted and lifted by a crane or other suitable lifting device or mechanism, the force provided by the weight of the cable, which may be predetermined, causes a given leaf spring 244 to depress and thereby an associated rotatable support element 224 is able to automatically move inwards.

Referring to Figure 10, there is shown a third embodiment of an overboarding quadrant 316, wherein each leaf spring 148 associated with each strut 140 of the first embodiment is replaced by a pair of pivotable or rocker arms 348 and a pair of coil springs 368. Elements which are similar or identical to those of the first embodiment are indicated by their reference numeral in Figures 5 to 8 with two hundred added for ease of reference, and as such further detailed description has been omitted for the sake of brevity.

A block or support element 346 is positioned centrally on a surface of each strut 340 opposing the axial guide surface 336 and a pair of pivotable arms 348 are pivotably attached to each block or support element 346 so as to share a common pivot axis at or adjacent to a first proximal end thereof. Each pivotable arm 348 of each pair of pivotable arms 348 extends away from the associated block or support element 346 and away from each other in a resting direction parallel or substantially parallel to a longitudinal extent of the associated strut 340. Each pivotable arm 348 is thus able to independently pivot in a radial or substantially radial direction with respect to the frame 326. A coil spring 368 is preferably interposed between the strut 340 and a strut facing surface of each of the pivotable arms 348. The coil spring 368 is preferably fixed at or adjacent to a second free distal end 370 of each pivotable arm 348. The free distal end 370 of each pivotable arm 348 is preferably adjacent to each aperture 338 and a rotatable support element 324 is mounted on the free end 370 such that a portion of each rotatable support element 324 may protrude through the aperture 338. Similarly to above, when the in use overboarding quadrant 316 is pivoted and lifted by a crane, the, preferably predetermined, force, strain or tension provided by the weight of the cable 310 causes a given coil spring 368 to depress and thereby the pivotable arm 348 and the associated rotatable support element 324 are able to automatically move radially inwards. The provision of pivotable arms 348 with coil springs 368, instead of leaf springs, provides the advantage that the resistance to radially inward motion is more easily able to be altered or tuned, for example during design and manufacture by providing more or less resistant coil springs.

Although pivotable arms are described which are able to pivot independently about the same or similar position, each arm may in fact be attached to the block or support element via a spring. This arrangement may allow each each arm to move radially inwards or outwards with repesct to the frame under the, preferably predetermined, force, strain or tension provided by the weight of the cable. The spring may additionally allow the arm to move axially if required.

Alternatively, the pair of arms may in fact be replaced by a single arm. This arm may be mounted onto a spring at or adjacent to the centre of the arm such that it is able to move radially or substantially radially inwards and outwards with respect to the frame under the, preferably predetermined, force, strain or tension provided by the weight of the cable.

Instead of or in addition to the coil springs 368, a torsion spring may be considered and incorporated at the pivot.

Referring to Figure 11, there is shown a fourth embodiment of an overboarding quadrant 416. This embodiment is similar to the third embodiment above, but each coil spring is replaced by an arm-leaf spring 468. Other aspects of this embodiment are similar or identical to those initially described. Elements which are similar or identical to those of the first embodiment are indicated by their reference numeral in Figures 5 to 8 with three hundred added for ease of reference, and as such further detailed description has been omitted for the sake of brevity.

The provision of pivotable arms 448 with arm-leaf springs 468 which project generally radially, instead of solely leaf springs which are in a generally tangential direction as initially described in the first embodiment, provide the advantage that the resistance to radially inward motion is more easily able to be altered or tuned during manufacture by providing more or less resistant arm-leaf springs 468. Furthermore, an arm-leaf spring or buckling spring may be considered more robust and less prone to fracture in a harsh working environment than a coil spring, for example, and may have desirable loaddisplacement characteristics.

Referring to Figure 12, there is shown a fifth embodiment of an overboarding quadrant 516, wherein the block element 546 associated with the pair of pivotable arms 548 is attached to the guide support 532 and at or adjacent to an end of the strut 540, instead of being positioned centrally on the strut 540 as in the third embodiment. Other aspects of this embodiment are again similar to those of the initially described first embodiment, and thus further detailed description has been omitted for the sake of brevity. Again, elements which are similar or identical to those of the first embodiment are indicated by their reference numeral in Figures 5 to 8 with four hundred added for ease of reference.

A second block element 546 is attached at or adjacent to the other guide support 532 which the strut 540 interposes, and at or adjacent to the other end of the strut 540. A pair of opposing block elements 546 is thus associated with each strut 540. Each pivotable arm 548 is pivotably attached to a block element 546, and each pivotable arm 548 extends away from the associated block element 546 and towards the other pivotable arm 548 in a resting direction parallel or substantially parallel to a longitudinal extent of the associated strut 540. Each pivotable arm 548 is thus able to pivot in a radial direction with respect to the frame 526. A coil spring 568 is interposed between the strut 540 and a strut 540 facing surface of each pivotable arm 548. Each coil spring 568 is preferably fixed at or adjacent to a free end 570 of each pivotable arm 548 which is not pivotably attached to each block element 546. The free end 570 is preferably adjacent to each aperture 538, and a rotatable support element 524 is mounted on the unsupported free end 570 such that a portion of the rotatable support element 524 projects through each aperture 538.

Referring to Figure 13 there is shown a sixth embodiment of an overboarding quadrant 616, similarly to the fifth embodiment, wherein each coil spring is replaced by an arm5 leaf spring 668. Other aspects of this embodiment are similar to those of the first embodiment described above. Elements which are similar or identical to the preceding embodiments are indicated by their reference numeral in Figures 5 to 8 with five hundred for ease of reference, and so further detailed description has again been omitted for the sake of brevity.

Although the radially-extending guide element is described as having only a singular radial guide arch, and a singular set of radial supports and guide-rotatable elements, it is appreciated that there may in fact be a first and second radially-extending guide element. These first and second radially-extending guide elements may be spaced-apart on either side of the axially extending guide surface and define a channel for the elongate flexible submersible element. This would thereby provide greater axial support for an in use elongate flexible submersible element.

A seventh embodiment of an overboarding quadrant 716, which as explained previously may not be in the form of an actual quadrant in a mathematical sense but is known as such in the technological field, may utilise a deformable roller 724 and is shown in

Figure 14.

As before, elements which are similar or identical to those of the preceding embodiments are denoted by the same or similar reference number with a prefix of ‘7’, and further detailed description is omitted.

The roller 724 preferably has an axle 724a which is fixed relative to the frame or support 726. The axle 724a may rotate or be entirely stationary, but is not in this embodiment depressible relative to the support 726 and axially-extending guide element 734.

The roller 724 has a roller body 724b which is formed of an elastically deformable material, such as rubber.

A plurality of compression openings 724c are formed in end faces of the roller body 724b. Each opening 724c is preferably a through-aperture which may be linear and extending in parallel or substantially parallel with the axle 724a. Optionally, the openings may be bottomed recesses, and/or in the case of a nadir, may follow an outer surface of the roller instead of a longitudinal extent of the axle.

The openings 724c are beneficially equi-angularly spaced around the axle 724a. However, other relative positioning may be found to be preferable on testing. Here the openings 724c have a circular cross-section however they may alternatively be slots for example with a or a substantially rectangular cross-section.

The openings 724c are preferably dimensioned to accommodate a typical working range of tension, strain or force imparted to or by the in use flexible elongate element when located on the overboarding quadrant 716. Once the predetermined range of force is achieved, which may in the order of tonnes and which may be greater than or equal to ten tonnes, the roller body 724b deforms via the openings 724c, enabling depression of the roller surface relative to the surrounding or adjacent axially-extending guide element 734.

It is therefore feasible to have rollers with different opening size to accommodate different working environments.

An overboarding wheel, crossed rollers with rotational axes which are not parallel with the axial axis X, or any other suitable movable or rotatable element may be considered.

Instead of rollers, it is envisaged that that the support elements may be plates which are movable inwardly relative to the axially-extending guide element. In this case, the plates would preferably be over-coated at least on their upper outwardly facing surface with a low-friction layer, such as a paint.

Said plates may be movable inwardly in a similar fashion to that as previously described, for example they may be mounted on coil springs, leaf springs or on elastically deformable material.

Although the arcuate guide path is described as comprising an axially-extending guide element and a radially-extending guide element, with both guide elements having rollers, the arcuate guide path may take other forms.

The arcuate guide path may comprise only of a plurality of diablo rollers, the flexible 5 elongate element being receivable within a central nadir or waisted portion of each diablo roller. The sides of the central nadir may thereby provide radial support for the flexible elongate element.

Alternatively, the arcuate guide path may comprise a plurality of rotatable spools. The spools may have a central cylindrical elongate portion aligned with an axis of rotation of the spool with a flange at either end of the elongate portion, each flange having a diameter greater than the elongate portion. The elongate portion would provide axial support for an in use flexible elongate element whilst the flanges would provide radial support.

The arcuate guide path may also instead comprise only an axial guide surface and a radially extending guide element, both without rollers or other rotatable support elements. The axial guide surface and the radially extending guide element may be formed from a non-stick surface or be otherwise lubricated to reduce frictional engagement of the flexible elongate element with the axial guide surface and radial guide surfaces without the use of rotational elements.

Although the movable support elements, being in this case rollers or plates, are preferably movable radially or substantially radially inwardly, the movement may not be radial. For example, the inward movement of some or all of the movable support elements may be parallel or substantially parallel with each other.

It is therefore possible to provide an overboarding quadrant for overboarding a cable, pipeline or other elongate flexible, preferably submersible, element without causing or whilst reducing potential damage. The overboarding quadrant has an arcuate guide path for guiding the cable, and this includes at least an axially-extending guide element having an axially-extending guide surface at or adjacent to a perimeter of the frame, along with a plurality of spaced-apart rotatable support elements. The rotatable support elements are movable radially inwardly to in use more uniformly distribute a pressure applied to the flexible elongate submersible element thereon. The rotatable support elements are also movable radially outwardly to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path.

The overboarding quadrant may be similarly used as described above in instances if overboarding the quadrant and/or cable over the side of the vessel or using the quadrant as part of a vertical lay system.

The overboarding quadrant can advantageously be incorporated into a system which 10 additionally includes a vessel, such as a cable or pipeline repair vessel for example, with an on-board deck-mounted crane for hoisting the quadrant.

The words ‘comprises/comprising’ and the words ‘having/including’ when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

1. An overboarding quadrant comprising:

a support for lifting and lowering a flexible elongate submersible element, the support defining an arcuate guide path for guiding the flexible elongate submersible element, the arcuate guide path including an axially-extending guide element having an axial guide surface and a plurality of spaced-apart rotatable support elements, an outer surface of the rotatable support elements being movable inwardly to in use more uniformly distribute a pressure applied to the flexible elongate submersible element thereon, and movable outwardly to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path.

2. An overboarding quadrant as claimed in claim 1, wherein the arcuate guide path further includes a radially-extending guide element along at least a majority of a longitudinal extent thereof which extends with at least a majority of the axiallyextending guide element.

3. An overboarding quadrant as claimed in claim 1 or claim 2, wherein the rotatable support elements are radially spring biased.

4. An overboarding quadrant as claimed in any one of the preceding claims wherein the rotatable support elements are mounted on leaf springs to in use move radially or substantially radially inwardly and outwardly.

5. An overboarding quadrant as claimed in any one of the preceding claims, wherein the axial guide surface is a continuous surface with a plurality of spaced-apart apertures.

6. An overboarding quadrant as claimed in claims 1 to 4, wherein the axial guide surface is a discontinuous surface.

7. An overboarding quadrant as claimed in any one of claims 2 to 6, wherein the radially-extending guide element has first and second guide elements which are spaced from one another by the axial guide surface.

8. An overboarding quadrant as claimed in any one of the preceding claims, wherein the arcuate guide path is semi-circular.

9. An overboarding quadrant as claimed in any of the preceding claims, wherein a plurality of arms, which are pivotable in a radial direction of the support, are preferably attached to the support.

10. An overboarding quadrant as claimed in claim 9, wherein each said rotatable support elements is mounted on a respective said arm.

11. An overboarding quadrant as claimed in claim 10, wherein a coil spring is interposed between a lower surface of each said arm and the support.

12. An overboarding quadrant as claimed in 11, wherein an arm-leaf spring or upright leaf spring may be provided between a lower surface of each said arm and the support.

13. An overboarding quadrant as claimed in any one of the preceding claims, wherein the rotatable support elements are rollers.

14. An overboarding quadrant as claimed in claim 13, wherein the rollers are diablo rollers.

15. An overboarding quadrant as claimed in any one of the preceding claims, wherein the rotatable support elements are elastically deformable when subjected to a predetermined force.

16. An overboarding quadrant as claimed in claim 15, wherein each rotatable support element includes a plurality of openings in end faces thereof to enable elastic deformation.

17. An overboarding quadrant as claimed in any of claims 2 to 16, wherein the radially-extending guide element has a plurality of spaced-apart guide-rotatable elements to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path.

18. An overboarding quadrant as claimed in claim 17, wherein the guide-rotatable elements are rollers.

19. An overboarding quadrant as claimed in any one of the preceding claims, wherein the support is a frame.

20. A flexible-elongate-element overboarding device comprising:

a support for lifting and lowering a flexible elongate submersible element, the support defining an arcuate guide path for guiding the flexible elongate submersible element, the arcuate guide path including an axially-extending guide element having an axial guide surface and a plurality of spaced-apart rotatable support elements, the support elements being movable inwardly to in use more uniformly distribute a pressure applied to the flexible elongate submersible element thereon, and movable outwardly to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path.

21. A flexible-elongate-element overboarding device as claimed in claim 20, wherein the movable support element is a low-friction plate having a coefficient of friction which is less than that of the axial guide surface.

22. A flexible-elongate-element overboarding device as claimed in claim 20 or claim 21, wherein the support elements automatically move inwardly on application of a predetermined force.

23. A flexible-elongate-element overboarding device as claimed in claim 22, wherein the said predetermined force is in the order of tonnes.

24. A vessel-mounted overboarding quadrant system using an overboarding quadrant or device as claimed in any one of the preceding claims, the system compromising:

a vessel;

a support on which at least a portion of a flexible elongate submersible element is receivable;

a lifting device for lifting and lowering the support into and out of water; the support defining an arcuate guide path for guiding the flexible elongate submersible element thereon;

the arcuate guide path including an axially-extending guide element; the axially-extending guide element having an axial guide surface and a plurality of spaced-apart rotatable support elements; and the rotatable support elements being movable inwardly to in use more uniformly distribute a pressure applied to the flexible elongate submersible element thereon, and movable outwardly to in use reduce frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path.

25. A method of overboarding a flexible elongate submersible element from a vessel using an overboarding quadrant or device as claimed in any one of claims 1 to 19 whilst preventing or limiting damage to said flexible elongate submersible element, the method comprising;

a support being positioned on a vessel, the support defining an arcuate guide path having a plurality of rotatable support elements, the arcuate guide path being in a plane parallel to a plane of a deck of the vessel;

moving the flexible elongate submersible element at or adjacent to and 5 around the arcuate guide path, the rotatable support elements reducing frictional engagement of the flexible elongate submersible element during movement along the arcuate guide path;

moving the support such that the arcuate guide path is at an angle to a plane of a deck of the vessel;

10 the plurality of rotatable support elements moving inwardly to more uniformly distribute a pressure applied to the flexible elongate submersible element thereon; and overboarding the support with the flexible elongate submersible element following the arcuate guide path.

Intellectual

Property

Office

Application No: Claims searched: