CN114981200A

CN114981200A - Marine vessel crane

Info

Publication number: CN114981200A
Application number: CN202080093797.8A
Authority: CN
Inventors: J·鲁登伯格; M·L·布林克曼
Original assignee: Itrec BV
Current assignee: Huisman Equipment BV
Priority date: 2019-12-19
Filing date: 2020-12-18
Publication date: 2022-08-30
Also published as: WO2021123236A1; NL2024512B1; EP4077197B1; EP4077197A1

Abstract

A marine vessel crane is configured for installation on a marine vessel, for example for handling one or more marine wind turbine components, for example for installing and/or maintaining a marine wind turbine. The crane comprises a base structure adapted to be mounted on a vessel and a revolving superstructure. The crane comprises an arm support which pivots up and down. The boom has a telescopic boom structure slidably mounted between distal end sections of boom legs of the main boom structure so as to be movable in a direction of the length of the main boom section between a retracted position and an extended position.

Description

Marine vessel crane

Technical Field

The present invention relates to a marine vessel crane configured for mounting on a marine vessel.

Background

In the field of offshore wind turbines, it is necessary to handle very heavy components like foundations, e.g. mono piles, which may have a mass of 1000 tons or more. Furthermore, there is a need to process components "at the height of the nacelle", which includes, for example, processing the nacelle itself and/or one or more components housed in and/or mounted on the nacelle, such as the gearbox, generator, hub, and/or rotor blades. Current designs propose or already have nacelles at heights above 100 meters (e.g., at 120 meters or more) in elevation, such as halade-X12 MW offshore wind generators. The handling of these assemblies therefore requires both very heavy load cranes and very tall cranes. It should be noted that the mass of the nacelle may also be several hundred tons, for example over 500 tons.

In a common method, an offshore wind turbine is installed or repaired using a jack-up vessel positioned near the wind turbine location, and then the jack-up legs are extended to raise the vessel at least partially, but in most cases completely, above the sea surface, providing a stable situation for crane operation.

It should be noted that the invention is mainly envisaged for use in the field of offshore wind turbines, for maintenance and also for installing and/or dismantling wind turbines. However, the crane of the invention may also be used in other offshore applications like oil and gas related operations, civil engineering operations, etc.

In said field, offshore cranes are known comprising:

-a base structure adapted to be mounted on the vessel, e.g. fixed to the hull of the vessel;

-a swivel superstructure, which is swivelable on a swivel bearing about a swivel axis relative to a base structure, said superstructure being provided with:

-a boom connecting member comprising a left side connector and a right side connector arranged at a distance from each other, said left and right side connectors together defining a horizontal arm

A frame pivot axis;

-a boom having a longitudinal axis, wherein the boom has inner ends connected to left and right side connectors of a boom connection member to pivot the boom up and down about a boom pivot axis, the boom pivot axis being perpendicular to the longitudinal axis of the boom;

-a pitching arrangement for pivoting the boom up and down, the pitching arrangement comprising a pitching winch and a variable length pitching system;

-a main hoisting system for hoisting a load, the main hoisting system comprising a main winch and an associated main hoisting cable.

It is known to provide such a boom with a single leg embodied as a lattice-like hollow frame structure. A known alternative embodiment is an a-frame boom which generally has an a-shape and has two connected boom legs, each implemented as a lattice hollow frame structure. Another known example is a double-legged boom with two parallel legs, each implemented as a lattice-like hollow frame structure, where the legs are interconnected by a number of cross-members distributed over the length of the legs, thereby interconnecting the boom legs.

Disclosure of Invention

The present invention aims to provide a crane with enhanced versatility and performance, for example in view of the increasing demands in the field of offshore wind turbines.

The invention provides an offshore crane according to claim 1.

The boom has a main boom structure with a left boom leg and a right boom leg, each of the two boom legs having proximal portions pivotally connected to a left side connector and a right side connector, respectively.

The length of each of the two boom legs is at least 60 meters, for example between 80 and 140 meters. For example, in practical designs, the legs of the main arm frame structure are over 100 meters long, for example about 120 meters long.

In embodiments, the legs are rigid, one-piece legs, such as welded steel one-piece legs, each leg having a fixed length. In another embodiment, the leg consists of end-to-end fixed leg modules, for example, with one or more intermediate leg modules selectively mountable in the structure of the leg to set the length of the leg to a desired length.

Each boom leg is embodied as a hollow frame structure, preferably a lattice-like hollow frame structure. The cross section of the hollow frame structure is defined by an inner side and a plurality of other sides. Here, the inboard sides of the left and right boom legs are spaced apart from each other to form a gap between the boom legs along the length of the main boom structure.

For example, each leg is embodied, at least over a major portion of its length (e.g., the entirety of the length), as a rectangular cross-section defined by an inner side, an outer side, a top side, and a bottom side.

In an embodiment, each leg is embodied over a part (e.g. a smaller part) of its length as a triangular cross-section defined by an inner side, a top surface and a bottom surface, which adjoin each other at an outer vertex remote from the inner side, for example forming a cross-section corresponding to an equilateral triangle or isosceles triangle.

The main arm frame structure comprises a plurality of cross members distributed over its length, which interconnect the left and right boom legs.

In embodiments, the legs are straight over their entire length, e.g. parallel to each other.

The two boom legs each have a distal section, wherein the distal end is distal to the proximal section.

The boom of the crane further comprises a telescopic boom structure. The telescopic boom structure is slidably mounted between the distal end sections of the two boom legs of the main boom structure so as to be movable in the direction of the length of the main boom section between a retracted position and an extended position.

The telescopic boom structure is embodied at least over a major part of its length (e.g. at least over a part of 75% of its length) as a hollow frame structure, for example a rectangular cross-section hollow frame structure having a top face, a bottom face and opposite side faces.

Preferably, the telescopic boom structure is mainly implemented as a lattice hollow frame structure.

The sides of the telescopic boom structure each extend adjacent an associated one of the inner sides of the distal section, which faces are parallel to each other and extend in the longitudinal direction of the boom.

For example, the inner side faces of the distal end sections each have parallel upper and lower chords interconnected by a mesh belt member in the plane of the inner side face, and the side faces of the telescopic boom structure each have parallel upper and lower chords interconnected by a mesh belt member in the plane of the inner side face of the telescopic boom structure, wherein bearing members are arranged between each pair of adjacent upper chords and each pair of adjacent lower chords to allow the telescopic boom structure to slide and to transfer loads between the telescopic boom structure and the distal end sections of the two legs of the main boom structure.

The telescopic boom structure is extendable and retractable with respect to the main boom structure within a range of at least 10 meters, for example within a range of at least 20 meters, for example between 20 and 40 meters.

The distal segments are interconnected by at least one of the cross-members, the at least one cross-member being located near the distal end. The at least one cross-member between the distal end sections is configured to allow extension and retraction movement of the retractable arm sections.

The telescopic arm support structure is provided with an arm support head at the tip end of the telescopic arm support structure.

In an embodiment, the variable length pitch system extends from the pitch winch to the boom head. In an alternative embodiment, the variable length pitch system extends from the pitch winch to the distal section, for example to the distal end thereof. Here, preferably, the crane boom is further provided with a stay mechanism. This mechanism has, for each of the boom legs, a fixed length strut extending from an anchoring member disposed on the boom leg near the proximal end of the boom leg to a top end of a strut extending from the distal section of the boom leg. A variable length stay extends from the top end of the strut to the boom head.

The main hoist cable extends from the main winch to a main cable pulley assembly disposed on the boom head.

In an embodiment thereof, the boom head is provided with an auxiliary boom member fixed thereto, and the crane is provided with an auxiliary hoist system having an auxiliary hoist winch, an auxiliary hoist cable driven by the winch, and an auxiliary pulley assembly on the auxiliary boom member from which an auxiliary load connector (e.g. a crane hook) is suspended.

In an embodiment, the two boom legs each have a proximal section extending from a proximal portion thereof and a central section adjoining the proximal section, a distal section of the boom leg adjoining the central section, wherein the proximal sections are parallel to each other, wherein the central sections converge towards each other in a direction towards the distal sections, and wherein the cross-member interconnects the boom legs at a location where the proximal and central sections adjoin, and wherein the cross-member interconnects the boom legs at a location where the central and distal sections adjoin. In a further development, in the retracted position of the telescopic arm sections, the inner ends thereof are located in the vicinity of the cross-members where the central and distal end sections abut.

In an embodiment, the distal end sections are each embodied as a lattice-like hollow frame structure, each having an inner side face, wherein the parallel upper and lower chords are interconnected by a mesh belt member in the plane of the inner side face, wherein the cross-members near the distal ends comprise a truss arranged in the plane between the upper chords and a truss arranged in the plane between the lower chords.

In an embodiment, the telescopic boom structure is implemented at least over a major part of its length (e.g. at least over a part of 75% of its length) as a hollow frame structure having a rectangular cross-section with a width of at least 6 meters and a height of at least 3 meters.

In an embodiment, the superstructure is provided with a cradle on which is mounted a pitch cable pulley assembly, whereby the pitch cable pulley assembly guides a pitch cable extending from a pitch winch to the boom head.

In an embodiment, the pitch system comprises:

-two pitch winches on the upper structure; and

two pitch cables, each pitch cable driven by a respective pitch winch, the pitch cables extending from a pitch cable pulley assembly mounted on the superstructure (e.g. on its pylon) spaced apart from each other (e.g. parallel to each other) to respective pitch cable connectors on the boom head or on the distal section, the pitch cable connectors being spaced apart from each other in the width direction of the boom, e.g. arranged on opposite sides of the boom head as seen in the width direction.

In an embodiment, the crane includes a stretching mechanism including a stretching winch, a winch-driven stretching cable, and a stretching cable pulley system having a plurality of pulleys. The extension mechanism is configured to engage on the telescopic boom structure so as to provide an extension movement thereof, preferably with the boom being oriented upwards, retraction of the telescopic boom structure being caused by the mass of the telescopic boom structure. In an alternative embodiment, retraction is accomplished by a winch or some other drive means. In embodiments, extension and/or retraction is accomplished by a rack and pinion mechanism.

In an embodiment, the crane comprises a locking mechanism configured to mechanically lock the telescopic boom to the distal section at least in its retracted and extended positions. For example, the locking mechanism includes one or more actuated locking pins or the like.

The invention also relates to a marine vessel comprising a crane as described herein.

The invention also relates to a jack-up offshore vessel comprising:

-a buoyant hull having a main deck,

-at least three self-elevating legs,

a plurality of lifting units, each lifting unit being associated with a respective jack-up leg, adapted to move the respective jack-up leg vertically relative to the hull and to bring the vessel in an operating position, wherein the legs engage the seabed and the hull is above the water surface,

-a crane as described herein.

In an embodiment, the crane is a leg-around crane, wherein the vessel's jack-up legs extend through the revolving superstructure and the slewing bearing extends around the jack-up legs.

In an embodiment, the crane is configured for a parking position beyond the legs, wherein the two boom legs are located at opposite sides of the jack-up leg in the parking position, such as a vessel having a boom support on which the boom rests in a substantially horizontal orientation.

In an embodiment, the crane is a leg-around crane, wherein the jack-up leg of the vessel extends through the revolving superstructure and the slewing bearing extends around the jack-up leg, and wherein the crane is configured for exceeding a parking position of the legs, wherein two boom legs are located at opposite sides of the jack-up leg in the parking position, such as a vessel having a boom support on which the boom rests in a substantially horizontal orientation.

In an embodiment, the vessel has two stern jack-up legs and two front jack-up legs, wherein the rear jack-up legs extend through the revolving superstructure and the slewing bearing extends around said jack-up legs, and wherein the crane is configured for passing a parking position of the legs, wherein the two boom legs are located at opposite sides of the front jack-up legs in the parking position, e.g. wherein a cross member arranged at the junction of the distal section and the central section of each boom leg is located at the rear side of the front jack-up legs when in the parking position.

A second aspect of the present invention relates to a jack-up offshore vessel comprising:

-a buoyant hull having a main deck,

-at least three jack-up legs,

an offshore vessel crane, e.g. for handling one or more offshore wind turbine assemblies, e.g. for installing and/or maintaining an offshore wind turbine, the crane comprising:

-a base structure fixed to the hull of the vessel;

-a swiveling superstructure, which is swivelable on a swivel bearing about a swivel axis with respect to the base structure, the superstructure being provided with:

-a boom connecting member comprising a left side connector and a right side connector at a distance from each other, the left and right side connectors together defining a horizontal boom pivot axis;

-a main hoisting system for hoisting a load, the main hoisting system comprising a main winch and an associated main hoisting cable;

wherein the boom has a main boom structure with a left boom leg and a right boom leg, each of the boom legs having a proximal portion pivotally connected to a left side connector and a right side connector, respectively,

wherein the length of each boom leg is at least 60 meters, for example between 80 and 140 meters,

wherein a cross section of each boom leg is defined by an inner side surface and a plurality of other surfaces, wherein the inner side surfaces of the left and right boom legs are spaced apart from each other to form a gap between the boom legs along the length of the main boom structure,

wherein the main arm frame structure comprises a plurality of cross members distributed over the length thereof, the plurality of cross members interconnecting the left side arm frame leg and the right side arm frame leg,

wherein the boom legs each have a distal section, wherein the distal end is distal to the proximal section,

wherein the boom further comprises a telescopic boom structure slidably mounted between the distal end sections of the boom legs of the main boom structure so as to be movable in a direction of the length of the main boom section between a retracted position and an extended position,

wherein the telescopic boom structure has a top face, a bottom face and opposite side faces, the side faces of the telescopic boom structure extending adjacent to an inner side face of the distal end section, the side faces being parallel to each other and extending in the longitudinal direction of the boom,

wherein the telescopic boom structure is extendable and retractable in a range of at least 10 meters, such as in a range of at least 20 meters, such as between 20 and 40 meters,

wherein the distal sections are interconnected by at least one of said cross members located near the distal end, said at least one cross member being configured to allow said extension and retraction movements of the telescopic boom structure,

the telescopic arm support structure is provided with an arm support head at the tip end of the telescopic arm support structure;

wherein the main hoisting cable extends from the main winch to a main cable pulley assembly on the boom head.

In embodiments, the crane of the vessel of the second aspect of the invention is provided with one or more of the features discussed herein (e.g. as claimed in the appended claims) with reference to the marine vessel crane of the first aspect of the invention.

In an embodiment of the second aspect of the invention, the crane is configured for a parking position beyond the legs, wherein the two boom legs are located at opposite sides of the jack-up legs in the parking position, such as a vessel with a boom support on which the boom rests in a substantially horizontal orientation.

In an embodiment of the second aspect of the invention, the crane is a leg-around crane, wherein the vessel's jack-up legs extend through the revolving superstructure and the slewing bearing extends around the jack-up legs.

In an embodiment of the second aspect of the invention, the crane is a leg-around crane, wherein the vessel's jack-up legs extend through the revolving superstructure and the slewing bearing extends around the jack-up legs, and wherein the crane is configured for exceeding a parking position of the legs, wherein two boom legs are located at opposite sides of the jack-up legs in the parking position, such as a vessel having a boom support on which the boom rests in a substantially horizontal orientation.

In an embodiment of the second aspect of the invention, the vessel has two stern jack-up legs and two front jack-up legs, wherein the rear jack-up legs extend through the revolving superstructure and the slew bearing extends around said jack-up legs, and wherein the crane is configured for a parking position beyond the legs, wherein the two boom legs are located on opposite sides of the front jack-up legs in the parking position, e.g. wherein the cross member arranged at the junction of the distal section and the central section of each boom leg is located on the rear side of the front jack-up leg when in the parking position.

The invention also relates to a method for hoisting an offshore wind turbine assembly, for example for installing and/or maintaining an offshore wind turbine, wherein a crane and/or an offshore vessel as described herein is utilized.

Drawings

The present invention will now be described with reference to the accompanying drawings. In the drawings:

figure 1 shows an example jack-up offshore vessel provided with a crane according to the invention,

fig. 2 shows the vessel of fig. 1 in a plan view, with the crane boom in a parking position beyond the legs,

fig. 3a shows a part of the vessel of fig. 1, where the boom is raised and extended,

fig. 3b, 3c show the crane and the stern leg 4 of the vessel of fig. 1, with the crane in an extended position and a retracted position respectively,

fig. 4a, 4b show the boom of the crane of fig. 1-3, with the telescopic boom structure in a retracted position,

fig. 5a, 5b show the boom of the crane of fig. 1-3, with the telescopic boom structure in an extended position,

figure 6 shows a cross section of the boom of the crane of figures 1-3 in the region of the distal sections of the two boom legs,

fig. 7 shows a jack-up offshore vessel provided with another example of a crane according to the invention, wherein the telescopic boom structure is retracted,

fig. 8 shows the vessel of fig. 7 with the telescopic boom structure extended.

Detailed Description

Referring to fig. 1-6, a jack-up offshore vessel particularly suited for handling offshore wind turbine assemblies will be discussed.

The ship 1 includes:

a buoyant hull 2 having a main deck 3,

two stern jack-up legs 4 and two front jack-up legs 5,

a plurality of lifting units 6, each lifting unit 6 being associated with a respective jack-up leg, adapted to move the respective jack-up leg vertically relative to the hull 2 and to bring the vessel in an operating position, wherein the jack-up

legs

4, 5 engage the seabed and the hull is above the water surface.

The vessel 1 is provided with a crane 10 for handling offshore wind turbine assemblies. The crane 10 in question may also be used for other purposes and be mounted on different types of vessels, such as semi-submersible lifting vessels and the like.

The crane 10 includes:

a base structure 11 fixed to the hull 2 of the vessel 1;

a revolving superstructure 12, revolvable relative to the base structure 11 about a revolving axis on revolving bearings 12a, said superstructure being provided with:

boom connection member comprising a left side connector 13a at a distance from each other

And a right-side connector 13b, the left-side connector 13a and the right-side connector 13b being common

Defining a horizontal boom pivot axis 14;

boom 20, having a longitudinal axis; the arm support is provided with inner ends of a left side connector and a right side connector which are connected to the arm

support connecting members

13a and 13b, so that the arm support can pivot up and down around an arm support pivot axis, and the arm support pivot axis is vertical to the longitudinal axis of the arm support;

a pitching arrangement for pivoting the boom up and down, the pitching arrangement comprising a pitching winch 40 and a variable length pitching system;

a main hoisting system for hoisting a load, the main hoisting system comprising a main winch 50 and an associated main hoisting cable 51.

Boom 20 will be discussed in more detail below.

The crane 10 is a leg-around crane. The stern jack-up leg 4 is shown extending through the gyrating superstructure 12 and the slewing bearing extends around the jack-up leg.

Crane 10, in particular boom 20, is configured for a parking position beyond the legs, wherein two boom legs are located on opposite sides of front jack-up leg 5 in the parking position. Boom 20 is supported on a boom support 80 of the vessel.

The boom has a main boom structure 21, said main boom structure 21 having a left boom leg 22 and a right boom leg 23. Each of the two

boom legs

22, 23 has a proximal portion pivotally connected to the left and

right side connectors

13a, 13b, respectively.

The length of each

boom leg

22, 23 is at least 60 meters, for example between 80 and 140 meters, here about 120 meters.

Each

boom leg

22, 23 is embodied as a hollow frame structure, here a lattice-like hollow frame structure. The cross-section of each

leg

22, 23 is defined by an inner side and a plurality of other faces.

The inside faces of the left boom leg 22 and the right boom leg 23 are spaced from each other to form a gap between the

boom legs

22, 23 along the length of the main boom structure 21.

The main boom frame structure 21 comprises a number of

cross members

24, 25, 26, 27 distributed over its length, which

cross members

24, 25, 26, 27 interconnect the left and

right boom legs

22, 23.

The two

boom legs

22, 23 each have a

proximal section

22a, 23a extending from a proximal portion thereof and a

central section

22b, 23b adjoining the proximal section and a

distal section

22c, 23c adjoining the central section.

Each of the boom legs has a

distal section

22c, 23c, said

distal section

22c, 23c having a

distal end

22d, 23d distal to the proximal portion of the boom leg.

In the depicted embodiment, the

proximal end segments

22a, 23a are parallel to each other.

In the depicted embodiment, the central segments 22b, 2b converge toward each other in a direction toward the

distal segments

22c, 23 c.

Cross-members 24 interconnect the boom legs near the proximal ends.

A cross member 25 interconnects the boom legs at the location where the

proximal sections

22a, 23a and the

central sections

22b, 23b abut.

The cross-member 26 interconnects the boom legs at the location where the

central sections

22b, 23b and

distal sections

22c, 23c abut.

Boom 20 further has a telescoping boom structure 30. Such a telescopic boom structure 30 is slidably mounted between the

distal end sections

22c, 23c of the boom legs of the main boom structure 21 so as to be movable in the direction of the length of the main boom section between a retracted position and an extended position. This is best shown in fig. 4a, 4b and 5a, 5 b.

The telescopic boom structure 30 is embodied as a hollow frame structure at least over a major part of its length (e.g. at least over a part of 75% of its length), see also fig. 6.

In more detail, the boom structure 30 has a hollow frame structure of rectangular cross-section, here preferably a lattice-like hollow frame structure, having a top surface 31, a bottom surface 32 and opposite side surfaces 33, 34.

The sides 33, 34 of the telescopic boom structure each extend adjacent to a respective inner side of one of the two distal end sections. These pairs of sides are parallel to each other and extend in the longitudinal direction of the boom.

The telescopic boom structure 30 is extendable and retractable in a range of at least 10 meters with respect to the main boom structure, for example in a range of at least 20 meters, for example in a range between 20 and 40 meters, here in a range of about 30 meters.

Fig. 6 shows that the

distal segments

22c, 23c are interconnected by cross-members 26, 27, with member 27 being located near

distal ends

22d, 23 d. These cross-members in the distal region of boom 20 are configured to allow extension and retraction movement of telescoping boom section 30.

The telescopic boom structure 30 is provided with a boom head 35 at the tip of the telescopic boom structure. In practice, the boom head 35 may be embodied as a welded construction of steel plates with reinforcements or the like.

In fig. 1-3, a variable length pitch system is shown extending from a pitch winch to a boom head 35 on a telescopic boom structure 30.

In fig. 1 and 3, a main hoist cable 51 is shown extending from the main winch 50 to a main cable pulley assembly 52 on the boom head 35. A main load connector (e.g., a main crane hook 53) is suspended from a pulley assembly 52 on the boom head by means of a cable 51. If desired, a plurality of main hoisting winches, cables and main load connectors may be provided, for example two main hoisting systems or possibly three main hoisting systems.

One or more main cables 51 are illustrated extending longitudinally through the telescopic boom structure 30.

A cross member 26 arranged at the junction of the proximal section and the central section of each boom leg is located at the rear side of the front jack-up leg 5 when in the parking position.

In the retracted position of the telescopic boom structure 30, its inner end is located in the vicinity of the cross member 26 at the location where the proximal section and the central section abut.

The

distal end sections

22c, 23c are each embodied as a lattice-like hollow frame structure, each having an inner side, wherein the parallel upper and lower chords are interconnected by a mesh belt member in the plane of the inner side.

The cross members 26 and 27 (at least the cross member 27 located near the distal end) include a truss 27a disposed in a plane between the upper chords and a truss 27b disposed in a plane between the lower chords.

The telescopic boom structure 30 is embodied at least over a major part of its length (for example at least over a part of 75% of its length) as a hollow frame structure having a rectangular cross section with a width of at least 6 meters and a height of at least 3 meters.

The superstructure 12 has a pylon 14a provided thereon, on which pylon 14a is mounted a pitch cable pulley assembly 15 to guide a pitch cable 41 extending from a pitch winch 40 to a boom head 35.

Preferably, the pitch system comprises:

two pitch winches 40 on the upper structure 12; and

two pitch cables 41, each pitch cable 41 being driven by a respective pitch winch 40, said pitch cables extending from pitch cable pulley assemblies 15 mounted on the superstructure (here, on its spreader 14a) spaced apart from each other (here, parallel to each other) to respective pitch cable connectors 42 on the boom head 35 spaced apart from each other in the width direction of the telescopic boom structure 30, here arranged on opposite sides of the boom head as seen in the width direction.

The crane 10 includes a stretching mechanism comprising a stretching winch 60, a winch driven stretching cable 61 and a stretching cable pulley system having a plurality of pulleys 62, 63. The extension mechanism is configured to engage on the telescopic boom structure 30 so as to provide extension movement thereof. In an embodiment, when the boom is oriented upwards, the retraction of the telescopic boom structure is caused by the mass of the telescopic boom structure, such that the structure 30 falls back between the distal sections of the main structure 21 under the effect of its mass.

The crane comprises a locking mechanism configured to mechanically lock the telescopic boom to the distal section at least in its retracted and extended positions.

As will be appreciated, the vessel and crane are well suited for hoisting of offshore wind turbine assemblies, for example for installation and/or maintenance of offshore wind turbines.

Fig. 7 and 8 show a jack-up offshore vessel provided with another example of a crane according to the invention. The telescopic boom structure is retracted in fig. 7 and extended in fig. 8.

The main difference with the crane described with reference to fig. 1-6 is the design of the pitch system. Although the crane of fig. 7, 8 still has two pitch winches 40 and two spaced pitch cables 41 on the superstructure, each pitch cable being driven by a respective pitch winch, these pitch cables now do not extend to the boom head 35. Instead, these pitch cables extend to respective pitch cable connectors 42 on the boom leg

distal end sections

22c, 23c, here at their outermost ends.

A further difference is that a stay mechanism 70 is provided, said stay mechanism 70 having a stay 71 of fixed length for each of the two

boom legs

22, 23, said stay 71 extending from an anchoring member 72 arranged on the boom leg near the proximal end of the boom leg to the top end of a stay 73 extending upwards from the distal section of the boom leg. The mechanism 70 further has a variable length stay 74, which stay 74 extends from the top end of the strut 73 to the boom head 35 on the telescopic structure 30. It can be seen that the variable length struts 74 allow the telescoping boom structure to extend and retract. Preferably, the variable length struts comprise two strut cable arrangements in the same plane as the respective fixed length struts. In an embodiment, each variable length stay includes a system of stay cables, pulleys, and stay cable winches to vary the effective length of the stay between the end of the stay and the boom head.

Claims

1. A marine vessel crane (10) configured for installation on a marine vessel (1), such as for handling one or more marine wind turbine components, such as for installing and/or maintaining a marine wind turbine, the crane comprising:

-a base structure (11) adapted to be mounted on a vessel, for example for fixing to the hull of the vessel;

-a swivelling superstructure (12) swivellable relative to the base structure about a swivel axis on a swivel bearing, said superstructure being provided with:

-a boom connecting member comprising a left side connector (13a) and a right side connector (13b) at a distance from each other, said left side connector (13a) and right side connector (13b) together defining a horizontal boom pivot axis (14);

-a boom (20) having a longitudinal axis, wherein the boom has inner ends connected to left and right side connectors of a boom connection member for pivoting the boom up and down about a boom pivot axis (14), the boom pivot axis (14) being perpendicular to the longitudinal axis of the boom;

-a pitching arrangement for pivoting the boom up and down, the pitching arrangement comprising a pitching winch (40) and a variable length pitching system (41);

-a main hoisting system for hoisting a load, the main hoisting system comprising a main winch (50) and an associated main hoisting cable (51);

wherein the boom has a main boom structure with a left boom leg (22) and a right boom leg (23), each of the boom legs having a proximal portion pivotally connected to a left side connector (13a) and a right side connector (13b), respectively,

wherein the length of each boom leg (22, 23) is at least 60 meters, for example between 80 and 140 meters,

wherein each boom leg is embodied as a hollow frame structure, preferably a lattice-like hollow frame structure, the cross section of which is defined by an inner side and a plurality of other faces, wherein the inner sides of the left and right boom legs (22, 23) are spaced apart from each other to form gaps between the boom legs along the length of the main boom frame structure,

wherein the main arm frame structure (21) comprises a plurality of cross members (24, 25, 26, 27) distributed over its length, the plurality of cross members (24, 25, 26, 27) interconnecting the left and right boom legs (22, 23),

wherein the boom legs (22, 23) each have a distal section (22c, 23c), wherein the distal ends (22d, 23d) are distal to the proximal section,

wherein the boom further comprises a telescopic boom structure (30) slidably mounted between distal end sections (22c, 23c) of boom legs (22, 23) of the main boom structure (21) so as to be movable in a direction of the length of the main boom section between a retracted position and an extended position,

wherein the telescopic boom structure (30) is embodied at least over a major part of its length, for example at least over 75% of its length, as a hollow frame structure, for example a hollow frame structure of rectangular cross section, preferably a lattice-like hollow frame structure, having a top face (31), a bottom face (32) and opposite side faces (33, 34), which side faces (33, 34) of the telescopic boom structure extend adjacent to the inner side faces of the distal end sections (22c, 23c), which side faces are parallel to one another and extend in the longitudinal direction of the boom,

wherein the telescopic boom structure (30) is extendable and retractable (60, 61, 62, 63) relative to the main boom structure (21) within a range of at least 10 meters, such as within a range of at least 20 meters, such as within a range between 20 and 40 meters,

wherein the distal sections (22c, 23c) are interconnected by at least one of said cross members (27) located near the distal end, said at least one cross member (27) being configured to allow said extension and retraction movements of the telescopic boom structure (30),

wherein the telescopic arm support structure (30) is provided with an arm support head (35) at the tip of the telescopic arm support structure;

wherein the main hoist cable (51) extends from the main winch (50) to a main cable pulley assembly (52) on the boom head (35).

2. Marine vessel crane according to claim 1, wherein the two boom legs (22, 23) each have a proximal section (22a, 23a) extending from a proximal portion thereof and a central section (22b, 23b) adjoining the proximal section, a distal section (22c, 23c) adjoining the boom leg of the central section, wherein the proximal sections (22a, 23a) are parallel to each other, wherein the central sections (22b, 23b) converge towards each other in a direction towards the distal section, wherein a cross member (25) interconnects the boom legs at a location where the proximal and central sections adjoin, wherein a cross member (26) interconnects the boom legs at a location where the central and distal sections adjoin.

3. Marine vessel crane according to claim 2, wherein in the retracted position of the telescopic boom structure (30) its inner end is located near the cross member (26) where the central section and the distal section adjoin.

4. Marine vessel crane according to any one or more of claims 1-3, wherein the distal end sections (22c, 23c) are each embodied as a lattice-like hollow frame structure, each having an inner side, wherein the parallel upper and lower chords are interconnected by a mesh belt member in the plane of the inner side, wherein the crossing members near the distal ends comprise a truss arranged in the plane between the upper chords and a truss arranged in the plane between the lower chords.

5. Marine vessel crane according to any one or more of claims 1-4, wherein the telescopic boom structure (30) is implemented as a hollow frame structure having a rectangular cross section with a width of at least 6 meters and a height of at least 3 meters at least over a major part of its length, such as at least over a part of 75% of its length.

6. A marine vessel crane according to any one or more of claims 1-5, wherein the superstructure (12) is provided with a cradle (14a) thereon, on which cradle (14a) a pitch cable pulley assembly (15) is mounted guiding the pitch cable (41).

7. Marine vessel crane according to any of claims 1-6, wherein the variable length pitch system (41) extends from the pitch winch (40) to the boom head (35).

8. Marine vessel crane according to any one or more of claims 1-6, wherein the variable length pitch system (41) extends from the pitch winch (40) to a distal section, such as to its distal end (22d, 23d), wherein preferably the boom 20 is further provided with a stay mechanism having a stay (71) of fixed length for each of the boom legs, the stay (71) of fixed length extending from an anchoring member (72) arranged on the boom leg (22, 23) near the proximal end of the boom leg to the top end of a stay (73) extending from the distal section (22c, 23c) of the boom leg, and boom 20 is further provided with a variable length stay (74), said variable length stay (74) extending from said top end of the stay to the boom head (35).

9. Marine vessel crane according to any one or more of claims 1-8, wherein the pitch system comprises:

-two pitch winches (40) on the upper structure; and

-two pitch cables (41), each pitch cable (41) being driven by a respective pitch winch, the pitch cables extending from respective pitch cable connectors (42) mounted on the superstructure, e.g. on its boom (14a), the pitch cable pulley assemblies (15) being spaced apart, e.g. parallel to each other, to the boom head or on the distal end section of the boom legs, the pitch cable connectors (42) being spaced apart from each other in the width direction of the boom, e.g. arranged on opposite sides of the boom head (35) as seen in the width direction.

10. Marine vessel crane according to any one or more of the claims 1-9, wherein the crane comprises a stretching mechanism for the telescopic boom structure, the stretching mechanism comprising a stretching winch (60), a winch driven stretching cable (61) and a stretching cable pulley system with a plurality of pulleys (62, 63), wherein the stretching mechanism is configured to engage on the telescopic boom structure (30) in order to provide its stretching movement, preferably wherein the retraction of the telescopic boom structure is caused by the mass of the telescopic boom structure when the boom is oriented upwards.

11. Marine vessel crane according to any one or more of claims 1-10, wherein the crane (10) comprises a locking mechanism configured to mechanically lock the telescopic boom to the distal section at least in its retracted and extended positions.

12. A marine vessel comprising a marine vessel crane (10) according to one or more of the preceding claims.

13. A jack-up offshore vessel (1) comprising:

-a buoyant hull (2) having a main deck (3),

-at least three jack-up legs (4, 5),

-a plurality of lifting units (6), each lifting unit (6) being associated with a respective jack-up leg, adapted to move the respective jack-up leg vertically relative to the hull and to bring the vessel in an operating position, wherein the legs engage the sea bed and the hull is above the water surface,

-a marine vessel crane according to one or more of the preceding claims 1-11.

14. Jack-up offshore vessel according to claim 13, wherein the crane (10) is a leg-around crane, wherein the vessel's jack-up legs extend through the revolving superstructure and the slewing bearing extends around the jack-up legs.

15. The jack-up offshore vessel according to claim 13 or 14, wherein the crane (10) is configured for a parking position beyond the legs, wherein the two boom legs are located at opposite sides of the jack-up leg in the parking position, such as a vessel having a boom support (80), on which boom support (80) the boom rests in a substantially horizontal orientation.

16. Jack-up offshore vessel according to claim 13, wherein the crane (10) is a leg-around crane, wherein the vessel's jack-up legs extend through the gyrating superstructure () and the slewing bearing extends around the jack-up legs, and wherein the crane is configured for exceeding a parking position of the legs, wherein two boom legs are located at opposite sides of the jack-up legs in the parking position, such as a vessel with boom rests on which the boom rests in a substantially horizontal orientation.

17. Jack-up offshore vessel according to claim 13, wherein the vessel (1) has two stern jack-up legs and two front jack-up legs, wherein the rear jack-up leg (4) extends through the revolving superstructure (12) and the slewing bearing extends around said jack-up leg, and wherein the crane (10) is configured for a parking position beyond the legs, wherein the two boom legs (22, 23) are located at opposite sides of the front jack-up leg (5) in the parking position, e.g. wherein a cross member (25) arranged at the junction of the distal section and the central section of each boom leg is located at the rear side of the front jack-up leg when in the parking position.

18. Method for hoisting an offshore wind turbine assembly, for example for installing and/or maintaining an offshore wind turbine, wherein a offshore vessel crane (10) and/or an offshore vessel (1) according to any one or more of claims 1-17 is utilized.