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Title:
OVERBOARDING QUADRANT
Document Type and Number:
WIPO Patent Application WO/2019/008325
Kind Code:
A1
Abstract:
An overboarding quadrant (116) for underwater remotely releasing a flexible elongate submersible element (110) positioned thereupon. The overboarding quadrant (116) comprises a support (126) for lifting and lowering a flexible elongate submersible element (110), at least one restraint (150) to hold the flexible elongate submersible element (110) captive, and a restraint control mechanism (156), which is operable remotely. The restraint control mechanism (156) is arranged to move the restraint (150) between a captive condition and a release condition. A system including an overboarding quadrant (116) and a remote controller is also provided.A method of releasing a flexible elongate submersible element (110) from an overboarding quadrant (116). A method of resetting an overboarding quadrant (116) is also provided.

Inventors:
SIMS, Colin John (Unit 4Aziz Court, Parkhill, Micheldever Hampshire SO21 3QX, SO21 3QX, GB)
MACKIE, Alan Andrew (Unit 4Aziz Court, Parkhill, Micheldever Hampshire SO21 3QX, SO21 3QX, GB)
Application Number:
GB2018/051746
Publication Date:
January 10, 2019
Filing Date:
June 22, 2018
Export Citation:
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Assignee:
MAATS TECH LIMITED (Unit 4, Aziz CourtParkhill, Micheldever Hampshire SO21 3QX, SO21 3QX, GB)
International Classes:
F16L1/20; F16L1/26; B63B35/03; B63B35/04; H02G1/10; F16L1/235
Attorney, Agent or Firm:
HOCKING, Adrian et al. (Albright IP Limited, County HouseBayshill Road, Cheltenham Gloucestershire GL50 3BA, GL50 3BA, GB)
Download PDF:
Claims:
Claims

1. An overboarding quadrant (116; 216) comprising:

a support (126) for lifting and lowering a flexible elongate submersible element (110); the support (126) defining an arcuate guide path (128) for guiding the flexible elongate submersible element (110);

at least one restraint (150) which is positionable at or adjacent to the arcuate guide path (128) for holding the flexible elongate submersible element (110) captive on the arcuate guide path (128); and

a restraint control mechanism (156) on the support (126) which is remotely operable, the restraint control mechanism (156) being arranged to enable movement of the or each restraint (150) between a captive condition in which the flexible elongate submersible element (110) is restrained to the arcuate guide path

(128) by the or each restraint (150), and a release condition in which the flexible elongate submersible element (110) is not restrained to the arcuate guide path (128) by the or each restraint (150).

2. An overboarding quadrant (116; 216) as claimed in claim 1, wherein me restraint control mechanism (156) comprises at least one elongate member (164; 264; 364) which is radially aligned with the arcuate guide path (128), directly or indirectly attachable to the restraint (150) and is movably attachable to the support (126).

3. An overboarding quadrant (116; 216) as claimed in claim 2, wherein the restraint control mechanism (156) further comprises at least one movable holding element (158) which interconnects the or each restraint (150) to the or each elongate member (164; 264; 364).

4. An overboarding quadrant (116; 216) as claimed in claim 3, the movable holding element (158) includes a restraint-holding arm (160) and an elongate-member attachment arm (162) arranged at an acute angle to one another.

5. An overboarding quadrant (116; 216) as claimed in claim 3 or claim 4, wherein the or each movable holding element (158) is spring biased to an unsecured condition, in which the restraint (150) is in a release condition. 6. An overboarding quadrant (116; 216) as claimed in any one of claims 2 to 5, wherein the or each elongate member (164; 264; 364) or the or each restraint (150) istensionable.

7. An overboarding quadrant (116) as claimed in any one of the preceding claims, wherein the restraint control mechanism (156) includes a remotely operable shackle (172; 372).

8. An overboarding quadrant (116) as claimed in claim 7, wherein the or each elongate member (164;

364) or the or each restraint (150) is releasable from the support (126) via the remotely operable shackle (172;

372).

9. An overboarding quadrant (216) as claimed in any one of claims 1 to 5, wherein the restraint control mechanism (156) includes a remotely operable rotatable element (270).

10. An overboarding quadrant (116; 216) as claimed in any one of the preceding claims, wherein a plurality of restraints (150) is releasable simultaneously.

11. An overboarding quadrant as claimed in any one of claims 1 to 9, wherein the plurality of restraints (150) is releasable individually.

12. An overboarding quadrant (116; 216) as claimed in any one of the preceding claims, wherein the arcuate guide path (128) is semi-circular.

13. An overboarding quadrant ( 116) as claimed in any one of the preceding claims, further comprising at least one guide-rotatable element (148) which is positioned at or adjacent to the arcuate guide path (128).

14. An overboarding quadrant as claimed in claim 1, wherein the restraint control mechanism comprises a circumferential elongate member which is circumferentially aligned with the arcuate guide path, directly or indirectly attachable to the restraint and which is movably attachable to the support.

15. A system for lowering from a vessel and remotely releasing a flexible elongate element (110), the system comprising an overboarding quadrant (116; 216) as claimed in any one of the preceding claims, and a remote controller for operating the remotely operable restraint control mechanism (156).

16. A method of remotely releasing a flexible elongate submersible element (110) from an overboarding quadrant (116), the method comprising the steps of:

a] providing an overboarding quadrant (116; 216) as claimed in any one of claims 1 to 14 in the captive condition;

b] operating the restraint control mechanism (156); and

c] lifting and pivoting the overboarding quadrant (116) to move the flexible elongate submersible element (110) from the overboarding quadrant (116).

17. A method as claimed in claim 16, wherein the or each restraint (150) remains intact whilst moving from a captive to a release condition.

18. A method of resetting the overboarding quadrant (116; 216), the method comprising the steps:

a] releasing the flexible elongate submersible element (110) according to the method of claim 16 or claim 17;

b] positioning a further flexible elongate submersible element (110) around the arcuate guide path (128); c] moving the or each restraint (150) to a captive condition by attaching the or each restraint (150) to the movable holding element (158) so as to secure the flexible elongate submersible element (110) to the arcuate guide path (128); and

d] movably fixing the or each elongate member (164; 264; 364) to the support (126).

19. A method as claimed in claim 18, wherein the steps a, b, c, dare performed in the order a, b, c, d.

20. A method as claimed in claim 18, wherein the steps a, b, c, d are performed in the order a, b, d, c.

21. An overboarding device ( 116; 216) comprising : a support for lifting and lowering a flexible elongate submersible element (110); the support (126) defining an arcuate guide path (128) for guiding the flexible elongate submersible element (110); at least one restraint (150) which is positionable at or adjacent to the arcuate guide path (128) for holding the flexible elongate submersible element (110) captive on the arcuate guide path (128); and a restraint control mechanism (156) on the support (126) which is remotely operable, the restraint control mechanism (156) being arranged to enable movement of the or each restraint (150) between a captive condition in which the flexible elongate submersible element (110) is restrained to the arcuate guide path (128) by the or each restraint(150), and a release condition in which the flexible elongate submersible element (110) is not restrained to the arcuate guide path (128) by the or each restraint(150).

Description:
Overboarding Quadrant

The present invention relates to an overboarding quadrant with a control release mechanism which is able to remotely release a flexible elongate submersible element positioned upon the overboarding quadrant. The invention further relates to a system comprising an overboarding quadrant and a remote controller, a method of remotely releasing a flexible elongate submersible element, and to a method for resetting and reusing an overboarding quadrant.

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 once positioned in their desired location, for example through anchor impact, 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 stem of a cable repair vessel the cut end of the damaged length of cable. The damaged section of cable is removed. The remaining cable is joined to a new length of cable . The extended cable is then passed along cable support elements on 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 which prevents or limits the cable from having a bend radius less than the minimum allowable bend radius of the cable. Damage to the cable is therefore prevented or limited. The cable is then connected to the other end of the previously damaged cable, the previously damaged cable having had the damaged section removed.

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 sea bed or ground 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 restraints, straps or ties in order to ensure that the cable is not unintentionally removed from the overboarding quadrant. 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 16, 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 cable 10 is then required to be removed from the overboarding quadrant 16 which involves the cutting of any restraints, straps or ties. This cutting typically occurs through the use of a remotely operated vehicle 24 which is manoeuvred by a skilled operator to a position whereby the restraints can be cut. This is typically a time consuming and costly procedure. Additionally, when cutting the restraints, great care must be taken that the cable 10 or sheathing of the cable is not damaged by unintentional mishandling of the cutting tool. If damage occurs, significant further monetary and time costs are incurred to allow a further repair to take place.

Furthermore, there is a risk that segments of the restraints are lost during the cutting process. In such instances fines may be incurred in line with the International Convention for the Prevention of Pollution from Ships, as well as national maritime pollution regulations.

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; at least one restraint which is positionable at or adjacent to the arcuate guide path for holding the flexible elongate submersible element captive on the arcuate guide path; and a restraint control mechanism on the support which is remotely operable, the restraint control mechanism being arranged to enable movement of the or each restraint between a captive condition, in which the flexible elongate submersible element is retained to the arcuate guide path by the or each restraint, and a release condition, in which the flexible elongate submersible element is not retained to the arcuate guide path by the or each restraint. The term 'quadrant' used herein and throughout is intended to mean or include the term 'device', and as such the two are to be considered interchangeable.

Providing a remotely operable restraint control mechanism allows for the restraints to be released, and thus the flexible elongate submersible element to be removed from the overboarding quadrant underwater, without the use of a remotely operated vehicle. This saves on time as well as reducing monetary costs. Additionally, by providing releasable, rather than frangible restraints, there is no requirement for cutting and so less risk of damage occurring to the cable or cable sheathing in the release process. Furthermore, there is a reduced chance of segments of the restraints being released into the sea, and thus less chance of pollution or the associated fines being incurred. The release of the cable which this mechanism provides may also allow for a more predictable deployment of the flexible elongate submersible element from the overboarding quadrant. Preferably, the restraint control mechanism may comprise at least one elongate member which is radially aligned with the arcuate guide path, directly or indirectly attachable to the restraint and is movably attachable to the support. The elongate members provide a means to interconnect a free end of the restraint to a or any point on the support. Preferably, the restraint control mechanism may further comprise at least one movable holding element which interconnects the or each restraint to the or each elongate member. A movable holding element enables the or each restraint to be indirectly connected and releasably engaged with the or each elongate member.

Advantageously, the movable holding element may include a restraint-holding arm and an elongate-member attachment arm arranged at an acute angle to one another. Providing each arm at an acute angle to one another allows for one arm to be used for the connection to the restraint, and one arm for connection to the elongate member. This prevents any need to detach or unloop the restraint directly from the elongate member.

Preferably, the or each movable holding element may be spring biased to an unsecured condition, in which the restraint is in a release condition. Spring biasing ensures that the movable holding element is able to release the restraint in the event that a force, such as a local underwater current, is biasing the movable holding element in the other direction and away from an unsecured condition.

In a preferable embodiment, the or each elongate member may be tensionable. The elongate member being tensionable allows for an elastic bias to assist release of the restraints.

Advantageously, the restraint control mechanism may include a remotely operable shackle. A remotely operable shackle may allow for the elongate member, and thus indirectly one end of the restraint, to be releasably attachable to the support via remote operation.

Preferably, the or each elongate member may be releasable from the support via the remotely operable shackle. The elongate members being releasable allows for the restraints to be unsecured at one end with respect to the frame and thus each restraint can be put into a release condition. The flexible elongate submersible element is therefore releasable. Beneficially, the restraint is releasable from the support via the remotely operable shackle. The restraint being directly releasable from the support, as opposed to being releasable via the elongate member, may allow for fewer parts within the construction of the overboarding quadrant and thus for a more cost and time effective constmction.

Altematively, the restraint control mechanism may include a remotely operable rotatable element. A release element that requires rotation to be set in a captive condition and to change to a release condition, may allow for ease of setting in use, due to being able to be set by the use of a rotatable tool such as a tommy bar.

Advantageously, a plurality of restraints may be releasable simultaneously. The restraints being movable simultaneously with respect to the frame allows for the flexible elongate submersible element to be released from the overboarding quadrant in as short as time as possible. Additionally, simultaneous release may prevent already released restraints to interfere with restraints which are still to be released. Beneficially, the plurality of restraints may be releasable individually. Individual movement of the restraints provides the option of a stage or sequential movement of each elongate member. This therefore can allow for the flexible elongate submersible element to be released and lowered more gradually from the overboarding quadrant.

In a preferable embodiment, the arcuate guide path may be semi-circular. A semi-circular guide path provides the maximum possible bend radius at any given point on the flexible elongate submersible element, which reduces the likelihood of damage to the cable in the shortest distance, with the minimum diameter of the quadrant, saving space on the deck of the vessel.

The or each restraint is preferably tensionable. In the event that the restraint in an extended, tensioned state when in a captive condition, the restraint would be biased to return to the relaxed state and thus the release condition. This provides similar advantages to the spring biasing, and thus ensures that the restraint can be released, even in the event that a force, such as a local current, is biasing the movable holding element in the other direction and away from an unsecured condition.

Beneficially the overboarding quadrant may further comprise at least one guide-rotatable element which is positioned at or adjacent to the arcuate guide path. A guide-rotatable element reduces any frictional engagement between that may occur between arcuate guide path and the flexible elongate submersible element.

Optionally, the restraint control mechanism may comprise a circumferential elongate member which is circumferentially aligned with the arcuate guide path, directly or indirectly attachable to the restraint and which is movably attachable to the support. A circumferential orientation may allow for multiple, circumferentially positioned restraints to be released or secured by a single elongate member. According to a second aspect of the present invention, there is provided a system for lowering from a vessel and remotely releasing a flexible elongate element, the system comprising an overboarding quadrant, preferably in accordance with the first aspect of the invention, and a remote controller for operating the remotely operable restraint control mechanism. The remote controller enables the remote operation of the restraint control mechanism and thus ensures that a person is not required to be locally present to trigger the release of the restraints. According to a third aspect of the present invention, there is provided a method of remotely releasing a flexible elongate submersible element from the overboarding quadrant, preferably in accordance with the first aspect of the invention, the method comprising the steps of: a] providing an overboarding quadrant in the captive condition; b] operating the restraint control mechanism; and c] lifting and pivoting the overboarding quadrant to move the flexible elongate submersible element from the overboarding quadrant. Preferably, the or each restraint remains intact whilst moving from a captive to a release condition. This increases the reusability of the overboarding quadrant and reduces the risk of fragments of restraint being released into the body of water and causing pollution. According to a fourth aspect of the present invention, there is provided a method of resetting the overboarding quadrant , the method comprising the steps: a] releasing the flexible elongate submersible element according to the method of the third aspect of the present invention; b] positioning a further flexible elongate submersible element around the arcuate guide path; c] moving the or each restraint to a captive condition by attaching the or each restraint to the movable holding element so as to secure the flexible elongate submersible element to the arcuate guide path; and d] movably fixing the or each elongate member to the support.

Preferably the steps of the method of resetting the overboarding quadrant is performed in the order a, b, c, d or a, b, d, c.

According to a fifth aspect of the present invention there is provided an 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; at least one restraint which is positionable at or adjacent to the arcuate guide path for holding the flexible elongate submersible element captive on the arcuate guide path; and a restraint control mechanism on the support which is remotely operable, the restraint control mechanism being arranged to enable movement of the or each restraint between a captive condition in which the flexible elongate submersible element is restrained to the arcuate guide path by the or each restraint, and a release condition in which the flexible elongate submersible element is not restrained to the arcuate guide path by the or each restraint.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows apian schematic of a vessel having an overboarding quadrant, in accordance with the state of the art; Figure 2 shows a perspective presentation 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 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 shows 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 is an isometric representation of the overboarding quadrant of Figure 5; Figure 7 shows an enlarged radial cross-section in the direction of axis X shown in Figures 5 and 6 of the overboarding quadrant of Figure 5, with a cable, pipeline or other flexible elongate submersible element thereon by way of example, showing in detail a movable holding element in a captive condition;

Figure 8 shows an enlargement of circle A of Figure 5; Figure 9 shows an enlarged portion, similar to that of Figure 8, of a second embodiment of an overboarding quadrant, in accordance with the first aspect of the present invention; and

Figure 10 shows an enlarged portion, similar to that of Figures 8 and 9, of a third embodiment of an overboarding quadrant, in accordance with the first aspect of the present invention.

Referring firstly to Figures 5 and 6 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. The overboarding quadrant 116 preferably has a semi-circular support, in this case being aframe 126, the curved exterior perimeter ofwliich defines an arcuate guide path 128.

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 part-parabolic, 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 130. A hub 132 is positioned at the centre of the elongate base portion 130 and may preferably be semi-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 130 and intersects with the flexible elongate element 110.

Spaced equiangularly and radially projecting from the hub 132 are, in this embodiment, seven guide supports 134, of which two form the elongate base portion 130. An axially-extending guide element 136, which may also be referred to as a lateral guide element, forms part of the arcuate guide path 128 and preferably extends in an arc from one end of the elongate base portion 130 to the other. The axially-extending guide element however, may not fully extend between each end of the elongate base portion. The axially-extending guide element 136 comprises an axial guide surface 138, which is supported by the plurality of guide supports 134. The axial guide surface 138 may preferably be a semi-circle although other arcuate shapes may be used, as explained above with reference to the frame 126.

The frame 126 further comprises a plurality of support engagement members 140, each support engagement member 140 being supported between adjacent guide supports 134. Each support engagement member 140 is radially spaced from the hub 132 to lie between the hub and the axial guide surface 138 as well as being adjacent to the axial guide surface 138.

The frame 126 here comprises a radially-extending guide element 142 which is fixed or integral with an axial edge of the axial guide surface 138, the radially-extending guide element 142 in this case taking the form of a radial guide arch 144 which matches or substantially matches the curvature and extent of the axial guide surface 138. The radially- extending guide element 142 may further comprise a plurality of radial supports 146 which interengage the axial guide surface 136 and the radial guide arch 144, and a plurality of guide-rotatable elements 148 which extend between or substantially between the axial guide surface 138 and the radial guide arch 144. The radial guide arch 144 may preferably be semi-circular with a radius which is greater than that of the axial guide surface 138 to which the radial guide arch 144 is affixed. The guide-rotatable elements 148 have an axis of rotation which is parallel with a radial direction of radially-extending guide element 142. The guide-rotatable elements 148 reduce the frictional engagement between an in use flexible elongate element 110 and the radially-extending guide element 142.

Alternatively or in addition to the guide-rotatable elements 148, the radially-extending guide element 142 may include a low-friction layer or skin. As shown in Figure 7, at least one, and preferably a plurality of restraints 150 may be attached to the frame 126. In this case six restraints 150 are provided. These restraints 150 may be straps, ties, cables, ropes, wires or any other kind of tether, and can be flexible, tensionable and/or extendable or inextensible. The restraints 150 are preferably attached at or adjacent to an axial edge 152, or a portion of the axial edge 152 which is radially proximal to the hub, of the axially- extending guide element 136 which is opposite to an axial edge 152 to which the radial guide arch 144 is fixed. The restraints 150 may be equiangularly arranged around the axially-extending guide element 136 and/or may be arranged symmetrically or asymmetrically with respect to a radially central line of the overboarding quadrant. At or adjacent to a free end of each restraint 150 there may be an integrally formed loop 154, hook, ring, aperture or any other attachment or fastening means. The restraint 150 here has a length at least equal to a width of the axial guide surface 138. However, the length of the restraint may be less than the width of the axial guide surface in an instance where there is at least one aperture in the axial guide surface providing a route therethrough. Preferably, the restraint 150 is sized so as to overhang the axial guide surface 138 so as to be engageable with the radially proximal most support engagement member 140 of the support. If the restraint 150 is extendable and tensionable, it may be that, in an untensioned state, the restraint 150 is not engageable with and does not extend to the support engagement member 140 however when extended and/or tensioned, the restraint 150 may extend and to and be engageable with the support engagement member 140.

Although six restraints 150 are described, it is appreciated that fewer than six restraints 150 may be provided, including only a single restraint 150, or more than six may be utilised as necessity dictates. It is also appreciated that the restraints 150 may be attached to any point on the frame 126, such as to a guide support 134, or may in fact be attached to the radially-extending guide element 142 creating a circumferential restraining array.

As best shown in Figure 7, the overboarding quadrant further comprises a restraint control mechanism 156. The restraint control mechanism 156 here firstly comprises aplurality of, and preferably one for each restraint 150, movable holding elements 158. Each movable holding element 158 preferably has a restraint-holding arm 160 and an elongate- member attachment arm 162 which preferably may be arranged at an acute angle to each other. Therefore, the movable holding element 158 may be or may be substantially V-shaped, tick-shaped or check mark-shaped. Although the movable holding element is described as having this form, it is appreciated that the restraint-holding arm and the elongate-member attachment arm may in fact be perpendicular to, at an obtuse angle to or collinear with each other.

Each movable holding element 158 is here pivotably attached to the support or frame 126, and preferably at a support engagement member 140 at a point of the movable holding element 158 which separates the restraint-holding arm 160 and the elongate member attachment arm 162. Each holding element 160, 162 may be radially aligned with its corresponding restraint 150 and the centre of the elongate base portion 130 and is preferably pivotable in a or a substantially radial direction.

In a preferable embodiment, the movable holding element 158 may include a spring element so as to be spring biased. In a relaxed, released or neutral state therefore, a free end of the restraint-holding arm 160 is preferably, at least in part, spring-biased directed towards the associated restraint 150 and the arcuate guide path 128. This position, orientation or range of positons or orientations of the movable holding element 158 may be referred to as an unsecured condition or state.

The restraint control mechanism 156 may additionally comprise an elongate member 164 which is attached at a first end 166 to the restraint-holding arm 160 of the movable holding element 158. The elongate member 164 is preferably extendable and therefore may be tensionable. The elongate member 164 may preferably be of such a length that a second end 168 (see Figure 5) cannot extend to the centre of the elongate base portion 130 in a relaxed state. However, in an extended, tensioned state, the second end 168 may extend to the centre of the elongate base portion 130. Alternatively, the elongate member may be of such a length that the second end can extend to the centre of the elongate base portion in an untensioned state. Additionally, it should be appreciated that the elongate member may extend to the elongate base portion via an indirect route, such as by using sheaves or fairleads, and therefore the required length of the elongate member may be influenced via this route. The elongate member may be a wire, cable, rope, strap, rigid bar or any other tether that may or may not be extendable. The restraint control mechanism 156 may also comprise an anchor element 170 and a, preferably remotely and manually openable and operable coupling, which is here a shackle 172. The shackle 172 is fixed at or adjacent to an edge portion 130a of the elongate base portion 130 which is radially distal from the arcuate guide path 128 and at or adjacent to or forming part of the hub 132. The anchor element 170 may be attached to the shackle 172 and thus, given that the shackle 172 is remotely opened, the anchor element 170 may be remotely releasable from the shackle 172 and thus be detached from the frame 126. The anchor element 170 is preferably substantially ring shaped, however it is appreciated that it may in fact be any other curvate or linear shape. Each elongate member 164 is also attached to the anchor element 170, preferably via a fastener 174 at the second end 168 of the elongate member 164. The fastener may take the form of a hook, ring, latch, shackle, be formed integrally as part of the elongate member or be any other permanent or temporary fastening means.

The shackle may preferably be remotely operable by acoustic means and thus may be an acoustic release shackle. Additionally or alternatively, the shackle may be pneumatically openable, hydraulically openable, hydrostatically operable, operable and/or openable by a remotely operated vehicle, such as via a remotely operated vehicle engageable handle, or operable and/or openable by a line to the surface. Although described as a shackle, the shackle may in fact be a latch or any other element capable of releasably retaining the anchor element.

Preferably, an attachment structure 176 is provided on the overboarding quadrant 116. The attachment structure 176 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 176 preferably has two parallel hoisting supports 178 which are set back in an axial direction from the elongate base portion 130 and are positioned either side of a centre of the elongate base portion 130. The provision of two hoisting supports 178 provides the advantage of preventing or limiting the rotation of the overboarding quadrant 116 during lifting as compared to a single hoisting support. Additionally, the positioning of these supports 178 in this way may allow for the free movement of the flexible elongate element 110 away from the overboarding quadrant 116 after release. 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 178 may preferably be proximal to an edge of the overboarding quadrant 116 which has the radially extending guide portion 150, and thus distal to the axial edge 152 to which the restraints 150 are attached. However, the hoisting supports may alternatively be proximal to the opposite edge of the overboarding quadrant. Interengaging each hoisting support 178 and the elongate base portion 130 is ahoisting support stmt 180a. The hoisting supports 178 may project perpendicularly to the elongate base portion 130 and parallel to a guide support 134 which may engage an apex of the hub 132 and an apex of the axially-extending guide element 136, axial guide surface 138 and/or a central radial guide support 134. Further hoisting support stmts 180a interengage the proximal most guide supports 134 and the hoisting supports 178. The hoisting supports 178 extend beyond the radial extent of the axial guide surface 138, where the hoisting supports 178 then extend angularly in a direction towards the overboarding quadrant 116.

A stmt 180b which is perpendicular to the hoisting supports 178 interengages the ends of the two hoisting supports 178 distal to the elongate base portion 130. Positioned at or adjacent to each of the ends of the two hoisting supports 178 distal to the elongate base portion 130 is an attachment portion 182. The attachment portion 182 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 126.

In use, the overboarding quadrant 116 is positioned on a vessel, preferably on a stem deck of the vessel. The overboarding quadrant 116 is initially positioned such that a radial plane of the frame 126 is substantially parallel to a plane of the deck of the vessel and preferably an apex of the axial guide surface 138 is distal to the stem of the vessel. The overboarding quadrant 116 is also positioned away from an edge of the stem. Similar positioning of an overboarding quadrant in accordance with the prior art is shown in Figure 1 and Figure 2. Whilst the overboarding quadrant is described as being in use positioned relative to the stem of the vessel, it is appreciated that the overboarding quadrant may in fact be similarly positioned relative to the side or bow of the vessel. Alternatively, the overboarding quadrant may be positioned on a structure that is at an angle to the deck of the vessel.

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 138 and rests on the radially-extending guide element 142. The remainder of the flexible elongate element 110 extends from the stem deck into the water. The in use flexible elongate submersible element may engage the plurality of guide-rotatable elements 148 which can rotate and thereby reduce the frictional engagement between the in use flexible elongate element 110 and the radially-extending guide element 142.

The end of the initial flexible elongate element 110 is then typically attached to the end of a further flexible elongate submersible element which extends to the stem and then into the water.

The completed in use flexible elongate submersible element 110 may then be restrained, tied, or strapped to the arcuate guide path 128 of the overboarding quadrant 116. To achieve this, the shackle 172 is first, preferably manually, opened and the anchor element 170 is inserted into the shackle 172 such that, when the shackle 172 is subsequently closed, the anchor element 170 and the shackle 172 engage, interengage or interconnect. Given that the anchor element 170 is connected to each of the elongate members 164 and that the elongate members 164 may be unable to extend to the centre of the elongate base portion 130 in an unextended state, in order to connect the anchor element 170 to the shackle 172, each elongate member 164 may therefore be required to be tensioned into an extended or tensioned state . Each elongate member 164 is thus able to extend to the centre of the elongate base portion 130. When the anchor element 170 is attached to the shackle 172, each elongate member 164 is in a first condition. The action of extending each of the elongate members 164 into a first condition substantially radially pivots the movable holding element 158 in a direction towards the elongate base portion 130. Said pivoting is such that a free end of the restraint-holding arm 160 may preferably be at least parallel with an axial direction X of the overboarding quadrant 116 and preferably the restraint-holding arm 160 is at least in part directed towards elongate base portion 130. This position, orientation or range of positons or orientations of the movable holding element 158 is referred to as a secured condition or state. If a biasing spring is included in the movable holding element 158, the aforementioned pivoting moves the spring to a compressed, active state. Alternatively, if the restraint is not parallel with a radial direction, the secured condition may in fact still be achieved even if the free end of the restraint-holding arm is aligned with an angle which is between an axial direction X and a radial direction.

The restraints 150 are positioned, whilst attached to the axial edge 152 of the axially-extending guide element 136, over the flexible elongate element and are attached to the restraint-holding arm 160 of the movable holding element 158. This attachment preferably takes the form of positioning the loop 154 at the free end of the restraint 150 over the free end of the restraint-holding arm 184 such that the restraint-holding arm 160 extends through and engages the loop 154. Given that the restraint-holding arm 160 is at least in part directed away from the restraint 150, the restraint 150 can be secured against the restraint-holding arm 160. In this way, the restraint 150 is in a captive condition and the flexible elongate cable is restrained to the arcuate guide path 128 of the overboarding quadrant 116, and is prevented from moving in a transverse, lateral or axial direction. Although the flexible elongate submersible element is described as being restrained to the arcuate guide path by movably fixing each elongate member to the frame first and then attaching the restraint to the movable holding element after this, it is appreciated that these two steps may occur in a reverse order.

The overboarding quadrant 116, with the in use flexible elongate submersible element 110 restrained to the arcuate guide path 128, is then typically moved on runners or winched and hoisted towards a stem edge of the vessel. 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 stem edge of the vessel.

The overboarding quadrant 116, with the flexible elongate element 110 still restrained to the axial guide surface 138 by means of the restraints 150, is lowered into the water and is then lowered to or near to the sea floor or ground beneath the water.

The restraints 150 are then to be moved to a release condition so as to allow the flexible submersible elongate element 110 to be unsecured from the arcuate guide path 128 and entirely removed from the overboarding quadrant 116. In order to release the restraints 150, the restraint control mechanism 156 is remotely operated, which here is initiated by the, preferably remote, opening of the shackle 172. In the instance that the shackle 172 is an acoustic release shackle, the remote opening may take the form of directing an acoustic signal, within a predetermined frequency range, from the in use vessel and towards the overboarding quadrant. When the acoustic signal is received by a sensor on the acoustic release shackle 172, the shackle 172 is caused to open either through pneumatic means or hydraulic means. Hydrostatic operating means, remotely operated vehicle operating means or operation by a guide line to the surface by also be considered for the operation of the shackle.

The opening of the shackle 172 has the effect that the anchor element 170 is now unsecured with respect to the elongate base portion 130. The elongate members 164, which were in the first, tensioned condition or state are biased to, and now return to, a second, relaxed condition. The movable holding element 158 is no longer retained in the secured condition and is free to pivot to the unsecured condition. In the event that biasing springs are included, the springs may move from a compressed or active state to a relaxed or neutral state, thus moving the movable holding element 158 to the unsecured condition. Additionally or alternatively, in the instance that the restraints 150 are formed from a flexible, tensionable material, and the restraints 150 have been required to be tensioned in order to extend and be attached to the movable holding element 158, each restraint 150 may be biased to return to a relaxed state and thus may assist each movable holding element 158 in pivoting to the unsecured condition.

Since the movable holding element 158 is now in an unsecured condition, the restraints 150 may be detached from the restraint-holding arm 160 with the loop 154 of the restraint 150 disengaging therefrom. In this way, the flexible elongate submersible element is no longer secured, tied, strapped or restrained to the arcuate guide path 128 or axial guide surface 138. The overboarding quadrant 116 is next rotated through manipulation by the crane such that the flexible elongate element 110 falls from arcuate guide path 128 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.

The overboarding quadrant 116 can then be reused and reset in the same way as described above, due to the fact that no feature is broken or lost in the securing or release of the flexible elongate submersible element 110.

A second embodiment of an overboarding quadrant 216, is shown in Figure 9, may utilise a rotatable element 270 and a shackle 272 to secure and release the elongate members 264, instead of an anchor element 170 and shackle 172, as in the first embodiment. Elements which are similar or identical to those of the preceding embodiment are denoted by the same or similar reference number with one hundred added, and further detailed description is omitted. The rotatable element 270 may take the form of a rotatable plate and may be rotatably attached at or adjacent to an edge portion 230a of the elongate base portion 230 which is radially distal from the arcuate guide path and in this case, at or adjacent to or forming part of the hub 232. Although the rotatable plate is described as being in this position, it is appreciated that it may in fact be positioned elsewhere on the support, such as on the arch of the hub or guide support. The rotatable plate 270 may have a substantially circular shape with a portion of the outer part of the circle removed. This portion may be or be substantially shaped like an arc of the circle. A radial extent of the substantially circular rotatable element 270 is aligned with plane R (see Figure 1). A plurality of detents 286, and preferably one for each elongate member 264, to releasably engage an end of each elongate member 264 may be positioned around, or in at least a portion of, the circumference of the rotatable element 270. The detent 286 in this embodiment is preferably a hook.

The detents 286 may preferably be equi-distantly spaced around half or substantially half of the circumference of the rotatable element 270. The detents 286 may be substantially slot shaped apertures with an undercut to provide a hook- shaped formation. The undercuts extend in an anticlockwise circumferential direction. In this way, each detent 286 may be substantially 'L-shaped'. The comers of each detent 286 may be substantially curvate, arcuate or smoothed to facilitate release of each elongate member 264. In this embodiment, the fastener 274 fixed to the end of each elongate member 264 which attaches to the rotatable element 270 may be a hook or catch.

Although the rotatable element 270 is described as being substantially in the shape of a circle, it is appreciated that it may in fact be non-circular, including other curved, polygonal or linear shapes.

A connecting shaft 288 is attached to the rotatable element 270, and preferably attached at or adjacent to a recessed portion of the rotatable plate 270. The connecting shaft 288 may be rotatably attached such that it is able to rotate in a radial plane of or parallel to that of the overboarding quadrant 216. Fixed to the other end of the connecting shaft 288 is one end of a return spring 290 which is attached at the other end to a cylinder 292. The spring 290 is extended into an active state by the movement of the connecting shaft 288 in a clockwise direction, whereby the shaft 288 is extended from the cylinder 292. The cylinder 292 may be rotatably attached to the elongate base portion 230, such that it is similarly able to rotate in a radial plane of the overboarding quadrant 216 to accommodate rotation of the plate 270.

A, preferably remotely releasable coupling, which here may be or include a further shackle 272, may be positioned at or adjacent to the elongate base portion 230 such that it is able to releasably hold the rotatable element 270 in a tensioned or engaged condition to the elongate base portion 230.

The rotatable element 270 may have an engagement element 294, such as a socket or aperture, positioned on an accessible axial face of the rotatable plate 270 to receive a tommy bar or Allen key. Alternatively, the engagement element 294 may be a nut or bolt head similarly positioned to be received by a spanner.

In use, to releasably attach each elongate member 264 to the rotatable element 270, the rotatable element 270 is first rotated. The rotation can be caused by engaging a tool, such as a tommy bar, Allen key or spanner, with the engagement element 294 and then rotating the tool. The rotatable element 270 preferably rotates so as to cause the connecting shaft 288 to move in a direction away from the longitudinal extent of the cylinder 292, extending the spring 290 into an active condition such that it is biased to return to a relaxed, neutral condition. The direction of the rotation is preferably in an opposite direction to the circumferential extent of the detent 286.

A release element is then engaged with the shackle 272 to hold the rotatable element 270 in place with the spring 290 still drawn into the active condition. The fastener 274 at the end of each elongate member 264 is then inserted or hooked into each detent 286, first along the part of the detent 286 parallel with the radial extent of the rotatable element 270, and then into the part of the detent 286 parallel with the circumferential extent of the rotatable element 270. In this way, each of the elongate member 264 is attached to the rotatable element 270 and is in a first condition.

To release each of the elongate members 264 from the rotatable element 270, and thus move each elongate member 264 to a second condition, the release element attached to the shackle 272, such as a rope, chain or other elongate flexible element, may be remotely operated so as to release the rotatable element 270. The remote operation may occur by any of the methods previously described. The spring 290, which was extended and in an active condition, is caused to return to the relaxed, neutral condition. This results in the connecting shaft 288, by nature of being attached to the spring 290, to be moved in a direction towards the cylinder 292. The movement of the connecting shaft 288, due to its attachment to the rotatable element 270, causes the rotatable element 270 to rotate in the opposite direction to that which it was originally rotated in. This rotation, which is in a direction parallel to the circumferential extent of the detent 286, causes each elongate member 264 to be released from its associated detent 286. Each elongate member 264 is thus able to move to the second condition and the flexible elongate submersible element is releasable as previously described.

Although a release element is suggested, possibly being operable from the deck of the associated ship, the shackle itself or associated mechanism may be remotely openable, such as by acoustic means, via a remotely operated vehicle engageable handle which is operatively connected to the rotatable element or via any other release method previously described, to release the rotatable element.

A third embodiment of an overboarding quadrant is shown in Figure 10, and may utilise a fixed anchor element 370 with each of the elongate members 364 being individually releasably attachable to the fixed anchor element 370. Elements which are similar or identical to those of the preceding embodiments are denoted by the same or similar references with one hundred added compared to the second embodiment.

The anchor element 370 may be fixed at or adjacent to an edge portion 330a of the elongate base portion 330 which is radially distal from the arcuate guide path. The anchor element 370 is preferably in the shape of semi-circle. However, other arcuate, curved or linear shapes may be considered. In this embodiment, the fastener at the end of each elongate member 364 is preferably a remotely operable and openable coupling, which here is yet a further shackle 372. Each shackle 372 is individually attachable to the fixed anchor element 370 and may be individually remotely and manually operable. The remote operation may take the form of an acoustic release and the shackle 372 may be openable by any of the methods previously described. Each elongate member 364 is thus positionable in a first condition.

To release each elongate member 364 from the anchor element 370, each shackle 372 may be remotely opened. Each shackle 372 may be opened individually, so as to allow the option of a staged or sequential release, or the shackles 372 may be arranged so as to be opened simultaneously. Having been released, each elongate member 364 is thus able to move to the second condition and the flexible elongate submersible element 110 is releasable as previously described.

Although the initial embodiment has been described as having a releasable anchor element, it is appreciated that it may not be necessary for the anchor element to be entirely releasable from the frame or support. For example, the anchor element may be radially slidably received on the frame. The anchor element may be slid to a first position radially distal from the arcuate guide surface to extend and tension the elongate members into a first condition. The anchor element may then be locked into this position through the use of a remotely operable and openable shackle. When the shackle is remotely opened, the anchor element may slide towards the arcuate guide surface and thus allow the elongate members to move to a second condition, allowing for the flexible elongate submersible element to be releasable. Whilst the elongate members are described as being attachable to and releasable from a point at a centre of the elongate base element, it is appreciated that the elongate members may be releasably attachable to other positions on the frame. For instance, each elongate member may be releasably attachable to an individual position proximal to the associated restraint, or the plurality of elongate members may be attachable to a centre of the overboarding quadrant.

The elongate members are described as being radially aligned with the arcuate guide path, however it is appreciated that there may in fact be only a single circumferential elongate member which is aligned with a circumferential extent of the arcuate guide path. The circumferential elongate member may be extended or tensioned so as to be able to extend around the circumferential extent of the arcuate guide path. Each restraint may be attached to this circumferentially aligned elongate member via a hook or loop so as to secure the flexible elongate submersible element to the guide path. A remotely releasable shackle may hold the circumferential elongate member in this extended or tensioned position or state. When the shackle is operated so as to release the elongate member, the elongate member may revert to an unextended or relaxed state and in this may release any and all restraints.

Although the overboarding quadrant is described as comprising elongate members, it is appreciated that the elongate members may not be necessary and that the restraints may be attached at one end to the support and at another to a shackle or other remotely operable releasable fastener. In this way, the flexible elongate submersible element may still be releasable from the arcuate guide path.

The overboarding quadrant is described as having a remotely releasable shackle positioned so as to interconnect the elongate member and the frame, however, it is appreciated that the remotely releasable shackle may in fact be positioned at other points within the restraint control mechanism. For example, a releasable shackle may be positioned so as to interconnect each elongate member and each movable holding element.

It is therefore possible to provide an overboarding quadrant for underwater remotely releasing a flexible elongate submersible element positioned thereupon. This is achieved with a frame supporting an arcuate guide path along which an in use flexible submersible elongate element may be positioned and restrained by restraints or straps. Each restraint may be remotely releasable.

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.