EP3261976A1

EP3261976A1 - Method for handling a faired cable towed by a vessel

Info

Publication number: EP3261976A1
Application number: EP16707094.5A
Authority: EP
Inventors: François Warnan; Dominique Durand; Jean-Philippe LONGUET; Marc LAZZARINI; Stéphane AUTRET; Jean-Jacques LOSSEC; Philippe PROST
Original assignee: Thales SA
Current assignee: Thales SA
Priority date: 2015-02-27
Filing date: 2016-02-26
Publication date: 2018-01-03
Anticipated expiration: 2036-02-26
Also published as: AU2016223409A1; US10457356B2; FR3033162B1; US20180029671A1; ES2937643T3; FR3033162A1; SG11201706876WA; CA2977706A1; EP3261976B1; WO2016135321A1; AU2016223409B2

Abstract

A method for handling a faired cable (1) using a fairing (2), said cable being towed by a vessel (100) on-board which is installed a winch (5) for winding up and unwinding the faired cable (1) through a guide device (4) for guiding the faired cable, the method comprising: - a first step (10) of monitoring the cable (1), in order to detect whether the fairing (2) has undergone a double twist around the cable comprising a complete submerged twist and a complete airborne twist, - and, when a double twist is detected, a first step (11) of hoisting the faired cable (1) during which the faired cable (1) is hoisted, the first hoisting step (11) being implemented in such a way that the complete submerged twist at least partially exits the water and does not enter the guide device (4).

Description

METHOD FOR HANDLING CARINE CABLE TRAILED BY A SHIP

The present invention relates to ducted tractive cables used on a ship to tow a submersible body dropped at sea and the handling of these cables. It relates more particularly to tractors trenches careened by hulls hinged together.

The context of the invention is that of a naval vessel or vessel intended to tow a submersible object such as a variable immersion sonar integrated in a towed body. In such a context, in the nonoperational phase the submersible body is stored on board the ship and the cable is wrapped around the drum of a winch for winding and unrolling the cable, that is to say to deploy and to retrieve the cable. Conversely, in the operational phase, the submersible body is immersed behind the ship and towed by the latter by means of the cable whose end connected to the submersible body is submerged. In other words, during the operational phase, the cable is deployed, it is towed by the ship and has a submerged end. The cable is wound by the winch through a guide device for guiding the cable. The guiding device makes it possible to limit the lateral movement of the cable. It conventionally includes a pulley.

To obtain a high immersion at high towing speeds, the towing cable is streamlined, which makes it possible to reduce its hydrodynamic drag in very large proportions. Figure 1A shows a portion of the cable 1 extending along an axis x. This cable is streamlined, it is covered with hulls having shapes designed to reduce hydrodynamic drag. The hulls form a fairing also called fairing column. The hulls are rigid. In other words, they do not deform under the effect of the hydrodynamic flow. The cable 1 is conventionally streamlined by means of a fairing or fairing column 3 comprising a series of hulls 2, or hulls. Each hull 2 comprises an elongate member having a hydrodynamic profile. The hydrodynamic profile is the shape of a section of the fairing section in a plane perpendicular to the x axis. The hydrodynamic profile of the hulls is, for example, as shown in FIG. 1B, in the form of a wing having a thick inner edge (or leading edge BA) housing a tubular channel in which the cable 1 passes and a thin outer edge (or trailing edge BF) allowing a less turbulent flow of water around the cable. The hydrodynamic profile has, for example, a droplet shape or is a NACA profile, that is to say a profile defined by NACA which is an acronym for the English expression "National Advisory Committee for Aeronautics". All hulls totally or partially cover the cable. The hulls are immobilized in translation relative to the cable along the x axis.

In normal operating state, the hulls are rotatably mounted around the cable, that is to say around the x-axis. Each hull is, however, linked to its two neighbors so as to be pivotable with respect thereto about an axis parallel to the x-axis of a small maximum angle of the order of a few degrees. It is indeed necessary that the hulls can rotate freely around the cable in order to be correctly oriented according to the different phases because it is not possible to control the orientation of the cable itself, these phases are: the following orientation the flow of water, the orientation to pass the pulleys, the slicing, the guiding device and the storage on the reel. As a result, the rotation of a shell causes a rotation of the hulls nearby and gradually that of all the hulls. Therefore, both when the cable is deployed in the water and when it is wrapped around the drum, any change in orientation of one of the hulls, affects gradually all hulls careening the cable. Thus when the cable is deployed at sea hulls are naturally oriented in the direction of the current generated by the movement of the building. In the same way during the winding of the cable around the winch drum, all the hulls adopt, as the cable rises, the same orientation relative to the drum, an orientation that makes it possible to wind the cable while maintaining the hulls parallel to each other. to others in turn.

However, the Applicant has found that when the cable is wrapped around the drum to recover the towed body, it happens occasionally that the fairing is strongly deteriorated or crushed at the time of its passage in the guiding devices, which may make the entire sonar system unavailable. It may even happen that this deteriorates the guiding device. As an example, some variable immersion sonar systems installed on certain vessels and operated normal by military crews encounter problems of crushing hulls about once a year and sometimes much more often. This situation leads to immobilization of the system, which may range from a few hours to a few months, during which maintenance operations must be carried out.

The object of the present invention is to provide a cable handling method that limits the risk of damage to the fairing of a towed cable to limit the risk of immobilization of the sonar system.

To this end, the applicant firstly, in the context of the present invention, identified and studied the cause of this problem of crushing the hulls by observation of the ducted cable in operational situation and by modeling ducted cable in operational situation and different forces acting on it, including hydrodynamic and aerodynamic flows and gravity.

During the operational phase, the fairway cable is towed by the vessel and has a submerged end. Very often, the tow point is a point on a pulley that is at a certain height above the water. By towing point is meant the position of the fulcrum of the cable on a device on board the ship, which is closest to the submerged end of the cable. As the ship advances, the drag moves away from the transom and disappears under the water a little further than the vertical point of the towing point. The length of ducted cable in an aerial situation is increased compared to the simple towing height above the water because the cable is inclined relative to the vertical. It is observed that the last hull which is still in engagement with the ship, that is to say the hull which is at the point of towing, often resting on the pulley or resting on a guidance device on board the ship , is correctly oriented in the direction of the flow, although it is well above the air (leading edge against the flow and trailing edge trolling.) The first keel in the water (it is ie the hull just immersed) is assumed to take a correct orientation in the flow coming from the speed of the ship (leading edge against the flow and trailing edge trolling) .But between these two remarkable hulls, the column fairing can bend as it is, in the air, just subject to vibration, an insignificant airflow and gravity. Under the effect of the stresses of the sea, the conditions of towing and the waves, situations of torsion of this air column are regularly observed. The first cause of torsion is caused by gravity as soon as the cable has moved away from the vertical, which necessarily happens as soon as the towing speed is sufficient. Under the effect of gravity, the fairing column between the towing point and the sea will twist on one side (in the air) and then straighten up (in the water). This is the nominal situation of the fairing column. This torsion is a function of the intrinsic stiffness of the fairing column but also the aerial length. A situation in which the overhead portion of the fairing 2 is a little twisted, i.e. twisted about the x-axis) is shown in FIG. 2A. In FIG. 2A, the vertical direction in the terrestrial reference is represented by the z axis and the orientation of the section of certain hulls in zones A, B and C delimited by dashed lines is shown. In the situation shown in FIG. 2A, the last hull 3 in engagement with the vessel is oriented vertically (trailing edge upwards) as shown in zone A. The hulls which are in the air between the pulley P and the surface of the water S are lying under the effect of gravity. In other words, as visible in zone B, the trailing edge of the hulls is oriented downwards (between the pulley P and the surface S of the water, the hulls have turned around the cable). On the other hand, the hulls in the water are rectified by the action of the water flow acting on the FO arrow as shown in the zone C (trailing and attacking edge located approximately at the same depth).

From time to time, depending on the sea conditions, packets of water or breaking waves fall more or less towards the transom of the ship, creating a momentarily inverse flow in the aerial part of the cable. which reigns lower and which corresponds to the speed of advancement of the ship. These water bodies are perfectly capable of further distorting the fairing column and placing it in opposition to the expected position in the normal towing flow. In this case, the fairing is twisted and performs, in its aerial part, a half turn around the cable. This means that two hulls of the game aerial of the fairing column, have trailing edges forming between them an angle of 180 degrees around the cable. The part of the fairing between these two hulls is twisted or twisted. From this situation, it may happen that parts of fairings that are upside down in relation to the average flow given by the speed of the ship, are then suddenly bathed again by this average flow (because of the movements of the ship, that of the waves, etc.) the upside-down part of the fairing is thus solicited to return in the right direction (linked to the normal average flow). She can then:

- cancel the U-turn and return to its original position by describing the reverse rotation of the one that had brought it upside down. It is then correctly oriented.

- or add to the existing U-turn another U-turn which brings it back to the correct orientation in the flow but which has the effect of twisting 1 turn (or 360 °) the aerial part of the fairing above it and twisting a portion below it a turn (or 360 °, but this time in the other direction). The part that was initially upside down returned to the correct orientation in the average flow related to the speed of the ship but so there were two twists of a turn one up in the air and the other below in the water. We speak of complete torsion of the fairing (which can be translated by twist in English terminology). This complete twist is a stable situation of the fairing column or fairing 2. It is shown in Figure 2B. This situation can be described as follows: between the towing point R and the surface of the water S, the fairing column performs a complete revolution in the direction of the arrow F1 around the cable. The fairing column 2 crosses the surface S and remains properly oriented on a certain length L1 of the order of a few meters or less sometimes. Then the fairing column 2 performs a complete turn in the water, in the opposite direction, represented by the arrow F2 to return to the correct orientation in the flow. In other words, the fairing undergoes a double complete twist around the cable. The double twist comprises a complete TA air twist, located above the surface of the water and a complete submerged Tl twist, located below the surface of the water. All the part of the fairing located below this double twist complete is no longer affected by what is happening above it (its hulls are correctly oriented in the flow).

The configuration in which the fairing undergoes a double twist is stable but strongly degraded and it is likely to bring major disturbances to the entire system.

The Applicant has discovered that it is when a fairing undergoes a double complete torsion that, under certain conditions, the fairing will be strongly deteriorated in the water and this deteriorated part will cause great damage to the entire careened system during winding of the cable and more specifically during its passage in the cable guide device. Specifically, the deteriorations will mainly consist of breaks in bonds between neighboring hulls.

By analyzing the double complete torsion, the Applicant has found that the submerged torsion can be considered as "hooked" on the cable. In other words, the position of the submerged torsion is fixed relative to the cable along the axis of the cable. On the other hand, its air counterpart, the aerial torsion, remains located at the same place between the point of towing R and the surface of the water S. It is not fixed with respect to the cable along the axis of the cable but fixed by relative to the surface S of the water or the point of towing. When the cable is hoisted up or down, hulls undergoing the submerged twist follow the movement of the cable that is hoisted up or down while the aerial twist remains fixed relative to the surface of the water. It follows that a course of the cable plunges the submerged torsion to a greater depth while the aerial torsion remains at the same place with respect to the surface of the water (the two torsions then move away from the one of the other). Figure 2C shows a situation in which the cable has been unrolled with respect to the situation of Figure 2B (see arrow). The distance L2 represents the distance between the portion of the fairing concerned by the submerged torsion and the point of entry of the fairing into the water is greater than the distance L1 which represents the same distance in the situation of Figure 2B. Conversely, hoisting of the cable, compared with the situation of FIG. 2B, according to the arrow represented in FIG. 2D, makes up the submerged torsion while the aerial torsion remains always in the same place with respect to the surface of the water (the two twists are then close to each other). One must then look at what happens for a twist of a submerged and towed ride as well. This twist which unfolds on a low height forces the fairings to sail upside down or across the stream. The action of the flux on these hulls is then very important (proportional to the surface, the angle, the density of the water and the square of the speed). This action results in powerful torsional torques that tend to force the hulls to align in the flow but they come up against the stiffness of the twisting turn that increases. It happens then that a balance occurs and that the twist of a turn is terribly reduced in height and the fairing undergoes violent efforts which translate, as we have seen, by very strong deformations. The formation of a double twist can lead to the deterioration of the submerged torsion. Indeed, when a double twist has formed, it will tighten under the effect of the towing speed. In other words, the complete turn of the fairing around the cable will take place over a shorter and shorter distance. Observations at sea have shown that the fairing column can perform a complete turn around the cable over a length of 50 cm. The hydrodynamic flow exerts a very important couple on the badly oriented hulls. The duration of exposure of the fairing to this submerged and towed torsion will gradually cause permanent deformations (or very long to be absorbed) making it for a long enough time totally unable to engage in the cable guide device well that its continuity is not broken. Another effect of this very important hydrodynamic torque is to simply permanently break the continuity of the fairing column. Side torsion air there is no damage, there is a twist applied but at no time it can damage the cable.

On the other hand, if the exposure time to the towing flow of a submerged torsion is low or if the towing speed is low, the torsion will not keep a memory of its deformation. The following effect will then occur if the cable is hoisted: The submerged torsion would go up at the same time as the cable, it would reach the surface and meet the aerial torsion and at that moment the two twists would vanish and disappear together. But that would not be the case if the violent distortion of the submerged twist was to continue. The plaintiff has therefore found that in the case of the rise of a submerged torsion which has not resorbed because it is old, the fairing has been long and very strongly constrained, it has kept the memory of its deformation and the submerged torsion comes out of the water still very tight when hoisting and does not disappear when hoisting. When the submerged torsion still very tight then presents itself to the guide device, for example the pulley, the hulls affected by this submerged torsion can not be placed correctly in the pulley because the pulley limits the lateral deflection but also because generally the pulley has a tight groove intended to keep the hulls edge upwards to facilitate the winding of the cable without damage to the winch. It acts as conformateur). The hulls pass in a direction other than that shown in Figure 2a in the pulley, they go upside down in the pulley, get stuck, and it is the whole fairing column that comes after the part of the fairing concerned by the old submerged torsion which is methodically destroyed if we continue the hoist because gradually, each hull follows the orientation of that which precedes it.

The invention proposes a cable handling method which is based on this study of the phenomenon of double twist and which makes it possible to limit the risks of damage to the fairing of the cable.

For this purpose, the subject of the invention is a method for handling a streamlined cable by means of a fairing, said cable being towed by a vessel on board which is fitted with a winch for winding and unwinding the faired cable. through a ducted cable guide device, the method comprising:

a first cable monitoring step making it possible to detect whether the fairing undergoes a double twist around the cable comprising a complete submerged torsion and a complete aerial torsion,

and, when a double twist is detected, a first step of hoisting the streamlined cable during which the streamlined cable is hoisted, the first hoisting step being implemented so that the complete submerged torsion at least partially water and does not enter the guiding device. Advantageously, the method comprises at least one of the following characteristics taken alone or in combination:

the first step of hoisting comprises a step of lifting the cable during which the towing point of the cable is raised by means of a lifting device on board the ship,

when the double twist is not absorbed at the end of the lifting step, the method comprises a step of winding the cable by means of a winch on board the ship,

the first monitoring step is implemented permanently or is repeated at time intervals below a threshold duration ds of not more than 10 minutes,

a duration d separates the detection of the double torsion and the beginning of the first step of hoisting the cable, the sum of the threshold duration ds and the duration separating the implementation of the first monitoring step at the time of the detection and the previous implementation of the first monitoring step is not more than 15 minutes,

the first hoisting step is carried out at least until the double torsion detected is absorbed,

the method comprises a first monitoring step making it possible to detect a double twist of the fairing implemented before each second hoisting step during which the cable of a length L greater than or equal to the sum of the cable is wound by means of the winch 1 meter and the altitude separating the towing point from the surface of the water,

the first step of hoisting is carried out at least partially by means of a winch with a nominal speed of the winch, the method comprising, when the double torsion does not resorb during the first hoisting step, and if the winding of the cable of the length L involves the crossing of the guide device by submerged torsion, a third step of hoisting the cable during which the immersed torsion belonging to the detected double torsion passes through the guiding device, the third hoisting step being implemented at the means of the winch at a hoisting speed lower than the nominal speed, the third hauling step is assisted manually or mechanically so as to properly position the fairing in the guiding device,

the hoisting of the cable is stopped at the end of the first hoisting stage until the double twist is absorbed,

when the double torsion is absorbed during the first hoisting step, the first hoisting step is followed by a final hoisting step carried out by means of the winch at the rated speed of the winch until the length of the cable wound by the means winch reaches the length L,

the method comprises, when no double torsion is detected during the first monitoring step, a second step of hoisting the cable of length L, carried out by means of a winch at the rated speed of the winch,

the method comprises a second monitoring step implemented during the first hoisting step and making it possible to detect the resorption of the double torsion and to monitor the position of a complete submerged torsion relative to the guiding device,

the method comprises fourth cable hoisting steps in which the cable of respective lengths shorter than the sum of 1 meter and the altitude separating the tow point from the surface of the water is wound up, the fourth hoisting steps being implemented at respective time intervals greater than or equal to at least 20 minutes during a predefined period, the cable not being unwound between two consecutive implementations of the fourth step,

the method comprises a fifth hauling step of winding the cable of a length less than the sum of 1 meter and the altitude separating the tow point from the surface of the water to the length before at least one step of unwinding of the cable,

the first hoisting step is implemented by means of a hoisting device, said hauling device being activated by automatically when the monitoring device detects a double twist.

The invention also relates to a device for handling a streamlined cable by means of a fairing towed by a ship, said device comprising a monitoring device for detecting whether the fairing undergoes a double twist around the cable comprising a torsion complete submerged and complete aerial torsion and hauling device for hoisting the cable when a double twist is detected so that the complete submerged torsion at least partially out of the water and does not enter the guiding device.

Advantageously, the device comprises an activation device for activating the hoisting by the hauling device and control means for controlling the hoisting of the cable so that the complete submerged twist at least partially out of the water and not does not enter the guiding device.

Advantageously, the device comprises an alert device for alerting an operator when a double twist is detected.

The invention also relates to a handling device configured to implement the method according to the invention, the monitoring device being configured to detect whether the fairing undergoes a double twist around the cable comprising a complete submerged twist and a complete twist and the hoisting device being configured to implement the first hoisting step when a double twist is detected by the monitoring device.

Advantageously, the handling device comprises an actuator configured to activate hoisting of the cable by means of the hoisting device when a double twist is detected by the monitoring device and a controller making it possible to control hoisting of the cable by means of the hauling device. so that the complete submerged twist at least partially out of the water and does not enter the guide device. Other features and advantages of the invention will appear on reading the detailed description which follows, given by way of non-limiting example and with reference to the appended drawings in which:

FIG. 1 has already been described, shows a section of ducted cable, FIG. 1B already described represents an example of section of a hull of a fairing in a plane M perpendicular to the axis of the cable and represented in FIG. AT,

FIG. 2A already described shows a towed towed cable partially immersed from its submerged portion to a guide pulley in a situation in which the cable is not subjected to double torsion, FIG. 2B represents the cable of FIG. 2A in FIG. same state of immersion (that is to say winding and unwinding) as in Figure 2A but undergoing a double twist; Fig. 2C shows the cable of Fig. 2A having the double twist of Fig. 2B in a configuration in which the cable has been unrolled with respect to Fig. 2B; FIG. 2D shows the cable of FIG. 2A having the double twist of FIG. 2B in a configuration in which the cable has been hoisted with respect to FIG. 2B,

FIG. 3 represents a vessel towing a towed object by means of a towing cable,

FIG. 4 represents a block diagram of the steps of an exemplary method according to a first embodiment,

FIG. 5 represents a block diagram of the steps of an exemplary method according to a second embodiment.

From one figure to another, the same elements are identified by the same references.

The invention relates to a method of handling a streamlined cable 1 towed by a naval vessel, such as a ship, to protect the fairing of the cable.

In Figure 3, there is shown a cable 1 may be a towing cable or electrotractor towed by a ship 100. The cable 1 is towed or towed by a ship. It is at least partially immersed. The cable comprises a fairing 3 comprising at least one fairing section comprising a plurality of hulls 2. The hulls of the same section of fairing are interconnected axially, that is to say along the towing cable. They are pivotally mounted around the cable and are hinged together by means of a coupling device so that the relative rotation of said hulls 2 relative to each other around the cable 1 is allowed. This clearance is allowed either freely with a stop. The rotation of a hull around the cable does not then cause the adjacent hull in rotation. The displacement can be obtained in a constrained manner with a more or less strong return to the aligned position (no relative rotation of the hulls relative to each other around the cable). In the latter case, the rotation of a hull around the cable rotates the adjacent hulls of the same section around the cable. In the case where the fairing comprises several sections, the sections are free to rotate relative to each other around the cable. Conventionally, the hulls of a fairing section are connected in pairs by individual coupling devices. Each coupling device for connecting a hull to another hull adjacent to the same section fairing only.

The cable tows a towed body 101, comprising for example one or more sonar antennas. The towed body 101 is mechanically secured to the cable 1 as appropriate. The launching and the exit of the water of the towed body 101 is carried out by means of a winch 5 arranged on a deck 103 of the ship 100. The winch 5 comprises a unrepresented drum dimensioned to allow the winding of the cable 1. The towed cable 1 can be wound around the winch 5 through a guiding device 4, as described above, for guiding the cable. The cable guide device also allows classically but not necessarily to orient the hulls relative to the drum winch. In addition, it conventionally makes it possible to secure the radius of curvature of the cable so that it does not fall below a certain threshold. In the nonlimiting example shown in FIG. 3, the guiding device is a pulley 4. It could, for example, comprise, in place of or in addition to the pulley, at least one guiding means or guide allowing limit the lateral deflection of the cable such as a deflector, a hull reverser, a fairlead to secure the radius of curvature of the cable so that it does not fall below a certain threshold and / or a slicing device to properly store the cable on the drum.

In the embodiment of Figure 3, a lifting device 6 is shipped on board the ship 100 to raise and lower the towing point. It comprises, in the nonlimiting example shown in FIG. 3, an articulated structure 7, for example an arm, to which the pulley 4 is fixed. The articulated structure 7 is able to pivot about an axis perpendicular to the plane of the Figure, substantially parallel to the deck of the ship, that is to say a substantially horizontal axis when the ship is in equilibrium, to move from a low position, as shown in solid lines in Figure 3, in which the pulley (or more generally the towing point) occupies a low position, at a high position (shown in broken lines in FIG. 3) in which the pulley (or more generally the towing point of the cable) is at a second altitude higher than the first altitude at which the pulley (or more generally the towing point of the cable) is in the lower position relative to the deck of the ship or in relation to the surface of the water. Therefore, when the articulated structure moves from its high position to its low position, it amounts to hoisting the cable or raising the tow point so as to pull a length I of the cable of the water without advancing the cable. direction of the guide device. Any other lifting device could be used to lift the tow point of the cable. Advantageously, the handling device is configured to allow water out of a cable length of between 1 m and 2 m.

The invention aims to limit the risk that part of the fairing undergoing a complete submerged torsion does not enter the cable guide device.

For this purpose, the method of handling the cable 1 according to the invention comprises a first step of monitoring the fairing 1 to detect whether the fairing 2 undergoes a double twist comprising a complete submerged torsion and a complete air torsion and, when a double twisting of the fairing 2 is detected, a first step of hoisting the cable 1 of hoisting the cable 1, the first monitoring step and the first hoisting step being implemented so that the torsion immersed at least partially out of the water and does not enter the guiding device.

To understand the effects of the method according to the invention, it is necessary to describe the effects of the first step of hoisting the cable following the detection of a double twist. It has been seen that the submerged torsion remains "hooked to the cable", that is to say that the part of the fairing undergoing complete submerged or submerged torsion occupies a fixed position with respect to the cable along the axis. cable. Therefore, by raising the part of the cable undergoing the submerged torsion (that is to say the hulls undergoing the submerged torsion) will thus gradually rise towards the surface, whatever its immersion. When the submerged torsion reaches above the surface of the water, the Applicant has found, by studying the phenomenon of double torsion, that the following two things can happen.

First, if the double twist is recent, that is, it has been formed for not more than 15 minutes, the torsion tightening of the fairing column is instantly reversible. In this case, during the first step of hoisting the cable, as soon as the first hulls wrongly oriented because of the submerged torsion start to come out of the water, or at worst when half of the part of the fairing concerned by the twist submerged is out of the water, the double twist is destabilized and suddenly it is undone at the same time as the aerial torsion. The fairing is then released from this double twist and returns to its nominal state and the system can be operated again in a nominal manner and, in particular, it is possible to immerse again the portion of cable that has been affected by the torsion immersed or to wind it around the drum of the winch without the guiding device being damaged.

- Second, if the double torsion is old, that is to say that it has been formed for more than 15 minutes, during the first step of hoisting the cable, the double twist of the fairing does not break naturally ( or she may not get rid of it). Indeed, if the double twist is old, it has tightened. It follows that even if the hydrodynamic force is released, the double twist will not be undone. It will eventually, but after a while and as a result of relaxation of possible viscoelastic phenomena. Therefore, if the cable is hoisted too far, the complete submerged submerged torsion will occur at the towing pulley or the cable guide system at the towing point. In other words, the part of the cable which was immersed at the time of detection of the double twist and around which the fairing was undergoing and still undergoes a complete twist back up and will enter the guide device. The first hoisting step is thus performed so that the part of the fairing undergoing complete torsion immersed at the time of detection of the double twist does not enter the guide device. Consequently, the method according to the invention makes it possible, when it is used, either to resorb a double twist, or, when it does not resorb, to prevent a submerged twist from entering the guide. The method according to the invention therefore makes it possible to limit the risks of deterioration of the fairing due to the appearance of the double twists. The method according to the invention does not require modification of the device for winding and unwinding the cable (winch and guiding device). The method according to the invention is particularly advantageous when the guiding device is too narrow so that hulls which are not oriented trailing edge upward when they are presented to the guiding device, can turn around by pivoting around the cable axis, to reach this position. In other words, the guide device acts as a shaper.

We will now describe an example of a first embodiment of the method according to the invention with reference to FIG. 4. In this embodiment, the first monitoring step 10 is implemented permanently or frequently for at least one towing the cable. In other words, the monitoring step is implemented permanently either by an automatic system or by the observation made by a crew member. In other words, the time between two implementations or successive achievements of the monitoring step less than or equal to 10 minutes and preferably less than or equal to 5 minutes. By towing the cable 1 is meant a situation in which the cable comprises a submerged end and in which the ship is moving on the water. Although there are more or less favorable conditions for the appearance of double twists, we can not predict when a double twist can appear. Continuous or frequent monitoring of the double twists thus makes it possible to ensure that when a double twist is detected, it is recent. Therefore, a double twist detected will be automatically resorbed when hoisting the cable of sufficient length, that is to say at the exit of the water from the submerged torsion, at worst when about half of the torsion submerged is out of the water. Furthermore, the Applicant has found that the submerged torsion is formed not far from the surface at 1 or 2 meters from the surface. The submerged torsion therefore remains at this depth if the cable has not been unrolled after formation of the submerged torsion.

When a double torsion is detected, a first step of hoisting 1 1 of the cable 1 consists in hoisting the cable. Advantageously, the first lifting step 1 1 is implemented until resorption of the double twist or, more generally, at least until resorption of the aerial torsion. The method of the invention allows, without modification of the towing device, to take into account the appearance of twists to resorb without risking to grind the fairing. This method makes it possible to guarantee the disappearance of the grinding of a portion of the fairing column due to the formation of a double twist.

The time between the beginning of the first hoisting step and the detection of the double twist is less than or equal to a threshold duration ds. The threshold duration ds is such that the sum of the threshold duration ds and the duration between the implementation of the first monitoring step at the time of detection and the previous implementation of the first monitoring step is at most equal to 15 minutes and preferably at most equal to 10 minutes. The length of time between implementation of the first monitoring step at the time of detection and previous implementation of the first monitoring step is zero when the first monitoring step is implemented permanently. In practice, the duration ds is between 5 and 10 minutes. This makes it possible to ensure that the double twist is always recent when implementing the first hoisting step 1 1, that is to say that it will disappear during hoisting. before the submerged torsion enters the guiding device. This method reduces the chances of grinding a portion of the fairing column due to the formation of a double twist. It allows to maintain the system without any interruption in operational condition.

The first lifting step 1 1 comprises a lifting step 12 consisting in raising the towing point of the cable so as to bring the tow point to an altitude greater than the altitude it occupied at the time of detection of the double torsion by means of a lifting device. The lifting device is for example the lifting device shown in FIG. 1, in which case the articulated structure is pivoted from a low position to a high position in which the altitude of the tow point of the cable is greater than altitude of the tow point of the cable in the situation where the lifting device is in its low position. The stroke of the towing point of the cable during the lifting step 12 is fixed, it lies between 1 and 2 m. It makes it possible to guarantee the resorption of submerged twists extending to the stroke of the lifting device. The advantage of the lifting operation is to operate here a simpler maneuver than hoisting the cable by winding the cable by means of the winch, and above all, which absolutely does not risk damaging the fairing in case of double torsion old because the cable does not progress towards the guiding device. If it is simpler and safer, however, this maneuver will not be able to resorb a double twist whose submerged portion is at a depth greater than the stroke of the towing point between its upper position and its lower position.

Advantageously, the method according to the first embodiment, comprises, when the double twist is not resorbed at the end of the lifting step 12, a winding step 13 of winding the cable 1 by means of the winch 5 until resorption of the double twist. This step is performed when the lifting device is in the up position.

Alternatively, the first hoisting step 11 comprises only the step of winding the cable, for example, when there is no lifting device. Alternatively, the first hoisting step includes only the lifting step. The first hoisting step 11 may be carried out so as to wind the cable of a predetermined length less than or equal to the altitude of the tow point in a calm sea state (that is to say when the axis boat is substantially horizontal in a terrestrial reference) plus 1 m. This is the minimum cable length separating the tow point from the entry point of the cable into the water. This feature ensures that a double twist just below the surface of the water does not enter the guiding device. In the latter case and in the case where the lifting step includes only the lifting step, the stroke of the lifting device being fixed, the unwinding of the cable is advantageously prohibited once the double twist is detected which limits the risks of increasing the depth of the submerged torsion.

In the example shown in FIG. 4, the method comprises, for example but not necessarily, after the first hoisting step 11, a deployment step consisting in deploying the cable. This step consists in putting the tow point back into the low position by means of the lifting device. As a variant, the deployment step consists in putting the cable back into the deployed state in which it was before the first hoisting step. In this case, it further comprises a cable unwinding step.

In the example shown in FIG. 4, the method comprises a second monitoring step 14 making it possible to detect the resorption of the twist. This step must in fact make it possible to detect the resorption of the aerial torsion. This step is here implemented continuously during the first hoisting step. Alternatively, it could be implemented at regular time intervals or only at the end of the lifting step and at regular time intervals or continuously during the winding step of the cable.

In a variant, the method according to the first embodiment does not include this second step of monitoring the fairing. It is not necessary, for example, when the first lifting step includes only the lifting step since hoisting the cable by lifting makes it possible to raise the towing point without bringing the submerged torsion of the guide device closer together. The method according to the first embodiment makes it possible to avoid the passage of the double twists in the guiding device (that is to say before a major hoisting of the cable) and makes it possible to avoid deterioration of the fairing related to the tightening of the submerged twist with time. On the other hand, it has the disadvantage of requiring continuous or frequent monitoring of the fairing which results in a significant mobilization of the crew or requires a monitoring device which has a very good reliability to avoid false alarms related to false detections of complete torsion and therefore unnecessary hoops.

We will now describe, with reference to FIG. 5, an example of a second embodiment of the invention that does not require constant or frequent monitoring of the fairing or that makes it possible to use a monitoring device that is less reliable than in the first embodiment. embodiment. In this second embodiment, the first monitoring step can be performed episodically or randomly during towing or be performed in certain predetermined situations only during towing. In this case, in the method according to the invention, it is assumed that when it is desired to maneuver the cable 1, it is not known if the fairing is affected by a double twist. However, we have seen that it is the hoisting of the cable 1, and more particularly the winding of the cable around the winch, which can lead to the grinding of the fairing during the passage of the immersed portion of the cable in the cable guide device. . Therefore, in order to prevent this from happening, the method according to the second embodiment comprises a first fairing monitoring step 20 for detecting a double twist of the fairing carried out before each second cable hoisting step. length L greater than or equal to a threshold length Ls equal to the altitude of the tow point relative to the surface of the water plus one meter. The first monitoring step 20 follows a towing step of the cable 19 during which the winch 5 blocks the winding / unwinding of the cable. It is for example implemented after receiving a winding order of the cable of a length L. When a double twist is detected, the second hauling step comprises a first hauling step 21 of the cable.

The method advantageously comprises a second monitoring step 22 during the first hauling step 21. The second monitoring step 22 makes it possible to detect whether the double torsion resorbs, for example by detecting whether the aerial torsion is resorbed, and to monitor the position of the submerged torsion relative to the guiding device. When the double torsion is absorbed during the first hauling step 21, the first hauling step is followed by a final hauling step 24, included in the second hauling step, of winding the cable by means of the winch up to the cable hoisted length can reach the length L. The winding of the cable can be continuous between the first hauling step and the final hauling step 24. It is advantageously carried out at the same speed.

When the double torsion does not resorb during the first hauling step 21, and when the length L is such that it involves the crossing of the guiding device by complete submerged torsion, the second hauling step advantageously comprises a third step of hoisting of the cable 23 of continuing the first hoisting step during the crossing of the guide device by submerged torsion. The cable is not unwound, between the first hoisting step and the final hoisting step or between the third hoisting step and the final hoisting step.

In the embodiment of Figure 5, the first hauling step 21 comprises a winding step performed by means of a winch. It is advantageously performed at the nominal operating speed of the winch. This nominal speed is conventionally between 0.2 m / s and 1.0 m / s. When the double torsion does not resorb during the first hauling step 21, it is then absolutely necessary to slow down the hauling speed as much as possible and it is preferable to check carefully that each hull is upright and correctly engages in the guides. For this purpose, the first step of hoisting is carried out at nominal speed and, for example, once the immersed torsion is completely out of the water and before that it enters the guide device, or when the submerged torsion partially leaves the water, begins the third stage of hoisting at a hoisting speed lower than the nominal speed. This third hoisting step can be assisted manually or mechanically to help the submerged torsion position itself correctly in the guide device because the guide device acts as a shaper.

For example, the cable winding is continuous between the first and the third hoisting step, but the hauling speed used during the third hauling step is lower than the hoisting speed used during the first hauling step. The third hoisting step is for example carried out at a speed at least two times lower than that at which the first hoisting step is performed. The advantage of performing this step at reduced speed is to limit the risk of deterioration of the fairing during its passage in the guiding device.

The same procedure can be used when the hulls undergoing the submerged torsion are deteriorated. The interest is to avoid further deterioration at the moment of the passage of the submerged torsion in the guiding device. When there are breaks in connection between the hulls, the first hull located upstream of a breakage seen from the winch will be presented to the guide device with the trailing edge facing down due to the gravity and if the device The guide is too narrow, or if the hoist is too fast, the hull will not be able to orient itself only trailing edge up. However, as the cable presses on the trailing edge when the hull is resting on the guide device, the keel wedged in the pulley will be crushed and deteriorated which will cause the deterioration of all hulls following. The reduced speed used during the third hoisting step and the mechanical or manual assistance are very advantageous in this case.

Alternatively, if the part of the fairing undergoing the submerged torsion is deteriorated (bent or broken hulls or rupture of the connection between hulls) at the end of the first hauling step, the method may comprise a fairing repair step before the implementation of the third step. When the double torsion is not absorbed during the first hauling step, the hoisting of the cable is advantageously stopped until the double torsion is resorbed because of the viscoelastic effect before implementing the final hoisting step. 24. The portion of the cable undergoing the submerged twist can be manually recovered and deposited on the bridge between these steps to promote the resorption of the double twist. After this wait, the system returns to its nominal state and can be operated again in a nominal way. The hoisting step consists in taking up the winding of the cable where it stopped during the first step of hoisting until winding of the length L. The double torsion being resorbed and the hulls in good condition, the step of Final hoisting 24 can be performed at the rated speed of the winch.

Alternatively, as in the first embodiment, the first hoisting step may comprise a lifting step. For this purpose, the first hoisting step begins with a first lifting step and if the double twist does not resorb at the end of the lifting step, a step of winding the cable. The method then comprises a deployment step at the end of the first hoisting step or the third hoisting step. Alternatively, the first hoisting step comprises only one winding step.

Advantageously, when no double torsion is detected during the first monitoring step 20, the monitoring step is followed by the second hoisting step 25 which can, for example, be carried out unattended and continuously at the speed nominal winch.

Advantageously, but not necessarily, the method comprises, during the towing of the cable, fourth steps of hoisting the cable 26 during which the cable is wound of respective lengths less than the threshold length Ls implemented at intervals of time at least equal to 20 minutes. In other words, the respective time intervals separating two fourth successive hoisting steps are greater than or equal to 20 minutes. The cable is not unrolled between two fourth steps of consecutive heaps. The fourth stages of hoisting allow to leave a possible submerged torsion of the water blind (that is to say without mobilization of the crew to carry out a possible monitoring). Moreover, since the fourth consecutive hoisting steps are spaced at least 20 minutes apart, if the double twist is out of the water, even if it is a double, remanent twist (i.e. say that has not resorbed at its exit from the water), it will have time to be absorbed before the next stage of hoisting and will not penetrate into the guiding device. These fourth hoisting steps therefore make it possible to absorb any double twists that would have formed on the surface and to limit the risks of detecting a double twist at the time of the monitoring step before hoisting the cable of a length greater than the length at least equal, that is to say greater than or equal to the threshold length Ls and therefore to limit the probability of having to implement the double torsion resorption procedure already described with reference to Figure 5. The fourth hoisting steps are advantageously carried out at regular time intervals (that is, two successive hoisting steps are separated by the same time interval). Advantageously, the cable winding lengths are the same during all the fourth steps. Alternatively, the time intervals and the winding lengths are different from one fourth step to another.

Advantageously, the method comprises, before at least one unwinding step 28 of the cable, while the cable is partially immersed, a fifth hauling step 27, during which the cable is wound with a hauling length less than the threshold length. ls. This step makes it possible to absorb recent double twists and makes it possible to limit the risks of occurrence of old double twists. Like the previous step, it limits the risk of detection of double twists at the time of the first monitoring step.

The fourth hoisting steps are carried out at respective time intervals at least equal to 20 minutes for at least one predefined period taken from a first period and at least a second period. The first period is a period extending from the beginning of the towing 19 to the first monitoring stage. A second period is a period extending between the end of a second hoisting step and the beginning of the first monitoring step subsequent to said second hauling step.

The fifth hoisting step is carried out before an implementation step is carried out at least for at least one other predefined period taken from a first period and at least a second period. Advantageously, the fifth step is implemented before each unwinding step taking place during at least one other predefined period taken from a first period and at least a second period.

In both embodiments, the first hoisting step is implemented after detecting a double twist. The method has no unwinding step of the cable between the moment when the double twist is detected and the implementation of the first hoisting step.

The monitoring steps to detect a double twist, to detect the resorption of a double twist and to monitor the distance between the submerged torsion of the guide device can be performed by visual inspection by the crew. Indeed, the aerial torsion is always visible by the ship's crew and the position of the submerged torsion relative to the guide device when it comes out of the water. It is effective but dependent on the attention of an operator. The main disadvantage lies in the immobilization of an operator who has to move in a back range and sometimes in difficult sea conditions and visions conditions that can be strongly degraded

Alternatively, at least one monitoring step is performed by a monitoring device. This is particularly advantageous in the case of the first embodiment where continuous or frequent monitoring is necessary and this makes it possible to absorb recent double twists and to avoid the consequences of the old double twists.

The invention also relates to a device for handling a streamlined cable towed by a ship. The device is able to implement the method according to the invention. The device includes a monitoring device for detecting whether the fairing undergoes a double twist around the cable including complete submerged torsion and complete aerial torsion.

The handling device further comprises a hoisting device for implementing the first hoisting step. In other words, the hauling device makes it possible to hoist the cable when a double twist is detected so that the complete submerged torsion at least partially leaves the water and does not penetrate into the guiding device.

Preferably, the monitoring device is configured to implement the monitoring step or steps and in particular the first monitoring step.

The monitoring device comprises for example an image sensor installed to capture images of the cable recurrently and an image processing device for detecting a double twist on the cable. It may alternatively comprise a capacitive detector extending within the hulls along the cable which crashes and whose capacity varies during the torsion of the hulls. The monitoring device comprises for example a computer receiving the capacity of the detector and comparing it to a predetermined threshold. For example, the double twist is detected when the capacitance of the detector exceeds a first predetermined threshold.

The monitoring device advantageously makes it possible to detect the disappearance of a double twist and possibly to monitor the distance between the submerged torsion and the guiding device. The disappearance of the double torsion is for example detected when the capacitance of the detector falls below a second predetermined threshold which may be, without limitation, the first threshold. Advantageously, the monitoring device is configured to detect the disappearance of a double twist and possibly to determine the distance between the submerged torsion and the guide device.

The hoisting device comprises for example a winch and possibly a lifting device as claimed previously.

Advantageously, the handling device is configured to implement the method according to the invention. The monitoring device is configured to implement the one or more monitoring steps of the invention. This implementation is performed at the desired times described in the present patent application (at a predetermined time interval and / or before each second hoisting step of a length L greater than or equal to a predetermined length).

The handling device comprises a hoisting system configured to implement the first hoisting step when a double twist is detected by the monitoring device. The hoisting system is advantageously configured to implement the other hoisting step (s) according to the invention. The hoisting steps are implemented at the desired times described in this patent application. The hoisting system comprises the hoisting device and an activating device or actuator for activating, or configured to activate, the first step of hoisting the cable by means of the hauling device when the double twist is detected and means of control, or controller, for controlling, or configured to control, the hoisting step (s) and in particular the first step of hoisting the cable so that the complete submerged twist is at least partially out of the water and does not penetrate the guiding device. The control device comprises for example a control device for controlling the hoisting device so as to perform the first hoisting step. The controller can be the actuator. For this purpose, the monitoring device is advantageously configured so as to make it possible to implement the second monitoring step, or configured so as to implement the second monitoring step, that is to say to detect the disappearance a double twist and / or the water outlet of a double immersed torsion and / or to compare the position of the submerged torsion with that of the guide device. The controller receives the information from the monitoring device.

Alternatively, the handling device comprises an alert device for alerting an operator when a double twist is detected. Advantageously, the warning device is configured to alert the operator when a double twist is detected. The operator then actuates and controls the hoisting device so as to implement the first hoisting step. The second monitoring step is then, for example, performed by visual inspection. The invention also relates to a cable system comprising a streamlined cable and a handling device according to the invention.

Claims

1. A method of handling a streamlined cable (1) by means of a shroud (2), said cable being towed by a ship (100) aboard which is embedded a winch (5) for winding and unrolling the cable carinated (1) through a guide device (4) of the streamlined cable, the method comprising:

a first monitoring step (10, 20) of the cable (1) making it possible to detect whether the fairing (2) undergoes a double twist around the cable comprising a complete submerged torsion and a complete aerial torsion,

and, when a double twist is detected, a first step of hoisting (1 1, 21) of the streamlined cable (1) during which the hoisted cable (1) is hoisted, the first hoisting step (1 1, 21 ) being implemented so that the complete submerged torsion at least partially out of the water and does not enter the guiding device (4).

2. A method of handling a streamlined cable (1) according to the preceding claim, wherein the first step of hoisting (1 1) comprises a step (12) for lifting the cable (1) in which one raises the point of towing (R) the cable (1) by means of a lifting device (6) on board the ship (100).

3. A method of handling a streamlined cable (1) according to the preceding claim, wherein when the double twist is not resorbed at the end of the lifting step (12), the method comprises a step (13). ) winding the cable (1) by means of a winch (5) on board the ship.

4. A method of handling a streamlined cable (1) according to any one of claims 1 to 3, wherein the first monitoring step (10) is implemented permanently or is repeated at time intervals less than a threshold duration ds at most equal to 10 minutes.

5. A method of handling a streamlined cable (1) according to the preceding claim, wherein a duration d separates the detection of the double twist and the beginning of the first cable hoisting step, the sum of the threshold time ds and the duration between the implementation of the first monitoring step at the time of detection and the previous implementation of the first monitoring step is not more than 15 minutes.

6. A method of handling a streamlined cable (1) according to any one of claims 4 to 5, wherein the first step of hoisting (1 1) is implemented at least until resorption of the double twist detected .

7. A method of handling a streamlined cable according to any one of claims 1 to 3, comprising a first monitoring step (20) for detecting a double twist of the fairing implemented before each second hoisting step (25; 21, 23, 24) during which the cable of a length L greater than or equal to the sum of 1 meter and the altitude separating the tow point from the surface of the water is wound up by means of the winch. .

8. A method of handling a streamlined cable according to claim 7, wherein the first step of hoisting (21) is performed at least partially by means of a winch (5) at rated speed of the winch, the method comprising, when the double torsion does not resorb during the first hauling step (21), and if the winding of the cable of the length L involves the crossing of the guiding device by the submerged torsion, a third step of hoisting (23) the cable during which the immersed torsion belonging to the detected double torsion passes through the guiding device, the third hauling step (23) being implemented by means of the winch at a hoisting speed lower than the nominal speed.

9. A method of handling a ducted cable according to the preceding claim, wherein the third hauling step is assisted manually or mechanically so as to properly position the fairing in the guiding device.

10. A method of handling a streamlined cable according to any one of claims 7 to 8, wherein the hoisting of the cable is stopped at the end of the first hoisting step until the double twist is absorbed.

1 1. A method of handling a rope according to any one of claims 7 to 10, wherein, when the double torsion is resorbed during the first hoisting step, the first hoisting step is followed by a final hoisting step performed at the winch at the nominal speed of the winch until the length of the cable wound by the winch reaches the length L.

12. A method of handling a cable according to claim 1, comprising, when no double torsion is detected during the first monitoring step (20), a second step of hauling (25) the cable of length L , carried out by means of a winch at the rated speed of the winch.

13. A method of handling a cable according to any one of claims 7 to 12, comprising a second monitoring step (22) implemented during the first hauling step (21) and for detecting the resorption of the double twist and monitor the position of a complete submerged torsion relative to the guiding device.

14. A method of handling a cable according to any one of claims 7 to 13, comprising fourth steps of hoisting the cable (26) in which the cable is wound of respective lengths less than the sum of 1 meter and the the altitude separating the towing point from the surface of the water, the fourth hoisting steps being carried out at respective time intervals greater than or equal to at least 20 minutes during a predefined period, the cable not being rolled out between two consecutive implementations of the fourth step.

15. A method of handling a cable according to any one of claims 7 to 14, comprising a fifth hoisting step of winding the cable (1) a length less than the sum of 1 meter and altitude separating the tow point from the surface of the water to the length before at least one unwinding step of the cable.

16. A method of handling a cable according to the preceding claim, wherein the first hoisting step is implemented by means of a hoisting device, said hauling device being activated automatically when the monitoring device detects a double twist.

17. Device for handling a cable, streamlined by means of a fairing, towed by a ship, said device comprising a monitoring device for detecting whether the fairing undergoes a double twist around the cable comprising a complete submerged torsion and a complete aerial torsion and hoisting device for hoisting the cable when a double twist is detected so that the complete submerged twist at least partially out of the water and does not enter the guide device.

18. A device for handling a cable according to the preceding claim, configured to implement the method according to any one of claims 1 to 1 6, the monitoring device being configured to detect whether the fairing undergoes a double twist around the cable comprising a complete submerged torsion and a complete aerial torsion and the hoisting device being configured to implement the first hoisting step when a double twist is detected by the monitoring device.

19. Device for handling a cable according to the preceding claim, comprising an actuator configured to activate hoisting. of the cable by means of the hoisting device when a double twist is detected by the monitoring device and a controller making it possible to control the hoisting of the cable by means of the hoisting device so that the complete submerged torsion at least partially leaves the hoist water and does not enter the guiding device.

20. Cable handling device according to claim 17, comprising an alert device for alerting an operator when a double twist is detected.