GB2549464A

GB2549464A - A windlass and a windlass assembly for lifting and lowering a bouy anchor chain

Info

Publication number: GB2549464A
Application number: GB1606364.6A
Authority: GB
Inventors: John Collard David
Original assignee: Monobouy Co Ltd
Current assignee: Monobouy Co Ltd
Priority date: 2016-04-13
Filing date: 2016-04-13
Publication date: 2017-10-25
Anticipated expiration: 2036-04-13
Also published as: GB2549464B

Abstract

An assembly 10 for a buoy 9 for lifting or lowering a buoy anchor chain 13a-c. The assembly comprises a windlass 20 having a motorised fixed block 22, a lifting line 24 and at least one motor (26, Fig 5) mounted on the fixed block. The at least one motor is mechanically engaged with a main drive gear wheel (28, Fig 6) of the fixed block to rotate the main drive gear wheel to cause movement of the lifting line. A stand (40, Fig 4) is connectable to the buoy for supporting the motorised fixed block substantially above a position of a buoy chain stopper15 a-c. A power unit (16, Fig 4) for powering operation of the at least one motor is also provided. A windlass of the assembly as described above is also disclosed.

Description

A Windlass And A Windlass Assembly For Lifting And Lowering A Buoy Anchor Chain Field of the Invention

The invention relates generally to the field of handling a buoy anchor chain, and more particularly, to an assembly for use at a buoy for lifting and lowering a buoy anchor chain.

Background of the Invention

Various methods have been used to assist with the buoy mooring process in open water involving retrieving the buoy anchor chains from the seabed to attach to the buoy and secure its position afloat of the water. In the case of a Catenary Anchor Leg Mooring (CALM) buoy, for example, the presently preferred process is to use a specially adapted marine vessel such as a ship having suitable lifting gear aboard for lifting buoy anchor chains from the sea bed for attachment to the buoy chain stoppers provided around the under-periphery of the CALM buoy. This is self-evidently a very expensive process requiring the presence of the marine vessel and its crew for the duration of the mooring process which may take several days to some weeks to perform for each buoy.

Devices such as block and tackle systems have been adopted for lifting and lowering of buoy anchor chains, for example, during maintenance or a chain replacement. However, such systems are known to provide only very limited stroke and are thus not generally suitable for retrieving buoy anchor chains from the seabed, but are primarily used to merely support an existing connected buoy anchor chain during a maintenance operation. In any event, such devices are also generally slow to operate. Alternatively, a maintenance watercraft equipped with high power motors or machineries could be arranged to approach the buoy to retrieve the buoy anchor chain from the sea bed.

It is also generally impractical to install a large scale lifting machine or equipment at the buoy itself due to the relatively large size and heavy weight of the lifting machine or equipment.

Objects of the Invention

An object of the present invention is to provide a device and an assembly for a buoy for lifting and lowering a buoy anchor chain from and to the sea bed.

Another object of the present invention is to mitigate or obviate to some degree one or more problems associated with known anchor chain lifting devices, or at least to provide a useful alternative.

The above objects are met by the combination of features of the main claims; the subclaims disclose further advantageous embodiments of the invention.

One skilled in the art will derive from the following description other objects of the invention. Therefore, the foregoing statements of object are not exhaustive and serve merely to illustrate some of the many objects of the present invention.

Summary of the Invention

In a first main aspect, the invention provides an assembly for a buoy for lifting or lowering a buoy anchor chain. The assembly comprises a windlass having a motorised fixed block and a lifting line. The windlass has at least one motor mounted on the fixed block, with said motor being mechanically engaged with a main drive gear wheel of the fixed block to rotate the main drive gear wheel to cause movement of the lifting line. The assembly further comprises a stand connected to the buoy for supporting the motorised fixed block substantially above a position of a buoy chain stopper; and a power unit for powering operation of the at least one motor.

In a second main aspect, the invention provides a windlass for a buoy for lifting or lowering a buoy anchor chain. The windlass comprises a motorised fixed block; a lifting line; and at least one motor mounted on the fixed block. The motor is mechanically engaged with a main drive gear wheel of the fixed block to rotate the main drive gear wheel to cause movement of the lifting line, wherein the fixed block is adapted to be supported by a stand connected to the buoy substantially above a position of a buoy chain stopper.

In a third main aspect, the invention provides a buoy having the assembly according to the first main aspect or the windlass according to the second main aspect.

In a fourth main aspect, the invention provides a method of securing an anchor chain to a buoy, comprising the steps of providing said buoy with the assembly according to the first main aspect or the windlass according to the second main aspect; and using said fixed block to raise a buoy anchor chain for attachment to a buoy chain stopper.

The summary of the invention does not necessarily disclose all the features essential for defining the invention; the invention may reside in a sub-combination of the disclosed features.

Brief Description of the Drawings

The foregoing and further features of the present invention will be apparent from the following description of preferred embodiments which are provided by way of example only in connection with the accompanying figure, of which:

Figure 1 is a perspective view showing a Catenary Anchor Leg Mooring (CALM) buoy installed with a prior art anchor chain lifting system ;

Figure 2 is a magnified view showing the prior art anchor chain lifting system of Figure 1;

Figure 3 is a front view showing an embodiment of an assembly for a buoy for lifting or lowering a buoy anchor chain according to the present invention;

Figure 4 is a side view of the embodiment of Figure 3;

Figure 5 is a perspective view showing a first side of an embodiment of a fixed block for a windlass according to the present invention;

Figure 6 is a perspective view showing a second side of the embodiment of Figure 5;

Figure 7 is a plane view showing the first side of the embodiment of Figure 5;

Figure 8 is a side view showing the embodiment of Figure 5;

Figure 9 is a perspective view showing an embodied chain wheel of the windlass according to the present invention;

Figure 10 is a first side view showing an embodied stand of the assembly according to the present invention;

Figure 11 is a second side view showing the stand of Figure 10;

Figure 12 is a front view showing the stand of Figure 10;

Figure 13 a perspective view showing a first side of an embodiment of a fixed block for a windlass according to the present invention; and

Figure 14 is a perspective view showing a second side of the embodiment of Figure 13.

Description of Preferred Embodiments

The following description is of preferred embodiments by way of example only and without limitation to the combination of features necessary for carrying the invention into effect.

Reference in this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but not other embodiments.

Referring to Figure 1, shown is a Catenary Anchor Leg Mooring (CALM) buoy 1 installed with a prior art anchor chain lifting system 2, with a magnified view of the prior art anchor chain lifting system 2 being shown in Figure 2. As shown in the figures, the conventional lifting system 2 for buoy anchor chains comprises a lifting device 3 such as a pulley system or a block and tackle system for use with a lifting line such as a rope, a cable or a chain (not shown). The lifting device 3 can be operated manually or driven by an electric winch 4 mounted on a surface of the buoy structure below and separate from the lifting device 3. The lifting device 3is supported at a support stand 5 also installed on the buoy surface. The buoy 1 is moored by a number of anchor chains 7a, 7b or 7c, etc. As mentioned, the block and tackle lifting system is known to be slow and inefficient.

Figures 3 to 4 show a first embodiment of an assembly 10 for a buoy 9 for lifting or lowering a buoy anchor chain according to the present invention. The buoy 9 preferably comprises a CALM buoy 9. The assembly 10 comprises a windlass 20 having a motorised fixed block 22 and a lifting line 24. The windlass 20 comprises at least one motor 26 mounted on the fixed block 22. The motor 26 is mechanically engaged with a main drive gear wheel 28 of the fixed block 22 to rotate the main drive gear wheel 28 to cause movement of the lifting line 24. Preferably, the fixed block 22 is provided with a plurality of motors 26 arranged to drive the main drive gear wheel 28. The buoy 9 can be designed to comprise a rotatable platform 11 such that the fixed block 22 of the windlass 20 can be positioned to face a specific direction for lifting a corresponding anchor chain 13a, 13b or 13c, etc. to engage said buoy anchor chain 13a, 13b. 13c, etc. with a corresponding buoy chain stopper 15.

The assembly 10 further comprises a stand 40 connected to the buoy 9 for supporting the motorised fixed block 22 substantially above a position of a buoy chain stopper 15. For example, the fixed block 22 may comprise a self-contained block assembly adapted to be mounted to a cross beam of the stand 40 by a single pin 30 at the upper portion of the fixed block 22. In one embodiment, the stand 40 may comprise a tripod arrangement with legs adapted to engage a buoy surface. In a further embodiment, the stand 40 may comprise an existing structure on the buoy 9.

The assembly 10 may also comprise a power unit 16 for powering operation of the at least one motor 26. Preferably, the power unit 16 comprises a hydraulic power unit 16 and that at least one of the plurality of motors 26 is a hydraulic motor driven by the hydraulic power unit 16. In one embodiment, the hydraulic power unit 16 can be diesel powered or pneumatically powered, and is preferred to be configured with a two speed system such that it is adapted to operate at, for example, a higher speed with lower stroke or at a lower speed with high stroke. More preferably, the power unit 16 is an easily transferable, portable unit located at a distance from the assembly 10 and can be connected with the windlass 20 via one or more hoses 18.

Features of the windlass 20 are more clearly shown in, for example. Figures 5 to 8, which illustrate an embodiment of the windlass 20 according to the present invention. Specifically, the windlass 20 can be configured to comprise a plurality of motors 26 mounted directly on the fixed block 22, with each of said plurality of motors 26 being mechanically engaged with the main drive gear wheel 28 to rotate the main drive gear wheel 28 to cause movement of the lifting line 24. For example, each of the motors 26 can be arranged to engage the main drive gear wheel 28 via a gear 29 or a gear train. In this embodiment, the windlass 20 comprises four motors 26, with one of them arranged at one side of the main drive gear wheel 28 and the other three arranged at the opposing side of the wheel 28, but different configurations of the motors 26 can be provided.

The windlass 20 is intended to lift and lower the buoy anchor chain 13 into a buoy chain stopper 15 during a maintenance or replacement operation. The chain stopper 15 is typically arranged approximately 5-10 m below the windlass 20. Preferably, the windlass 20 is adapted to be operated at a speed of about 0.1 m/min to 3 m/min. The assembly 10 is preferred to be configured with a working load limit (WLL) of about 300kN to 500 kN.

In one embodiment, the lifting line 24 may comprise a lifting chain 24a provided with means such as, but not limited to, a shackle or a strop and hook 31 for attaching to a buoy anchor chain 13. In this embodiment, the fixed block 22 comprises a chain wheel 32 such as the one as shown in Figure 9, which can be driven by the main drive gear wheel 28. Specifically, a circumferential surface of said chain wheel 32 is shaped to engage chain links of the lifting chain 24a. Preferably, the lifting line 24 comprises a Grade 10 lifting chain 24a with a thickness of about 20-30 mm and a length of about 50-80 m and more preferably, at least 50 m. Optionally, the lifting line 24 can be provided with one or more stopping means such as a shackle or the like 33 for preventing the lifting line 24 from running off the windlass 20.

In the embodiment as shown in, for example. Figures 5 and 6, the fixed block 22 may comprise first and second spaced apart support plates 34, 36 arranged in a parallel configuration having the chain wheel 32 rotatably mounted therebetween. The main drive gear wheel 28 is arranged to be mounted to an exterior surface 34a of the first support plate 34, with the at least one motor 26 mounted to an opposing surface 34b of the first support plate 34 to thereby provide a compact structure for the fixed block 22. Preferably, the fixed block 22 may comprise a disk brake system 35 for automatically arresting movement of the lifting line 24 in the event of loss of power to the at least one motor 26. A counter-balance valve may also be provided for the lowering operation.

Preferably, the assembly 10 may further comprise a control unit 37 for controlling operation of one or more of the windlass 20 and the power unit 16. For example, the control unit 37 may be configured to control functions such as up/down, high/low speed and/or emergency stop of the lifting or lowering operation. A gauge 39 such as a pressure gauge may also be provided to indicate load on the windlass 20 and/or the motors 26.

Referring to Figures 10 to 14, shown is a further embodiment of the assembly 10 and the windlass 20 according to the present invention. The windlass 20 is configured with similar features to those of the previous embodiments. In this particular embodiment, the windlass 20 comprises 4 motors 26 which are positioned generally symmetrically around the main drive gear wheel 28, that is, two on each side of the wheel 28. In addition, the main drive gear wheel 28 is covered with a protective cover plate 38 at the exterior surface 34a of the first support plate 34.

In one embodiment, the assembly 10 is designed for use as a temporary arrangement for lifting and lowering a buoy anchor chain 13 and that the windlass 20 is preferred to be utilized for a maintenance operation of a predetermined period of time such as about one month. In a further embodiment, it is preferred that windlass 20 is to be used for about 24 times only, with each operation being last for about 20 minutes with a pause of 30 minutes between operations. In practice, the assembly 10 will be transferred to and be installed at the buoy surface and therefore, it is preferred that the weight of the assembly 10 including the stand 40, the windlass 20 and the power unit 16 be kept at minimum. For example, the windlass 20 is preferred to have a weight of about 700 kg to 900 kg.

In one other aspect of the present invention, it is provided with a buoy 9 having an assembly 10 or a windlass 20 as described in the above embodiments, and that the buoy 9 may comprise a Catenary Anchor Leg Mooring (CALM) buoy 9.

In yet a further aspect of the present invention, it is provided a method of securing an anchor chain 13 to a buoy 9. The anchor chain 13 can be any anchor chains such as one on a marine vessel for anchoring said vessel or a buoy anchor chain. The method comprises the steps of providing said buoy 9 with an assembly 10 or a windlass 20 as described above; and using said fixed block 22 to raise a buoy anchor chain 13 for attachment to a buoy chain stopper 15 a. The method may further comprise the steps of providing said assembly 10 or said windlass 20 on a rotatable platform 11 of the buoy 9; rotating said platform 11 of the buoy 9 to position said assembly 10 or windlass 20 above the position of a next buoy chain stopper 15b; and using said assembly 10 or windlass 20 to raise the buoy anchor chain 13 for attachment to said next buoy chain stopper 15b.

The present invention is advantageous in that it provides a compact and light-weight windlass or windlass assembly for lifting and lowering a buoy anchor chain during an anchor chain deployment on a large buoy such as a CALM buoy. Despite the portability of the windlass, it is capable of providing sufficient stroke for lifting and lowering the heavy anchor chain efficiently. Particularly, the windlass assembly of the present invention can be configured with an overall weight of about 750 kg, and is effective to operate at a working load limit of about 300 to 500 kN. Furthermore, the motorized windlass allows lifting of the anchor chain in a continuous operation, which is a significant improvement over the conventional block and tackle system.

Although the windlass and the windlass assembly as described in the various embodiments relate mainly to the lifting and lowering of a buoy anchor chain of a buoy, it can be envisaged that the present invention should not be limited only to this application. Instead, it would be appreciated that the present invention can be applied in lifting and lowering of other types of heavy chains or cables in the sea such as, but not limited to, anchor chains for anchoring a ship, a boat, other marine vessels or buoyant structures.

The present description illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope.

Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any manner. It can be appreciated that any of the features described herein may be used with any embodiment. The illustrative embodiments are not exclusive of each other or of other embodiments not recited herein. Accordingly, the invention also provides embodiments that comprise combinations of one or more of the illustrative embodiments described above. Modifications and variations of the invention as herein set forth can be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated by the appended claims.

In the claims hereof, any element expressed as a means for performing a specified function is intended to encompass any way of performing that function. The invention as defined by such claims resides in the fact that the functionalities provided by the various recited means are combined and brought together in the manner which the claims call for. It is thus regarded that any means that can provide those functionalities are equivalent to those shown herein.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art.

Claims

1. An assembly for a buoy for lifting or lowering a buoy anchor chain, said assembly comprising: a windlass comprising a motorised fixed block and a lifting line, said windlass having at least one motor mounted on the fixed block, said motor being mechanically engaged with a main drive gear wheel of the fixed block to rotate the main drive gear wheel to cause movement of the lifting line; a stand connected to the buoy for supporting the motorised fixed block substantially above a position of a buoy chain stopper; and a power unit for powering operation of the at least one motor.

2. The assembly according to claim 1, wherein the windlass has a plurality of motors mounted on the fixed block, each of said plurality of motors being mechanically engaged with the main drive gear wheel to rotate the main drive gear wheel to cause movement of the lifting line.

3. The assembly according to claim 2, wherein each of said plurality of motors is engaged with the main drive gear wheel via a gear or a gear train.

4. The assembly according to claim 2 or claim 3, wherein the plurality of motors are positioned generally symmetrically around the main drive gear wheel.

5. The assembly according to any one of claims 2 to 4, wherein the fixed block has four or more motors.

6. The assembly according to any one of the preceding claims wherein the at least one motor is a hydraulic motor.

7. The assembly according to any one of the preceding claims, wherein the lifting line comprises a lifting chain provided with means for attaching to a buoy anchor chain.

8. The assembly according to claim 7, wherein the means for attaching the lifting chain to a buoy anchor chain comprises a shackle or a strop and hook.

9. The assembly according to claim 7 or claim 8, wherein the fixed block has a chain wheel driven by the main drive gear wheel, a circumferential surface of said chain wheel being shaped to engage chain links of the lifting chain.

10. The assembly according to any one of the preceding claims, wherein the fixed block comprises a self-contained block assembly adapted to be mounted to the stand by a single pin connection.

11. The assembly according to any one of the preceding claims, wherein the stand comprises an existing structure on the buoy.

12. The assembly according to claim 9, wherein the fixed block comprises first and second spaced apart support plates arranged in a parallel configuration having the chain wheel rotatably mounted therebetween, the main drive gear wheel being mounted to an exterior surface of the first support plate with the at least one motor mounted to an opposing surface of the first support plate to thereby provide a compact structure for the fixed block.

13. The assembly according to any one of the preceding claims, wherein the fixed block comprises a disk brake system for automatically arresting movement of the lifting line in the event of loss of power to the at least one motor.

14. The assembly according to any one of the preceding claims, wherein the stand comprises a tripod arrangement with legs adapted to engage a buoy surface.

15. The assembly according to any one of the preceding claims, wherein the power unit comprises a hydraulic power unit.

16. The assembly according to any one of the preceding claims, wherein the assembly has a working load limit of about 300 kN to 500 kN

17. The assembly according to any one of the preceding claims, wherein the lifting line has a length of about 50-80 m and preferably 50 m.

18. The assembly according to any one of the preceding claims, wherein the lifting line has a thickness of about 20-30 mm.

19. The assembly according to any one of the preceding claims, wherein the lifting line comprises one or more stopping means for preventing the lifting line from running off the windlass.

20. The assembly according to any one of the preceding claims, further comprising a control unit for controlling operation of one or more of the windlass and the power unit.

21. The assembly according to any one of the preceding claims, wherein the windlass is adapted to be operated at a speed of about 0.1 m/min to 3 m/min.

22. The assembly according to any one of the preceding claims, wherein the windlass has a weight of about 700 kg to 900 kg.

23. A windlass for a buoy for lifting or lowering a buoy anchor chain, said windlass comprising: a motorised fixed block; a lifting line; at least one motor mounted on the fixed block, said motor being mechanically engaged with a main drive gear wheel of the fixed block to rotate the main drive gear wheel to cause movement of the lifting line; wherein the fixed block is adapted to be supported by a stand connected to the buoy substantially above a position of a buoy chain stopper.

24. A buoy having an assembly according to any one of claims 1 to 22 or a windlass according to claim 23.

25. The buoy according to claim 24, wherein the buoy comprises a Catenary Anchor Leg Mooring (CALM) buoy.

26. A method of securing an anchor chain to a buoy, comprising the steps of: providing said buoy with an assembly according to any one of claims 1 to 22 or a windlass according to claim 23; and using said fixed block to raise a buoy anchor chain for attachment to a buoy chain stopper.

27. The method according to claim 26, further comprising the steps of: providing said assembly according to any one of claims 1 to 22 or said windlass according to claim 23 on a rotatable platform of the buoy; rotating said platform of the buoy to position said assembly or windlass above the position of a next buoy chain stopper; and using said assembly or windlass to raise the buoy anchor chain for attachment to said next buoy chain stopper.

28. An assembly for a buoy substantially as hereinbefore described.

29. A CALM buoy substantially as hereinbefore described.

30. A windlass for a buoy substantially as hereinbefore described.

31. A method of securing an anchor chain to a buoy substantially as hereinbefore described.