MARINE ROPE HAVING AN INDIVIDUAL COATING OF EACH CORE

Abstract

The invention concerns the field of marine ropes, and more specifically a marine rope (1) comprising a plurality of cores (2; 2a, 2b), an individual coating (3) around each core (2; 2a, 2b), and a permeable protective sheath (4) around the plurality of cores (2; 2a, 2b). Each core (2; 2a, 2b) comprises a fiber strand or braid and each individual coating (3) is watertight and has a melting temperature lower than that of the corresponding core and an elongation at break greater than that of the corresponding core.

Description

BACKGROUND OF HE INVENTION

The present invention relates to the field of ropes and more specifically that of marine ropes, in particular those used for mooring lines.

When such mooring lines are used in shallow waters, the ropes must be protected from impacts, on the one hand, notably impacts with fishnets, and from marine organisms, on the other hand, that can implant themselves deep in the center of the ropes.

To protect marine ropes from impacts, the use of a protective sheath is known, for example, made of aramid fabric, as disclosed in Japanese patent application publication JP 2014-031602, a braided sheath, as in international application publication WO 2017/178484 A1 or German utility model DE 20 2010 013519 U1, or stranded steel wires, as in patent application publication US 2015/113936.

In order to prevent marine organisms, especially mollusks, from being able to nest in the center of the rope and damage it, the use of essentially watertight coatings, typically of polyurethane is known. These coatings can especially be positioned under the protective sheath, in order to also protect them from impacts, as disclosed in international patent application publication WO 2006/118465 or in European patent application publication EP 0,252,830 A1. However, the ropes used in long-term mooring lines can be subjected to very high cyclic loads, generating high heat. The passage of water through the rope to evacuate this heat and prevent the rope from melting may be impeded by coatings that protect against marine organisms. This impedes the use of large-diameter ropes in long-term mooring lines.

SUBJECT AND SUMMARY OF THE INVENTION

The present disclosure seeks to remedy these disadvantages, by proposing a marine rope combining good protection against impact and colonization by marine organisms with good cooling by water, even with large rope diameters. For this, according to a first aspect, this marine rope may comprise a plurality of cores, an individual coating around each core, and a protective sheath around the plurality of cores. Each core of the plurality of cores can comprise a strand of fibers or a braid of fibers and each individual coating can be watertight, so as to prevent the colonization of the corresponding core by marine organisms, and have a melting temperature lower than that of the corresponding core, so as to melt before this core in the event of overheating of the rope, and an elongation at break greater than that of the corresponding core, to prevent it tearing from before the core breaks. The sheath can be permeable so as to allow the passage of water and the circulation of water between the cores.

By means of these arrangements, water can penetrate through the permeable protective sheath and circulate between the cores to cool them, while the individual coatings protect each core from marine organisms, By multiplying the number of cores, large-diameter ropes can be obtained, consequently having a high load capacity, whose cooling in the context of long-term marine mooring, for example mooring of floating platforms, nevertheless remains satisfactory. Thus, the plurality of cores can comprise at least four cores.

When the cores comprise fiber strands, it is necessary to balance the torsional moments induced by tensile forces on these strands. For this, the plurality of cores can comprise as many strands of fibers stranded in one direction as strands of fibers stranded in another opposite direction.

The permeable protective sheath can notably be braided around the plurality of cores, thus allowing high-strength fibers to be used, while ensuring its permeability and therefore the cooling of the cores by the interstices among the braided fibers of this sheath. The permeable protective sheath can notably comprise aramid and/or high-modulus polyethylene to ensure good mechanical protection from impacts. “High-modulus polyethylene” (HMPE) means polyethylene with extremely long molecular chains, i.e., of the order of several hundred thousand monomer units. It is also known by the name ultra-high molecular weight polyethylene (UHMPE or UHMWPE) or high-performance polyethylene (HDPE).

To ensure a good seal of the individual coating around each core and prevent implantation of marine organisms, the individual coating around each core can comprise polyurethane.

To ensure good tensile strength to the rope, the plurality of cores can comprise synthetic fibers, and especially polyester, polyethylene, aramid and/or polyimide fibers.

The present disclosure also concerns a mooring line comprising the abovementioned marine rope, as well as the use of such a mooring line for a floating body, and especially for long-term mooring of a floating platform such as, for example, a wind turbine platform.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical teachings of this disclosure will be better understood and its advantages will appear more clearly upon reading the detailed non-limiting examples. The description refers to the attached drawings, in which:

FIG. 1A is an exploded view of a first example of marine rope,

FIG. 1B is a cross-sectional view, along plane IB-IB, of the marine rope of FIG. 1A,

FIG. 2A is an exploded view of a second example of marine rope,

FIG. 2B is a cross-sectional view, along plane IIB-IIB, of the marine rope of FIG. 2A,

FIG. 3A is an exploded view of a third example of marine rope,

FIG. 3B is a cross-sectional view, along plane IIIB-IIIB, of the marine rope of FIG. 3A,

FIG. 4A is an exploded view of a fourth example of marine rope,

FIG. 4B is a cross-sectional view, along plane IVB-IVB, of the marine rope of FIG. 4A, and

FIG. 5 is a schematic view of a floating platform moored to a seabed by several mooring lines.

DETAILED DESCRIPTION OF THE INVENTION

A marine rope 1 according to a first example can comprise, as illustrated in FIGS. 1A and 1B, a plurality of cores 2a, 2b to transmit tensile forces, an individual coating 3 around each core 2a, 2b and a permeable protective sheath 4 around the plurality of cores.

As illustrated, each core 2a, 2b can be formed by a strand of fibers. These fibers can be synthetic fibers, and especially aramid and/or high-modulus polyethylene, providing a very high tensile capacity with a limited weight. In order to equilibrate the moment of torsion generated by pulling on each core 2a, 2b, the plurality of cores 2a, 2b may also comprise as many strands of fibers stranded in one direction as strands of fibers stranded in the other direction. Thus, as in the example illustrated in FIGS. 1A and 1B, the plurality of cores 2a, 2b can comprise two cores 2a each formed by a strand turning in a first direction, and two cores 2b each formed by a strand turning in a second direction, opposite to the first direction.

In order to protect from marine organisms, and especially mollusks that can nest between the fibers, each core 2a, 2b can be covered with an individual watertight coating 3. These individual coatings can be of a watertight material having a melting temperature lower than that of the corresponding core and an elongation at break greater than that of the corresponding core. If cores 2a, 2b are polyester, polyethylene, aramid and/or polyimide fibers, the material for individual coatings 3 can thus be polyurethane, for example.

Finally, permeable protective sheath 4 protects cores 2a, 2b as well as individual coatings 3, against impacts and friction. As illustrated in FIG. 1A, it can be braided, for example from aramid and/or high-modulus polyethylene fibers, offering good impact resistance and low friction. The braiding can nevertheless be fairly open, so as to allow water to circulate through this sheath 4 to cool cores 2a, 2b at the interior.

Although in this first example illustrated cores 2a, 2b are four in number, it is also possible to have a higher number. Thus, for example, as shown in the second example illustrated in FIGS. 2A and 2B, cores 2a, 2b can be eight in number. As in the first example, these cores 2a, 2b can be formed by fiber strands, and comprise as many fibers stranded in one direction as fibers stranded in another, opposite, direction. Thus, as illustrated in FIGS. 2A and 2B, the plurality of cores 2a, 2b can comprise ten cores 2a each formed by a strand turning in a first direction, and ten cores 2b each formed by a strand turning in a second direction, opposite to the first direction. The remaining characteristics of marine rope 1 according to this second example can be identical or similar to those of the first example, and the elements of this rope 1 therefore will be given the same references in these FIGS. 2A, 2B as in FIGS. 1A and 1B.

Although in the preceding examples cores 2a, 2b are formed by fiber strands, it is also possible to envisage having marine ropes with 2 cores formed by braids, as illustrated, for example, in FIGS. 3A to 4B. These braids can also be formed by synthetic fibers, and especially aramid and/or high-modulus polyethylene, providing a very high pulling capacity with a limited weight. In the example of FIGS. 3A and 3B, these braided cores 2 are four in number, as in the first example, but it is also possible that they could be greater in number, as in the example of FIGS. 4A and 4B, where they are eight. The remaining characteristics of marine ropes 1 according to these third and fourth examples can be identical or similar to those of the first two examples, and therefore will be given the same references in these FIGS. 3A to 4B as in FIGS. 1A to 2B.

These marine ropes 1 can especially be used for mooring lines, such as mooring lines 11 for floating platform 10 illustrated in FIG. 5, that can tie this floating platform 10 to anchors 12 on seabed 13 in order to maintain its position, for example for the use of offshore wind power.

Although the present invention has been described by referring to specific examples of embodiment, it is obvious that various modifications and changes can be made without exceeding the general scope of the invention as defined by the claims. Moreover, individual characteristics of the different examples discussed can be combined into additional embodiments. Thus, for example, it would be possible to envisage combining braided cores and stranded cores in the same rope. Consequently, the description and the drawings should be considered in an illustrative rather than a restrictive sense.

Claims

1. A marine rope comprising: plurality of cores, each core comprising a strand of fibers or a braid of fibers,an individual coating around each core, each individual coating being watertight and having a melting temperature lower than that of the corresponding core and an elongation at break greater than that of the corresponding core, anda protective sheath around the plurality of cores, characterized in that the sheath is permeable so as to allow the passage of water and the circulation of water between the cores.

2. The marine rope according to claim 1, wherein the plurality of cores comprises at least four cores.

3. The marine rope according to claim 1, wherein the plurality of cores can comprise as many strands of fibers stranded in one direction as strands of fibers stranded in another opposite direction.

4. The marine rope according to claim 1, wherein the permeable protective sheath is braided around the plurality of cores.

5. The marine rope according to claim 1, wherein the permeable protective sheath comprises aramid and/or high-modulus polyethylene.

6. The marine rope according to claim 1, wherein the individual coating around each core comprises polyurethane.

7. The marine rope according to claim 1, wherein the plurality of cores comprise synthetic fibers.

8. The marine rope according to claim 7, wherein the synthetic fibers comprise polyester, polyethylene, aramid and/or polyamide fibers.

9. A mooring line comprising the marine rope according to claim 1.

10. A method of using the mooring line according to claim 9 for mooring of a floating body.