Offshore crane vessel and method for operating an offshore crane vessel

Abstract

The present invention relates to the field of offshore crane vessels, including a crane, for example for use in the operation of one or more offshore wind turbine components. The crane comprises a superstructure pivotable relative to a cradle and a boom having a length of between 60 meters and 200 meters. A boom hoisting assembly is provided for pivoting the boom about a horizontal boom pivot axis. The crane further comprises a primary lifting arrangement for lifting a load, comprising a primary lifting block assembly supported by the head structure. According to the invention, the head structure is a moving head structure slidable along a portion of the boom from a tip on the boom to a second position.

Description

[Technical field]

[0001] The present invention relates to the field of offshore crane vessels, for example including cranes, for use in the operation of one or more offshore wind turbine components, for example for the installation and / or maintenance of offshore wind turbines. [Background technology]

[0002] In the field of offshore wind turbines, there is a need to handle very heavy components such as foundations, e.g. monopiles, which can have a mass of 1000 tons or more. Furthermore, there is a need to handle components "at nacelle height", including, for example, handling the nacelle itself and / or one or more components housed in and / or attached to the nacelle, e.g. gearbox, generator, hub and / or rotor blades. Current designs propose or already have nacelles at heights of more than 100 meters above sea level, e.g. 120 meters or more, e.g. the Haliade-X 12 MW offshore wind turbine. Thus, handling such components requires both heavy lift cranes and very tall cranes. It is noted that the mass of the nacelle can also exceed several hundreds of tons, e.g. 500 tons.

[0003] In a typical approach, offshore wind turbines are installed or serviced using a jack-up vessel positioned near the site of the wind turbine, and then the jack-up legs are extended and the vessel is at least partially, but almost completely, raised above the water to provide a stable condition for crane operations.

[0004] It is noted that the invention is primarily envisaged for the field of offshore wind turbines, for maintenance and for installation and / or removal of wind turbines, but the crane of the invention may also be used for other offshore applications such as oil and gas related works, civil engineering works, etc.

[0005] In this field, offshore crane vessels are known. This offshore crane vessel is The vessel comprises a hull, a deck, and a crane; The crane, a platform attached to or integrally formed with the hull of the vessel; a superstructure pivotally supported by the cradle for rotation of the superstructure relative to the cradle about a vertical axis of rotation, the superstructure comprising a boom connection member; A boom having a longitudinal axis and a length between a pivot end and a tip end of 60 meters to 200 meters, the pivot end being connected to a boom connection member so that the boom can pivot up and down about a horizontal boom pivot axis, the length of the boom being such that in a horizontal rest position, the tip end projects outside the periphery of the vessel's hull; a boom rest for supporting the boom in a horizontal rest position; a boom hoist assembly for pivoting the boom about a horizontal boom pivot axis, the boom hoist assembly including a boom hoist winch and an elongated hoist member extending to the boom; a main lifting device for lifting a load, the main lifting device comprising a main lifting winch, at least one associated main lifting cable, and a main lifting block assembly supported by a head structure; Equipped with.

[0006] For example, handling one or more offshore wind turbine components for installation and / or maintenance of the offshore wind turbine requires a tall crane, i.e. the crane will have a long boom to have a long reach. A long boom has a length of at least 60 meters, e.g. 80 meters to 200 meters. Such a boom will project outside the perimeter of the vessel's deck when the boom is in a horizontal orientation, e.g. in a boom stowed position, e.g. during transport. Summary of the Invention [Problem to be solved by the invention]

[0007] The volume and weight of the extended boom and main lifting block assembly presents some drawbacks. A known solution is to provide a telescoping boom as disclosed in WO 2020 / 244973 of the same applicant. [Means for solving the problem]

[0008] It is an object of a first aspect of the present invention to provide an alternative offshore vessel crane.

[0009] According to a first aspect of the present invention, the offshore crane vessel is characterized in that the head structure is a moving head structure slidable along a portion of the boom from a tip end on the boom to a second position, and in the horizontal rest position of the boom and in the second position of the moving head structure the main lifting block assembly is positioned above the deck of the vessel.

[0010] The advantage of the retractable moving head structure in the second position is that the weight of the moving head structure and the main lifting block assembly is brought above deck, preferably near the boom rest. This prevents fatigue and / or bending of the boom, especially during voyages. The retractability allows for the selection of an advantageous distribution of weight on the vessel by selecting the desired location of the center of gravity of the main block.

[0011] Another advantage of weight sliding is that it allows the natural frequency of the boom to be adjusted, thus preventing the boom from vibrating during voyage.

[0012] Another advantage of having the main block lifting assembly in a second location above the deck is the accessibility to the moving head structure and the main block lifting assembly for inspection, maintenance and greasing.

[0013] Yet another advantage of retracting the moving head structure and main block lifting assembly is that there is more clearance against waves during voyages. The boom in its horizontal rest position is normally positioned 20 to 35 meters above sea level. By removing the volume of the moving head structure and main lifting block assembly, and possibly the main load suspension system suspended therefrom, this 25 to 35 meters between the sea level and the boom is free space, providing clearance against waves.

[0014] Yet another advantage of storing the moving head structure and main block lifting assembly is that there is more clearance in the port. As mentioned above, the boom in its horizontal rest position is usually located 20-35 meters above sea level, which is generally not a problem on a reef. However, the volume of the main lifting block assembly closer to the waterline is often a problem. By removing the volume of the moving head structure and main lifting block assembly, and possibly the main load suspension system suspended therefrom, the space between the waterline and the boom is free space, providing clearance for docking the vessel into the port.

[0015] According to the method according to the invention, the offshore crane vessel of the first aspect of the invention is brought to a resting position having the advantages mentioned above. Such a method is providing an offshore crane vessel including a moving head structure fixed to a tip of a boom; pivoting the boom to a horizontal rest position by a boom hoist assembly; supporting the boom on a boom rest; Detaching the moving head structure from the tip; sliding a moving head structure including a primary lifting block assembly along the boom from a tip end on the boom to a second position; Includes.

[0016] According to one embodiment, in this rest position, the main lifting block assembly is supported in a main lifting block assembly support. Optionally, the moving head structure is also secured to the boom in the second position.

[0017] The slidable moving head structure and the boom along which the moving head structure can slide can be of relatively simple structure. The boom needs to be strong enough to support the moving head structure and allow it to slide. Thus, a stiffening structure may be desirable. However, the boom does not need to be hollow as is required for, for example, a telescoping boom section. It is envisioned that the boom's cords act as rails for the moving head structure. In particular, if the sliding is performed in a horizontal position of the boom, the additional forces on the boom during sliding are limited and do not require significant modifications of the boom structure.

[0018] The offshore crane vessel of the present invention may be a monohull or multihull vessel, a jack-up vessel or even a barge. It comprises a hull including a deck. The crane cradle is attached to the vessel's hull or is formed integrally with the hull. In the case of a jack-up vessel, it is conceivable that the cradle is formed around the legs of the jack-up vessel to form a so-called "leg crane".

[0019] The superworks is pivotally supported by the cradle for rotation of the superworks relative to the cradle about a vertical axis of rotation. The superworks includes a boom connection member.

[0020] The crane boom has a longitudinal axis and a length between the pivot end and the tip of the boom is between 60 meters and 200 meters. The pivot end is connected to a boom connection member of the superstructure such that the boom can pivot up and down about a horizontal boom pivot axis. The length of the boom is such that in a horizontal rest position, the tip of the boom projects outside the outer periphery of the vessel's hull. In some cases the boom extends significantly outside the periphery, for example by more than 5 meters, for example by more than 10 meters.

[0021] The ship is provided with a boom rest for supporting the boom in a horizontal rest position, for example when the crane is not in use, e.g. during transport, in port, etc. The horizontal rest position is approximately horizontal and in practical embodiments may be offset by 1°-15°.

[0022] Cranes of this type include a boom hoist assembly for pivoting the boom about a horizontal boom pivot axis, the boom hoist assembly including a boom hoist winch and an elongated hoisting member extending to the tip of the boom, the elongated hoisting member including a hoist cable extending from the winch and preferably through a hoist cable guide provided on the superstructure.

[0023] A primary lifting arrangement is provided for lifting a load. The primary lifting arrangement comprises a primary lifting winch, at least one associated primary lifting cable, and a primary lifting block assembly supported by a head structure. The primary lifting cable extends from the primary lifting winch to the primary lifting block assembly. The primary lifting block assembly comprises a number of sheaves for the lifting cables. The primary load suspension is preferably suspended from the primary block lifting assembly.

[0024] In accordance with the present invention, the head structure is a moving head structure slidable along a portion of the boom from a tip on the boom to a second position. In the horizontal rest position of the boom and the second position of the moving head structure, the main lifting block assembly is positioned above the deck of the vessel.

[0025] The moving head structure is embodied to encompass the entire boom, for example as a box. It is also conceivable that the moving head structure has a U-shape extending over the bottom and (some) sides of the boom.

[0026] According to one embodiment, a main lifting block assembly support adapted to support the weight of the main lifting block assembly and possibly the weight of the moving head structure is provided on the deck of the vessel. Advantageously, the main lifting block assembly support is provided alongside the cradle and the boom rest. It is also conceivable that the main lifting block assembly support is formed integrally with the boom rest. In the horizontal rest position of the boom and the second position of the main lifting block assembly, the main lifting block assembly is aligned with the main lifting block assembly support. This alignment allows the main lifting block assembly support to support the weight of the moving head structure and possibly the weight of the main lifting block assembly in the rest position of the boom.

[0027] Advantageously, the primary lifting block assembly support enables and simplifies installation and maintenance of the primary lifting block assembly, and potentially also enables changes to block and / or cable configurations within the primary lifting block assembly.

[0028] According to one embodiment, a head drive is provided for sliding the moving head structure along the boom. Such a head drive comprises, for example, a head winch and a head cable extending between the head winch and the moving head structure. Such a drive system is known, for example, as a tugger winch and tugger cable. Other systems are also conceivable, for example hydraulic systems or systems comprising a rack and pinion type arrangement.

[0029] According to one embodiment, the moving head structure is removably fixable to the boom at the tip of the boom, preferably also at the second position of the moving head structure, so that the moving head structure is fixed to the boom at its tip during the lifting operation and can be removed and slidable. In some cases, a fastening mechanism is applied that can be moved to the second position together with the moving head structure to fix the moving head structure to the boom at the second position.

[0030] According to one embodiment, a jib including an auxiliary lifting block is connected to the moving head structure and is slidable along the boom with the moving head structure. Such auxiliary lifting blocks are often present and therefore also protrude outside the periphery of the vessel's hull. This storing of the jib and auxiliary lifting block in close proximity with the three head structures is considered to be due to the above-mentioned advantages of the present invention, including increased spacing and improved weight distribution. It is envisaged that the jib is configured as disclosed in WO2020225157.

[0031] According to one embodiment, the main lifting block assembly is pivotally supported by the moving head structure about a horizontal pivot structure. This may be advantageous during lifting operations. In addition, this may be advantageous when the main lifting block assembly is in a second position on the moving head structure. When pivoted to a horizontal position, the distance to the deck may be increased in an embodiment, thereby resulting in an open deck space.

[0032] According to one embodiment, the second position on the boom is at a distance from the pivot end that is 50% to 90% of the length of the boom. Most importantly, in the second position of the moving head structure, the main lifting block assembly is positioned above the deck of the vessel. However, further weight-related advantages are achieved if the second position is further away from the pivot end. As will be explained later, further advantages are also contemplated with respect to boom hoisting, where the second position is closer to the deck than is necessary.

[0033] According to one embodiment, the boom is embodied as a hollow box structure, preferably a lattice-like hollow box structure. A possible advantageous configuration of the same applicant is disclosed in WO 2018 / 208158. It is known to provide a boom with a single leg embodied as a lattice-like hollow box structure. A known alternative is an A-frame boom, generally having the shape of an A, with two boom legs connected, each embodied as a lattice-like hollow box structure. Another known example is a bipedal boom including two parallel legs, each embodied as a lattice-like hollow box structure, the legs being interconnected by a number of cross members interconnecting the boom legs distributed over their length.

[0034] According to one embodiment, the boom section between the second position of the moving head structure and the tip is removable and can be placed, preferably temporarily, on the deck of the vessel. Preferably, this is the end of the boom. When this end is removed from the boom, in the horizontal rest position, the boom may no longer protrude outside the outer periphery of the vessel's hull.

[0035] According to one embodiment, there is provided a boom hoist assembly for pivoting a boom about a horizontal boom pivot axis. The boom hoist assembly comprises a boom winch and an elongated hoisting member extending to the boom. The boom hoist assembly advantageously also comprises a hoist cable extending from the boom hoist winch.

[0036] Many of the above advantages are achieved by the elongated boom hoisting member extending to the tip of the boom.

[0037] According to an advantageous embodiment, the elongated hoisting member can also engage the boom at a second hoisting position opposite the main lifting block assembly at the second position of the moving head structure. This allows the load of the moving head structure including the main lifting block assembly to be transferred to the boom hoisting assembly. Such an arrangement including the hoisting member opposite the moving head structure is advantageous for hoisting the boom from a substantially horizontal rest position. In particular, with a heavy moving head structure and a very long boom including the main lifting block assembly at its tip, hoisting causes high buckling loads on the boom. Therefore, it is advantageous to be able to hoist the boom from a rest position while the moving head structure and the main lifting block assembly are in the second close position. Once fully hoisted, the moving head structure and the main lifting block assembly are slid along the boom to its tip.

[0038] If it is desired to hoist the moving head structure at a second hoisting location opposite the primary lifting block assembly at the second location, the boom is advantageously stiffened at this location to enable the load of the moving head structure, including the primary lifting block assembly, to be transferred to the boom hoisting assembly.

[0039] According to one embodiment, the elongated hoisting member is connected to the moving head structure and is slidable along the boom with the moving head structure. In such an embodiment, the moving head structure may allow for the transfer of loads. In an alternative embodiment, the elongated hoisting member comprises an end fixed to the tip of the boom and an auxiliary structure attachable to the boom at a second hoisting position opposite the main lifting block assembly at the second location of the moving head structure. Also, the end of the elongated hoisting member is removable from the boom and can be attached to the boom at the tip and at a second hoisting position opposite the main lifting block assembly at the second location of the moving head structure. Optionally, the end is slidable along the boom.

[0040] The moving head structure has the above mentioned advantages of moving the volume and weight of the head structure and main block lifting assembly.

[0041] Furthermore, the moving head structure enables the inventive method of operation of such an offshore crane vessel.

[0042] According to one embodiment, the crane may then be moved to an alternative operating position; The method comprises: securing the moving head structure to the boom at a second location; operating a crane including a moving head structure at a second location; Further includes:

[0043] Such operations ao include pivoting the boom by the boom hoist assembly away from a horizontal rest position.

[0044] According to the method of the present invention, the crane is moved to an alternative operating position, The method comprises: providing an offshore crane vessel including a moving head structure secured at a tip of a boom; Detaching the moving head structure from the tip; Sliding the moving head structure along the boom from a tip end on the boom to a second position; securing the moving head structure to the boom at a second location; operating a crane including a moving head structure at a second location; Includes.

[0045] This alternative operating position is particularly advantageous in the case of very long booms, which are difficult to hoist with elongated hoisting members that extend all the way to the tip of the boom.

[0046] According to an embodiment of the present invention, the elongated rafter in the second position of the moving head structure slides with the moving head structure to a position closer to the pivot end of the boom. In an alternative embodiment, the elongated rafter comprises an auxiliary structure attachable to the boom at a second rafter position opposite the second position of the moving head structure. In either case, the elongated rafter engages at a position closer to the pivot end of the boom, which is highly advantageous for bending the elongated boom.

[0047] After the initial flexion from a horizontal resting position, The method is: removing the moving head structure from the second location; Sliding the moving head structure along the boom from the second position to a tip of the boom; fastening the moving head structure to a boom at a tip portion; operating a crane including a moving head structure at a tip end; It is possible that the following may be included:

[0048] The moving head structure at the tip allows for further lifting motion.

[0049] According to one embodiment, the hoisting member moves to the tip together with the moving head structure. According to an alternative embodiment, the auxiliary structure of the elongated hoisting member is detached from the boom in the second hoisting position.

[0050] According to one embodiment, it is contemplated that the crane is moved to the alternative operating position with the boom in a non-horizontal position pivoted above the boom, possibly with the boom supported by the boom stop, and therefore the step of removing and sliding the moving head structure is performed with the boom out of the rest position.

[0051] A second aspect of the invention relates to a crane, preferably a crane on an offshore crane vessel, This crane is a cradle; and an upper structure, pivotally supported by the cradle for rotation of the upper structure relative to the cradle about a vertical axis of rotation, the upper structure comprising a boom connection member; A boom having a longitudinal axis and a length between a pivot end and a tip end of 60 meters to 200 meters, the pivot end being connected to a boom connection member such that the boom can pivot up and down about a horizontal boom pivot axis; a boom rest for supporting the boom in a horizontal rest position; a boom hoist assembly for pivoting the boom about a horizontal boom pivot axis, the boom hoist assembly including a boom hoist winch and an elongated hoist member extending to the boom; a main lifting device for lifting a load, the main lifting device comprising a main lifting winch, at least one associated main lifting cable, and a main lifting block assembly supported by a head structure; Equipped with.

[0052] A disadvantage of a very long boom, including a heavy moving head structure and a primary lifting block assembly at its tip, is that ruffling causes buckling loads on the boom, especially when the boom is ruffled from its substantially horizontal rest position.

[0053] It is an object of the second aspect of the present invention to provide an alternative crane.

[0054] In accordance with a second aspect of the present invention, this is achieved by the head structure being a moving head structure slidable along a portion of the boom from a tip end to a second position on the boom, and the elongated hoisting member being capable of engaging the boom at the tip end and at a second hoisting position opposite the main lifting block assembly of the second position of the moving head structure.

[0055] This allows the load of the moving head structure, including the primary lifting block assembly, to be transferred to the boom hoist assembly. Such an arrangement, including a hoisting member opposite the moving head structure, is advantageous for hoisting the boom from a substantially horizontal rest position. Particularly with a heavy moving head structure and a very long boom, including the primary lifting block assembly at its tip, hoisting causes high buckling loads on the boom. It is therefore advantageous to be able to hoist the boom from a rest position while the moving head structure and the primary lifting block assembly are in the second close position. Once fully hoisted, the moving head structure and the primary lifting block assembly are slid along the boom to its tip.

[0056] When it is desired to hoist the moving head structure at a second hoisting location opposite the primary lifting block assembly at the second location, the boom is advantageously stiffened at this location to enable the load of the moving head structure, including the primary lifting block assembly, to be transferred to the boom hoisting assembly.

[0057] According to one embodiment, the elongated hoisting member is connected to the moving head structure and is slidable along the boom with the moving head structure. In such an embodiment, the moving head structure may allow for the transfer of loads. In an alternative embodiment, the elongated hoisting member comprises an end fixed to the tip of the boom and an auxiliary structure attachable to the boom at a second hoisting position opposite the main lifting block assembly at the second location of the moving head structure. Also, the end of the elongated hoisting member is removable from the boom and can be attached to the boom at the tip and at a second hoisting position opposite the main lifting block assembly at the second location of the moving head structure. Optionally, the end is slidable along the boom.

[0058] A second aspect of the invention also relates to a method of moving a crane to an alternative operating position, comprising: The method comprises: providing a crane including a moving head structure secured at a tip of a boom; Detaching the moving head structure from the tip; Sliding the moving head structure along the boom from the tip to a second position on the boom; securing the moving head structure to the boom at a second location; operating a crane including a moving head structure at a second location; Includes.

[0059] This alternative operating position is particularly advantageous in the case of very long booms, where luffing is difficult with elongated luffing members that extend all the way to the tip of the boom.

[0060] According to an embodiment of the present invention, the elongated rafter in the second position of the moving head structure slides with the moving head structure to a closer position to the pivot end of the boom. In an alternative embodiment, the elongated rafter comprises an auxiliary structure attachable to the boom at a second rafter position opposite the second position of the moving head structure. In either case, the elongated rafter engages at a position closer to the pivot end of the boom, which is highly advantageous for bending the elongated boom.

[0061] After the initial flexion from a horizontal resting position, The method is: removing the moving head structure from the second location; Sliding the moving head structure along the boom from the second position to a tip of the boom; fastening the moving head structure to a boom at a tip portion; operating a crane including a moving head structure at a tip end; It is possible that the following may be included:

[0062] The moving head structure at the tip allows for further lifting motion.

[0063] According to one embodiment, the hoisting member moves to the tip together with the moving head structure. According to an alternative embodiment, the auxiliary structure of the elongated hoisting member is detached from the boom in the second hoisting position.

[0064] According to one embodiment, it is contemplated that the crane may be moved to an alternative operating position with the boom in a non-horizontal position pivoted above the boom, and possibly with the boom supported by a boom stop.

[0065] The present invention will now be described with reference to the drawings, in which like reference numerals refer to like parts throughout. [Brief description of the drawings]

[0066] [Figure 1] FIG. 2 shows an offshore crane vessel in which the boom protrudes outside the outer periphery of the vessel's hull in the horizontal rest position of the boom. [Diagram 2] FIG. 1 shows an example of an offshore crane vessel according to the present invention with the boom in a horizontal rest position and the head structure in a close position. [Diagram 3] FIG. 3 shows the vessel of FIG. 2 with the boom in an upwardly pivoted position and the head structure at the tip of the boom. [Figure 4] FIG. 3 shows the vessel of FIG. 2 with the boom in an upwardly pivoted position and the head structure in an inboard position. [Figure 5A] 3A-3D show steps of a method of operating the offshore crane vessel of FIG. 2. [Figure 5B] 3A-3D show steps of a method of operating the offshore crane vessel of FIG. 2. [Figure 5C] 3A-3D show steps of a method of operating the offshore crane vessel of FIG. 2. [Figure 6] FIG. 1 shows a moving head structure that is slidable along a portion of the boom of an offshore crane vessel according to the present invention. [Figure 7] FIG. 7 shows details of the moving head structure of FIG. 6. [Figure 8] FIG. 2 is a diagram showing a boom of an offshore crane vessel according to the present invention, with a head structure attached to the tip of the boom. [Figure 9]FIG. 13 shows a boom of the offshore crane vessel according to the present invention with the head structure installed in a second position and the main lifting block assembly pivoted upwards. [Figure 10] FIG. 1 shows a boom of an offshore crane vessel according to the present invention including a pivotable main lifting block assembly and a jib supporting a fixed secondary lifting section, the jib being connected to a moving head structure. [Figure 11] FIG. 2 shows a boom of an offshore crane vessel according to the invention, with the jib supporting a fixed auxiliary lifting block, the jib being connected to a moving head structure. [Figure 12] FIG. 2 shows a main lifting block assembly for an offshore crane vessel according to the present invention. [Figure 13A] 1 shows an operating position of an offshore crane vessel according to the invention including a folding boom; FIG. [Figure 13B] 1 shows an operating position of an offshore crane vessel according to the invention including a folding boom; FIG. [Figure 13C] 1 shows an operating position of an offshore crane vessel according to the invention including a folding boom; FIG. [Figure 14] FIG. 2 shows an offshore crane vessel according to the present invention with the boom in a horizontal rest position and the head structure in a distal position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] In the drawings, Figures 1, 14 and 2 show an offshore crane vessel 1 comprising a hull 2, a deck 3 and a crane 10. The crane 10 comprises a platform 11 attached to or integrally formed with the hull 2 ​​of the vessel 1. The crane is an upper structure 12 pivotally supported by the frame 11 for rotation of the upper structure 12 relative to the frame 11 about a vertical axis of rotation, the upper structure 12 including a boom connection member 30; A boom 50, 50' having a longitudinal axis A and a length between a pivot end 52 and a tip end 51 of 60 meters to 200 meters, the pivot end being connected to a boom connection member 30 so that the boom 50 can pivot up and down about a horizontal boom pivot axis HA, the length of the boom 50 being such that in the horizontal rest position shown in Figures 1 and 2, the tip end 51 protrudes significantly outside the outer periphery of the hull 2 ​​of the vessel 1; a boom rest 80 for supporting the boom 50 in a horizontal rest position; a boom hoist assembly 35 for pivoting the boom 50 about a horizontal boom pivot axis HA, the boom hoist assembly 35 comprising a boom hoist winch 45 and an elongated hoist member 40 extending to the boom; A main lifting device 70 for lifting a load, comprising a main lifting winch 72, at least one associated main lifting cable 71, and a main lifting block assembly 75 supported by a head structure 60, the main lifting cable 71 extending from the main lifting winch 72 to the main lifting block assembly 75. It further comprises:

[0068] The boom 50 in Fig. 1 protrudes outwardly from the outer periphery of the hull 2 ​​of the vessel 1 in the boom's rest position. The main lifting block assembly 75 is positioned at the tip 51 of the boom 50 in Fig. 1. This causes the main lifting block assembly 75 to protrude outwardly from the outer periphery of the hull 2 ​​of the vessel 1 in the boom's rest position. The volume and weight of the protruding boom and main lifting block assembly have several disadvantages.

[0069] 1 and 2 is a moving head structure 60 that is slidable along a portion of the boom 50 from the tip 51 to a second position P2 on the boom 50. The head structure 60 is translatable from the position shown in FIG. 1 at the tip 51 to a position P2 as shown in FIG. 2, where the boom 50 is also in its horizontal rest position and in the second position P2 of the moving head structure 60 the main lifting block assembly 75 is positioned above the deck 3 of the vessel 1.

[0070] 1 and 2, the main lifting block assembly 75 is freely suspended from, and therefore supported by, the head structure 60. The main lifting block assembly support is provided on the vessel deck alongside the cradle and boom rest, and it can be envisaged that in the horizontal rest position of the boom and the second position of the lifting block assembly, the lifting block assembly is aligned with the main lifting block assembly support such that in the rest position of the boom the weight of the moving head structure and the main lifting block assembly is supported by the main lifting block assembly support.

[0071] The position of the boom 50 in Figure 1 is referred to above as a horizontal rest position and may be used, for example, during transport. It should be understood that the rest position may be equally offset from the horizontal, for example with the boom pointing upwards, so long as the boom 50 is supported by the boom rest 80. It should be noted that the boom rest 80 in Figure 1 may be located outside the deck 3 as shown in Figure 1, or its location may be, for example, further inboard.

[0072] The boom 50 is shown embodied as a lattice-like hollow box structure, although it should be noted that this is not required by the present invention.

[0073] In Figure 3, the vessel 1 of Figure 2 is shown with the boom 50 in an upwardly pivoted position and the head structure 60 at the tip 51 of the boom 50. In Figure 4, the vessel 1 of Figure 2 is shown with the boom 50 in an upwardly pivoted position and the head structure at an inboard position, i.e., the head structure 60 in Figure 4 is closer to the pivot end 52 of the boom 50 than the head structure 60 in Figure 3.

[0074] The method according to the present invention involves moving the crane 10 to an alternative operating position, for example from the position shown in FIG. This method is removing the moving head structure 60 from the tip portion 51, i.e., the fixing of the moving head structure 60 is removable; Sliding the moving head structure 60 including the main lifting block assembly 75 along the boom 50 from the tip 51 to a second position P2 on the boom 50; fixing the moving head structure 60 to the boom 50 at a second position P2; operating the crane 10 including the moving head structure 60 at a second position P2, for example as shown in FIG. Includes.

[0075] Optionally, the above steps are performed with the boom pivoted upwardly and in a non-horizontal position, as shown in Figures 3 and 4. Optionally, the boom 50 is supported by a boom stop.

[0076] 3 and 4, the hoisting device is connected to the moving head structure 60, so that the hoisting member 40 moves with the moving head structure 60. That is, the hoisting device is slidable along the boom 50 together with the moving head structure 60. As a result, the hoisting device appropriately adjusts the elongated hoisting member 40 for the second position P2 in FIG. 4. Alternatively, the hoisting device can be connected to a second hoisting position on the boom 50.

[0077] 5A-5C are diagrams illustrating steps of a method of operating the offshore crane vessel of FIG. 2. In the method, the crane is moved to a temporary deployment position; This method is pivoting the boom 50 by a boom hoist assembly from an upward pivot position as shown in FIG. 5A to a horizontal rest position as shown in FIG. 5B; supporting the boom on a boom rest 80; removing the moving head structure 60 from the tip portion 51; Sliding the moving head structure 60 including the main lifting block assembly 75 along the boom 50 from the tip 51 on the boom 50 to a second position P2; supporting the primary lifting block assembly on a primary lifting block assembly support; may include:

[0078] Further, the crane may be moved to an alternative operating position. The method described above then includes: fixing the moving head structure 60 to the boom 50 at a second position P2; operating a crane including a moving head structure 60 at a second position P2; It may further include.

[0079] FIG. 6 shows a moving head structure 160 slidable along a portion of the boom 150 of an offshore crane vessel according to the invention. The boom 150 is a gooseneck boom with a cross section tapering towards the tip 151. However, the boom may have an equal constant cross section. A jib 200 supporting an auxiliary lifting block 220 is connected to the boom 150. The boom 150 is provided with a rail 210 along which the moving head structure 160 can slide by a sliding movement S1, as also shown in the intermediate position P1 and in the second position P2 of the head structure 160. To reach P2, the head structure 160 has moved a distance d1 along the slidable portion of the boom 150. This slidable portion allows the translation of the head structure along the boom. A head drive can be provided to achieve this sliding movement S1, so as to slide the moving head structure 160 along the boom 150.

[0080] FIG. 6 further illustrates that the elongated relief members 140 can be attached to the struts 230 .

[0081] The head structure 160 of Figure 6 is shown in more detail in Figure 7. Here it can be seen that the head structure 160 comprises a sliding member 161, for example a skid shoe, which can slide along a rail 210. The head structure shown in Figure 7 further comprises a sheave 240.

[0082] In Fig. 8 a boom 350 of an offshore crane vessel according to the invention is shown, with the head structure 160 arranged at a tip 351 of the boom 350. The boom 350 is further provided with an arrangement 360, for example in a second position P2, for releasably fixing the head structure 160 to the arrangement 360. The releasable fixing may be achieved, for example, using a mounting device 165, for example a cylindrical locking pin, which engages with the arrangement 360.

[0083] Figure 9 illustrates the boom 350 with the head structure 160 in the second position P2 and the primary lifting block assembly 175 pivoted upward relative to the suspended position as shown in Figure 8. That is, the primary lifting block assembly 175 is pivotally supported by the moving head structure 160 about a horizontal pivot structure. In Figure 9, the primary lifting block assembly 175 is pivoted to a horizontal position.

[0084] The main lifting block assembly, pivotally supported as described with respect to FIG. 9, is also shown in FIGS.

[0085] 10 shows a boom 450 of an offshore crane vessel according to the present invention, comprising a pivotable main lifting block assembly 175 and a jib 400 supporting a fixed auxiliary lifting block 420, the jib 400 being connected to a moving head structure 460. That is, the jib 400 including the auxiliary lifting block 420 is connected to the moving head structure 460 and can slide along the boom 450 together with the moving head structure 460, for example by a sliding motion S2 as shown in FIG.

[0086] The auxiliary lifting blocks may be pivotable, which is shown in FIG.

[0087] In FIG. 12, details of the main lifting block assembly of the offshore crane vessel according to the present invention are shown.

[0088] In Figures 13A-13C the working position of the offshore crane vessel according to the invention is shown for a folding boom, i.e. the boom section between the second position P2 of the moving head structure 60 and the tip 851 is removable and can be preferably temporarily placed on the deck 3 of the vessel. Thus, in the horizontal rest position of the boom 850, as shown in Figures 13A-13C, the boom 850 no longer protrudes outside the outer circumference of the vessel 1. [Explanation of symbols]

[0089] 1 offshore crane vessel, 2 hull, 3 deck, 10 crane, 11 frame, 12 upper structure, 30 boom connection member, 35 boom hoisting assembly, 40 hoisting member, 45 boom hoisting winch, 50 boom, 50' boom, 51 tip, 52 pivot end, 60 head structure, moving head structure, 70 main lifting device, 71 main lifting cable, 72 main lifting winch, 75 main lifting block assembly, 80 boom rest, 140 hoisting member, 150 boom, 151 tip, 160 head structure, moving head structure, 161 sliding member, 165 mounting device, 175 main lifting block assembly, 200 jib, 210 rail, 220 auxiliary lifting block, 230 strut, 240 sheave, 350 boom, 351 Tip, 360 Equipment, 400 Jib, 420 Auxiliary lifting block, 450 Boom, 460 Moving head structure, 475 Auxiliary lifting block, 850 Boom, 851 Tip

Claims

1. An offshore crane vessel having a hull, a deck, and a crane, The crane, a platform attached to or integrally formed with the hull of the vessel; a superstructure pivotally supported by the cradle for rotation of the superstructure relative to the cradle about a vertical axis of rotation, the superstructure comprising a boom connection member; a boom having a longitudinal axis and a length between a pivot end and a tip end of between 60 meters and 200 meters, said pivot end being connected to said boom connection member such that said boom can pivot up and down about a horizontal boom pivot axis, said length of said boom being such that in a horizontal rest position, said tip end projects outside the periphery of the hull of the vessel; a boom rest for supporting the boom in the horizontal rest position; a boom hoist assembly for pivoting the boom about the horizontal boom pivot axis, the boom hoist assembly comprising a boom hoist winch and an elongated hoist member extending to the boom; a main lifting apparatus for lifting a load comprising a main lifting winch, at least one associated main lifting cable, and a main lifting block assembly supported by a head structure; the head structure being a moving head structure slidable along a portion of the boom from the tip end on the boom to a second position, and in the horizontal rest position of the boom and in the second position of the moving head structure, the main lifting block assembly is positioned above the deck of the vessel. An offshore crane vessel characterized by:

2. 2. The offshore crane vessel of claim 1, wherein a main lifting block assembly support is provided on the deck of the vessel, and in the horizontal rest position of the boom and in the second position of the main lifting block assembly, the main lifting block assembly is aligned with the main lifting block assembly support.

3. The offshore crane vessel according to claim 1 , wherein a head drive is provided for sliding the moving head structure along the boom.

4. The offshore crane vessel according to claim 1, wherein the moving head structure is removably securable to the boom at the tip of the boom, preferably also at the second position of the moving head structure.

5. The offshore crane vessel according to claim 1 , wherein a jib including an auxiliary lifting block is connected to the moving head structure and is slidable together with the moving head structure along the boom.

6. The offshore crane vessel according to claim 1 , wherein the main lifting block assembly is pivotally supported by the moving head structure about a horizontal pivot structure.

7. The offshore crane vessel of claim 1, wherein the second position on the boom is at a distance from the pivot end that is between 50% and 90% of the length of the boom.

8. The offshore crane vessel according to claim 1 , wherein the boom is embodied as a hollow box structure.

9. 2. The offshore crane vessel according to claim 1, wherein the boom section between the second position and the tip of the moving head structure is removable and can be preferably temporarily placed on the deck of the vessel.

10. The offshore crane vessel of claim 1 , wherein the elongated rafter is connected to the moving head structure and is slidable together with the moving head structure along the boom.

11. 2. The offshore crane vessel of claim 1, wherein the elongated hoisting member comprises an end fixed to the tip of the boom and an auxiliary structure attachable to the boom at a second hoisting position opposite the main lifting block assembly at the second position of the moving head structure.

12. A method for operating an offshore crane vessel according to one or more of the preceding claims.

13. The method further comprising: providing an offshore crane vessel including the moving head structure fixed to the tip of the boom; pivoting the boom to the horizontal rest position by the boom hoist assembly; supporting the boom on the boom rest; detaching the moving head structure from the tip; sliding the moving head structure along the boom from the tip to the second position on the boom; The method of claim 12, comprising:

14. The crane is moved to an alternate operating position, and the method further comprises: detaching the moving head structure from the tip; sliding a moving head structure including the primary lifting block assembly along the boom from the tip to the second position on the boom; securing the moving head structure to the boom at the second location; operating the crane including the moving head structure at the second location; The method of claim 12, comprising:

15. A crane. a cradle and superstructure, the superstructure pivotally supported by the cradle for rotation of the superstructure relative to the cradle about a vertical axis of rotation, the superstructure comprising a boom connection member; a boom having a longitudinal axis and a length between a pivot end and a tip end of between 60 meters and 200 meters, said pivot end being connected to said boom connection member such that said boom can pivot up and down about a horizontal boom pivot axis; a boom rest for supporting the boom in the horizontal rest position; a boom hoist assembly for pivoting the boom about the horizontal boom pivot axis, the boom hoist assembly comprising a boom hoist winch and an elongated hoist member extending to the boom; a main lifting apparatus for lifting a load comprising a main lifting winch, at least one associated main lifting cable, and a main lifting block assembly supported by a head structure; the head structure is a moving head structure slidable along a portion of the boom from the tip end to a second position on the boom and engageable with the boom at the tip end and at a second hoisting position opposite the main lifting block assembly at the second position of the moving head structure; A crane characterized by:

16. A crane as described in claim 15, wherein the boom is reinforced at the second location of the moving head structure, enabling the load of the moving head structure including the main lifting block assembly to be transferred to the boom hoisting assembly, and enabling hoisting at the second hoisting position opposite the main lifting block assembly at the second location of the moving head structure.

17. A crane as described in claim 15, wherein the elongated rafter member is connected to the moving head structure and is slidable together with the moving head structure along the boom.

18. A crane as described in claim 15, wherein the elongated hoisting member has an end fixed to the tip of the boom and an auxiliary structure attachable to the boom at the second hoisting position opposite the main lifting block assembly at the second position of the moving head structure.

19. A crane as described in claim 15, wherein an end of the elongated hoisting member is removable from the boom and can be attached to the boom at the tip and at the second position of the moving head structure opposite the main lifting block assembly.

20. A method for moving a crane to an alternate operating position, comprising the steps of: providing a crane as claimed in claim 15, wherein said moving head structure is fixed to said tip of said boom; detaching the moving head structure from the tip; sliding the moving head structure along the boom from the tip end on the boom to the second position; securing the moving head structure to the boom at the second location; operating the crane including the moving head structure at the second location; A method comprising:

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