The invention relates to a coupling device for use in a mooring system for floating structures, subjected to pulling forces or tension arising in the mooring system.

Background of the Invention

A typical floating aqueous fish farm plant consists of a number of cages interconnected with neighboring cages and arranged in a predefined array of floating cages. The farm plant is moored to anchoring points on the seabed and/or shore by means of a number of mooring lines, extending from the farm plant to the anchoring points.

A cage system in a floating aqueous fish farm plant and/or other type of floating plants required to be moored to the seabed and/or shore require a mooring system comprising a large number of mooring lines pointing in horizontal and/or vertical direction and/or arranged in a sideways and/or downwards inclined or slanted direction. Such systems are often configured in such way that nodes of mooring lines are required.

A typical cage comprises one or more floating collars, a net suspended from the collar(s), a mooring point for mooring the cage to one or more of the neighboring cages and/or to anchor points on the seabed/shore.

For quite some time the aquaculture fish farm industry has expressed a desire to reduce use of steel components in the upper part of the water known as the splash zone, which is the first 15 meters downwards from the surface. The splash zone is the area where corrosion is most extreme and where the effect of waves and wind are largest. Strict regulations require periodical inspection, such inspection requiring visual control. If tendency to severe corrosion, detrimental wear and tear, or the like is discovered, for example during such inspection, the affected component or components must be replaced. Commonly such visual inspections are preformed below sea level by divers or by remotely operated cameras. Replacement or repair is always performed by lifting the defect part out of the sea.

The purpose of the mooring system is to keep the floating structure in a fixed position, as well as to secure that the individual floating cages are retained in a spaced relation. The mooring system is dimensioned to secure the installation and consists of mooring lines in all four directions. Mooring lines are selected to match the type of environment they are to be used in, where weather, water current, and other properties of the surroundings are taken into consideration.

Previously, mooring systems consist of mooring lines attached to a large metal collar suspended with buoys in one end and to the anchors on the other end, said elements representing a risk for collision or interference between collar and nets when subjected to waves and heavy sea.

Several of these coupling elements are used in a mooring system. The introduction of a coupling element adds balance to the mooring system, ensuring that the float collars are on a somewhat fixed distance from each other, yet still safely secured. Various alternatives to the steel ring are used in current mooring systems. Most widely used is a mooring plate, which is a round galvanized steel plate with holes.

In a typical mooring system, every float collar is attached to a mooring plate on all four sides using a fiber rope in a type of crowfoot configuration where three ropes are connected to the float collar and the other end of these three ropes are connected at the mooring plate. The mooring plates in the middle of the farm will thusly be surrounded with float collars and will have four collars attached to every plate. The mooring plates on the edges of the farm will have float collars on one side and will always have two collars attached to every plate. The mooring plates on the corners of the farm, will always only have one collar attached to it.

The mooring plates are also interconnected with straight fiber rope mooring lines in order to add the stability needed. These lines make up a square for every float collar in the system. The mooring plates on the edges as well as the mooring plates on the corners will also have mooring lines that stretch to the bottom of the water body where they are bolted, attached to an anchor, or fastened in another suitable way. These same plates are also attached to a buoy which holds the frame at a given depth, normally between seven and ten meters below the sea level. This system allows a build-up of a farm with as many float collars as needed, in any direction.

Any line attached to any mooring plate will be fastened using several more steel components, such as shackles, thimbles, links and chains. Thimbles are used to increase the contact surface between the rope/mooring line and the coupling element and to protect the lines, in order to reduce strain and gnaw on the rope. This can be used in one end or in both ends of the mooring line, whereupon the other end of the thimble usually is connected to a link or a ring. In prior art, there are known steel and plastic thimbles.

Traditionally, steel thimbles are used to form a closed loop or an eye. It is also known to use tube thimbles made of plastic material. Here the tube thimble is given a general U-shape with straight and parallel legs and a curved bottom region, and where the outer bottom surface of the U-shaped thimble is removed, enabling a rope or a wire more easily to be thread in through one of the legs at the bottom to the top and to be bent and threaded in through the other leg from the opposite end from the top to the bottom of the leg, following the U shape of the thimble, whereupon the rope or wire end is spliced to form a closed loop or thimble eye. When a rope or wire with such tube thimble of plastic material, fixed to a body, is tensioned, the thimble legs tend to be bent inward towards each other, whereby the legs of the thimble and the U-shaped bottom tend to be pressed towards each other, deformed to a more or less V-shape around the rig at the thimble bottom, thus forming an abrupt and weakened point shaped transfer zone. A detrimental effect of this behavior is that the loop end of the rope or wire may be more pointed, reducing the thimble effect and exposing the wire or rope to an increased wear and tear, thus creating a possible weak link in the system rather than enhancing the mooring system.

A possible drawback with thimbles made of steel or plastic material is that they are not form stable if subjected to high tension in the lines. Contrary to thimbles of plastic material, which regain the original shape when the tension in the line is relieved, steel thimbles tend to retain the deformed shape. This may have a detrimental effect on the wire or rope reducing the protecting property of the thimble.

Prior art technology requires high maintenance costs and frequent quality assurance, as well as higher risk of component failure that may lead to escaping of fish. Thus, it is a need for an improved system for establishing multiple connections in a mooring system with several mooring lines interconnected and jointed in a mooring node, avoiding the drawbacks of the prior art solution.

Among publications relating to mooring one can mention: WO2012154054 (A1) and US 2100569 A. Objects of the present invention

At least some of the following object are intended to be solved by the invention or by embodiments of the invention.

A object of the invention is to provide components to be used in a mooring system that is reliable and requires less maintenance than existing components.

A object of the present invention is to provide connecting points or nodes between a structure and one or more lines,

Another object of the invention is to configure and design a thimble device system and choosing a thimble material having properties allowing the thimble device system to regain its initial shape and configuration when the tension in the line ceases or is released.

Another object of the invention is to provide a thimble device allowing connection to a structure, where the thimble device allows for several lines or wires to be connected substantially at one single contact point on the structure and also configured to withstand large tension in the line(s) without any substantial degree of deformation.

An object of the present invention is to reduce or remove the disadvantages of the prior art solutions by eliminating or at least substantially remove the need for using metal parts or elements in the mooring system, thereby also eliminating failure caused by corrosion, and sharp edges associated with the mooring system in the splash zone.

Yet another object of the present invention is to provide a coupling element in a mooring system that can withstand strain from forces in any and all directions.

Another object of one embodiment of the present invention is to provide a connecting element that reinforces the connection between the thimble and the link, or ring, preventing deformation and damage of the tube thimble when exposed to strain and/or tension.

There is also an objection of the present invention is to provide a connecting element that reduces gnaw on the rope by allowing the inner surface of the thimble to be rotatably arranged on the outer single curved surface of the connecting element.

There is an objective of the invention to provide a system where said thimbles can be made of a plastic material, such as polyurethane.

Another objective of the invention is to provide a method for fastening the thimbles to the coupling element where a thimble is threaded onto the coupling element before a mooring line or a rope is inserted and then spliced together to create a loop.

Further, an objective of the fastening method is that when the pull force bending the legs outward have been released the thimble will enfold around the coupling element and have a tight secured grip.

Yet one objective of an embodiment of the invention the object is to provide a mooring system where the one or more tube thimbles are axially fixed in sideways manner on the coupling element in-between two or more locking bodies.

Another objective of the present invention is to provide a method where the system can be used in a fish farm to keep floating installations in a more or less fixed position and where the connecting system can be connected to several different elements such as anchors, buoys, floating collars etc.

Summary of the present Invention

In one aspect the invention relates to a coupling device for use in a mooring system for floating structures. The coupling device is subjected to pulling forces or tension arising in the mooring system. Said coupling device comprises a circumferentially coupling element, such as a ring, and where one or more U- shaped tube thimbles are threaded onto the coupling element and linked with mooring lines. The coupling element has locking bodies on each side and adjacent to one or more tube thimbles on the coupling element.

The curved inner surface of the U- shaped tube thimble can be provided with a contact surface complementary to the contact surface of the coupling element.

At least one or more units of U-shaped tube thimbles can comprise two or more U- shaped tube thimbles, placed neighbouring and can be fixed together along the U- shape end of the thimbles, and/or a bushing plate fixed to an inner surface of the U- shaped tube thimbles forming an integrated part of the thimble, facing towards and can be in contact with a corresponding surface on the coupling element when fixed on the coupling element and/or forming a single point of attachment in respect of the coupling element.

A width of the bushing plate can correspond to a width of the U-shaped tube thimbles at their closed bottom end and that a length of the bushing plates corresponds to the corresponding width of the assembled U-shaped tube thimbles.

The bushing plate can be curved both lengthwise and crosswise, both crosswise and lengthwise curvature being adapted to corresponding contact surface of the coupling element.

A pair of legs of one of the thimbles in the assembled U-shaped tube thimble can form an angle with the legs of the neighboring U-shaped tube thimbles, the angle being configured to match an ideal angle for a mooring line when assembled.

The coupling element can be in the form of a ring with a radius R and having a circular cross section with a radius r, the crosswise and lengthwise curves of the bushing plate can be adapted to the correspondingly curved surfaces of the ring.

The legs of a thimble can bend inward until the legs touch or almost touch each other, creating an eye in the thimble.

The thimble can be made from a plastic material, such as polyurethane.

The coupling element can have a steel core in the middle and can be covered by a plastic material, such as polyurethane.

The one or more U-shaped tube thimbles are rotatably arranged on the curved outer surface of a connecting element connected onto the coupling element.

The curved inner surface of the U-shaped tube thimble can be provided with a contact surface complementary to the outer contact surface of the connecting element and/or the inner surface of the connecting element can be provided with a contact surface complementary to the contact surface of the coupling element. In another aspect the invention relates to a coupling device used in a mooring system for floating structures, subjected to pulling forces or tension in any and all directions. Said coupling device comprises a coupling element constructed as a circumferentially coupling element, with locking bodies arranged on said coupling element to fit a tube thimble in-between two locking bodies.

A tube thimble can be arranged in-between two locking bodies.

In another aspect the invention relates to a method for connecting the coupling device, by:

- bending the legs of the thimble outwards and inserting the coupling element into the center hole of the thimble, creating a tight grip when the legs are released,

- inserting a mooring line in through one of the of the legs of the thimble from the bottom opening to the top, to be bent and threaded in through the top of the other leg from the opposite end and down to the bottom end of the leg, whereupon the rope or wire end is spliced to form a closed loop or thimble eye connecting the other end of the rope, wire or other flexible material to the desired position such as at a buoy, net cage and/or anchor, and

- wherein one or more of the tube thimbles are each arranged in-between two locking bodies arranged on said coupling element.

The node system presented do not need as frequent maintenance and replacement of part of the nodes and mooring system as existing systems. Moreover, the system is robust and not prone to corrosion. A further advantage is that the system is stable and allow a single contact point for a spread of lines in different directions, still avoiding collapse of the thimble when subjected to high tension.

A advantage of the system is that the thimble configuration due to the properties of the thimble material or combination of materials used; and the configuration, dimensions and shape of the thimble units may withstand large tensional forces in the lines and regain its original shape and configuration once the tension in the line’s ceases, thus avoiding more or less permanent deformation, all due to its flexible properties.

Yet another advantage is that the system reduces the risk for failure of the node and thus eliminated or at least substantially reduced risk for causing damage to the cage itself.

The present invention relates in general to a system used for mooring tie-in floating and/or stationary structures together and a method for establishing such systems. More particularly, the invention relates to a coupling device for use in a mooring tie-in system for floating and/or stationary structures together, where the system may be subjected to pulling forces or tension in any and all directions. In one embodiment the system comprises a connecting element with double flanges on the sides and a transversally running slot configured to fit a link or a ring or onto the coupling element, and where a unit in the form of a U-shaped tube thimble is threaded onto the connecting element, further connected to a link in the slot and where the thimble is connected with a mooring line. The link, ring or the connecting element can be connected to a shackle, which in turn can be connected to a chain or a rope or directly to a stationary or floating body, such as an anchor. The invention also relates to a method and use of such coupling element for mooring lines in a mooring system that may be subjected to pulling forces in any and all directions.

Brief Description of the Drawings

Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings wherein:

Figure 1 shows schematically an overview of an aquaculture fish farming plant, comprising a number of interconnected cages, moored in a mooring system;

Figure 2 shows schematically a typical coupling element in the form of a ring-shaped node peripherally arranged at one side of the plant and with a configuration of connected mooring line, an anchor line and three interconnecting lines provided with different types of thimbles and closed end loops or eyes;

Figure 3 shows schematically one embodiment of a coupling element, intended to be used in a node system according to the present invention;

Figure 4 shows schematically an embodiment with an integrated three tube thimble configuration according to the present invention, connected in parallel to each other, forming an integrated multi-thimble unit, all in according to the present invention;

Figure 5 shows schematically a perspective of the coupling element with an assembled integrated multi-thimble unit configuration, consisting of three tube thimbles attached on the coupling element;

Figure 6 shows schematically and in perspective a U-shaped connecting element with a slot according to an embodiment of the invention;

Figure 7 shows schematically and in perspective a front view of the U-shaped connecting element with a slot according to an embodiment of the invention; Figure 8 shows schematically and in perspective another embodiment of the U- shaped connecting element with a slot;

Figure 9 shows schematically and in perspective, seen from the side the U- shaped connecting element according to an embodiment of the invention;

Figure 10 shows schematically and in perspective a coupling system with a coupling element inside a tube thimble connected with a link;

Figure 11 shows schematically and in perspective a coupling device with locking bodies arranged; and

Figure 12 shows in a coupling device with locking bodies arranged adjacent to tube thimbles of different dimensions.

Detailed Description of the Invention

In the following, an embodiment of the invention shall be described in further detail, used in connection with mooring of an aquaculture cage assembly 10 in a marine environment. The assembly or plant 10 shown in Figure 1 comprises six cages 11, arranged in two interconnected rows 12, each of the two rows 12 containing three cages 11. The cages 11 are interconnected by an array of connection lines 13, 14, forming a rectangular framework for mooring of thecages 11. The interconnecting lines 13, 14 are interconnected at nodes 15, the nodes 15 also functioning as attachment points for mooring lines 18 for mooring the cages 11 and as attachment points for anchor lines 16 extending between the nodes 15 and anchors 17 on the seabed. According to the embodiment shown, the anchor lines 16 extend from the nodes 15 positioned along the outer periphery of the plant 10. For clarity, only one cage 11 is shown, while the position of the other cages is indicated by rings, the cages being of a type having a circular shape and may comprise one or more hollow floating rings (not shown), forming suspension for the net.

As further indicated in Figure 1, the cage 11 shown is connected to the four nodes 15 by means of three mooring lines 18 at each point. The configuration of the nodes 15 shall be described in further details below in connection with Figures 2 and 4.

As shown in Figure 1 , every cage 11 is attached to a node 15 by means of mooring lines 18. The mooring lines 18 extend between nodes at each of the four corners of the framework formed by the interconnecting lines 13, 14, and the cage 11. The lines 18 may for example a fiber rope attachment of a crowfoot type configuration where three ropes or lines 18 are connected to attachment points (not shown) on the float collar (not shown) from which the net of the cage 11 is suspended and the other end of these three ropes are fixed at a corresponding node 15. The nodes 15 in the middle of the farm plant, i.e. between the two rows of cages 11 shown will thusly be surrounded with float collars and will have four floating collars attached to them in addition to the four interconnecting lines 13,14. The nodes 15 along the peripheral sides of the farm 10 will have float collars on one side and will have two cages 11 attached to every node 15. The nodes 15 at the corners of the farm, will only have one float cage 11 attached to it together with two interconnecting lines 13,14 and two anchor lines 16. The nodes 15 are also interconnected with straight fiber rope interconnecting mooring lines 13, 14 in order to add the stability needed. These lines 13, 14 make up a square for every cage 11 in the system. The nodes 15 along the periphery as well as the nodes 15 at the corners will also have anchoring lines 16 extending to the seabed, fixed to an anchor 17, or fastened in another suitable way. Each of the nodes 15 is also each attached to a buoy 20 (only one buoy is shown). The buoys like the rest of the mooring system are configured to have the necessary strength for the intended use and purpose.

This system is flexible and may be assembled with many cages, expanding the size of the plant lengthwise and/or crosswise, achieved merely by adding numbers of interconnecting lines 13,14, nodes 15, cages 11 and anchor lines 16 with corresponding anchors 17.

One end of each of the interconnecting lines 13, 14, mooring lines 18 and anchor lines 16 are as shown in more detail, moveably attached together at the nodes 15. Referring to Figure 2, one embodiment of a node 15 shall now be discussed in further details.

According to the embodiment shown in Figure 2, two different looped groups of line ends are shown. One of the groups are single thimble loops or eyes 23, such line ends being the ends of either the interconnected lines 13, 14 and/or the anchor lines 16, while the other group comprises a plurality of interconnected thimble loops or eyes for connecting the cage 11 with the frame of interconnected lines 13,14 at the joint between two interconnecting lines 13.14. A main embodiment of the invention is this configuration where one or more single thimbles 22 are arranged on the coupling element 21 in the mooring system. The configuration of another embodiment of the second group of thimbles shall be described below in relation to Figures 3 and 4.

Reference is made to Figures 3 and 4, where one embodiment of the thimble group according to the present invention will be described in more details. As indicated above, the present invention is configured to replace the prior art steel, mooring plates and steel thimbles, used in connection nodes 15 in a mooring system of an aquaculture farming plant 10, for example configured as shown in Figure 1.

According to one embodiment of the invention, such system comprises a coupling element 21 shown here in the form of a closed ring-shaped structure, for example formed as a closed ring with circular or oval shape, ref. Figure 3. The coupling element 21 has a cross-sectional curvature r perpendicular to the curvature R. The purpose of the ring-shaped body 21 is to interconnect the various lines 13,14,16,18 in a secure way, thus serving as a connection point for one or more lines. Figure 4 shows schematically a view of an embodiment of a multi-thimble solution 25 according to the invention. According to the embodiment shown, the multi-thimble solution 25 comprises three separate U-shaped tube thimbles 26, arranged side by side and rigidly fixed together. The thimbles 25, 26 are preferably made of a plastic material, such as polyurethane, known to withstand the aggressive sea conditions in the splash zone. The system according to the present application has no sharp edges that could cause damage to the net or to the fiber ropes. Due to this construction, the interval for periodic inspections is much longer than for the prior art mooring plates and other products used in this part or mooring systems.

Each of the thimbles 25, 26 has a general U-shape and comprises a hollow tube 27, where a part of the material of the tube 27 at the bottom of the U-shaped thimble 25,26 is cut-off, providing access to the outer bottom surface of the U-shaped tube thimble 25, 26, making it easier to thread a rope or wire through the thimble 25,26 for forming a loop or a closed eye at the end of the respective line.

According to one embodiment of the present invention two or more U-shaped thimbles 26 may be arranged side by side, rigidly fixed together at the lower region of the U-shaped thimbles 25, 26, forming a one unitary, integrated body. This may be achieved as part of the moulding process of the multiple thimble unit 25, or by welding or gluing individual units together. According to the present invention a bushing 29 may be arranged across the inner curved bottom of the U-shaped tube thimble/the multiple U-shaped tube thimbles 25. The purpose and configuration of the bushing 29 is to prevent the bottom part of the U-shaped tube thimble unit 25, 26 from becoming deformed when subjected to large tension on the associate line(s).

The bushing 29 forms an integrated part of the thimble 25,26 and is\givena shape and configuration adapted to the shape and form of the inner curved part of the thimble(s) 25,26 on the one side and the form and shape of the coupling element 21 on the opposite side. According to one embodiment the bushing 29 is formed in the moulding process of the thimble variant in question, thus forming an integrated, homogeneous part of the thimble 25, 26.

According to the multiple U-shaped tube thimble 25 shown in Figure 4, the bushing has a convex surface corresponding to the concave inner surface at the bottom of the multiple U-shaped tube thimble 25. The opposite surface of the bushing 29 has a concave surface, the curvature being adapted to fit around the corresponding inner curvature of the coupling element 21. The thickness of the bushing is chosen to give the sufficient rigidity of the thimble 25, 26. The convex surface of the bushing 29 is completely matched to the undulated concave surface of the multiple U-shaped thimble 25, enhancing the rigidity of the thimble 25.

The length of the bushing 29 is longer than the total length along the concave surface of the multiple U-shaped tube thimble 26’, extending outside of each side of the multiple U-shaped tube thimble 25. The bushing 29 is also curved in lengthwise direction to adapt to the corresponding curvature of a ring-shaped coupling element 21.

According to another embodiment of the invention the coupling element 21 is replaced by a connecting element 30, with reference to Figure 10. The purpose of the connecting element 30 is to serve as a reinforcement for a single connection point for either one of the various lines 13,14,16,18, through a single tube thimble 22, creating a single point of attachment. Alternatively connecting elements 30 can be used in a multiple thimble solution in a double, triple 25, 26 or otherwise multiple thimble (not shown in the figures).

According to this embodiment, the thimble 22 is threaded onto a coupling element 30, as shown in Figure 10. The U-shaped coupling element 30 is formed as a body with a cross-sectional curvature r perpendicular to an axial notch 38, and a parallel cross-sectional curvature R, as seen in Figure 8.

The connecting element 30 has a single curved, convex outer surface corresponding to the concave inner surface at the center hole of the U-shaped tube thimble 22. The inner surface of the tube thimble is rotatably on the single curved outer surface of the coupling element, when the thimble is threaded onto the coupling element. Outer flanges 32 of the connecting element 30 will lock the thimble 22 in a sideways manner, as the flanges 32 lay adjacent to the outer surface of the thimble while in the position where the thimble is threaded onto the connecting element, as seen in Figure 10. In one embodiment the thimble can be locked in a sideways manner by adding one or more notches and corresponding taps on each side of the inner surface of the tube thimble and the outer surface of the connecting element in the direction of the rotary movement where the taps are locked in the notches, (not shown). This can be added to the device or replace the flanges.

The slot 38 in the U-shaped connecting element 30 is adapted to fit around the curvature of a link 34 or a ring. The dimension of the connecting element 30 is chosen to give the sufficient rigidity of the thimble 22, 25, 26. The convex surface of the connecting element 30 is completely matched to the undulated concave surface of the U-shaped thimble 22, enhancing the rigidity of the thimble 22.

At the sides of the connecting element 30, flanges 32 are extending perpendicular to the slot 38, as shown in Figure 6, 8 and 9. The flanges lock the component sideways only, thus allowing rotation of the U-shaped tube thimble 22 around the connecting element 30. This will allow for dynamic movement of the connection together with the water current without any friction between the rope and the U-shaped tube thimble, preventing gnawing.

With reference to Figure 10, an embodiment is shown where a link 34 is coupled in the slot 38 of the connecting element 30 with a tube thimble 22 threaded onto, slot facing towards the legs 28 of the thimble. A rope or a wire would be threaded into the one of the bottom legs 28 of the thimble 22, to then be bent at the top and threaded into the opposite leg from the top to the bottom, following the U- shape of the thimble, and then being spliced in a loop or an eye, locking the connecting element and the link (not shown). This configuration creates two pairs of cooperative sliding surfaces complementary arranged. The convex outer surface of the connecting element 30 operates with the inner concave surface of the tube thimble 22, and the inner surface of the connecting element operates with the outer surface of the link. In an alternative embodiment (not in the figures), a separate connecting element 30 could be placed inside each center hole of a multiple tube thimble configuration as shown in Figure 4, e.g. three separate connecting elements 30 in one triple tube thimble 25. In another alternative embodiment (not shown in the figures), one large variant of the connecting element 30 could be used for a multiple tube thimble, such as a double tube thimble or a triple tube thimble for instance, where the length of the connecting element 30 is configured to match the multiple tube thimble 25.

The slot in Figure 6, 7 and 8 is shown as a deep notch starting at the surface of the connecting element 30, but it could also be formed as a narrow notch. The slot is shown as U- shape, but it could also be flat or have other forms created to match the surface of a link 34 or a ring. In an embodiment of the invention the body of the connecting element 30 has a U-shaped form, with an outer cross-sectional curvature r perpendicular to an axial slot 38, and a parallel cross-sectional curvature R.

The connecting element 30 is not restricted to have a U-shaped form. In one embodiment it can be shaped as a closed structure, where the slot is going straight through the element, placed in an arbitrary position.

The connecting element 30 may be used in a single, double, triple or other multiple versions of the thimble solution. The connecting element 30 can be used as a separate unit fitted in each center hole of the thimble in a single, double, triple or other multiple versions of the thimble solution. Alternatively, one connecting element 30 can be used as joint element for each center hole of a multiple tube thimble, such as a double or triple tube thimble.

According to an embodiment, the legs 28 of the U-shaped thimbles 25,26, 22 may point slightly towards each other in a direction towards the free end of the legs 28, thus allowing the thimbles 25,26,22 to be snapped onto the closed ring shaped coupling element 21 or onto the connecting element 30 prior to threading and splicing the rope or wire, thus avoiding the thimbles 26 to drop unintentionally off the closed ring shape coupling element 21, ref. Figure 4.

As seen in Figure 10, an embodiment of a coupling system 36 is shown, where the legs of the thimble have grooves 40 on the inside, creating an easier positioning insertion of the connecting element 30 into the thimble center hole. This coupling system 36 also shows a version of the thimble where the entrance into the center hole has two taps 42, one on each side, to ensure a more secure grip of the connecting element 30.

As further indicated in Figure 4, the multi-thimble solution 25 is provided with a reinforcement and stiffening plate with a shape complimentary to the curvature of the inner bottom of the U-shaped individual thimbles 26.

Although a U-shaped tube formed thimble solution with a downwards and outwards open end is shown, it should be appreciated that a closed solution may be used. Moreover, dimensions and angles of the thimbles 22, 25, 26 and shape, curvature and dimensions of the bushing 29 and connecting element 30 will be adapted to the forces appearing at the site of use and of the type of plant to be moored.

It should also be appreciated that the coupling element 21 may be configured to be split for entering completed eyes or loops of a line onto the coupling element 21 without having to mount the lines out in the field. It should also be noted that the construction, configuration or shape of or material used in the coupling element 21 or ring or in the connecting element 30 may be stainless steel, a polymer coated steel ring or other suitable, corrosion resisting material. The connecting element 30 could also be made of a plastic material such as polyurethane.

According to another embodiment of the invention, locking bodies 50 are arranged on coupling element 21 , spaced apart at a distance to fit a tube thimble 22, 25,26 in- between two locking bodies 50. This is shown in figure 11. As seen in this figure the locking bodies 50 are spaced apart at different distances to fit tube thimbles of different sizes. As an illustration only, the space a shows a spacing for a small tube thimble 22 and the space b shows a spacing for a larger tube thimble 22. This is a way of example only and is not limited to the invention. Any such combination is possible according to the invention. On a coupling element 21 there may be several different spacing for several tube thimbles 22 of different sizes and multiplicity such as single thimble, double thimble, triple thimble and so on. When the tube thimble 22 is arranged on the coupling element 21 adjacent to a locking body 50 on each side, the thimble 22 is locked in a sideways grip. Thus, the thimble is unable to slide or move along the ring. This is illustrated in figure 12. As seen in this figure there are several small and large tube thimbles 22, 25, 26 that are locked on the coupling element 21. The advantage with this embodiment is that when the coupling element 21 is not in a horizontal position, the position of the one or more thimbles 22 will be fixed on the coupling element 21. According to the invention the locking bodies can be used on one or more single thimbles, one or more double or multiple thimbles or on a combination thereof. The locking bodies 50 may also be used to defines a limited area on the coupling element 21 for instance for dividing the coupling element 21 in four quadrants where the one or more thimbles can move freely within the defined space.