EP2396626A2

EP2396626A2 - Device for measuring cable length

Info

Publication number: EP2396626A2
Application number: EP10707092A
Authority: EP
Inventors: Mathieu Deleignies
Original assignee: Nereus Technologies
Current assignee: Nereus Technologies
Priority date: 2009-02-16
Filing date: 2010-02-12
Publication date: 2011-12-21
Also published as: WO2010092256A2; FR2942313A1; FR2942315A1; WO2010092256A3; FR2942313B1

Abstract

The invention relates to a cable (1) provided with marks (2), which are fixed at predefined intervals along the cable. The measurement device comprises an electronic detection means (6), which is suitable for automatically detecting, on the moving cable (1), every local change in the transverse geometry linked to the presence of a mark (2). More specifically, the device can also comprise a wheel (3) suitable for being rotated by the cable (1), an encoder (4) suitable for detecting the number of turns made by the wheel (3), and an electronic acquisition and processing means for calculating a corrected cable length according to the number of wheel turns detected by the encoder (4) and the detection signal provided by the electronic mark detection means (6).

Description

DEVICE FOR MEASURING THE LENGTH OF CABLES

Object of the Invention The present invention relates to a device for measuring the length of cables, in particular multi-strand cables of trawlers during fishing.

The invention also relates to the method of implementing the device. Technological background and state of the art

The trawl net is a towed net of a trawler, having a characteristic funnel-shaped shape enclosed by a pocket at the stern (called the "cul" of the trawl), extended at the front by wings to widen its range and equipped with current models of two divergent panels, which by plate effect, allow the opening of the trawl. It can be towed by one or two ships. The trawl is dragged by multi-strand wire ropes, commonly known as "funes", connected to a winch on the port side and a winch on the starboard side respectively. To determine the length of the funnels leaving the winch on a fishing trawler, it is known to have at regular intervals visual marks on the funnels, for example in the form of local extra thicknesses of the cable, which will be observed and counted by the crewman lying on a winch. Thus, to facilitate the counting, it is possible, for example, to have, for example, a mark at 25 m, two marks at 50 m, three marks at 75 m and then start again with a mark at 100 m, and so on. The crewman determines the cable length unwound by multiplying the number of marks counted and the inter-mark length. It is very important for the proper positioning of the trawl maintain constant symmetry between the port and starboard cables.

In order to obtain a measurement of cable length without the need for a crewman, most of the "semi-automatic" devices of the state of the art use the signal of an encoder implanted in a sheave. a pulley) driven by the cable. It is the pressure force provided by the cable on the sheave that allows to rotate it and count the number of turns to be made, ie, if we know the diameter of the sheave where the cable runs, the length of the unwound cable ¹ .

Nevertheless, the material of sheaves used is commonly a steel for reasons of mechanical strength. Indeed, a large fraction of the traction is transmitted to the axis of the pulley, depending on the angle of the cable, to ensure friction, which involves the wear of the pulley. As the cable is also often made of steel and under variable conditions of use (dry, wet, greasy, worn cable, etc.), the coefficient of adhesion between the cable and the sheave is low (of the order 0.1) and variable. Finally, the structure of the cable itself, twisted strands, is problematic in minimizing the contact area between the cable and the sheave, with again the obligation to establish at the cable a significant angle between the upstream and the downstream of the shea. These properties imply that during the measurement, a slip occurs between the cable and the sheave which does not make it possible to obtain a relative measurement with an error of the order of 0.3% at best (announced), but often closer to 1% (measured). In addition, this means is mechanically complex and expensive because, because of this slip problem, it is often coupled to a cable traction device. EP-A-0 116 026 discloses a device for detecting the tension or force exerted on a cable to which a fishing net can be fixed. This detection device comprises a system with several rollers or pulleys, at least one of said rollers being disposed on one side of the cable and at least one other of said rollers being disposed on the other side of the cable, one of the rollers being provided with a cell for measuring the voltage or force exerted on the cable which is for example incorporated in the axis of the central roller. These rollers are mounted on a rigid frame mounted for rotation or tilting on an axis to allow tilting relative to for example a cable guide carriage on which this device is mounted. Detectors are preferably provided for measuring the number of rotational revolutions of one of the rollers. It is thus possible to accurately measure the tension exerted on the cable and the length of unwound cable. This system does not allow to control the sliding of the cable on the rollers, as indicated above.

WO-A-91 18261 discloses a method and apparatus for accurately measuring the length of an elongate object, such as a communications cable, as it travels. An appropriate measuring apparatus comprises combined features of a marking system and a coding system. The measurement of length is based on the magnetic detection of magnetic marks fixed along the cable and on the optical detection, by means of a laser switch, of optically detectable marks and applied on the cable by the marking system.

In US Pat. No. 4,718,168, there is provided a method of measuring the length of a cable equipped at its end with a drilling tool. For the setting In this method, magnetic marks are fixed on the cable at regular intervals. A length of cable is measured by counting the number of turns of a wheel driven by the cable, and this length is corrected by detecting the magnetic marks of the running cable by means of a magnetic detector. Similar methods are also described in U.S. Patents 5,546,672 and 5,062,048.

The technical solutions described in these publications WO-A-91 18261, US Pat. No. 4,718,168, US Pat. No. 5,546,672 and US Pat. No. 5,062,048 can not in practice be used for cables, such as in particular trawler funnels, which are operated under conditions where they undergo high mechanical stresses, including significant and repeated friction forces. Indeed the magnetic or optical marks implemented in these solutions would not withstand such constraints. In addition to detect these magnetic or optical marks, it is necessary to implement a detector that must necessarily be positioned in the immediate vicinity of the cable. Such a detection solution is therefore difficult to implement on cables carrying bulky elements, such as for example trawler cables carrying swivels, chains, etc.. Goals of the invention

The present invention aims to overcome the disadvantages of the state of the art.

In particular, the invention aims to propose a new technical solution for easier and more reliable measurement of the running length of a cable, and in particular of a multi-strand cable, such as in particular a trawler cable, likely to be exploited under aggressive mechanical conditions. In particular, the invention aims, in the case of a trawl, allow to releasing, reliably and easily, always the same length of cable to port and starboard, to ensure optimal opening of the trawl.

Main characteristic elements of the invention

A first object of the present invention thus relates to a new device for measuring the length of a running cable provided with marks, which are fixed along the cable at predefined intervals. Said measuring device comprises electronic detection means, which are able to automatically detect, on the running cable, each local change in transverse geometry related to the presence of a mark.

According to particular embodiments of the invention, the aforementioned device further comprises one or more of the following characteristics, taken separately or, where appropriate, in combination with each other:

the cable comprises several strands, and the marks are inserted between the strands of the cable;

each mark comprises a body inserted between the strands of the cable, so as to locally modify the transverse geometry of the cable by a local spacing of the strands of the cable;

- the body of each mark is completely surrounded by the strands of the cable; - the marks form local extra thicknesses on the cable;

the electronic detection means comprise a sensor which makes it possible to detect on the moving cable each local change of geometry transverse corresponding to a mark, without being in contact with said cable;

said sensor is a laser distance sensor, or an ultrasonic distance sensor, or an inductive sensor;

the device comprises a roller on which the marked cable passes and which is targeted by the sensor to enable it to detect a local change of transverse geometry corresponding to a mark;

- The device comprises display means for displaying on a screen the number of marks detected by the electronic detection means; the electronic detection means are able to detect each local change in transverse geometry of the cable which is less than a predefined maximum threshold (Smax);

the electronic detection means are able to detect each local change in transverse geometry of the cable which is greater than a predefined minimum threshold (Smin);

the device comprises a wheel capable of being rotated by the cable, an encoder able to detect the number of revolutions made by the wheel, and electronic acquisition and processing means which make it possible to calculate a length of cable corrected to from the number of wheel turns detected by the encoder, and from the detection signal delivered by the electronic means for detecting marks;

- The device comprises display means for displaying on a screen the corrected cable length which is calculated by electronic means of acquisition and processing. A second object of the present invention relates to a new method for estimating the length of a running cable, during which marks are fixed on the cable at predefined intervals, and the scrolling cable is automatically detected on the cable local change of transverse geometry corresponding to a mark.

According to particular embodiments of the invention, the aforesaid method further comprises one or more of the following characteristics, taken separately or, where appropriate, in combination with each other:

- We count and display on a screen the number of marks detected on the cable scrolling; the cable comprises several strands, and the marks are inserted between the strands of the cable;

- the body of each mark is completely surrounded by the strands of the cable;

- the marks form local extra thicknesses on the cable; the detection of each local change of transverse geometry corresponding to a mark is made on the running cable by means of a sensor which is not in contact with said cable;

the sensor is a laser distance sensor, or an ultrasonic distance sensor, or an inductive sensor;

- a mark is detected and is counted when the local change of transverse geometry of the cable scrolling is less than a predefined maximum threshold (Smax);

a mark is detected and is counted when the local change of transverse geometry of the running cable is greater than a predefined minimum threshold (Smin);

the cable rotates a wheel and the number of revolutions made by the wheel is automatically detected in the form of a first signal; simultaneously, each local change of transverse geometry corresponding to a mark is detected on the running cable in the form of a second signal; - A length of the cable that has run is calculated automatically from the first signal and the diameter of the wheel, and this length of cable having scrolled is corrected automatically by means of the second signal. the corrected cable length is displayed on a screen; the cable is a trawler cable

Finally, a third object of the present invention relates to a use of the device described above, for the measurement of unreeled lengths of funes of fishing trawls.

Brief description of the figures

Figure 1 shows a multi-strand wire rope with a mark for length measurement according to a first embodiment.

FIG. 2 represents the multi-strand wire rope of FIG. 1 rotating a sheave which is equipped with an encoder to detect and count the number of turns made by the sheave.

Figure 3A shows a multi-strand wire rope with its length measuring device according to one embodiment of the invention.

Figure 3B shows in perspective an industrial embodiment of the device of the present invention.

FIG. 4 is an exemplary block diagram of the main components of the measuring device according to the invention.

Figure 5 shows schematically the evolution of the corrected measure over time.

Fig. 6A is a cross-sectional view of an exemplary multi-strand cable in a portion of the cable devoid of mark.

Fig. 6B is a cross-sectional view of an example of a multi-strand cable, in a portion of the cable provided with a foreign body inserted between the strands of the cable, so as to form a mark.

FIG. 7 shows a portion of trawler multi-strand cable, said cable being provided with a swivel and a mark, of the type of that of FIG. 3B, as well as an example of an electrical signal delivered by a sensor of FIG. measurement device, when said portion of cable passes in front of said sensor, and an example of a detection signal obtained after processing of the signal delivered by the sensor.

Description of a preferred embodiment of the invention

In order to overcome the disadvantages of the state of the art, according to the present invention, a method of estimating and correcting the run length of a multi-strand cable 1. With reference to the particular example of FIG. 6A, this cable 1 is for example a multi-strand metal cable 1, of the trawler cable type, comprising a central core Ib, surrounded by a plurality of strands twisted la, for example steel. The number of strands of FIG. 6A is not limiting of the invention.

The length measurement prediction is carried out (FIGS. 3A 'and 3B) using an encoder 4 positioned on a sheave 3 (grooved wheel) which is rotated by the cable 1 in tension.

The cable 1 has markings 2 which are carried by the cable 1 at predefined intervals, and which make it possible to locally modify the transverse geometry of the cable 1.

These marks 2 are preferably inserted between the strands 1a of the cable 1. The insertion of the marks 2 between the strands 1a of the cable 1 allows a reliable and robust fastening over time of each mark 2 on the cable 1. The marks 2 resist and the mechanical stress experienced by the cable 1, including the significant friction experienced by this cable in use. In addition, the insertion of a mark 2 between the strands 1a of the cable 1 advantageously makes it possible to locally increase the diameter of the cable, this local diameter change being detectable by the measuring device of the invention in the form of a detection signal 7 provided by electronic detection means 6 having a suitable sensor βa or equivalent placed in the device (Figure 3A).

In the particular variant of FIGS. 1 to 3, each mark 2 appears at the periphery of the cable in the form of a detectable local excess thickness. In another variant embodiment illustrated in FIG. 6B, each mark 2 is constituted by a solid body 2a inserted between the strands 1a and the core Ib of the cable, so as to locally separate the strands Ib of the cable with respect to the others, and achieve a local increase in the diameter of the cable 1 which is detectable by the sensor βa. In this variant of FIG. 6B, the body 2a constituting the mark 2 is completely surrounded by the strands 1a and does not protrude outside the strands 1a. The body 2a with a function of mark 2 is thus mechanically protected by the strands 1a, and in particular is protected from the friction experienced by the cable 1. This type of mark is therefore advantageously very robust in time. The sensor βa is advantageously a laser distance sensor, which makes it possible to detect on the moving cable 1 each local change in transverse geometry that corresponds to the presence of a mark 2. Any type of sensor, analog or digital, to detect a local change of transverse geometry of the cable 1, which corresponds to the presence of a mark 2, can be used. An ultrasonic distance sensor can also be used. It is also possible to use an inductive sensor. However, in the latter case, as the approach distance is much smaller (less than 10 mm), the system must be specially adapted to protect the sensor. In addition, a laser or ultrasonic distance sensor may advantageously be positioned at a greater distance from the cable and consequently allows the passage of bodies carried by the cable 1, and having a greater transverse bulk than the marks 2. , such as for example a swivel 9 carried by a cable 1 trawler (Figure 7). The implementation of a contactless sensor βa is preferential according to the invention. Nevertheless, it is also conceivable to use a sensor, which is in contact with the cable 1 in movement, and which makes it possible to detect each local change in transverse geometry of the cable 1 corresponding to the presence of a mark 2.

Advantageously, there will be provided a protective metal shield of the sensor 6a which could be hooked by the movable elements and in particular by the flapping of the cable. An example of an industrial embodiment of the device according to the invention is shown in FIG. 3B.

When the sensor βa is a laser or ultrasonic distance sensor, it makes it possible to measure the instantaneous distance between the cable 1 and the sensor 6a. In the embodiment of FIG. 3B, the sensor 6a is preferably arranged to aim the cable passing over a roller 8 (FIG. 3B). Indeed, at this point there is no risk of flapping of the cable, and the distance measurement between the cable 1 and the sensor 6a allows a more precise measurement of the local diameter variation of the cable 1 resulting from the presence of the mark 2.

The number of revolutions made by the sheave 3 is counted automatically by means of the encoder 4 in the form of a first counting signal 5. At the same time, each local change of transverse geometry of the moving cable 1 corresponding to a mark 2 is detected by the electronic detection means 6 by means of the sensor 6a, in the form of a second detection signal 7. These two signals 5 and 7 are processed by an acquisition and processing electronics 10 (for example, PLCs, industrial PCs , etc. - Figure 4).

An example of a cable length measurement algorithm implemented automatically by electronics acquisition and processing 10 will now be described.

(a) Between two successive marks Mi and Mi ₊ i, the acquisition and processing electronics 10 automatically calculate a length of cable ("length [i, i ₊ i]") as follows: length [i _; i ₊ i] = length [^ + estimated length [i, -i ₊ i]

The variable "length [±]" is the corrected cable length from the previous iteration, and is initialized to zero at the start of the algorithm (length [ _O1 = O).

The variable "estimated_length [i _; i ₊ i] "is an estimate of the length of the cable that has run, and which is calculated, for example at each turn of sheave 3, by the acquisition and processing electronics 10, from the first signal 5 and the internal diameter of the sheave 3. This estimated length (estimated length [i _; i ₊ i]) is equal to the number of shifts 3 shifts the internal diameter of the sheave where the cable passes 1. At the same time, the acquisition electronics and processing 10 accurately accounts for the number of marks 2 detected by the sensor 6a on the cable 1 running, from the detection signal 7, by means of a counter of marks ("counter__marks"). Acquisition and processing electronics

10 is parameterized with the distance between two successive marks ("distance_inter-marks") on the cable 1, which distance for simplification can be constant.

(b) When the next mark Mi ₊ i is detected by the detection means 6, the acquisition and processing electronics 10 automatically calculate a length correction ("Correction [i ₊ i]) and a corrected cable length ("Length [i ₊ u") as follows: Correction _{Ii + 1]} = (counter_ of _marks * distancejnter-marks) - length ^ _; i _+1]

Thus the length of the cable at the passage of the mark Mi ₊ i is precisely: length _{[i + 1]} = length [i] + estimated length [i _; i ₊ i] ₊ Correction _t i ₊ i]

The measurement algorithm is reiterated in the above step (a). Numeric example

It is assumed that the marks are positioned every 25 meters (distancejnter-marks = 25m). The cable 1 scrolls and the estimate (estimated_length [o _; i]) gives just before the passage of the first mark 24, 1 meters. The correction is then worth:

Correction ^ _] = 25 - 24.1 = 0.9 meters. At the passage of the first detected mark, the length corrected Length ^ _] is equal to 25 meters (length ^ _] = length ^ _] + estimated length _[0 ; i] + Correction ^ _] = 0m + 24,1m + 0,9m). At the passage of the second mark, the length

(length [ _{1] 2} ] = length ^] + estimated length [i; ₂ ])) is 49.5 meters. The correction is then worth:

Correction _[2] = 2 * 25 - 49.5 = 0.5 meters.

At the passage of the second detected mark, the corrected length length ^ _] is equal to 50 meters (length ^ _] = length ^ _] + estimated length [i, 2] + Correction _[2 ])

Thus, the error made between two marks is of the order of 0.3% to 1% of the inter-mark length. At each detected mark, the measurement accuracy is reduced to the positioning of the mark on the cable. This can be in absolute value less than 0.1 meter, whatever evening cable length unwound. An example of evolution of the estimated and corrected measure over time is shown schematically in Figure 5.

With reference to FIG. 7, the cable 1 can also carry additional elements, which are larger than a mark 2, such as, for example, a swivel 9. In this case, it is necessary for the measuring device of the invention to be capable of to automatically discriminate a mark 2 from an additional element 9.

FIG. 7 shows an example of time evolution of the amplitude of the detection signal 7a delivered by the sensor 6a, when the cable portion 1 of FIG. 7 passes in front of the sensor βa. In this example, the distance between the sensor 6a and the cable (including if necessary the swivel 9 or a mark 2) is small (that is to say, the greater the transverse dimension of the cable 1 is important), and the higher the amplitude of the signal 7a is important. To detect each mark 2, the electronic detection means 6 are designed to process (FIG. 4- block 6b) the detection signal 7a delivered by the sensor 6a by comparing it with two thresholds: Smin; Smax (Figure 7). A mark 2 is detected automatically by the electronic detection means 6, when the amplitude of the detection signal 7a is greater than Smin and less than Smax. The electronic detection means 6 inform the acquisition and processing electronics 10 of each mark detection by means of the detection signal 7 (FIGS. 4 and 7). The acquisition and processing electronics 10 (PLC, industrial PCs, etc.) automatically calculate the corrected cable length (length _{[i +} i]). In another variant embodiment, the automatic detection of marks from the thresholds Smin, Smax can also be carried out by the acquisition and processing electronics 10, directly from the signal 7a delivered by the sensor 6a.

With reference to FIG. 4, the device comprises display means 11 which make it possible to display on a screen the corrected length of cable (length [i ₊ i]) which is calculated by electronic means of acquisition and processing and / or displaying the number of marks 2 ("tag_counter"). detected by the electronic detection means 6.

Advantages of the invention

Except for a particular maneuver, such as the hooking of the trawl on the fishing gear, the trawler captain may maneuver both the port and starboard winches alone.

During the launching of the trawl which lasts several hours, it is possible that the relief of the seabed necessitates modifying the lengths of cables to port and starboard. It is the same in case of change of course (turn). Again, the captain can perform the maneuver alone, without additional personnel, which is economical or more comfortable (eg more staff awakening in the middle of the night).

Better cable length management ensures optimal trawl opening, which ensures better fishing.

Whereas, according to the state of the art, absolute confidence can not be placed in the encoder wheel, the technology according to the invention which provides a reliable measurement of length tends to encourage the use of more "automated" devices.

Claims

1. Device for measuring the length of a cable (1) running, the cable (1) being provided with marks (2), which are fixed along the cable at predefined intervals, said device comprising electronic detection means (6), which are able to automatically detect, on the cable (1) in scrolling, each local change of transverse geometry related to the presence of a mark (2).

2. Device according to claim 1, characterized in that the cable (1) comprises several strands (la), and the marks (2) are inserted between the strands (la) of the cable.

3. Device according to claim 2, characterized in that each mark (2) comprises a body

(2a) inserted between the strands (la) of the cable (1), so as to modify locally the transverse geometry of the cable

(1) by a local spacing of the strands (la) of the cable (1).

4. Device according to claim 3, characterized in that the body (2a) of each mark (2) is completely surrounded by the strands (la) of the cable.

5. Device according to any one of claims 1 to 4, characterized in that the marks

(2) form local extra thicknesses on the cable (1).

6. Device according to any one of claims 1 to 5, characterized in that the electronic detection means (6) comprise a sensor (6a) for detecting on the cable (1) scrolling, each local change of geometry transverse corresponding to a mark (2), without being in contact with said cable (1).

7. Device according to claim 6, characterized in that the sensor (6a) is a laser distance sensor.

8. Device according to claim 6, characterized in that the sensor (6a) is an ultrasonic distance sensor.

9. Device according to claim 6, characterized in that the sensor (6a) is an inductive sensor.

10. Device according to any one of claims 1 to 9, characterized in that it comprises a roller (8) on which passes the cable (1) marked and which is targeted by the sensor (6a) to allow it- ci to detect a local change of transverse geometry corresponding to a mark (2).

11. Device according to any one of claims 1 to 10, characterized in that it comprises display means (11) for displaying on a screen the number of marks (2) detected by the electronic detection means. (6).

12. Device according to any one of claims 1 to 11, characterized in that the electronic detection means (6) are adapted to detect each local change in transverse geometry of the cable (1) which is less than a maximum threshold (Smax ) predefined.

13. Device according to any one of claims 1 to 12, characterized in that the electronic detection means (6) are adapted to detect each local change in transverse geometry of the cable (1) which is greater than a minimum threshold (Smin ) predefined.

14. Device according to any one of claims 1 to 13, characterized in that it comprises a wheel (3) adapted to be rotated by the cable (1), an encoder (4) capable of detecting the number of turns made by the wheel (3), and electronic acquisition and processing means (10) which make it possible to calculate a length of cable corrected to from the number of wheel turns detected by the encoder (4), and the detection signal (7) delivered by the electronic means (6) for detecting marks.

15. Device according to claim 14, characterized in that it comprises display means for displaying on a screen the corrected cable length which is calculated by electronic means of acquisition and processing.

16. A method of estimating the length of a cable (1) running, during which is fixed on the cable (1) marks (2) at predetermined intervals, and is detected automatically on the cable (1) in scrolling each local change of transverse geometry corresponding to a mark (2).

17. The method of claim 16, characterized in that counts and displays on a screen the number of marks detected on the cable scrolling.

18. The method of claim 16 or claim 17, characterized in that the cable (1) comprises several strands (la), and the marks (2) are inserted between the strands (la) of the cable.

19. The method of claim 18, characterized in that each mark (2) comprises a body (2a) inserted between the strands (la) of the cable (1), so as to locally modify the transverse geometry of the cable.

(1) by a local spacing of the strands (la) of the cable (1).

20. The method of claim 19, characterized in that the body (2a) of each mark (2) is completely surrounded by the strands (la) of the cable.

21. Process according to any one of Claims 16 to 19, characterized in that the marks

(2) form local extra thicknesses on the cable (1).

22. Method according to any one of claims 16 to 21, characterized in that the detection of each local change of transverse geometry corresponding to a mark (2) is performed on the running cable by means of a sensor (βa) which is not in contact with said cable (1).

23. The method of claim 22, characterized in that the sensor (βa) is a laser distance sensor.

24. The method of claim 22, characterized in that the sensor (6a) is an ultrasonic distance sensor.

25. The method of claim 22, characterized in that the sensor (6a) is an inductive sensor.

26. A method according to any one of claims 16 to 25, characterized in that a mark (2) is detected and is counted when the local change of transverse geometry of the cable (1) scrolling is less than a maximum threshold (Smax) predefined.

27. Process according to any one of Claims 16 to 26, characterized in that a mark

(2) is detected and is counted when the local change in transverse geometry of the moving cable (1) is greater than a predefined minimum threshold (Smin).

28. Method according to any one of claims 16 to 27, during which the cable rotates a wheel (3) and: - the number of revolutions made by the wheel (3) is detected automatically in the form of a first signal (5); simultaneously, each local change of transverse geometry corresponding to a mark (2) is detected on the traveling cable (1) in the form of a second signal (7); a length of the running cable (1) is automatically calculated from the first signal (5) and the diameter of the wheel, and this length of cable (1) having been deflected is corrected automatically by means of the second signal (7).

29. The method of claim 28, characterized in that one displays on a screen the corrected cable length.

30. Method according to any one of claims 16 to 29, wherein the cable (1) is a trawler cable

31. Use of the device, referred to in any one of claims 1 to 15, for measuring unreeled lengths of funes of fishing trawls.