Mooring member

Abstract

A mooring member comprises a rope configured for extending between a vessel floating in a body of water and an anchoring device. The mooring member comprises a plurality of functional elements, wherein a first functional element is wound onto at least a portion of the rope, a second functional element is wound onto the first functional element, and so on, until an outermost functional element is wound onto a second-to-outermost functional element. The functional elements are wound in a helical configuration, and are configured to provide at least one of the following functions: damage protection, buoyancy, optical detection, sonar detection, stiffness control, and anti-fouling.

Claims

1. A mooring member for extending between a vessel floating in a body of water and an anchoring device, comprising: a fibre rope; and a plurality of functional elements each wound as a different layer around at least a portion of the fibre rope, wherein one or more of the plurality of functional elements comprises a filler material comprising a plurality of hollow or solid micro-spheres, the plurality of functional elements further comprising: a first functional element at a first layer including a first filler material having a first colour, a second functional element at a second layer wound around the first layer wherein the second functional element includes a second filler material having a second colour different from the first colour, wherein all of the plurality of functional elements are wound in a helical configuration, are capable of moving with respect to the fibre rope, and are extruded elongated elements; and wherein the first colour and the second color provide an optically discernible indication of a depth of damage to the mooring member.

2. The mooring member of claim 1, wherein the plurality of functional elements include a base material comprising a thermoplastic.

3. The mooring member of claim 1, wherein one or more of the plurality of functional elements comprise a third filler material configured to improve an abrasion and cut resistance of the plurality of functional elements.

4. A mooring member for extending between a vessel floating in a body of water and an anchoring device, comprising: a fibre rope including a bundle of core strands extending along a first direction; a membrane enclosing the fibre rope; and a plurality of functional elements wound around the fibre rope and the membrane, comprising: a first functional element including a single or multiple strands that are wound in a helical configuration such that a first winding of the functional element and an adjacent second winding of the functional element have a gap therebetween; a second functional element wound in a helical configuration around the first functional element; wherein the plurality of functional elements are capable of moving with respect to the fibre rope; wherein the plurality of functional elements are extruded elongated elements; and wherein one or more of the plurality of functional elements comprises a filler material comprising a plurality of hollow or solid micro-spheres, or filler materials that improve the functional element's cut resistance and abrasion resistance.

5. The mooring member of claim 4, wherein one or more of the plurality of function elements comprise a filler material comprising a hydrophobic material.

6. The mooring member of claim 4, wherein one or more of the plurality of functional elements comprises a filler material comprising at least one lubricating agent configured to reduce seawater absorption.

7. The mooring member of claim 6, wherein the at least one lubricating agent comprises at least one of a MoS.sub.2, PTFE, glass fibre, carbon fibre, aramid fibre, basalt, or other amorphous or hydrophobic filler.

8. The mooring member of claim 4, wherein one or more of the plurality of function elements comprise a filler material comprising one or more anti-fouling agents.

9. The mooring member of claim 4, wherein the gap between the windings is provided in order to avoid axial compression between each winding and to allow for a certain bending radius, whereby, when the fibre rope is bent, a distance between the windings on an outer radius increases, whereas the windings on an inner radius move towards each other and the gap is reduced.

10. The mooring member of claim 4, wherein at least one of the plurality of functional elements includes buoyant properties or/and swelling properties configured to reduce or eliminate catenary and improve stiffness of the mooring member.

11. The mooring member of claim 4, wherein at least one of the plurality of functional elements is designed and manufactured with at least one specific function suitable for the fibre rope's operational requirements, the at least one specific function comprising one or more of wear resistance, mechanical toughness, high PV tolerances where the P describes a contact pressure between an abrading object and a respective functional element and where the V describes a velocity between the abrading object and the respective functional element, buoyancy, visual detection and damage reporting, sonar detection, stiffness control, and fouling prevention.

12. The mooring member of claim 4, wherein the plurality of functional elements further comprises an outermost functional element that is fastened to one or more layers of the plurality of function elements below by a holding or locking mechanism.

13. The mooring member of claim 4, further comprising: an outer braided structure surrounding the plurality of functional elements.

14. A mooring member for extending between a vessel floating in a body of water and an anchoring device, comprising: a fibre rope; and a plurality of functional elements each wound as a different layer around at least a portion of the fibre rope comprising: a first functional element at a first layer including a first filler material having a first colour; a second functional element at a second layer wound around the first layer wherein the second functional element includes a second filler material having a second colour different from the first colour; wherein all of the plurality of functional elements are wound in a helical configuration, are capable of moving with respect to the fibre rope, and are extruded elongated elements; and wherein the first colour and the second color provide an optically discernible indication of a depth of damage to the mooring member, and wherein one or more of the plurality of functional elements comprise a filler material which exhibits swelling properties when in contact with water.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other characteristics of the invention will become clear from the following description of a preferential form of embodiment, given as a non-restrictive example, with reference to the attached schematic drawings, wherein:

(2) FIG. 1 is a perspective view of a portion of a synthetic fibre rope furnished with a number of the functional elements according to the invention, shown as individual tapes wrapped in a helical fashion around the rope and secured with an outer fastener in the form of a braided structure;

(3) FIG. 2 is a cross-sectional drawing of an embodiment of the invention, corresponding to the plane P in FIG. 1, but the rope has been removed and only two layers of functional elements are shown (for clarity of illustration);

(4) FIG. 3 is an axial section (along longitudinal axis x in FIG. 1), corresponding to the portion A in FIG. 1, but showing only two layers of functional elements (for clarity of illustration);

(5) FIG. 4 corresponds to FIG. 3 but shows the displacement of the functional elements when the rope is bent;

(6) FIG. 5 shows the functional elements' placement on the rope in different orientations and helical angles;

(7) FIG. 6 is part of a cross-section of a number of functional elements, indicating how different functional elements have different properties and functions;

(8) FIG. 7 shows (in cross-section) four different embodiments of the functional elements;

(9) FIG. 8 shows (in cross-section) different variants of layers of functional elements (of different cross-sectional shapes);

(10) FIGS. 9a and 9b show the invention applied on the mooring lines of a floating platform;

(11) FIG. 10 is a sketch indicating one application of the invention;

(12) FIG. 11 is shows various embodiments of the functional elements, used for protecting connections between ropes;

(13) FIG. 12 shows (in cross-section) two different embodiments of gripping elements;

(14) FIG. 13 is a plan view of an embodiment of an end portion of the mooring member having an end termination device;

(15) FIG. 14 is a perspective view of the end termination device shown in FIG. 13, in a partly disassembled state; and

(16) FIG. 15 is a perspective view of a portion of the disassembled end termination device, in which a few sub-ropes have been removed in order to display guide grooves on the thimble.

DETAILED DESCRIPTION OF A PREFERENTIAL EMBODIMENT

(17) The following description will use terms such as horizontal, vertical, lateral, back and forth, up and down, upper, lower, inner, outer, forward, rear, etc. These terms generally refer to the views and orientations as shown in the drawings and that are associated with a normal use of the invention. The terms are used for the reader's convenience only and shall not be limiting.

(18) FIG. 1 shows a portion of an embodiment of the mooring line 6, hereinafter also referred to as a mooring member 6. A synthetic fibre rope 1 comprises in the illustrated embodiment a bundle of core strands 2 surrounded by a braided jacket 3. A membrane 7 is arranged between the jacket 3 and the bundle of core strands 2. This membrane prevents ingress of particles that could damage the core strands. A fibre rope of this type is well known in the art, and is commonly used as mooring lines. The rope strands may for example be made of synthetic polyester, polyethylene or polyamide. Other fibre types are conceivable. For mooring purposes, the rope 1 outer diameter (i.e. including the jacket 3) may range between 80 mm and 300 mm. The invention shall, however, not be limited to such dimensions.

(19) Although the invention in the following is described with respect to a fibre rope made up of a bundle of core strands 2, it should be understood that the invention is equally applicable for a rope comprising a number of sub-ropes. Therefore, reference number 2, in the figures and the following description, may refer to rope strands or to sub-ropes.

(20) Arranged around the rope 1 are a number of so-called functional elements 4, in the illustrated embodiment wound around the rope in a helical manner (i.e. describing a helix). FIG. 1 shows a rope carrying five functional elements, labelled 4.sub.1 to 4.sub.5, one layered on top of the other. The innermost layer 4.sub.1 bears against the rope jacket 3, the next layer 4.sub.2 bears against the innermost layer 4.sub.1, and so on, until the outermost layer 4.sub.5 which is exposed to the surroundings. The outermost layer 4.sub.5 is held in place (i.e. fastened to the layer(s) below) by an outer braided structure 5. It should be understood that this braided structure 5 may be substituted by any other suitable holding or locking means. The innermost layer 4.sub.1 preferably comprises serrations 13a (see FIG. 12a) or castellations 13b (see FIG. 12b) that serve as gripping members into the rope jacket 3. The functional elements are thus connected to the rope, but are also capable of moving with respect to the rope (due to e.g. rope bending). Other, equivalent, gripping means may be used. The layers of functional elements thus form a compound structure, which allows water to circulate through the layers and into the rope. The functional elements' helical configuration accommodates axial movement, e.g. elongation, of the rope.

(21) In the illustrated embodiment, each functional element 4.sub.1-4.sub.5 comprises an elongated, tape-shaped, member, and each tape-shaped member is wound around the rope in a helical manner. The functional elements may therefore in the following also be referred to as tapes. As is clearly shown in FIGS. 5a-c, the pitch angle and respective orientation of each of the functional elements may be varied according to specific requirements. For example, as shown in FIGS. 5a-c, the windings of adjacent elements 4.sub.1, 4.sub.2 may be in opposite directions. The various elements may also have different thicknesses and widths.

(22) The functional elements (tapes) are typically manufactured by extrusion or/and pultrusion, and their base material typically comprise a thermoplastic, from the semi-crystalline families such as polyamides, polyolefins, fluoroplastics or more amorphous thermoplastics (such as polystyrene), or combinations of these.

(23) Examples of possible tape cross-sections are shown in FIG. 7: a) rectangular; b) stepped; c) notched; d) circular. The invention is, however, not limited to these cross-sections.

(24) FIG. 8 illustrates (schematically) how different cross-sectioned tapes may be arranged in layers when applied onto a fibre rope (not shown in FIG. 8): a) rectangular cross-sectionstaggered; b) stepped cross-sectioninverted and staggered; c) notched cross-sectioninverted and staggered; d) notched cross-sectioninverted.

(25) FIG. 3 shows how two layers 4.sub.1, 4.sub.2 of functional elements are staggered, and FIG. 4 shows how the functional elements are displaced when the rope (not shown in FIG. 4) is bent. The functional elements are wound (helically) onto the fibre rope, with a distance (gap) d.sub.1 between the windings, in order to avoid axial compression between each winding and to allow for a certain bending radius. When the rope is bent (FIG. 4), the distance between the windings on the outer radius increases (to d.sub.2), whereas the windings on the inner radius are moving towards each other (i.e., gap reduction, towards abutment).

(26) The functional elements may be designed and manufactured with one or more specific function, suitable for the fibre rope's operational requirements (e.g. mooring). Such specific functions may comprise, but not necessarily be limited to: Wear resistancefor protection against: cuts (e.g. by trawl wire), abrasion (e.g. against seabed), and damages by dropped objects. Toughness and other mechanical properties. High PV tolerance (where the P describes the contact pressure between the abrading object and the functional element and where the V describes the velocity between the abrading object the functional element). Buoyancyfor controlling buoyancy, e.g. at specific portions along the mooring line, for example to reduce catenary. Visual (optical) detection and damage reporting. Sonar detection. Stiffness control. Fouling prevention.

(27) Thus, one or more of the functional elements may have a filler material, comprising a plurality of hollow or solid micro-spheres 12 (see FIG. 6), made of e.g. glass, ceramic spheres, nanoclay, talcum, calcium carbonate. The hollow spheres will contribute to reducing the density of the functional element and hence increase its buoyancy. Other filler materials will improve the functional element's cut resistance and abrasion resistance. Optical fibres or strain gages may be incorporated in the functional element to monitor the elongation of the mooring line. Filler materials may also comprise lubricating agents such as MoS.sub.2 or PTFE, glass fibre, carbon fibre, aramid fibre, and/or basalt, or other amorphous or hydrophobic fillers in order to reduce seawater absorption. Filler materials may also comprise anti-fouling agents in order to prevent algae, mussels and barnacles growth (which would add submerged weight).

(28) Filler materials of different colours may be incorporated in different functional elements, thus making one functional element optically discernible from another. This is illustrated in FIG. 1, where the five different functional elements have different colours. This feature provides for an optional detection and assessment (e.g. via a ROV-controlled camera) of cuts and other damages. The different colours will indicate penetration depth of the cut and the magnitude of the damage.

(29) The hollow spheres 12 are detectable by sonar signals S, in a manner which per se is well known. Therefore, a mooring line 6 in which one (e.g. the outermost) functional element comprises spheres 12 (FIG. 6) will be have a potential for being detected by the fishing vessels' on-board sonar (e.g. echo-sounder, used as fish-finder), and trawl wire impact may be avoided. FIG. 10 illustrated this situation.

(30) In one embodiment, one or more of the functional elements incorporates a filler material which exhibits swelling properties when in contact with water. When a mooring member having such functional element is installed and brought in contact with the seawater, that functional element (which is wrapped around the fibre rope as described above) will swell and effectively increase the stiffness of the mooring member following installation.

(31) The functional elements may be used on the entire mooring line 6, or on parts of it. Also, functional elements with different properties may be used on different parts of the mooring line 6. For example, functional elements having particular abrasion- and cut resistant properties may be used on the portion of the mooring line 6 that is connected to the seabed and in contact with the seabed (see FIG. 9a). Functional elements having buoyant properties or/and swelling properties, as described above), may be applied to the mooring line to reduce or eliminate catenary and improve stiffness. FIG. 9b shows two possible configurations.

(32) FIG. 11 illustrates an embodiment of the functional elements. When two ropes 1a, 1b, are joined, for example conventional spliced eyes connected by shackles (or H-links), functional elements in the form of a casing 4 protect the joint (see FIG. 11a). The casing may comprise casing halves 14a,b, joined by bolts (FIG. 11b) or clamps. Other is fastening means, such as seizing, may be used.

(33) The casing 4 may comprise any one of the materials and properties mentioned in the relation to the functional elements described above, and may be manufactured to different shapes (FIG. 11c).

(34) FIG. 13 shows an end portion of the mooring line 6, clad with one or more of the functional elements 4, and connected to an end termination device 14. The end termination device 14 comprises a housing 15, a connection eye 16 (for a shackle, etc.), and a removable cover 17. Crimp rings 20 are used to secure the ends of the functional elements 4, near the housing. In FIG. 14, the cover has been removed, showing how the sub-ropes (alternatively core strands) 2 are looped around a thimble 18 (connected to the housing) and spliced in a region SP (splice not shown, covered by the functional elements 4). The housing 15 and the thimble 18 are made of a high-strength material (e.g. stainless steel) suited for the application. In use, the mooring line may be cut to a desired length, a portion of the jacket removed to expose a required length of sub-ropes 2. The sub-ropes 2 are curved in a loop L as shown in FIG. 14, and spliced onto themselves (in a manner known in the art. As shown in FIG. 15, the thimble 18 comprises guide grooves 19 for individual sub-ropes. During assembly, the loop L is placed around the thimble 18, the cover 17 is fitted onto the housing, and one or more functional element 4 are wrapped around the core strand, in a configuration shown in FIG. 13. The end termination device 14 thus protects the synthetic mooring line end termination against cuts, chafing and abrasion.

(35) Although the invention has been described with reference to synthetic fibre ropes, it should be understood that the invention is also applicable on other types of ropes and mooring lines.

(36) The fibre rope may for example be a polyester mooring line, with diameter and minimum breaking load ranging between approximately

(37) a) 110 mm and 380 tonnes, respectively, and

(38) b) 260 mm and 2000 tonnes, respectively.

(39) The fibre rope may also for example be a Dyneema mooring line, with diameter and minimum breaking load ranging between approximately

(40) a) 80 mm and 370 tonnes, respectively, and

(41) b) 190 mm and 2500 tonnes, respectively.

(42) The invention has been described using the term rope. It should be understood however, that in the context of this invention, the terms hawser and cable are considered to be equivalent terms to that of rope.