EP3068685B1 - Fairlead for guiding an anchoring element - Google Patents

Description

The present invention relates to a fairlead for guiding an anchoring element. In particular, it finds application in permanent anchor devices with an integrated chain stopper, in areas such as marine, offshore and marine renewable energies.

The design of immersed anchor devices, of the submerged fairlead type with integrated chain stopper, requires taking into account the forces experienced by the anchor line at the level of the apparatus, the behavior of the anchor line at the interface with the device and the ease of installation of the anchor line.

This type of equipment has had its first developments with offshore drilling platforms.

Permanent long-term anchorages are common to offshore sectors, with Floating Production Storage and Offloading (FPSO) and Floating Storage Regazification Units (FSRUs) as potential stay several decades on their production site.

New developments in the field of Renewable Marine Energies (RMEs) complete the pre-existing offshore market.

Offshore structures such as floating production supports, construction or drilling platforms, loading and unloading buoys, and recently the floating platforms of EMRs (offshore wind turbines, thermal energy of the seas, etc ...) are anchored on a desired site by means of anchor lines consisting of chains and / or cables connecting them to the anchoring points with the seabed.

Typically, for permanent anchors, chains connected to the anchor points are used, going up to the floating unit via fairleads serving as chain entry guides. We also use chain traction systems (winches, windlasses ...) and finally chain restraining systems (chain stoppers) located on the deck of the floating unit.

Owing to their imposing size, anchored platforms require the use of numerous chains, anchors, anchors and additional equipment. In addition, in order not to increase the existing bulk on the deck of these platforms, the anchoring devices are placed outside the deck, for example in hull planks, whether in an emergent or submerged manner.

In general, the anchor lines are pre-installed and connected to the anchor points. Then messenger lines are passed, from the deck of the floating unit, in the fairleads, termination connectors connecting these messenger lines to the anchor lines.

The anchor lines are then energized to the pre-tension required for anchoring, and the chain stops are activated to maintain the anchor lines in their configuration.

One of the requirements on this type of anchoring device is that they must allow to pass the chain and / or cable, line accessories (Kenter mesh, special connectors) and the messenger line.

Once the platform is secured by anchoring, the anchor chains are continuously working under the stresses induced by wind, swell, tides and currents. The movements produced on the anchor chains accelerate fatigue breakage of the chains if curved guide guns or small radius sprockets are used. This is why anchor gear is usually designed with curved guides or large radius sprockets.

Anchoring equipment of this type is known, such as that described in FIG. US 4,742,993 . This is a curved guide fairlead for anchor cables that can rotate freely around a vertical axis connected to the floating unit.

In this document, the device is designed for cables, and therefore does not include a chain stopper immersed.

Another type of anchoring equipment is described in US5,441,008 . It is a fairlead mounted via a double pivoting connection on a rigid arm at the end of which a chain stopper is integrated.

The system uses a tubular body connected to a separate hinged assembly, and does not allow passing of the messenger line cable, chain, Kenter meshes and special connectors, as is usually required as part of the installation. anchor lines.

None of these anchors can be used on existing anchor systems. Indeed, the existing technology uses a bulky underwater fairlead equipped with a 7-pocket sprocket. During installation, a messenger cable is unloaded from the floating unit and connected by an Anchor Handling Tugs Supply (AHTS) to the pre-installed anchor line. The messenger line is then pulled from the floating unit, passing the messenger cable and line accessories through the fairlead to a massive deck equipment on which the chain is then mounted. This equipment allows carry out the final phase of the installation by putting the anchor line to the right pretension. When the required pretension is obtained, the chain stopper is engaged.

The fact that the chain stopper is located on the bridge of the floating unit therefore encumber the bridge in parallel to increase the efforts on it. Because of this presence on the bridge, the loads transmitted by the anchor lines are brought back on the bridge, which requires the use of more massive equipment and therefore more space to resist and transmit loads.

Another type of anchoring equipment is known as described in US 5,845,893 . This is a fairlead with an integrated chain stopper featuring the most common architecture currently.

The foundations attaching the system to the floating support have a vertical axis pivotal connection with a first moving body. This body serves as guidance to the anchor chain via the use of a sprocket or curved guide directly integrated. An arm having at its end (anchor point side) the chain stopper is connected to the pivoting body via a horizontal axis pivotable connection allowing the final to accommodate changes in azimuth angles and elevation of the line. anchor.

However, the only means of maintenance is to leave the operating site and bring the floating unit back to the cuttlefish hold.

An improvement of this system in its maintenance is described in US 2012/0160146 . It is therefore a question of facilitating the maintenance of the system described in US 5,845,893 , by adding in the upper and lower parts of the foundations guiding pins allowing removal of the equipment from above.

In all these systems, the stopper is fixed which induces that any twist or torsion is taken over the next mesh of that maintained in the stopper. In the case of an extreme twist, this can be particularly detrimental to the fatigue strength of the anchor chain.

The loads and stresses that weigh on the anchoring lines at the level of the floating support are of different natures: corrosion and wear phenomena, impacts, fatigue in flexion (mainly out-of-plane bending), high tensions, phenomenon of spin / twist lines.

The known systems generally respond to the problem of fatigue in flexion out of the plane, but none solves the problem of spin / torsion of the anchor line. During a spin of the anchor line, the chain behaves non-linearly, which disrupts its normal operation. In addition, during an extreme spin (of the order of 15 °), the mesh undergoing this spin has its fatigue life drop very sharply.

One of the aims of the invention is therefore to solve the aforementioned problems, by proposing an anchor type anchor-type embedded chain stopper integrated which solves the problem of spin / torsion of the anchor line at the interface with the anchor.

Thus, the subject of the invention is a guide fairlead of an anchoring element having a longitudinal axis and allowing the anchoring of a unit, such as a floating unit, to an anchor point, said fairlead comprising guide means adapted to guide the anchoring element in translation between the unit and the anchor point, and locking means adapted to block the translation of the anchoring element in the guide means.

The locking means are mounted on the guide means at least partially free in rotation about an axis parallel to the longitudinal axis of the anchoring element when it is guided in the guide means.

• les moyens de guidage comprennent une bague d'appui et des premiers moyens de limitation de rotation, et les moyens de blocage comprennent un support pivotant monté pivotant contre la bague d'appui, et pourvu de deuxièmes moyens de limitation de rotation aptes à coopérer avec les premiers moyens de limitation de rotation pour limiter la rotation des moyens de blocage,
• les premiers moyens de limitation de rotation comprennent au moins une gorge circulaire formant au moins un arc de cercle centré sur l'axe de rotation des moyens de blocage, et les deuxièmes moyens de limitation de rotation comprennent au moins un élément apte à être guidé dans la gorge circulaire,
• les moyens de blocage comprennent au moins un élément de blocage de type clapet monté pivotant sur le support entre une première position de blocage dans laquelle l'élément de blocage est apte à bloquer l'élément d'ancrage en translation dans les moyens de guidage, et une deuxième position sans blocage dans laquelle l'élément de blocage laisse l'élément d'ancrage libre en translation dans les moyens de guidage,
• le ou les éléments de blocage sont pourvus de moyens d'actionnement mécaniques, hydrauliques ou électriques, permettant le passage de ces éléments de blocage de la position de blocage à la position sans blocage et réciproquement,
• les moyens d'actionnement comprennent au moins un élément de type vérin dont une extrémité est reliée au support et l'autre extrémité est reliée à l'élément de blocage, en sorte que le déploiement des moyens d'actionnement entraîne le pivotement des éléments de blocage de la position de blocage vers la position sans blocage,
• les moyens d'actionnement comprennent au moins un câble fixé sur l'élément de blocage, par exemple par l'intermédiaire d'un élément de type anneau, en sorte qu'une traction sur le câble entraîne le pivotement de l'élément de blocage de la position de blocage vers la position sans blocage,
• les moyens de guidage comprennent un premier ensemble de guidage destiné à guider l'élément d'ancrage selon une première direction et comprenant une interface de fixation permettant la fixation du chaumard sur l'unité, et un deuxième ensemble de guidage, monté pivotant par rapport au premier ensemble de guidage autour d'un axe et destiné à guider l'élément d'ancrage dans une deuxième direction formant un angle non nul par rapport à la première direction, et les moyens de blocage sont montés sur le deuxième ensemble de guidage,
• le premier ensemble de guidage comprend un support de guidage monté libre en rotation, autour d'un axe parallèle à la première direction, par rapport à l'interface de fixation, et un guide définissant au moins en partie un passage pour l'élément d'ancrage,
• l'axe de pivotement du deuxième ensemble de guidage par rapport au premier ensemble de guidage est formé dans une première partie du guide et sensiblement à l'opposé des moyens de blocage,
• les moyens de guidage comprennent des moyens de transition permettant de guider l'élément d'ancrage au niveau de la transition entre les première et deuxième directions de guidage,
• les moyens de transition comprennent un élément de type barbotin monté libre en rotation autour d'un axe formé dans une deuxième partie du guide,
• les moyens de transition comprennent un élément de type guide incurvé formé, ou logé, dans le guide,
• les moyens de guidage comprennent un cône de guidage destiné à faciliter l'entrée de l'élément d'ancrage dans le deuxième ensemble de guidage.

According to various alternative embodiments, the system comprises one or more of the features presented below, which may be taken individually or in any technically possible combination:

• the guiding means comprise a bearing ring and first rotation limiting means, and the locking means comprise a pivoting support pivotally mounted against the bearing ring, and provided with second rotation limiting means able to cooperate with the first rotation limiting means for limiting the rotation of the locking means,
• the first means for limiting rotation comprise at least one circular groove forming at least one circular arc centered on the axis of rotation of the locking means, and the second rotation limiting means comprise at least one element that can be guided in the circular groove,
• the locking means comprise at least one valve-type locking element pivotally mounted on the support between a first locking position in which the locking element is able to block the anchoring element in translation in the guide means, and a second non-locking position in which the locking element leaves the free anchoring element in translation in the guide means,
• the locking element or elements are provided with mechanical, hydraulic or electrical actuating means, allowing the passage of these locking elements from the locking position to the non-locking position and vice versa,
• the actuating means comprise at least one jack-type element, one end of which is connected to the support and the other end is connected to the locking element, so that the deployment of the actuating means causes the locking elements of the blocking position to pivot towards the position without blocking,
• the actuating means comprise at least one cable fixed on the locking element, for example by means of a ring-type element, so that traction on the cable causes the locking element to pivot from the lock position to the unlocked position,
• the guide means comprise a first guide assembly for guiding the anchoring element in a first direction and comprising a fixing interface for fixing the fairlead on the unit, and a second guide assembly pivotally mounted relative to at the first guide assembly about an axis and intended to guide the anchoring element in a second direction forming a non-zero angle with respect to the first direction, and the locking means are mounted on the second guide assembly,
• the first guide assembly comprises a guide support rotatably mounted about an axis parallel to the first direction with respect to the attachment interface, and a guide defining at least a portion for the element anchor,
• the pivot axis of the second guide assembly with respect to the first guide assembly is formed in a first portion of the guide and substantially opposite the locking means,
• the guide means comprise transition means for guiding the anchoring element at the level of the transition between the first and second guide directions,
• the transition means comprise a gypsy-type element mounted free to rotate about an axis formed in a second part of the guide,
• the transition means comprise a curved guide-type element formed, or housed, in the guide,
• the guide means comprise a guide cone for facilitating entry of the anchoring element into the second guide assembly.

Thus, the solution proposed by the invention secures the fatigue strength of the chain, reducing the strong degradation that occurs in the case of an extreme twist between two meshes, thanks to the torsional flexibility of the chain stopper system, also called locking means, over a defined angle range.

This flexibility allows the stopper, and therefore the mesh of the chain held by the stopper, to pivot about the axis of the anchor line. Tensile stresses and other bending behaviors in-the-plane and out-of-plane are always present at the first meshes located downstream of the chain stopper (holding mesh and meshes following), but the phenomenon of spin / twist is reported on several additional meshes located upstream of the chain stopper. The torsional loads are then distributed over more meshes than in the classical case and the risk of occurrence of an extreme tendril is greatly reduced.

• figure 1 : représentation schématique d'un exemple de chaumard de guidage selon l'invention ;
• figures 2a et 2b : représentations schématiques d'un exemple de moyens de blocage équipant le chaumard de la figure 1 ;
• figures 3a et 3b : représentations schématiques d'un deuxième ensemble de guidage formant une partie des moyens de guidage du chaumard de la figure 1 ;
• figures 4a, 4b : représentations schématiques du chaumard de la figure 1, avec précisions sur un exemple de moyens d'actionnement mécaniques des moyens de blocage.

The features and advantages of the invention will appear on reading the description which follows, given solely by way of example, and not by way of limitation, with reference to the following appended figures:

• figure 1 : schematic representation of an example of guide fairlead according to the invention;
• Figures 2a and 2b : schematic representations of an example of locking means equipping the fairlead of the figure 1 ;
• Figures 3a and 3b : schematic representations of a second guide assembly forming part of the guide means of the fairlead of the figure 1 ;
• Figures 4a, 4b : schematic representations of the fairlead figure 1 , with details on an example of mechanical actuation means of the locking means.

The fairlead shown figures 1 and 4a firstly comprises a fixing interface 6 intended to interface with the floating unit.

The upper and lower parts of this fixing interface 6, generally called foundations 6, incorporate a vertically oriented axis of rotation.

A guide support 7 pivoting about this axis is mounted between the two foundations 6. This guide support 7 constitutes a passage zone of the anchoring element C, not shown on FIG. figure 1 but represented on the Figure 4A in the form of an anchor chain C.

In this example, the guide support 7 supports a guide 8, 9 which at least partially defines a first passage for the anchoring element C.

The fixing interface assembly 6, guiding support 7 and guide 8, 9 constitutes a first guide assembly 1 which makes it possible to guide the anchoring element C in a first direction.

In the example where the fairlead is fixed in shell plating, for anchoring a floating unit to an anchor point on a seabed, this first guide direction is generally substantially vertical.

Furthermore, a guide arm 2, extended by a guide cone 4 intended to facilitate the entry of the anchoring element C into the guide arm 2, forms a second guide assembly 2, 4.

The guide arm 2 is pivotally mounted on the first guide assembly 1 via an axis of rotation 2a, preferably perpendicular to the axis of pivoting of the guide support 7 of the first guide assembly 1.

In the example where the fairlead is fixed in shell plating, for the anchoring of a floating unit to an anchorage point located on a seabed, the pivot axis of the guide support 7 of the first set 1 being generally substantially vertical, the axis 2a is substantially horizontal.

The second guide assembly 2, 4 is intended to guide the anchoring element C in a second direction which forms a non-zero angle with the first guide direction.

This second guide assembly 2, 4, and in particular the arm 2, allows the system to accommodate variations in elevation angles of the anchoring element C which is an anchor chain C in this example. This anchor chain C passes into the arm 2 via the guide cone 4 and via locking means not shown on the figures 1 and 4a , before going back to the first guide assembly 1.

Transition means 3 are provided for guiding the anchoring element C at the transition between the first and second guide directions, therefore between the first guide assembly 1 and the second guide assembly 2, 4.

In the example shown on the figures 1 , 4a, 4b these transition means comprise a gypsy type element 3, provided with a groove in addition to its footprints. This gypsy 3 is mounted free to rotate about an axis 8a formed in a portion 8 of the guide 8, 9 pivoting from the first guide assembly 1.

Another possibility for these transition means is the integration within the guide 8, 9 pivoting a curved guide, which is then formed in, or housed in this guide 8, 9 pivoting.

Such a curved guide is comparable to a guide rail integrated in the guide 8, 9 pivoting, with a given operating radius.

The first guide assembly 1, the second guide assembly 2, 4 and the transition means 3 thus constitute guide means 1 to 4, which make it possible to guide the anchoring element C in translation between the unit we want to anchor and anchor.

Locking means 5, visible on the figures 1 and 4b but shown in more detail in an example on Figures 2a and 2b , are mounted on the guide means 1 to 4, with a certain degree of freedom in rotation about an axis parallel to the longitudinal axis of the anchoring element C.

These blocking means 5, also called chain stopper 5 in the case where the anchoring element C is an anchor chain C, are preferably mounted at the end of the arm 2 of the second set of 2, 4, substantially opposite the pivot axis 2a of the arm 2 relative to the guide 8, 9 of the first guide assembly 1.

In the example represented in particular on Figures 2a and 2b , the locking means 5 comprise a pivoting support 12, 19. This pivoting support 12, 19 comprises a support element 12 provided with a ring 19, visible only on the figure 2b . This ring 19 is pivotally mounted against a support ring 10 disposed in the guide means 1 to 4.

More specifically, in this example, the support ring 10 is disposed at the end of the arm 2 of the second guide assembly 2, 4, as shown in FIG. figure 3a .

Thus, the locking means 5 can pivot on the arm 2, thanks to the cooperation between the ring 19 and the support ring 10.

Furthermore, the locking means 5 comprise second rotation limiting means 13a to 13d which cooperate with first rotation limiting means 15a to 15d disposed in the guide means 1 to 4.

More specifically, in this example, the first rotation limiting means 15a to 15d comprise circular grooves 15a to 15d centered on the axis of rotation of the ring 19 with respect to the bearing ring 10, thus centered on the rotation axis of the locking means 5.

Furthermore, the second rotation limiting means 13a to 13d comprise elements 13a to 13d, such as pins 13a to 13d, which are each guided in rotation in the circular grooves 15a to 15d.

The rotation as the assembly of the locking means 5 relative to the arm 2 can be obtained with a single circular groove 15a to 15d cooperating with a single stud-type element 13a to 13d.

But preferably four circular grooves 15a to 15d and four stud-like elements 13a to 13d are used equidistant on a circle centered on the axis of rotation of the locking means 5.

In the example represented in particular on Figures 2a and 2b , the locking means 5 comprise two locking elements 11a, 11b, of the type of valves 11a, 11b pivotally mounted on the support 12.

More precisely, these locking elements 11a, 11b pivot on the support 12 between a locking position in which the anchoring element C is locked in translation. in the guide means 1 to 4, and a non-locking position in which the anchoring element C is free in translation in these guide means 1 to 4.

In the example with two locking elements 11a, 11b, of the type of valves 11a, 11b, in the locked position, the valves 11a and 11b stop the anchoring element C which passes through an opening 20 in the support 12, thus blocking its translation. In the non-locking position, these valves 11a and 11b pivot away from the support 12, which has the effect of releasing the anchoring element C.

The shape of the opening 20 in the support 12, and the valves 11a, 11b, depends on the nature of the anchoring element C.

Thus, in the example shown in the figures, the anchoring element C is a chain C consisting of several links, and the opening 20 has a shape adapted to the passage of each link of the chain C. Moreover, the Valves 11a, 11b are adapted to lock the chain C between two of its links in the locking position.

In another example, such as the one shown in figure 4b , a single valve-type locking element is used (not referenced) for the blocking means 5. In such an example in the locking position, the single valve comes to stop the anchoring element C against the edge of a opening formed in the support 12, thus blocking its translation. In the non-locking position, the single valve pivots away from the support 12, thus releasing the anchoring element C.

Thus, the blocking means 5 or stopper 5 are allowed to pivot about the longitudinal axis of the anchor line, at the end of the second guide assembly 2, 4, in a predefined angular range. In the example presented, the allowed angular range is defined by the dimension of the studs 13a to 13d and the length of the grooves 15a to 15d.

Remote actuating means are provided on the blocking means 5, in order to enable activation or deactivation of the locking in translation of the anchoring element C in the guide means 1 to 4.

A first example of actuating means 14a, 14b is shown on the Figures 2a and 2b .

These are means 14a, 14b electrical or hydraulic, which allow the passage of the locking element or elements 11a, 11b from the locking position to the non-locking position, and vice versa.

They may be actuators of the hydraulic or electric cylinder type 14a, 14b. We will then use an actuator 14a, 14b of this type by locking element 11a, 11b.

Specifically, one of the ends of each actuator 14a, 14b is connected to the support 12, rotating about an axis parallel to the main plane of the support member 12, and opposite the pivot axis of the element of blocking 11a, 11b associated with the free end of this locking element 11a, 11b. The other end of each actuator 14a, 14b is connected to the locking element 11a, 11b associated, in rotation about an axis parallel to the axis of pivoting of the locking element 11a, 11b relative to the support piece 12.

The connection point of each actuator 14a, 14b to the associated blocking element 11a, 11b is sufficiently raised relative to the point of connection of this actuator 14a, 14b with the support 12, and sufficiently far from the pivot axis of this blocking element 11a, 11b relative to the support 12, so that the deployment of each actuator 14a, 14b effectively causes the pivoting of the locking element 11a, 11b associated with the locking position to the unlocking position.

The hydraulic or electrical wiring, not shown in the figures, goes back to the edge servitudes, so that these actuating means 14a, 14b can be operated remotely.

The actuating means may also be mechanical actuating means 16a, 16b, 17a, 17b, 18a, 18b allowing the passage of the locking element or elements 11a, 11b from the blocking position to the non-locking position, and reciprocally.

An example of such mechanical means is represented in part by figure 1 as well as Figure 4a and 4b .

The principle of such mechanical means consists in particular in providing the entire system with cables and accessories for returning to enable remote actuation of the locking elements 11a, 11b.

More specifically, the guide means 1 to 4 are provided with rings 18a, 18b for guiding cables 16a, 16b along the guide means 1 to 4. Such rings 18a, 18b can be arranged for example on the arm 2 of the second guide assembly 2, 4.

Each cable 16a, 16b is fixed on a locking element 11a, 11b, for example by means of rings 17a, 17b.

Thus, traction on one of the cables 16a, 16b causes the pivoting element 11a, 11b to pivot from the locking position to the non-locking position.

It is possible to provide force return means for the locking elements 11a, 11b so that when the cables 16a, 16b are released, these locking elements 11a, 11b automatically return and remain in the locking position.

It is also possible to provide a system for controlling the tension in the anchoring lines by using force sensors positioned for example on the arm 2.

The fairlead according to the invention thus makes it possible to substantially reduce the forces due to torsion on the part of the anchoring element C which is held at the level of the blocking means 5. In the case of the use of a chain anchoring C, substantially reduces such forces on the mesh which is held at the level of the chain stopper 5.

This fairlead allows a rotation of the anchoring element C around its longitudinal axis over a defined range of angles. This relative freedom in rotation reduces all the problems on the units for which the anchor line may have twisted.

In addition, in operation, the possibility of disengagement of the mesh of an anchor chain C from the specific housings provided at the level of the locking element or elements 11a, 11b of the chain stopper 5 is greatly reduced.

This fairlead thus improves the behavior of the anchor line C, reduces the stresses on the holding portion of the anchor line C, such as the holding mesh of an anchor chain C, and facilitates the installation of the anchor line C when connecting this anchor line C to a unit such as a floating unit.

The present description is given by way of example and is not limiting of the invention.

In particular, the invention is not limited to the exclusive use of two locking elements 11a, 11b in the locking means, a single element, as shown in FIG. figure 4b , or more than two, may also be suitable.

Also, the invention is not limited to means for limiting the rotation of the locking means 5 relative to the guide means 1 to 4, which consist in the cooperation between circular grooves 15a to 15d with studs 13a to 13d. . Other solutions are possible to obtain this limitation.

Also, the invention is not limited to the exclusive use of a gypsy type transition means 3. A curved guide type transition means (not shown) which is formed in, or housed in the pivotable guide 8, 9 may also be suitable.

Claims (14)

1. A fairlead for guiding an anchoring element (C) having a longitudinal axis and allowing the anchoring of a unit, such as a floating unit, to an anchoring point, said fairlead comprising guide means (1 to 4) able to guide the translation of the anchoring element (C) between the unit and the anchoring point, and blocking means (5) able to block the translation of the anchoring element (C) in the guide means (1 to 4),
   characterized in that the blocking means (5) are mounted on the guide means (1 to 4) at least partially freely rotating around an axis parallel to the longitudinal axis of the anchoring element (C) when the latter is guided in the guide means (1 to 4).
2. The fairlead according to claim 1, characterized in that

   - the guide means (1 to 4) comprise a bearing ring (10) and first rotation limiting means (15a to 15d),

   - and in that the blocking means (5) comprise a pivoting support (12, 19) mounted pivoting against the bearing ring (10), and provided with a second rotation limiting means (13a to 13d) able to cooperate with the first rotation limiting means (15a to 15d) to limit the rotation of the blocking means (5).
3. The fairlead according to claim 2, characterized in that the first rotation limiting means (15a to 15d) comprise at least one circular groove (15a to 15d) forming at least one arc of circle centered on the rotation axis of the blocking means(5), and in that the second rotation limiting means (13a to 13d) comprise at least one element (13a to 13d) able to be guided in the circular groove (15a to 15d).
4. The fairlead according to any one of claims 2 and 3, characterized in that the blocking means (5) comprise at least one blocking element (11a, 11b) of the gate type mounted pivoting on the support (12) between a first blocking position in which the blocking element (11a, 11b) is able to block the anchoring element (C) in translation in the guide means (1 to 4), and a second position without blocking in which the blocking element (11a, 11b) leaves the anchoring element (C) freely translating in the guide means (1 to 4).
5. The fairlead according to claim 4, characterized in that the blocking element(s) (11a, 11b) are provided with mechanical (16a, 16b, 17a, 17b, 18a, 18b), hydraulic (14a, 14b) or electric (14a, 14b) actuating means (14a, 14b, 16a, 16b, 17a, 17b, 18a, 18b), allowing the passage of these blocking elements (11a, 11b) from the blocking position to the position without blocking, and vice versa.
6. The fairlead according to claim 5, characterized in that the actuating means (14a, 14b) comprise at least one element of the jack type whereof one end is connected to the support (12) and the other end is connected to the blocking element (11a, 11b), such that the deployment of the actuating means (14a, 14b) drives the pivoting of the blocking elements (11a, 11b) from the blocking position toward the position without blocking.
7. The fairlead according to claim 5, characterized in that the actuating means (16a, 16b, 17a, 17b, 18a, 18b) comprise at least one cable (16a, 16b) fixed on the blocking element (11a, 11b), for example via an element of the ring type (17a, 17b), such that traction on the cable (16a, 16b) drives the pivoting of the blocking element from the blocking position (11a, 11b) toward the position without blocking.
8. The fairlead according to any one of claims 1 to 7, characterized in that the guide means (1 to 4) comprise a first guide assembly (1) designed to guide the anchoring element (C) in a first direction and comprising a fastening interface (6) allowing the fastening of the fairlead on the unit, and a second guide assembly (2, 4), mounted pivoting relative to the first guide assembly (1) around an axis (2a) and intended to guide the anchoring element (C) in a second direction forming a non-zero angle relative to the first direction, and in that the blocking means (5) are mounted on the second guide assembly (2, 4).
9. The fairlead according to claim 8, characterized in that the first guide assembly (1) comprises a guide support (7) mounted freely rotating, around an axis parallel to the first direction, relative to the fastening interface (6), and a guide (8, 9) defining at least part of a passage for the anchoring element (C).
10. The fairlead according to claim 9, characterized in that the pivot axis (2a) of the second guide assembly (2, 4) relative to the first guide assembly (1) is formed in a first part (9) of the guide (8, 9) and substantially opposite the blocking means (5).
11. The fairlead according to any one of claims 8 to 10, characterized in that the guide means (1 to 4) comprise transition means (3) making it possible to guide the anchoring element (C) at the transition between the first and second guide directions.
12. The fairlead according to claim 11, characterized in that the transition means (3) comprise an element of the guide wheel type (3) mounted freely rotating around an axis (8a) formed in a second part (8) of the guide (8, 9).
13. The fairlead according to claim 11, characterized in that the transition means (3) comprise an element of the curved guide type formed, or housed, in the guide (8, 9).
14. The fairlead according to any one of claims 8 to 13, characterized in that the guide means (1 to 4) comprise a guide cone (4) intended to facilitate the entry of the anchoring element (C) in the second guide element (2, 4).

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