WO2023242427A2

WO2023242427A2 - Crane and method for the assembly and installation of offshore wind turbines

Info

Publication number: WO2023242427A2
Application number: PCT/EP2023/066321
Authority: WO
Inventors: Diederick Bernardus Wijning
Original assignee: Itrec B.V.
Priority date: 2022-06-17
Filing date: 2023-06-16
Publication date: 2023-12-21
Also published as: WO2023242427A3

Abstract

The invention relates to a crane that can be used for both assembling and installing large wind turbines. Furthermore, the crane allows for assembly of large size wind turbines at the installation location. Therefore, the wind turbine does not need to be transported in an assembled and/or upright position, which facilitates transport. A crane according to the invention can be switched between an assembly configuration and an installation configuration. In the assembly configuration, the boom is in a retracted position and the jib is in the hoisting position for hoisting a nacelle on top of a wind turbine mast. In the clearance position the boom is in a hoisting position and the jib is moved backward to enable a mast to be supported by the boom of the crane.

Description

CRANE AND METHOD FOR THE ASSEMBLY AND INSTALLATION OF OFFSHORE WIND TURBINES

The present invention relates to a crane for the assembly and installation of offshore wind turbines having a nacelle with a horizontal axis rotational hub that is arranged on top of a wind turbine mast. The crane and method are in particular directed towards mounting a nacelle on an upstanding wind turbine mast, and subsequently installing the mast with the nacelle on a wind turbine foundation. The crane can also be used for demounting a nacelle, and for deinstalling an offshore wind turbine mast with nacelle.

Offshore wind turbines are mounted on a soil-bound foundation, e.g. on a monopile foundation, a jacket type foundation, etc. or floating foundation, e.g. a spar type foundation. Assembly and installation of the wind turbine, can be done using a crane on a vessel in floating condition or on a so-called jack-up type vessel.

Offshore wind turbines can be assembled on sea or on shore. When assembled on sea, often a jack up vessel is used that first installs the mast of the wind turbine, and subsequently mounts the nacelle on top of the mast and the blades to the hub of the nacelle.

Alternatively, wind turbines are assembled on shore. The fully assembled wind turbine is subsequently transported, on a vessel or on a floating foundation, to the wind farm, i.e. the site where the wind turbine is to be used.

In the wind industry, there is a trend towards larger wind turbines and a desire to install offshore wind turbines at locations with larger water depths than currently encountered.

Currently, the largest wind turbines are 12MWwind turbines. In the near future 15MW and even 20MW offshore wind turbines are expected.

A mast for a 15MWwind turbine may have a length of 120 meters. Such a mast may have a weight of over 1000mt, for example have a weight of 1200mt. A mast for a 20MWwind turbine may have a length of 140 meters. Such a mast may have a weight of over 1600mt, for example have a weight of 1800mt. The nacelle of a 15MWwind turbine may have a weight of about 900mt, while a 20MW nacelle may have a weight of more thanlOOOmt for example have a weight of 110Omt. The large size of these wind turbines makes them unfit to be transported in an assembled state. The wind turbines are too high to be efficiently transported on a vessel in an upright position. Due to the height of the mast, it is furthermore complicated to mount the components on a wind turbine foundation, in particular on a floating wind turbine foundation from a floating vessel.

In the prior art, boom type cranes are used to lift wind turbines, i.e. wind turbines up to 10 -12 MW. These cranes typically have a boom that extends above the top end of the mast of the wind turbine to be lifted. Thus the wind turbine can be supported hanging below the top of the boom. These cranes can not be used for lifting the new types of wind turbines because the top end of the mast extends above the top end of the boom. Furthermore, adapting such a crane for lifting the new types of wind turbines would require the crane to be provided with an extremely long boom. This would not only make the crane heavy and bulky, such a long boom would also complicate handling the wind turbine within the contour of the vessel.

Publication WO2019240585 discloses a wind turbine installation crane. The crane is configured for lifting and installing an assembled wind turbine. The boom of the crane is configured for lifting the mast of a wind turbine with the top end of the mast extending above the top end of the crane. The crane cannot be used for mounting a nacelle on the mast of such a wind turbine. Thus, the wind turbine needs to be transported in an assembled state, i.e. at least with the nacelle mounted on the mast, and with the mast already in an upright position. Thus transporting wind turbines is difficult because the wind turbine elevates the center of gravity of the vessel. Therefore, transport, if possible, is limited to days with calm seas, i.e. with no or limited waves and no substantial wind. Similar cranes are disclosed in CN 102502422 and CN 102425145.

It is an object of the invention to provide an improved crane for the installation of wind turbines, more in particular to provide a crane that enables transport and installation of large size wind turbines, i.e. wind turbines of 15MW or more, preferably with a single vessel.

It is a further object of the invention to provide a crane and a method for installing tall offshore wind turbines at sea in a fast, safe, reliable and cost-effective manner.

The invention therefore provides a crane according to claim 1, which crane can be used for both assembling and installing wind turbines, in particular large size wind turbines, i.e. wind turbines of 15MWor more. Furthermore, the crane allows for assembly of large size wind turbines at the installation location. Therefore, the wind turbine does not need to be transported in an assembled and/or upright position, which facilitates transport.

A crane according to the invention combines a relatively short boom that is configured for engaging a mast below the top end thereof, with a jib that can be moved relative to the boom between a hoisting position and a clearance position. The boom of the crane can be pivoted between a hoisting position and a clearance position, in which it is retracted relative to the hoisting position, as well. Thus, according to the invention, the crane can be switched between an assembly configuration and an installation configuration.

The hoisting position of the boom is the position of the boom for supporting a wind turbine mast, e.g. with nacelle on top thereof. When the boom is in the clearance position, the boom is retracted, i.e. pivoted upwards, relative to the hoisting position. This retracted position of the boom allows for using the jib, when in the in hoisting position, for installing a nacelle on a wind turbine mast within reach of the crane, in particular of the relatively short boom thereof. Mounting the nacelle on a mast that is set up within reach of the crane is beneficial because typically the available deck space on a vessel is limited.

Because the crane according to the invention, in the assembly configuration, allows for installing a nacelle on top of a wind turbine mast, the mast can be transported without the nacelle mounted thereon. Keeping the nacelle on the deck during transport keeps the center of gravity of the vessel low, which is beneficial for the stability of the vessel. Preferably the assembly configuration also enables upending of the mast of the wind turbine i.e. lifting the top end of the wind turbine mast to bring the mast from a horizontal transport position into a vertical and upright assembly and installation position. Thus, in this case, the mast can be transported in a horizontal configuration, which keeps the center of gravity low as well.

The invention thus provides a crane with a relatively short boom, i.e. a compact crane with a low center of gravity, that can be used for both assembling and installing a wind turbine mast with nacelle. This crane configuration is in particular beneficial for the installation of large size wind turbines, i.e. wind turbines in the range of 15MW- 20 MW, and especially for assembly and mounting thereof on a floating foundation.

The crane according to claim 1 is suitable for the assembly and installation of offshore wind turbines. It is movable into an assembly configuration, for mounting a nacelle on an upright mast, and an installation configuration, for mounting the mast, e.g. provided with the nacelle, on a foundation. The crane comprises:

- a crane base;

- a crane housing; and

- a slew bearing, wherein the slew bearing is provided between the crane base and the crane housing, to enable the crane housing to slew about a vertical slew axis.

The crane further comprises a boom, wherein the boom extends between a base end and a head end. The boom is at the base end pivotable mounted to the crane housing, in particular bout a horizontal boom pivot axis. The head end of the boom is thus remote from the boom pivot axis.

The crane further comprises a jib, which is connected to the boom at or near a head end of the boom such as to be pivotable relative to the boom about a horizontal jib pivot axis.

The boom of the crane has at the head end a left support arm supporting a left crown block for a hoisting wire of a first hoisting assembly of the crane and a right support arm supporting a right crown block for a hoisting wire of a second hoisting assembly of the crane. The first and second hoisting assemblies are configured for hoisting a mast of a wind turbine. They respectively comprise a first and second winch, and a first and second load connector. the support arms extend from the boom to define between them a mast receiving space, the first and second crown block are arranged on the respective support arms to be spaced apart with the mast receiving space between them, to enable the mast to be supported by the first and the second hoisting assembly in the mast receiving space.

A hoisting wire of a third hoisting assembly of the crane departs from a head end of the jib remote from the jib pivot axis for hoisting a nacelle. The third hoisting assembly further comprises a third winch and a third load connector.

Optionally, the crane further comprises a luffing assembly comprising a boom luffing winch and an associated boom luffing wire, wherein the boom luffing winch is mounted on the crane housing and the boom luffing wire extends between the boom luffing winch and the boom.

The boom is pivotable about the horizontal boom pivot axis between a hoisting position thereof, for supporting the mast of the wind turbine in the mast receiving space; and a clearance position thereof, in which the boom is retracted relative to the hoisting position. The pivoting of the boom can be accomplished by the luffing assembly if present, however, alternative constructions as known in the art can be used as well.

The jib is pivotable relative to the boom about the horizontal jib pivot axis between a hoisting position thereof, for mounting the nacelle, and a clearance position thereof, in which the jib is retracted relative to the hoisting position thereof.

The crane is movable into the assembly configuration by pivoting the boom into the clearance position thereof and the jib into the hoisting position thereof, to enable the nacelle of the wind turbine to be placed onto a top end of the mast by means of the third hoisting assembly.

The crane is movable into the installation configuration by pivoting the boom into the hoisting position thereof and the jib into the clearance position thereof, to enable the mast of the wind turbine to be supported in the mast receiving space by the first and second hoisting assembly with a top end of the mast higher than the head end of the boom. For example, with a nacelle on top of the head end of the boom.

A crane according to the invention can thus be switched between a assembly configuration and an installation configuration. In the assembly configuration, the boom is in a retracted position and the jib is in the hoisting position. Thus, the jib extends over the mast receiving space between the left crown block and the right crown block, to enable the third hoisting assembly to lift an object past the left and right crown block and past the mast receiving space and to mount that object on top of a mast next to the crane. In the clearance position the jib is moved away from above the mast receiving space to enable the first and the second hoisting assembly to support a mast received in the mast receiving space, the mast extending with its top end above the head end of the boom, and therefore also extending above a base end of the jib connected to the head end of the boom.

Providing the jib with a clearance position, in which clearance position the jib does not interfere with the mast inside the mast receiving space, preferably in which the jib does not extend above the mast receiving space at all, i.e. is clear therefrom in a top view, allows for using a boom that is, compared to the length of the wind turbine mast, relatively short, to lift a mast. And although the boom is relatively short, compared to the mast, the crane can be used for mounting a nacelle on top of an extremely long mast, and for lifting the extremely long mast with a nacelle to mount the mast onto a wind turbine foundation. With a crane according to the invention, the boom can be moved between a hoisting position, for supporting the mast of the wind turbine, and a clearance position, in which the boom is retracted relative to the lifting position.

Providing the jib with a clearance position allows for a single crane, having a relatively short boom compared to the length of a wind turbine mast, to both mount the nacelle on the mast and installing the mast with nacelle.

The crane, more in particular the boom of the crane, is dimensioned to receive the mast of a wind turbine between the first and second support arms, between the first and second crown blocks arranged thereon, with a top end of the mast, and e.g. the nacelle mounted thereon, above the head end of the boom, thus above the first and support arms and crown blocks. When supporting the mast with nacelle, this arrangement allows for positioning the crown blocks relatively close together, and thus for increased stability, because the nacelle, which is wider than the mast, does not need to be received between the crown blocks.

In an embodiment, the distance between the left crown block and the right clown block is less than twice the diameter of the mast, more in particular of the diameter of the upper end of the mast, for example is one and a half times the diameter of the diameter of the mast, more in particular of the upper end of the mast.

It should be noted that the first and the second hoisting assembly can be linked to function as a single hoisting assembly.

It is envisaged that the boom of the crane according to the invention comprises a main body, the left and the right support arm extending relative to the main body of the boom so that the support arms provide the boom with a fork shaped top end, the main body of the boom forming the stem of the fork. In an embodiment, the support arms extend parallel to a longitudinal axis of the main body of the boom, providing the top end of the boom with a II- shaped top end. In such an embodiment, the main body preferably comprises two legs, connected by cross beams, and the support arms form continuations of those legs. In an alternative embodiment, the support arms extend outwards relative to the main body, providing the top end of the boom with a V-shaped top end.

In an embodiment the support arms extend in front of the boom, in order to define laterally between them the mast receiving space forwards of the head end of the boom and the horizontal pivot axis of the jib, and the first and second crown blocks are arranged on the respective support arms on respective lateral sides of the mast receiving space. It is noted that herein, the forwards direction is to be taken to mean the horizontal direction from the boom pivot axis towards the head end of the jib.

In an embodiment the installation configuration is such as to enable the mast to be supported in the mast receiving space, with a nacelle on top of the top end of the mast clear from the jib. Thus, the hoisting position of the boom and the clearance position of the jib in the installation configuration are such as to give room to the nacelle when placed on top of the top end of the mast, which extends above the head end of the boom.

In an embodiment the support arms are configured and arranged such that these are in the assembly position clear from the mast, e.g. extend backwards from the mast. Other configurations are possible, e.g. wherein the support arms are moved laterally outwards.

In an embodiment, the support arms of the boom are integral parts of the boom, i.e. form a continuation of the construction of the boom. For example the boom may comprise two parallel legs, extending between the base and the head end of the boom, and the upper ends of these legs form the support arms. The legs may be connected by cross beams at regular intervals, providing the boom with an H-shape or ladder like configuration. In such an embodiment, the support arms are an integral part of the boom, and cannot pivot relative to the boom. The boom, or at least the parallel legs of the boom including the support arms, can be a continuous construction, e.g. a continuous truss, which allows for a simple and rigid construction. As an alternative, the boom may comprise a torsion box, the torsion box forming the main body of the boom, with the left and right support arm mounted to the torsion box. Also in such a configuration, the left and right arm may be an integral component of the boom, i.e. a continuation of the components of the torsion box.

In an embodiment, the left and right support arm may be pivotable moveable mounted on the boom, for example may be pivoted relative to a main body of the boom between an active position for supporting a wind turbine, and an inactive position, for example for when the crane is in the assembly configuration.

In an embodiment, the left and right support arms extend away from the main body of the boom at a front side thereof, i.e. the side of the main body that faces a load supported by the first and the second hoisting assembly, to space the crown blocks away from the main body of the boom. Thus, when the boom is in the retracted position, i.e. is in a substantially upright position, the hoisting wires and load connectors of the hoisting assemblies are supported away from the boom.

In an embodiment, the left and the right support arm are at a top end provided with transverse structures, the transverse structures extending away from the boom at a frontside and at a backside thereof, wherein the transverse structures support the crown blocks at the front side of the boom and are connected with the boom luffing wires at the back side of the boom, the transverse structures providing the boom with a hammerhead shape when seen in side view.

In such an embodiment, the boom is essentially T-shaped when seen in side view. Thus, when the boom is in the retracted position, i.e. is in a substantially upright position, the hoisting wires and load connectors of the hoisting assemblies are supported away from the boom. Furthermore, the connection points for the luffing wires are also spaced form the main body of the boom, which is in particular beneficial for luffing the boom out of, or into, a lowered storage position, for example for when the vessel travels between destinations.

In a preferred embodiment, the transverse structures at the top end of the boom are triangular-shaped, with one point of the triangle attached to the boom. Preferably, the structure comprises a frame that forms the outline of the triangle, to provide a strong and lightweight construction.

In an embodiment, the jib is pivotably mounted to the boom at or near the top end thereof. In such an embodiment, the jib is connected to the boom via one or more hinges, enabling the jib to be pivoted about a jib pivot axis between the hoisting position and the clearance position.

In an embodiment, the jib is a telescopic jib, or a foldable jib, allowing of at least a top end of the jib to be moved relative to a base end of the jib, to move the top end of the jib away from a mast supported by the crane. Thus, in such an embodiment, the top end of the jib can be moved relative to the base end of the jib between an active position, for hoisting a nacelle, and an inactive position, for when the jib is in the clearance position. Thus, when the jib is moved into the clearance position, the top end of the jib is moved into the inactive position. This provides the jib with a compact configuration when in the clearance position.

Preferably, the jib is mounted to a back side of the boom, i.e. to a side of the boom facing away from a load that is supported by the first and the second hoisting assembly.

Furthermore, the jib preferably is mounted to the boom between the left and the right support arm, and at or near the base ends of the left and right support arm. A lower part of the jib preferably extends between the left support arm and the right support arm of the boom, when the jib is in the hoisting position.

In an embodiment, the boom is pivotably mounted to the crane housing such that the boom can pivot about a boom pivot axis, and the jib is pivotably mounted to the boom such that the jib can pivot about a jib pivot axis, and wherein the boom pivot axis is parallel to the jib pivot axis.

In a further embodiment, the crane furthermore comprises a jib luffing winch and an associated jib luffing wire, wherein the luffing wire extends between the jib luffing winch and the jib, to enable pivoting of the jib relative to the boom between the hoisting position and the clearance position.

In an embodiment, the boom is provided with a jib stop, which jib stop is configured to stop the jib when it is moved into the assembly position. The jib stop may for example comprise one or more hydraulic cylinders that provide a resilient stop for receiving the jib and for positioning the jib relative to the boom in the clearance position. In an embodiment, the jib is pulled by a jib luffing winch against the jib stop when in the clearance position.

In an embodiment, the boom is provided with a jib actuator, e.g. one or more cylinders or electric spindles configured to push the jib or one or more winches to pull the jib, for moving the jib out of the clearance position and towards the hoisting position. This is beneficial because the jib, when in the clearance position, may be positioned close to the vertical, vertically or even beyond the vertical position, such that gravity does not pull the jib towards hoisting position. Thus, a jib actuator may be required to allow for the jib to be moved between the clearance position and the hoisting position.

In an embodiment, the boom is provided with a jib lock for securing the jib relative to the boom in the clearance position. In addition or as an alternative, the boom is provided with a jib lock for securing the jib relative to the boom in the hoisting position

In a further embodiment, the boom pivot axis and the jib pivot axis define a plane, and wherein the jib, or at least a top end of the jib, is on a first side of this plane when in the assembly position, and is on an opposite, second side of this plane when in the installation position. In an embodiment, the jib is provided with a crown block for the hoisting wire of the third hoisting assembly, and the crown block is located on a front side of the boom, i.e. the side of the boom facing towards a load supported by the first and second hoisting assembly, when the jib is in hoisting position and is located on a back side of the boom, i.e. the side of the boom facing away from a load supported by the first and second hoisting assembly, when the jib is in the clearance position.

In an alternative embodiment, the jib is telescopically mounted on the boom. In such an embodiment, the jib is moved in a longitudinal direction, i.e. parallel to a longitudinal axis of the jib, between the hoisting position and the clearance position. In such an embodiment, the jib may extend alongside and adjacent the boom, when in the clearance position.

In an embodiment, the length of the jib and the angle between the jib and the boom is such that when the crane is in the assembly configuration, the hosing assembly can lift a nacelle past the left and right support arm of the boom. In this context it is submitted that the left and the right support arm preferably are spaced far enough for a mast to be supported between them, but to close for a nacelle to pass between them. By positioning the left and the right support arm this close together, the boom can be kept compact.

In an embodiment, the jib can be pivoted forward, i.e. can be lowered relative to the hoisting position, into a knuckle boom position to provide the crane with a knuckle boom configuration, for lifting objects close to the deck surface, for example for moving objects between the vessel and a supply vessel. In such an embodiment, the angle between the boom and the jib, when the jib is in the knuckle boom position, is less than 90 degrees, preferably is smaller than 45 degrees, for example is 35 degrees. Furthermore, in such an embodiment, the jib, more in particular the crown block of the jib, is configured for supporting the hoisting wire when the jib is in the hoisting position and when the jib is in the knuckle boom position. In the latter position, the hoisting wire exits the crown block in a direction away form the jib, and in the former position the hoisting wire exits the crown block in a direction towards or alongside the jib.

In an embodiment, when the crane is in the assembly configuration, the boom is in a substantially vertical position, i.e. is substantially parallel to a slew axis of the slew bearing of the crane. This allows for the jib to hoist a load substantially parallel to the boom, and along the boom and along the first and second crown block. In an embodiment, the crane housing is provided with a boom stop, which boom stop is configured to stop the boom when the boom is moved into the clearance position. The boom stop may for example comprise one or more hydraulic cylinders that provide a resilient stop for receiving the boom and for positioning the boom relative to the crane housing in the clearance position. In an embodiment, the boom is pulled by the boom luffing winch against the boom stop when in the clearance position.

In an embodiment, the crane housing is provided with a boom actuator, e.g. one or more cylinders or spindles to push the boom or one or more winches to pull the boom, for moving the boom out of the clearance position and towards the hoisting position. This is beneficial because the boom, when in the clearance position, may be positioned vertically, or closely to the vertical, such that gravity does not pull the boom towards hoisting position. Thus, a boom actuator may be required to allow for the boom to be moved between the clearance position and the hoisting position.

In an embodiment, the boom is provided with a boom lock, for securing the boom relative to the crane housing in the clearance position.

In an embodiment, the crane is configured to hoist a wind turbine masts having a length of over 100 meters, preferably over 110 meters, for example of 120 meters, more preferably of 140 meters. In an embodiment, the boom has a length of at most two third, i.e. 67%, the length of a 15 MW wind turbine mast

In an embodiment the boom has a length in the range of 75 to 80 meters, preferably has a length of about 78 meters, and/or has a width of over 18 meters, for example has a width of about 20 meters, and wherein the support arms preferably have a length of over 15 meters, for example have a length of about 20 meters. A crane according to the invention allows for a boom having such a length to be used for lifting the mast of a 15Mwat or even a 20Mwat wind turbine.

In an embodiment, the jib has a length of at least three quarters, i.e. 75% the length of the boom, preferably has a length of at least four fifth, i.e. 80%, the length of the boom.

In an embodiment, the jib has a length of over 70 meters, for example has a length of about 72 meters. A crane according to the invention allows for a jib having such a length to be used for mounting a nacelle on a mast of a 15MW or even a 20M W wind turbine. In an embodiment, the crane comprises, preferably the first hoisting assembly and the second hoisting assembly each comprise, a heave compensation mechanism to compensate for sea induced vertical movement of a load supported by the first and second hoisting device relative to a foundation, preferably relative to a floating foundation. Thus, the crane can safely land a wind turbine on a foundation, in particular from a crane according to the invention on a floating vessel can thus safely install a wind turbine on a foundation, e.g. a floating foundation.

A crane according to the invention is configured for the assembly and installation of offshore wind turbines. Therefore, the crane is to be mounted on wind turbine installation vessels. Furthermore, a crane according to the invention allows for assembling a wind turbine by mounting a nacelle on a mast, on the vessel.

Furthermore, the crane can be used, preferably in the assembly configuration, for upending a wind turbine mast, i.e. lifting the top end of the wind turbine mast to bring the mast from a horizontal transport position into a vertical and upright assembly and installation position.

Also, the crane can be used for assembling a wind turbined mast comprising multiple, for example three, mast sections. Thus, the crane, would first assemble the wind turbine mast, and subsequently mount the nacelle on the assembled mast, after which the combined mast and nacelle are mounted on a foundation, for example a floating foundation.

The invention furthermore provides a vessel, preferably a semisubmersible vessel, provided with a crane according to the invention, for the assembly and installation of offshore wind turbines.

In an embodiment, a vessel according to the invention has a storage deck for transport of wind turbine components, preferably has a storage deck for supporting a wind turbine mast having a length of at least 100 meters in a horizontal position, wherein the deck height of the top end of the boom of the crane, when the crane is in the assembly position, is less than the deck height of the wind turbine mast supported in the upright position on the deck of the vessel, such that the boom can lift the mast with the top end thereof extending above the top end of the boom.

In a further embodiment of a vessel according to the invention, the deck height of the top end of the jib, when the crane is in the assembly configuration position, is above the mast and a nacelle mounted on that mast. In an embodiment of a vessel according to the invention, the vessel has a longitudinal axis, and the crane is mounted on that vertical axis, such that vertical movement of the crane caused by roll of the vessel is minimized.

In an embodiment, the vessel comprises a foundation gripper, for engaging a floating foundation and for damping movements in the horizontal plane of the floating foundation relative to the vessel, preferably for substantially eliminating movements in the horizontal plane relative of the floating foundation relative to the vessel.

In an embodiment, the foundation gripper is mounted to the vessel adjacent the crane, such that when the foundation gripper engages a floating foundation, and the crane supports a wind turbine, i.e. a wind turbine mast with nacelle, in an installation position, i.e. next to the vessel with the front of the boom facing away from the vessel, the supported wind turbine is positioned above the floating foundation engaged by the foundation gripper.

In a further embodiment, the vessel has a longitudinal axis, and the foundation gripper is, and preferably the crane are, mounted on that vertical axis, such that vertical movement of the foundation gripper caused by roll of the vessel is minimized.

In an embodiment, the vessel is furthermore provided with at least one suppressor arm, wherein the suppressor arm is configured to project from the vessel in a floating foundation engagement position, the suppressor arm being provided with a floating foundation engagement device for engaging with a floating foundation, preferably for engaging with a floating foundation connector mounted on the floating foundation, and for exerting a downward force, i.e. a force directed in the z-direction, onto said floating foundation In a further embodiment, the vessel is provided with two suppressor arms, positioned on opposite sides of the crane, and on opposite sides of a foundation gripper mounted adjacent the crane, for engaging a floating foundation on opposite sides thereof.

The invention furthermore provides a method for assembling and installing an offshore wind turbine, wherein the method comprises using a crane according to the invention mounted on a vessel, or using a vessel according to the invention.

In an embodiment, the method furthermore comprises:

- positioning the crane in the assembly configuration,

- preferably using the crane in the assembly configuration to up end a wind turbine mast, or alternatively, using a mast upend device to upend a wind turbine mast without assistance of the crane; - using the crane in the assembly configuration to mount a nacelle on the upended wind turbine mast;

- positioning the crane in the installation configuration; and

- hoisting the mast with the nacelle from the vessel and onto a foundation, preferably onto a floating foundation.

Preferably, once the mast and nacelle are installed on the wind turbine foundation, a dedicated crane is used for mounting the blades to the wind turbine. Preferably, especially in case the wind turbine foundation is a floating foundation, the crane dedicated for installation of the blades is set up on the wind turbine foundation as well, i.e. is not set up to operate form a vessel.

It is submitted that, when using a crane for supporting a mast of a wind turbine, hoisting wires preferably are provided on opposite sides of the mast. Furthermore, the hoisting wires preferably support the weight at or near a lower end of the mast, and are held adjacent the mast, e.g. by wire guides or a yolk, above the center of gravity of the mast, or of the combined mast and nacelle. This configuration of hoisting a mast is known in the prior art, and allows for a very stable support of the mast, and of the combined mast and nacelle.

It is submitted that a crane according to the invention is configured for supporting and installing a wind turbine mast, e.g. with a nacelle mounted on that mast. Preferably, the mast with nacelle is installed on a foundation, e.g. a floating foundation, prior to blades being attached to the nacelle. Thus, when herein is referred to the crane according to the invention supporting a wind turbine, this refers to a wind turbine mast provided with a nacelle, and not to a fully assembled wind turbine, i.e. a nacelle mounted on a mast with blades already attached to the hub of the nacelle.

According to a further aspect, the invention provides a method for mounting an offshore wind turbine, or part thereof, on a floating foundation from a floating vessel provided with a wind turbine installation crane comprising a hoisting assembly, wherein the crane preferably is a crane according to the invention.

According to the further aspect of the invention, the vessel is provided with a foundation gripper configured for engaging a floating foundation and for subsequently dampen movement of that foundation relative to the vessel in the xy plane, i.e. in the horizontal plane, preferably while allowing for movement in the z-direction, i.e. in the vertical direction, wherein the method comprises the steps: - positioning the vessel adjacent the floating foundation;

- providing the foundation gripper with xy compensation, i.e. actively moving the foundation gripper to eliminate movement of the foundation gripper relative to the floating foundation relative in the xy plane;

- engaging the floating foundation with the foundation gripper, preferably engaging a foundation connector mounted on the floating foundation with the foundation gripper, while providing the foundation gripper with xy compensation;

- ending the xy compensation of the foundation gripper and starting with xy damping, i.e. reduce, e.g. dampen, the movement of the floating foundation relative to the vessel in the xy plane; and

- increasing the xy damping to further reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the xy plane, and preferably fully connect the foundation gripper with the floating foundation; wherein the vessel is furthermore provided with at least one suppressor arm, wherein the suppressor arm is configured to project from the vessel in a floating foundation engagement position, the suppressor arm being provided with a floating foundation engagement device for engaging a floating foundation, preferably for engaging a suppressor coupling provided on the floating foundation, e.g. a suppressor coupling provided on a floating foundation connector mounted on the floating foundation, and for exerting a downward force, i.e. a force directed in the z-direction, onto said floating foundation, wherein the method furthermore comprises the steps:

- if necessary, positioning the suppressor arm in the floating foundation engagement position;

- providing the engagement device of the suppressor arm with z compensation, i.e. actively moving the engagement device, or an end of the arm supporting the engagement device, to eliminate movement of the engagement device relative to the floating foundation in the z direction;

- engaging the floating foundation with the engagement device, preferably engaging a suppressor coupling provided on the floating foundation, while providing z compensation; - ending the z compensation and starting with damping the movement of the floating foundation relative to the vessel in the z direction;

- increasing the z damping to further reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the z direction and preferably thus fully connect the suppressor arm with the floating foundation;

- moving the wind turbine from a position above the deck to a position above the floating foundation, preferably while using a ballast system of the vessel to keep the vessel even keel, and supporting the wind turbine above the floating foundation using a wind turbine installation crane;

- removing ballast water from the floating foundation, preferably from a column of the floating foundation onto which the wind turbine is to be mounted, preferably by pumping the ballast water from the floating foundation into ballast tanks of the vessel, preferably ballast tanks located near or at the crane supporting the wind turbine, to create an upward force of the floating foundation against the suppressor arm, wherein the upward force preferably is similar or larger than the gravitational force of the wind turbine supported by the crane;

- landing the wind turbine on the floating foundation, optionally while providing the wind turbine with z-compensation using the hoisting assembly of the crane, i.e. using the hoisting assembly to reduce, preferably eliminate, sea state induced movement of the wind turbine relative to the floating foundation; and

- connecting the wind turbine to the floating foundation by bolting the wind turbine mast to the floating foundation, e.g. by bolting a floating foundation connector mounted on the floating foundation to a wind turbine mast connector mounted to the wind turbine mast.

This method according to a further aspect of the invention utilises, in addition to a foundation clamp, at least one suppressor arm, preferably two suppressor arms positioned on opposite sides of the floating foundation, to control movement of the floating foundation relative to the vessel. The suppressor arms are configured to support an upward force of the floating foundation, and to thus enable pushing downward on the floating foundation using the weight of the vessel to control the movement of the floating foundation in the z direction. The at least one suppressor arm, or z beam, and the method utilising the at least one suppressor arm thus enable an effective and efficient way for controlling the movement of a floating foundation relative to a vessel, and thus facilitate installing a wind turbine on the floating foundation using a crane or similar wind turbine support construction mounted on that vessel.

In a further embodiment of the method, the floating foundation is provided with a floating foundation connector and the wind turbine mast is provided with a wind turbine mast connector which floating foundation connector and wind turbine mast connector are configured to cooperate to provide a quick connection, i.e. a connection without bolting, between the floating foundation and the wind turbine mast, and wherein the method further comprises: by landing the wind turbine on the floating foundation establishing a quick connection such that the wind turbine mast and the floating foundation move in unison.

In a further embodiment of the method, the foundation connector is provided with an abutment surface for engagement by the floating foundation engagement device of the suppressor arm.

In an embodiment of the method, the floating foundation connector and the wind turbine mast connector are provided with click fingers and one or more click finger engagement edges for establishing the quick connection between the floating foundation connector and the wind turbine mast connector.

In an embodiment of the method, the floating foundation connector and the wind turbine mast connector are provided with guides for aligning the floating foundation connector relative to the wind turbine mast connector about the z axis, while landing the wind turbine mast on the floating foundation.

In an embodiment of the method, the mass of the water removed from the floating foundation is at least similar, preferably larger than the mass of the wind turbine supported by the wind turbine installation crane above the floating foundation, e.g. the mass of the water is about 21 mt, such that the floating foundation pushes upwards against the abutment surface with a force similar to or larger than the gravitational force of the wind turbine supported by the crane. In an embodiment of the method, further comprising the step of transferring the total weight of the wind turbine, i.e. the wind turbine mast and the nacelle mounted on the wind turbine mast, onto the floating foundation, only after establishing the quick connection.

The foundation clamp is provided with actuators for actively moving the foundation clamp relative to the vessel in the xy plane.

The foundation clamp is configured to engage the foundation, and to fully connect with the foundation such that there is no, or only limited, movement in the xy plane between the foundation clamp and the floating foundation. Furthermore, the foundation clamp is configured to allow for vertical movement of the floating foundation relative to the foundation clamp, while the foundation clamp is in engagement with the floating foundation, i.e. while movement of the foundation clamp relative to the floating foundation is limited or is eliminated.

It is submitted that increasing the z damping, to further reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the z direction, may be achieved by or may be done in combination with removing ballast water from the floating foundation and/or removing ballast water from the vessel to increase the upward force of the floating foundation against the suppressor arm and/or the downward force of the suppressor arm on the floating foundation respectively.

It is submitted that when removing ballast water from the floating foundation, preferably from a column of the floating foundation onto which the wind turbine is to be mounted, preferably by pumping the ballast water from the floating foundation into ballast tanks of the vessel, preferably ballast tanks located near or at the crane supporting the wind turbine, the amount of water transferred preferably is such that the floating foundation pushes upwards to the suppressor arm with a force equal to, or slightly larger than the gravitational force of the wind turbine supported by the crane, i.e. the force required to support the wind turbine.

It is submitted that the method according to the further aspect of the invention is described for mounting a wind turbine mast with a nacelle mounted thereon on a floating foundation. The method may also be used for mounting only a wind turbine mast, or for mounting a fully assembled wind turbine, i.e. a wind turbine mast provided with a nacelle provided with blades, onto a wind turbine foundation, in particular a floating wind turbine foundation. In an embodiment, the foundation clamp comprises one or more jaws that can be moved between an open position for receiving part of the floating foundation, and a closed position for enclosing the received part of the floating foundation, which jaws are provided with floating foundation engagement devices for engaging, i.e. contacting the floating foundation. In such an embodiment of the foundation clamp, engaging the foundation comprises receiving part of the floating foundation in the foundation clamp, moving the jaws from the open position into the closed position, and subsequently engaging the floating foundation with the engagement devices. In such an embodiment, the engagement devices may be configured for providing the xy compensation, while the jaws of the foundation clamp move with the vessel.

In an embodiment, the foundation clamp comprises one or more sensors to monitor the movement of the foundation relative to the vessel, and actuators for moving the foundation clamp at least in the xy plane relative to the vessel.

It is submitted that in an embodiment, information regarding the position of the floating foundation relative to the vessel can be communicated by a foundation clamp control system to the crane supporting the wind turbine. Thus the crane can use this information for actively positioning the supported wind turbine relative to the floating foundation, preferably to the floating foundation while it is held by the foundation clamp. It is furthermore submitted that the foundation clamp comprises dampers for dampening the movement of the floating foundation in the xy direction. A control system of the foundation clamp may generate positional data of the position of the floating foundation relative to the vessel based on information obtained from the dampening of movement of the floating foundation relative to the vessel.

According to a second aspect, the invention furthermore relates to a mast upend device, a method for assembly and installation of a mast and a nacelle of a wind turbine, on an offshore wind turbine foundation, using a vessel comprising a mast upend device, and a vessel provided with a mast upend device.

In the prior art it is proposed to transport the masts in an upright position, see for example WO2022/074336 and WO2019245366, or to transport the wind turbines fully assembled, see for example WO2019240585.

In the wind turbine industry, there is a trend towards larger wind turbines and a desire to install offshore wind turbines at locations with larger water depths than currently encountered. Currently, the largest wind turbines are 12mw wind turbines. In the near future 15mw and even 20mw offshore wind turbines are expected.

A mast for a 15mw wind turbine may have a length of 120 meters. Such a mast may have a weight of over 1000mt, for example have a weight of 1200mt. A mast for a 20mw wind turbine may have a length of 140 meters. Such a mast may have a weight of over 1600mt, for example have a weight of 1800mt. The nacelle of a 15MWwind turbine may have a weight of about 900mt, while a 20MW nacelle may have a weight of more thanlOOOmt for example have a weight of 110Omt.

The large size of these wind turbines makes them unfit to be transported in an assembled state. The wind turbines are too high to be efficiently transported on a vessel in an upright position. Due to the height of the mast, it is furthermore complicated to mount the components on a wind turbine foundation, in particular on a floating wind turbine foundation from a floating vessel.

Transporting the wind turbine in separate components, stored on a storage deck, allows for keeping the center of gravity low, which provides the transport vessel with better stability and thus provides the vessel with an increased operational window. Also, transporting the wind turbine in disassembled state facilitates transporting multiple wind turbines.

Preferably the wind turbine masts are transported in a horizontal transport position. The horizontal transport position, compare to transporting the masts in an upright position, keeps the center of gravity of the mast close to the deck. However, the horizontal transport position requires the mast to be upended, i.e. to be brought into the upright position, when the wind turbine is to be assembled and/or the mast is to be mounted on a wind turbine foundation.

Typically, a crane is used to upend the mast of a wind turbine, after which the mast is temporarily fixed to the deck in the upright position to enable assembly of the wind turbine. However, with the large capacity wind turbines and increased length of these masts, securing the masts to the deck requires elaborate clamps or mounts.

Also, when using a crane, the flexibility of the hoisting wire allows for movement of the load lifted by the crane. With the increasing length of wind turbine masts, the length of the hoisting wire used for upending the mast increases as well. And therefore the risk of swing of the mast during the upending increases as well. It is an object of the invention to overcome one or more of the drawbacks mentioned above. In addition or as an alternative, it is furthermore an object of the invention to provide a method and a device suitable for handling masts of tall wind turbines, more in particular to upend and support wind turbine masts having a length of a 100 meters or more. It is a further object to provide a method and a device that enable assembling and installation of large wind turbines, in particular the mounting of the nacelle on a mast and installation of the combined mast and nacelle on a wind turbine foundation.

According to the second aspect, the invention provides a method according to claim 31 and a vessel according to claim 37. According to the second aspect of the invention, the mast is upended using an upend device, which upend device is also used to support the mast in an assembly position to enable the crane to mount a nacelle on top of the mast. The upend device supports the mast during the upend process and while the nacelle is mounted on the mast. Only when the mast is to be mounted on the wind turbine foundation, the mast is released from the upend device.

By using the upend device instead of a crane for upending the mast, the position of the mast is fully controlled during the upend process. Furthermore, because the upend device also supports the mast during the assembly process, the position of the mast is controlled up until the mast is to be lifted from the vessel onto a foundation. There is no need for complicated deck clamping devices or mounts to support the mast, and there is no need to position a crane supported mast onto such clamping devices or mount after upending the mast. Thus, the upending of the mast is facilitated.

According to the second aspect, the invention provides a method for assembly and installation of a wind turbine on an offshore wind turbine foundation, using a vessel comprising a storage deck, a mast upend device and a wind turbine assembly crane, the method comprising: transporting on the storage deck of the vessel a wind turbine mast and a nacelle separate from the mast, preferably multiple wind turbine masts and nacelles separated from the masts, to a wind turbine installation site where the wind turbine foundation is arranged, with the wind turbine mast in a horizontal transport position; placing the wind turbine mast, in a horizontal position, on an upend arm of the upend device, wherein the upend arm extends between a bottom end and a top end, and along the wind turbine mast; upending the wind turbine mast, from the horizontal position into a vertical assembly position, by pivoting the upend arm using an upend arm drive, supporting the mast in the assembly position, preferably vertically above the deck of the vessel, using the upend arm; lifting a nacelle from the deck, using a crane mounted on the vessel, preferably using the installation crane, and onto the top end of the wind turbine mast supported in the assembly position by the upend arm, and connecting the nacelle to the wind turbine mast; connecting the wind turbine installation crane to the assembly of mast and nacelle, preferably without blades attached to a hub of the nacelle; releasing the mast from the upend device and operating the installation crane to position the mast above the wind turbine foundation, and to lower the mast on the wind turbine foundation; disconnecting the installation crane form the wind turbine mast.

In an embodiment, the method further comprises mounting blades to a hub of the nacelle, using a blade installation crane, which blade installation crane preferably is mounted on the wind turbine foundation. This method allows for a vessel dedicated to mounting the assembly of mast and nacelle, i.e. without the blades, and a vessel dedicated to mounting blades to the nacelle, preferably by the temporarily installation of a blade installation device, e.g. a blade installation crane, on the floating foundation. The upending, assembly and installation of mast and nacelle requires a large crane and a large vessel. The blade installation vessel can be much smaller, in particular when a blade installation crane is to be mounted on the floating foundation. Thus, both types of vessel can be sued for the specific function they are designed for, which allows for an efficient use of the vessels.

In an embodiment, the method further comprises mounting a blade installation crane on the wind turbine foundation, preferably using the wind turbine installation crane. In such an embodiment, the vessel with the upend device is also used for mounting a blade installation crane on the floating foundation. In an embodiment, the blade installation crane is already mounted to the mast and/or on an extension at the bottom end of the mast, and the mast and is installed on the floating foundation in combination with the blade installation crane. In such a method, the blade installation crane, after the blades are installed, may be removed from the foundation by another vessel. Also, the blades to be mounted to the nacelle may be presented to the blade installation crane from a vessel other than the vessel with the upend device, for example from a blade transport vessel, dedicated to the transport and presenting of blades to the blade installation crane only.

In an embodiment of the method, the upend arm extends between a bottom end and a top end, and the upend arm at the bottom end is pivotable mounted to the support frame and moving the upend arm is done by pivoting the arm relative to the support frame. Thus, in such an embodiment, the upend arm, and thus the mast, is pivoted about a single pivot axis when upending the mast. This allows for a simple and robust design of the upend device.

In an alternative embodiment, the upend movement may comprise a composed movement, e.g. comprise translation as well as rotation.

In an embodiment, the pivot axis of the upend device is provided close to the deck, i.e. between the deck and a mast supported in a horizontal position in the upend device, and close to the bottom end of the upend arm. Thus positioning the pivot axis allows for upending the mast above deck, i.e. with the bottom end of the mast in the assembly position located above the deck of the vessel.

In an embodiment, the upend arm comprises:

- a mast support at or near the bottom end thereof, for restraining the mast in a lateral direction and for supporting the mast in a longitudinal direction when in the assembly position; and

- a mast restraint, mounted to the upend arm at or near a top end thereof, for restraining the mast in the lateral direction, and placing the wind turbine mast, in a horizontal position, on an upend arm of the upend device, further comprises receiving the mast in the mast support and the mast restraint and thus engaging the mast at a bottom end thereof and at a location away from the bottom end but also away from the top end of the mast.

In such an embodiment, the mast is engaged at two, spaced apart, locations. However, the top end of the mast is free. Thus, the upend device is provided with an secure grip of the mast, i.e. a grip that does prevent lateral movement and or pivoting movement of the mast relative to the upend device, without engaging large sections of the mast and without engaging the mast at the bottom end and the top end thereof, which would require a long upend arm.

In an embodiment, the drive of the upend device comprises one or more drive arms, wherein the one or more drive arms are with one end pivotable connected to the upend arm and with an opposite end linked to a track, e.g. a skid track or rack, and wherein moving the upend arm comprises moving the opposite end along the track. Using drive arms for upending the upend arm provides a connection, via the drive arm, between the upend arm and the vessel, providing the upend arm with lateral support and thus with additional stability, in particular when the upend device supports a mast in an assembly position.

In an embodiment, the mast is provided with a first and a second connector for connecting to a first and a second hoisting assembly of the crane to the mast, wherein the connectors are provided on opposite sides of the mast. For example, in an embodiment, the two connectors are part of a stability yoke that is mounted to the mast. In a further embodiment, the mast is positioned in the upend device with one connector at the side of the mast facing the deck and the other connector at the side of the mast facing away from the deck. Thus, an imaginary line through the two connectors and through the center of the mast would extend in a direction perpendicular to the surface of the deck. Such an embodiment is in particular beneficial when the crane is set up at a side of the upend device.

In an alternative embodiment, the crane is set up in front of the upend device. In such an embodiment, the mast may be provided with two connectors at opposite sides of the mast, and the mast is positioned in the upend device such that an imaginary line through the two connectors and through the center of the mast would run parallel to the surface of the deck.

In an embodiment, the hoisting wire of the installation crane is connected to the mast via a stability yoke and/or stability wires on opposite sides of the mast, wherein the stability wires are attached to the mast at a bottom end thereof, extend along the mast, and are connected to the mast, preferably above the center of gravity of the combined mast and nacelle and below the upper end of the mast, to keep the mast upright while supporting it at the bottom end thereof.

In an embodiment, the stability yoke and/or the stability wires are preferably mounted to the mast prior to upending. Thus, once the mast is in the assembly position, the stability yoke and stability wires are already in place, and do not need to be mounted. This is beneficial in particular when using a stability yoke because these are mounted on an upper part of the mast, and thus at a significant height above the deck when the mast is in the upright assembly position. According to the second aspect the invention furthermore provides a method for assembly and installation of a wind turbine, more in particular the mast and the nacelle of a wind turbine, on an offshore wind turbine foundation, using a vessel comprising a wind turbine components storage deck, a mast upend device and a wind turbine assembly crane and wind turbine installation crane, wherein the wind turbine assembly crane preferably is also the wind turbine installation crane, the method comprising: transporting a wind turbine mast and a nacelle to a wind turbine installation site on a deck of a vessel, with the wind turbine mast in a horizontal transport position wherein the center of gravity of the wind turbine mast is located close to the deck of the vessel to facilitate transport by vessel; placing the wind turbine mast, in a horizontal position, on an upend arm of the upend device, wherein the upend arm extends between a bottom end and a top end, and along the wind turbine mast, and wherein the upend arm is provided at the bottom end thereof with a mast support that engages the mast at or near the bottom end of the mast and is provided with a mast restraint at a position away from the bottom end of the upend arm, and; upending the wind turbine mast, from the horizontal transport position into a vertical assembly position, by pivoting the upend arm, preferably at the bottom end thereof, using an upend arm drive, supporting the mast in the assembly position, preferably vertically above the deck of the vessel, using the upend arm; lifting a nacelle from the storage deck of the vessel, using a wind turbine assembly crane mounted on the vessel, onto the top end of the wind turbine mast supported in the assembly position by the upend arm, and bolt the nacelle to the wind turbine mast; connecting the hoisting wire of a wind turbine installation crane, which wind turbine installation crane preferably is also the wind turbine assembly crane, to the mast; releasing the top end of the mast by opening the mast restraint and optionally by opening the mast support, and lifting the mast out of the upend device; slewing the installation crane to position the mast above the wind turbine foundation adjacent the vessel, and lowering the mast to install the mast on the wind turbine foundation; disconnecting the hoisting wire of the installation crane from the wind turbine mast.

According to the second aspect, the invention furthermore provides a wind turbine assembly and installation vessel, for assembly and installation of a wind turbine on an offshore wind turbine foundation, wherein the vessel comprises:

- a floating hull;

- a storage deck, for transporting wind turbine components, e.g. multiple masts and nacelles wherein the nacelles are separated from the masts, to a wind turbine installation site where a wind turbine foundation is arranged;

- a wind turbine installation crane, for lifting an assembly of a wind turbine mast and a nacelle onto the wind turbine foundation;

- an upend device, for upending the mast, i.e. for moving the wind turbine mast from a horizontal transport position into a vertical assembly position, and for supporting the wind turbine mast above deck in the assembly position to enable a crane, preferably the installation crane, to mount a nacelle onto a top end of the mast; wherein the upend device comprises;

- a deck mounted support frame;

- an upend arm, moveable supported by the support frame, wherein the upend arm extends along part of the mast when the mast is received in the upend device, and engages the mast at or near a bottom end thereof and away from the bottom end as well;

-a drive for upending the upend arm, e.g. one or more hydraulic cylinders, skid arms, etc. for moving the upend arm and to thus enable the upend device to upend a mast without assistance of the crane.

In an embodiment, the upend arm extends between a bottom end and a top end, and wherein the upend arm at the bottom end is pivotable mounted to the support frame.

In an embodiment, the upend arm comprises: - a mast support at or near the bottom end thereof, for restraining the mast in a lateral direction and for supporting the mast in a longitudinal direction when in the assembly position; and

- a mast restraint, mounted to the upend arm at or near a top end thereof, for restraining the mast in the lateral direction.

In a further embodiment, the upend arm comprises:

- a main frame, the main frame extending between a bottom end and a top end, and the main frame extending along the mast supported by the upend arm.

- a mast support, mounted to the main frame at or near the bottom end thereof, for restraining the mast in a lateral direction and for supporting the mast in a longitudinal direction when in the assembly position; and

- a mast restraint, mounted to the main frame at or near a top end thereof, for restraining the mast in the lateral direction.

In an embodiment, the drive of the upend device comprises one or more skid tracks or racks, and one or more drive arms per skid track or rack, wherein the one or more drive arms are with one end pivotable connected to the upend arm and with an opposite end linked to a skid cart or a pinion drive for moving that end along the skid track or rack respectively.

Alternative drives and/or configurations of these drives may also be used for moving the upend arm.

In an embodiment, the upend device comprises a track and a drive arm, wherein the drive arm is at one end pivotable connected to the upend arm, or to a main frame of the upend arm, and at an opposite track end is provided with a track cart, for moving along the skid track, such that by moving the track end of the arm, the upend arm can be lowered and raised, for example can be pivoted between a position for supporting the mast in a horizontal position, and the assembly position, for supporting the mast in a vertical or upright position to enable assembly of the wind turbine, i.e. to enable mounting a nacelle on the mast.

In an embodiment, the storage deck is provided with multiple mast support cradles, for supporting masts in a horizontal transport position, such that the center of gravity of the wind turbine mast is located close to the deck of the vessel to facilitate transport by vessel, and parallel to each other on the storage deck.

In a further embodiment, the cradles are provided with a recess for stability wires extending along the mast. Thus, the masts can be stored in the cradles with stability wires for hoisting the mast with the crane, and possibly in combination with a stability yoke already mounted to the mast. Thus, directly after upending the mast, the crane can be connected to the stability wires and/or the stability yoke.

In an embodiment, the upend device only engages a lower part of a wind turbine mast to be upended, such that an upper part, preferably at least one third of the mast, extends above the upend device, when the upend device supports the mast in the assembly position. Engaging only the lower end of the mast, preferably at two locations, i.e. one at the bottom end of the mast and one away from the bottom end of the mast, allows for using the upend device with the extra-long masts of high capacity wind turbines.

In an embodiment, the upend device is mounted on the storage deck, such that the upend arm is parallel to masts that are stored on the storage deck, when the arm is in a lowered position for receiving a mast in a horizontal position.

In an embodiment, the upend device is configured to engage the lower end of the wind turbine mast, preferably at least a lowest one third of the wind turbine mast, while the upper end of the mast, preferably at least an upper most one third of the wind turbine mast, extends above the upend device when supported in the assembly position.

In an embodiment, the upend arm comprises a frame that extends along the wind turbine mast and that is positioned below the mast, i.e. between the deck and the mast, when it supports the mast in a horizontal position. In an alternative embodiment, the upend arm comprises a frame having two legs that extend along the wind turbine mast on opposite sides thereof, such that the mast, i.e. a lower part of the mast, is received between the two legs of the frame.

In an embodiment, the upend arm comprises an A-shaped frame, comprising two legs and multiple cross beams connecting the legs, and preferably a mast restraint and a mast support are connected to the A-frame at a top end and at the bottom end thereof, respectively.

In an embodiment, the mast restraint is ring shaped and comprises one or more pivotable doors incorporated in the ring shape, wherein the one or more pivotable doors enable the ring shape to be opened for receiving the mast within inside the ring shaped restraint.

In an embodiment, the restraint is provided with recesses for passing stability wires between the mast and the restraint, such that the mast can be supported with stability wires, and preferably a stability yoke, already mounted. Thus, the mast can be connected to the hoisting assemblies of the crane directly after upending. In an embodiment, the mast restraint is pivotable connected to the upend arm, such that the restraint can be pivoted between an active position, in which it extends perpendicular to a longitudinal axis of the upend arm, and a passive position, in which it extends parallel to the longitudinal axis of the upend arm.

In an embodiment, the support is configured to be coupled with a mast section, e.g. a mast connector section, to support the mast when in the assembly position and to restrain movement of the mast in a lateral direction, i.e. in a direction perpendicular to a longitudinal axis of the mast. In such an embodiment, the mast is to be provided with a mast connector at the bottom end thereof. Such a mast connector can be configured for providing a quick connection with a foundation, or with a foundation connector mounted on the floating foundation, when installing the mast on the wind turbine foundation.

In an embodiment, the mast can be provided with a temporarily support, for example fixed around the mast at a bottom end thereof, that is configured to be coupled with the mast or a support of the mast.

The second aspect of the invention furthermore provides a use of a vessel according to the invention in a method according to the invention, preferably in combination with an assembly and installation crane according to the first aspect of the invention.

The second aspect of the invention furthermore provides an assembly comprising a vessel according to the invention, a wind turbine mast, nacelle, and wind turbine connector mounted to a bottom end of the mast, wherein the wind turbine connector and a mast support of the upend device are configured to cooperate, to enable a simple and robust connection between the upend device, preferably the support of the upend arm of the upend device, and the mast.

The second aspect of the invention furthermore provides a wind turbine assembly and installation vessel, for assembly and installation of a wind turbine, more in particular the mast and the nacelle of a wind turbine, on an offshore wind turbine foundation, wherein the vessel comprises:

- a floating hull;

- a wind turbine components storage deck, for storing components of a wind turbine, e.g. a mast and a nacelle, to enable the vessel to transport the wind turbine components to a wind turbine installation site; - a crane, for hoisting wind turbine components stored on the wind turbine component storage deck, and preferably for lifting a wind turbine mast provided with a nacelle onto a wind turbine foundation;

- a upend device, for upending the mast of a wind turbine, i.e. for moving the mast from a horizontal transport position into a vertical assembly position, and for supporting the mast above deck in the assembly position to enable the crane to mount a nacelle onto a top end of the mast; wherein the upend device comprises;

- a deck mounted support frame;

- an upend arm, extending between a bottom end and a top end, wherein the upend arm at the bottom end is pivotable mounted to the support frame;

- a mast support, mounted to the upend arm at or near the bottom end thereof, for restraining the mast in a lateral direction and for supporting the mast in a longitudinal direction when in the assembly position; and

-a drive for upending the upend arm, e.g. one or more hydraulic cylinders, skid arms, etc. to enable the upend device to upend a mast without assistance of the crane

It will be appreciated that in a further embodiment according to the invention, the crane for the assembly and installation of offshore wind turbines as discussed above can be combined with an upend device according to the invention, to provide a vessel and/or a method that further improves on the prior art. All embodiments as discussed above of the upend device according to the second aspect of the invention, as well as each and every other technical feature addressed with reference to the assembly and installation crane according to the first aspect of the present invention, and vice versa, can be combined.

According to a third aspect, the invention furthermore provides a suppressor arm, a suppressor structure comprising at least two suppressor arms and a method for controlling movement of a floating foundation relative to a floating vessel to enable mounting an offshore wind turbine, or part thereof, on the floating foundation from the vessel.

A suppressor structure according to the third aspect of the invention is configured to be mounted on, or is mounted on, a vessel for controlling movement of a floating foundation relative to the vessel, to enable mounting an offshore wind turbine, or part thereof, on the floating foundation from the floating vessel, wherein the suppressor structure comprises at least two suppressor arms that are each configured to project from the vessel in a floating foundation engagement position, in which position the suppressor arms are positioned on opposite sides of a column of the floating foundation, onto which column the wind turbine is to be mounted, and wherein the suppressor arms are provided with a floating foundation engagement device for engaging the floating foundation, preferably for engaging a suppressor coupling provided on the floating foundation or on a floating foundation connector mounted on the floating foundation, and for exerting a downward force, i.e. a force directed in the z-direction, onto said floating foundation to reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the z direction.

The suppressor arms according to the third aspect of the invention are thus configured to support an upward force of the floating foundation, and thus enable pushing downward on the floating foundation using the weight of the vessel to control the movement of the floating foundation in the z direction.

The suppressor arms, and the method utilising the suppressor arms, thus enable an effective and efficient way for controlling the movement of a floating foundation relative to a vessel, and thus facilitate installing a wind turbine on the floating foundation using a crane or similar wind turbine support construction mounted on that vessel.

In an embodiment, the suppressor structure comprises an engagement device drive for providing the engagement device with z compensation, i.e. for actively moving the engagement device, or the end of the suppressor arms supporting the engagement device, to eliminate movement of the engagement device relative to the floating foundation in the z direction,

In an embodiment of the suppressor structure, the engagement device drive is furthermore configured to dampen the movement of the floating foundation relative to the vessel in the z direction, when the engagement device engages the floating foundation, to reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the z direction and preferably to thus fully connect the suppressor arm with the floating foundation. It is submitted that the suppressor arm and the suppressor structure are configured to dampen, and preferably for exerting a downward force, i.e. a force directed in the z-direction, onto a floating foundation and to thus reduce, and preferably eliminate, the movement of the floating foundation relative to the vessel in the z direction, the suppressor arm and suppressor structure can thus be used in combination with a foundation clamp configured for engaging a floating foundation and for subsequently dampen movement of that foundation relative to the vessel in the xy plane, i.e. in the horizontal plane, wherein the clamp allows for movement in the z-direction, i.e. in the vertical direction.

As an alternative, or in addition to such a foundation clamp, in an embodiment, the suppressor structure is configured for moving the beams in an x- and y-direction relative to a deck of the vessel the suppressor structure is mounted on, to enable the suppressor beams, and thus the foundation engagement device, to move with the floating foundation in the x and y direction, preferably wherein the range of movement in the x-direction and y-direction is at least 2m preferably is at least 3m, for example is 6m.

In a further embodiment, the suppressor structure comprises an x-y drive for moving the suppressor beams, and thus the foundation engagement device, in the x- and y-direction,

In yet a further embodiment, the x-y drive is configured to enable passive movement of the suppressor beams, and thus of the foundation engagement device, in the x- and y-direction, the movement of the floating foundation causing the passive movement of the suppressor beams and thus of the foundation engagement device.

In an embodiment, the suppressor structure comprises a suppressor arms control system and one or more sensors to monitor the movement of the foundation relative to the vessel.

In an embodiment, the support structure is configured to dampen movement of the floating foundation in the x- and y-direction relative to the vessel, e.g. comprises one or more damping cylinders and/or an x-y drive configured to dampen movement of the suppressor beams in the x- and y- direction.

In an embodiment of the suppressor structure, the foundation engagement device comprises a ring shaped frame for engaging the floating foundation around a mount for attaching the mast of the wind turbine to the floating foundation. In a further embodiment of the suppressor structure, the ring shaped frame is provided with one or more pivotable doors incorporated in the ring shaped frame, wherein the one or more pivotable doors enable the ring shaped frame to be opened for receiving the mount for attaching the mast and/or the mast inside the ring shaped frame, and to to allow for moving the mount for attaching the mast and/or the mast of the wind turbine into and out of the ring shaped frame in a lateral direction relative to the ring shaped frame.

61. Suppressor structure according to one or more of the claims 51-60, wherein the suppressor arms are configured for engaging a suppressor coupling provided on the floating foundation, e.g. a suppressor coupling provided on a floating foundation connector mounted on the floating foundation.

In an embodiment, the foundation connector is provided with an abutment surface for engagement by the floating foundation engagement device of the suppressor arm.

In an embodiment of the suppressor structure, the suppressor beams each have a mass of at least 800mt preferably have a mass of at least 900 mt, for example have a mass of 1000mt.

According to the third aspect, the invention furthermore provides a vessel comprising a suppressor structure according to the third aspect of the invention.

In an embodiment of the vessel according to the third aspect of the invention, the suppressor structure is mounted on the vessel with the two suppressor arms positioned on opposite sides of the crane, for engaging a floating foundation. According to the third aspect, the invention furthermore provides a method for controlling movement of a floating foundation relative to a floating vessel to enable mounting an offshore wind turbine, or part thereof, on the floating foundation from the vessel, wherein the vessel is provided with a wind turbine installation crane for landing the wind turbine, or part thereof, on the floating foundation, and with a suppressor structure for exerting a downward force, i.e. a force directed in the z-direction, onto the floating foundation. wherein the suppressor structure comprises at least two suppressor arms that are each configured to project from the vessel in a floating foundation engagement position, in which position the suppressor arms are positioned on opposite sides of a column of the floating foundation, onto which column the wind turbine is to be mounted, and wherein the suppressor arms are provided with a floating foundation engagement device for engaging a floating foundation, preferably for engaging a suppressor coupling provided on the floating foundation or on a floating foundation connector mounted on the floating foundation, and for exerting a downward force, i.e. a force directed in the z-direction, onto said floating foundation to reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the z direction, wherein the method comprises the steps:

- positioning the vessel adjacent the floating foundation;

- optionally, positioning the suppressor arms in the floating foundation engagement position;

- providing the engagement device of the suppressor arms with z compensation, i.e. actively moving the engagement device, or the end of the suppressor arms supporting the engagement device, to eliminate movement of the engagement device relative to the floating foundation in the z direction;

- engaging the floating foundation with the engagement device, preferably engaging a suppressor coupling provided on the floating foundation, while providing z compensation;

- ending the z compensation and starting with damping the movement of the floating foundation relative to the vessel in the z direction; - increasing the z damping to further reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the z direction and preferably thus fully connect the suppressor arms with the floating foundation.

In an embodiment, the method comprises:

- moving the wind turbine, or part thereof, from a position above the deck to a position above the floating foundation, preferably while using a ballast system of the vessel to keep the vessel even keel, and supporting the wind turbine above the floating foundation using the wind turbine installation crane;

- removing ballast water from the floating foundation, preferably from the column of the floating foundation onto which the wind turbine is to be mounted, to create an upward force of the floating foundation against the suppressor arms, wherein the upward force preferably is similar to or larger than the gravitational force of the wind turbine supported by the crane;

- landing the wind turbine on the floating foundation; and

In an embodiment, the method, prior to engaging the floating foundation with the engagement device, furthermore comprises:

- providing the suppressor beams, and thus the foundation engagement device, with xy compensation, i.e. actively moving the suppressor beams to eliminate movement of the suppressor beams, and thus of the foundation engagement device, relative to the floating foundation in the xy plane;

- engaging the floating foundation with the foundation engagement device, preferably engaging a foundation connector mounted on the floating foundation with the foundation engagement device, while providing xy compensation;

- ending the xy compensation of the foundation engagement device and starting with xy damping, i.e. dampen the movement of the floating foundation relative to the vessel in the xy plane; and - increasing the xy damping to further reduce and to preferably eliminate the movement of the floating foundation relative to the vessel in the xy plane, and preferably fully connect the foundation engagement device with the floating foundation.

In an embodiment of the method, the mass of the water removed from the floating foundation is at least similar, preferably larger than the mass of the wind turbine supported by the wind turbine installation crane above the floating foundation, e.g. the mass of the water is about 21 mt, such that the floating foundation pushes upwards against the abutment device with a force similar to or larger than the gravitational force of the wind turbine supported by the crane.

It is submitted that the method according to the further aspect of the invention is described for mounting a wind turbine mast with a nacelle mounted thereon on a floating foundation. The method may also be used for mounting only a wind turbine mast, or for mounting a fully assembled wind turbine, i.e. a wind turbine mast provided with a nacelle provided with blades, onto a wind turbine foundation, in particular a floating wind turbine foundation.

It is submitted that the suppressor structure according to the third aspect of the invention can be used with a crane according to the first aspect of the invention, or with any alternative type of crane. Furthermore, the suppressor structure according to the third aspect of the invention may be used to enable mounting a wind turbine mast with a nacelle mounted thereon on a floating foundation, and for mounting only a wind turbine mast, and for mounting a fully assembled wind turbine, i.e. a wind turbine mast provided with a nacelle provided with blades.

It will be appreciated that all embodiments of the suppressor structure according to the third aspect of the invention, as well as each and every other technical feature addressed with reference to the other aspects of the invention, can be combined. For example, according to the invention, a crane according to the first aspect of the invention can be used in combination with a suppressor structure according to a third aspect of the invention.

Whilst primarily presented for illustrative purposes with reference to one or more of the figures, any of the technical features addressed below may be combined with any of the dependent or independent claims of this application either alone or in any other technically possible combination with one or more other technical features.

In the drawings:

Fig. 1 shows a side view of an exemplary embodiment of a crane according to the invention mounted on a vessel, wherein the crane is in a installation configuration and is supporting a nacelle above a wind turbine mast in an upright position;

Fig. 2 shows a side view of the crane of Fig. 1 in a installation configuration, having hoisting wires attached to the mast of the wind turbine, and with the nacelle mounted on the wind turbine mast;

Fig. 3 shows a side view of the crane of Fig. 1 in an installation configuration supporting the wind turbine mast, with the nacelle mounted thereon, in an installation position above a floating wind turbine foundation;

Fig. 4 shows a frontal view of the crane of Fig. 1 in an installation configuration, supporting the wind turbine mast and the nacelle mounted thereon, in an installation position above the floating foundation.

Fig. 5 shows a frontal view and a side view of the boom and jib of the crane of Fig. 1 in isolation, the jib being positioned parallel to the boom;

Fig. 6 shows a top view of the vessel according to the invention, with only the crane base of a crane according to the invention depicted;

Fig. 7 shows a side view of another exemplary embodiment of a crane according to the invention, wherein a jib of the crane is lowered into a knuckle boom position relative to a boom of the crane; Fig. 8 shows a side view of a crane with an alternative jib design in the assembly configuration;

Fig. 9 shows a side view of the crane of Fig. 8 in the installation configuration;

Fig. 10 shows a rear view of a boom and jib in isolation;

Fig. 11 shows a side view of the crane of Fig. 8 in a hoisting configuration;

Fig. 12 shows a side view of an exemplary embodiment of an upend device according to a second aspect of the invention, supporting a mast in a horizontal position;

Fig. 13 shows a side view of the upend device of Fig. 12, supporting a mast in an assembly position; and

Fig. 14 shows a frontal view of the upend device of Fig 12, with part of the mast in see through to show a frame of the upend device, supporting a mast in the assembly position.

Figure 1 shows a side view of an exemplary embodiment of a crane 1 for the assembly and installation of offshore wind turbines according to the invention, mounted on a vessel 10, in the embodiment shown a semisubmersible vesslOel.

According to the invention, the crane 1 can be switched between an assembly configuration, in which it is depicted in figure 1, for mounting a nacelle 2 on an upright mast wind turbine mast 3, and an installation configuration, in which it is depicted in figure 2, for mounting the wind turbine mast 3 with the nacelle 2 mounted thereon, on a foundation 4.

The crane 1 comprises a crane base 5, a crane housing 6 and a slew bearing 7. The slew bearing 7 is provided between the crane base 5 and the crane housing 6, to enable the crane housing 6 to slew about a vertical slew axis 8.

The crane 1 furthermore comprises a first hoisting assembly and a second hoisting assembly for hoisting a mast of a wind turbine, and a third hoisting assembly for hoisting a nacelle.

Each of these hoisting assemblies comprises a winch, an associated hoisting wire 11 , 12, 13 and a load connector 14, 15, 16.

The crane 1 furthermore comprises a boom 9 and a boom luffing assembly 17 for luffing the boom 9 between a hoisting position, depicted in figure 1, for supporting the mast of a wind turbine, and a clearance position, depicted in figure 2, in which the boom 9 is retracted relative to the lifting position of the boom 9.

The boom 9 extends between a base end 18 and a head end 19. The boom 9 is at the base end 18 pivotable mounted to the crane housing 6, and has at the head end 19 a left support arm 20 supporting a left crown block 21 for the first hoisting assembly and a right support arm 22 supporting a right crown block 23 for the second hoisting assembly. The left crown block 21 and the right crown block 23 are spaced apart such that between the left and the right crown block there is a mast receiving space 24. The mast receiving space 24 is dimensioned such that the mast of a wind turbine can be supported between the left and the right support arm 20, 22 by the first and the second hoisting assembly in the mast receiving space 24

The boom luffing assembly 17 comprises a boom luffing winch and an associated boom luffing wire 25. The luffing winch is mounted on the crane housing 6 and the boom luffing wire 25 extends between the luffing winch and the boom 9, to enable pivoting of the boom between the hoisting position, for supporting the mast of the wind turbine, and the clearance position, in which the boom is retracted relative to the lifting position.

The boom 9 is, at the head end 19 of the boom 9, about level with a base end 26 of the left support arm 20 and a base end 27 of the right support arm 22, provided with a jib 29.

According to the invention, the jib 29 can be moved relative to the boom 9 between a hoisting position, depicted in figure 1 , and a clearance position, depicted in figure 2.

When in the hoisting position, the jib 29 enables mounting a nacelle on a wind turbine mast using the third hoisting assembly.

In the clearance position, the jib 9 is retracted relative to the hoisting position, to enable the crane to support the mast of the wind turbine with a nacelle mounted thereon, using the first and second hoisting assembly.

Thus, when the crane 1 according to the invention is in the assembly configuration, the boom 9 is in the clearance position and the jib 29 is in the hoisting position, and when the crane 1 is in the installation configuration, the boom 9 is in the hoisting position and the jib 29 is in the clearance position.

According to the invention, the crane 9 can thus be used for both assembling, i.e. mounting a nacelle on top of a wind turbine mast, and installing, i.e. mounting the mast with nacelle on a foundation, large size wind turbines, i.e. wind turbines of 15mw or more. Furthermore, the crane allows for assembly of large size wind turbines at the installation location. Therefore, the wind turbine does not need to be transported in an assembled and/or upright position, which facilitates transport. Figure 3 shows the crane 9 supporting the mast with nacelle in an installation position above a floating foundation 28.

In the preferred embodiment shown, the first hoisting assembly and the second hoisting assembly each comprise a heave compensation mechanism to compensate for sea induced vertical movement of the mast 3 with nacelle 2 supported by the crane 1 relative to the floating foundation 28. Thus, the crane 1 can safely land the wind turbine, i.e. mast with nacelle, on the foundation 28.

Once the combined mast 3 and nacelle 2 are installed on the wind turbine foundation 28, a dedicated crane is used for mounting the blades to the wind turbine.

Figure 4 shows a frontal view of the crane 1 , supporting the wind turbine mast 3 and the nacelle 2 mounted thereon, in the installation position above the floating foundation 28.

The hoisting wires 11,12 of the first and second hoisting assembly are provided on opposite sides of the wind turbine mast 3. The hoisting wires extend from the left and right crown block 21, 23, via a wire guide 51 mounted above the center of gravity of the mast, towards fastening points 52 at the bottom end of the wind turbine mast. Thus, the hoisting wires 11 ,12 support the weight of the wind turbine mast and nacelle at the lower end of the mast, and are held adjacent the mast by the wire guide 51 above the center of gravity of the combined mast and nacelle. This configuration for hoisting a wind turbine is known in the prior art, and allows for a very stable support of the wind turbine, and of the combined mast and nacelle.

In the exemplary embodiment shown in figure 4, the boom 9 comprises two parallel legs 30 that extend between the base end of the boom 18 and the head end of the boom 19. The legs 30 are connected by cross beams 31 at regular intervals, providing the boom with an Flshape.

Figure 5 shows a frontal view and a side view of the boom 9 and jib 29 of the crane 1 in isolation, the jib 29 being positioned parallel to the boom 9. In the embodiment shown, the jib 29 has a length of at least of at about four fifth, i.e. 80%, the length of the boom.

In the embodiment shown, the support arms 26, 27 are an integral part of the boom 9, i.e. form a continuation of the construction of the boom. The parallel legs 30 of the boom including the support arms 26,27 are a continuous construction, which provides a simple and rigid construction.

Furthermore, in the embodiment shown, the left support arm 26 and the right support arm 27 are at a top end provided with transverse, in the particular embodiment shown triangular shaped, structures 32, that provide the boom with a hammerhead shape when seen in side view. The arms 26,27 thus are not an extension of the legs 30 of the boom 9, but extend away from the boom at a frontside 33 and at a backside 34 thereof. The transverse structures 32 of the arms 26,27 support the crown blocks 21 ,23 at the front side of the boom and at the back side of the boom support the boom luffing wire of the luffing assembly 17.

The boom 9 is pivotably mounted to the crane housing 6 such that the boom can pivot about a boom pivot axis 35, and the jib is pivotably mounted to the boom such that the jib can pivot about a jib pivot axis 36. The boom pivot axis 35 is parallel to the jib pivot axis 36.

In the particular embodiment shown, the jib 29 is pivotably mounted to the boom 9 at the head end 19 thereof. Furthermore, the boom pivot axis 35 and the jib pivot axis 36 define a plane, and the jib is on a first side of this plane when in the assembly position, and is on an opposite, second side of this plane when in the installation position.

The crane 1 comprises a jib luffing winch and an associated jib luffing wire 37. The jib luffing wire 37 extends between the jib luffing winch and the jib, and in the embodiment shown passes over a gantry 38 mounted on the crane housing 6, to enable pivoting of the jib 29 relative to the boom 9 between the hoisting position and the clearance position.

Furthermore, in the embodiment shown, the jib 29 is provided with multiple luffing wire spacers 38, mounted on the jib at the pivot axis and extending in a radial direction, for spacing the luffing wire relative to the pivot axis and thus provide the lifting system with leverage for lifting the jib. It is submitted that the use of luffing wire spacers in this way is generally known in the prior art and is in particular utilised with knuckle boom type cranes. It is furthermore noted that the luffing wire where it is to be engaged by the luffing wire spacers may be embodied as a chain or metal rods.

Proving the jib luffing wire spacers allows for the jib to be pivoted forward, i.e. to be lowered, to provide the crane with a knuckleboom configuration, shown in figure 7, for lifting objects close to the deck surface, for example for moving objects between the vessel and a supply vessel. In the embodiment shown, the boom 9 is at the head end thereof provided with a jib stop 39, which jib stop is configured to stop the jib 29 when it is moved into the clearance position. Thus when the jib is pulled by the jib luffing assembly from the assembly position shown in g figure 1 into the clearance position shown in figure 2, the jib is received in the jib stop. This procedure may be performed with the boom in a lowered position, to prevent gravity from pulling the jib towards the jib stop. Also, when the jib is to be moved out of the clearance position. In addition or as an alternative, the jib stop is configured to engage the jib while it is moved out of the hoisting position and provides pressure to the jib while it is pulled by the jib luffing assembly into the clearance position to prevent gravity from moving the jib.

Furthermore, in the embodiment shown, the boom is provided with a jib actuator, in the embodiment shown in the form of cylinders integrated in the jib stop, for pushing the jib out of the clearance position and towards the hoisting position.

Furthermore, in the embodiment shown, the boom is provided, at the head end thereof, with a jib lock, for securing the jib relative to the boom in the clearance position. Thus, the jib can not move relative to the boom while the crane is used for installing a wind turbine.

In the embodiment shown, when the crane 1 is in the assembly configuration, the boom 9 is in a substantially vertical position, i.e. is substantially parallel to a slew axis of the slew bearing of the crane. The crane 1 is provided with a boom stop 40, which boom stop is configured to stop the boom when the boom is moved into the clearance position.

Furthermore, the crane 1 is provided with a boom lock, for securing the boom relative to the crane housing in the clearance position.

Furthermore, in the embodiment shown, the crane housing is provided with a boom actuator, e.g. one or more cylinders to push the boom or one or more winches to pull the boom, for moving the boom out of the clearance position and towards the hoisting position.

In the embodiment shown, the crane 1 is mounted on a semisubmersible vessel 10. A top view of the vessel 10 is shown in figure 6. The vessel has a storage deck 41 for transport of wind turbine components, in the embodiment shown for supporting a wind turbine masts 3 having a length of at least 100 meters in a horizontal position and nacelles 2 to be mounted on the wind turbine masts. According to the invention, when the crane is in the assembly position the deck height of the head end of the boom of the crane is less than the deck height of the wind turbine mast supported in the upright position on the deck of the vessel, see for example figure 1, such that the boom can lift the mast with the top end thereof extending above the top end of the boom.

In the embodiment shown, the storage deck is provided with upend tracks 42 for guiding an upend trolley 43 for supporting the bottom end 44 of a wind turbine mast, to enable the crane 1 for upending masts. For upending, the crane 1 is set up in the assembly configuration, and the hoisting assemblies are coupled to a top end 45 of the mast supported in an upend location 46 above the upend track. While lifting the top end of the mast, the bottom end of the mast is guided by the upend trolley along the upend track, until the mast is in the upright position. The mast is subsequently secured in this position, preferably using the upend trolley, to enable the crane to hoist a nacelle on top of the mast.

It is noted that the crane can also be sued for moving masts from a storage location on the deck to an upend location above the upend track. In the embodiment shown, the crane may be set up in the knuckle boom configuration for moving the masts to the upend location.

In the embodiment shown, the vessel comprises a foundation gripper 47, for engaging a floating foundation and for damping movements in the horizontal plane of the floating foundation relative to the vessel, preferably for substantially eliminating movements in the horizontal plane relative of the floating foundation relative to the vessel.

Furthermore, in the preferred embodiment shown, the vessel 1 is provided with at two suppressor arms 48. The suppressor arms 48 are configured to project from the vessel in a floating foundation engagement position, in which they are depicted in figure 6. The suppressor arms are provided with a floating foundation engagement device 53 for engaging with the floating foundation. In the preferred embodiment shown, the floating foundation is provided with a floating foundation connector 49, see for example figure 4, mounted on the floating foundation 28. The floating foundation connector 49 is mounted on the floating foundation and provides the floating foundation with two supports 50 for engagement by the respective suppressor arms. In an alternative embodiment, the supports for engagement with the suppressor arms can also be provided directly on the floating foundation.

When the suppressor arms 48 are in engagement with the floating foundation 28, they can exert and for exerting a downward force, i.e. a force directed in the z-direction, onto the floating foundation to reduce, preferably eliminate, vertical movement of the floating foundation relative to the vessel.

In the embodiment shown, the two suppressor arms 48 are part of a suppressor structure 54 that is mounted on the vessel for controlling movement of a floating foundation relative to the vessel. The suppressor structure comprises the two suppressor arms, that each project from the vessel in a floating foundation engagement position. In this floating foundation engagement position, the suppressor arms are positioned on opposite sides of the floating foundation, more in particular on opposite sides of the column 55 whereon the wind turbine is to be mounted. Furthermore, the suppressor arms are provided with a floating foundation engagement device for engaging a floating foundation, and for exerting a downward force, i.e. a force directed in the z-direction, onto said floating foundation.

It is submitted that the suppressor structure can be used with a crane according to the invention, or with any alternative type of crane. Furthermore, the suppressor structure can used for mounting any load on a floating wind turbine foundation, for example for mounting a wind turbine mast with a nacelle mounted thereon on a floating foundation, and for mounting only a wind turbine mast, or for mounting a fully assembled wind turbine, i.e. a wind turbine mast provided with a nacelle provided with blades.

The crane 1 mounted on the semisubmersible vessel 10 allows for a method for assembling and installing an offshore wind turbine according to the invention In an embodiment, the method comprises:

- positioning the crane 1 in the assembly configuration, depicted in figure 1;

- using the crane 1 in the assembly configuration to up end a wind turbine mast 3 located on the deck of the vessel 10 in the upend location 46, depicted in figure 6;

- using the crane 1 in the assembly configuration to mount a nacelle on the upended wind turbine mast, depicted in figure 1;

- positioning the crane in the installation configuration, depicted in figure 2; and

- hoisting the mast 3 with the nacelle 2 from the vessel 10 and onto the floating foundation 4, depicted in figure 3.

Figure 8 shows a side view of another exemplary embodiment of a crane 101 for the assembly and installation of offshore wind turbines according to the invention, mounted on a vessel 110, in the embodiment shown a semisubmersible vessel. According to the invention, the crane 101 can be switched between an assembly configuration, in which it is depicted in figure 8, for mounting a nacelle 102 on an upright wind turbine mast 103, and an installation configuration, in which it is depicted in figure 9, for mounting the wind turbine mast 103 with the nacelle 102 mounted thereon, on a foundation 4.

The crane 101 comprises a first hoisting assembly and a second hoisting assembly for hoisting a mast of a wind turbine, and a third hoisting assembly for hoisting a nacelle. Each of these hoisting assemblies comprises a winch, an associated hoisting wire 111 , 112, 113 and a load connector 114, 115, 116.

The crane 1 furthermore comprises a boom 109 and a boom luffing assembly 117 for luffing the boom 109 between a hoisting position, depicted in figure 9, for supporting the mast of a wind turbine, and a clearance position, depicted in figure 8, in which the boom 109 is retracted relative to the lifting position of the boom.

According to the invention, the crane comprises a jib 129 that can be moved relative to the boom 109 between a hoisting position, depicted in figure 8, and a clearance position, depicted in figure 9.

When in the hoisting position, the jib 129 enables mounting a nacelle on a wind turbine mast using the third hoisting assembly.

In the clearance position, the jib 109 is retracted relative to the hoisting position, to enable the crane to support the mast of the wind turbine with a nacelle mounted thereon, using the first and second hoisting assembly.

Fig. 10 shows a rear view of the boom 109 and the jib 129 in isolation.

The boom 109 extends between a base end 118 and a head end 119. The boom 109 has at the head end 19 a left support arm 120 supporting a left crown block 121 for the first hoisting assembly and a right support arm 122 supporting a right crown block 123 for the second hoisting assembly. The left crown block 121 and the right crown block 123 are spaced apart such that between the left and the right crown block there is a mast receiving space.

In the embodiment shown, the boom has an A-frame, or H-frame, comprising two parallel legs and multiple cross beams. This A-frame shape allows supporting the left and the right crown block, and for a triangular shaped jib, see figure 10. The crane 101 comprises a jib luffing winch and an associated jib luffing wire 137. The jib luffing wire 137 extends between the jib luffing winch and the jib, and in the embodiment shown passes over a gantry 138 mounted on the crane housing 106, to enable pivoting of the jib 129 relative to the boom 109 between the hoisting position and the clearance position.

Furthermore, in the embodiment shown, the jib 129 is provided with multiple luffing wire spacers 138, mounted on the jib at the pivot axis and extending in a radial direction, for spacing the luffing wire relative to the pivot axis and thus provide the lifting system with leverage for lifting the jib. It is submitted that the use of luffing wire spacers in this way is generally known in the prior art and is in particular utilised with knuckle boom type cranes. It is furthermore noted that the luffing wire where it is to be engaged by the luffing wire spacers may be embodied as a chain or metal rods.

In the embodiment shown, the boom 109 is at the head end thereof is provided with a jib stop 139, which jib stop is configured to stop the jib 129 when it is moved into the clearance position. Thus when the jib is pulled by the jib luffing assembly from the assembly position shown in figure 8 into the clearance position shown in figure 9, the jib is received in the jib stop. The jib comprises hydraulic cylinders that resiliently receive the jib.

The jib stop is configured to receive the jib when the jib is pulled through the vertical, after which the luffing wire can no longer support the jib, and to prevent the jib from falling into the clearance position. In addition the jib stop is, more in particular the hydraulic cylinders of the jib stop are, configured to push the jib out of the clearance position and through the vertical, such that the jib luffing assembly can again be used for positioning the jib.

Figure 11 shows a side view of the crane of figure 8 in a hoisting configuration. In this particular configuration the boom is in a substantially upright position and the jib in a substantially horizontal position.

Figures 12-14 show an exemplary embodiment of a wind turbine assembly and installation vessel 60 with an upend device 61 according to the second aspect of the invention.

Figure 12 shows a side view of an exemplary embodiment of the upend device 61 , supporting a mast 62 in a horizontal position. Figure 13 shows a side view of the upend device 61 supporting the mast 62 in an assembly position. In these figures only part of the vessel is shown. For example the hoisting crane, which is shown in figure 14, is not depicted in figures 12 and 13.

The wind turbine assembly and installation vessel 60 is configured for assembly and installation of a wind turbine on an offshore wind turbine foundation.

The vessel 60 comprises a floating hull 63, a storage deck 64, a wind turbine installation crane 65 and an upend device 61.

The storage deck 64 enables transporting wind turbine components, e.g. multiple masts and nacelles, wherein the nacelles are separated from the masts, to a wind turbine installation site where the wind turbine foundation is arranged.

The wind turbine installation crane 65 is configured for lifting an assembly of a wind turbine mast and a nacelle onto the wind turbine foundation. In the particular embodiment shown, the wind turbine assembly and installation crane is a crane according to the first aspect of the invention.

The upend device 61 is configured for upending the mast 62, i.e. for moving the wind turbine mast 62 from a horizontal position into a vertical assembly position. The former is shown in figure 12, the latter is shown in figures 13 and 14.

The upending device 61 is furthermore configured for supporting the wind turbine mast 62 above the deck 64 of the vessel 60 in the assembly position. This assembly position allows for the crane 60 to mount a nacelle 67 onto a top end 68 of the mast 62. The latter is shown in figure 14.

The upend device 61 comprises a deck mounted support frame 69, an upend arm 70 and a drive 71.

The upend arm 70 is moveable supported by the support frame 69, and extends along part of the mast 62 when the mast is received in the upend device. The upend arm extends between a bottom end 73 and a top end 74, and is in the embodiment shown at the bottom end pivotable mounted to the support frame 69.

The upend arm 70 engages the mast at or near a bottom end 72 thereof and away from the bottom end as well. In the embodiment shown, the upend arm comprises a mast support 75 and a mast restraint 76.

The mast support 75 is provided at the bottom end 73 of the upend arm for restraining the mast 62 in a lateral direction and for supporting the mast in a longitudinal direction when in the assembly position.

The mast restraint 76 is mounted to the upend arm 70 at a top end 74 thereof, for restraining the mast in the lateral direction.

The upend device is provided with drive 71 for upending the upend arm 70, i.e. for moving the upend arm, and to thus enable the upend device to upend a mast without assistance of the crane.

In the particular embodiment shown, the upend drive 71 of the upend device comprises three tracks 77 and three drive arms 78, one per track. The drive arms 78 are with one end pivotable connected to the upend arm 70 and with an opposite end linked to a cart 79 for moving that end along the track 77.

In the preferred embodiment shown, the upend device 61 only engages a lower part of a wind turbine mast 62 to be upended. The upper part of the mast 62 extends above the upend device, when the upend device supports the mast in the assembly position.

The storage deck is provided with multiple mast support cradles 80, for supporting masts 62 in a horizontal transport position, such that the center of gravity of the wind turbine mast is located close to the deck 81 of the vessel 60 to facilitate transport by vessel, and parallel to each other on the storage deck 64.

In the embodiment shown, the upend device 61 is mounted on the storage deck 64, such that the upend arm 70 is parallel to masts that are stored on the storage deck, when the arm is in a lowered position for receiving a mast in a horizontal position.

Furthermore, in the embodiment shown, the upend arm 70 comprises an A-shaped frame 82, comprising two legs 83 and multiple cross beams 84 connecting the legs. The mast restraint 76 and the mast support 75 are connected to the A-frame at a top end and at the bottom end thereof, respectively. Figure 14 shows a frontal view of the upend device 61 , with part of the mast 62 in see through to show the A-shaped frame 82 of the upend device 61 , supporting the mast 62 in the assembly position.

Also, in the embodiment shown, the mast support 75 is configured to be coupled with a mast connector section 85, to support the mast when in the assembly position and to restrain movement of the mast in a lateral direction, i.e. in a direction perpendicular to a longitudinal axis of the mast. The mast connector section is configured to cooperate with the upend arm, and is configured to couple with the foundation onto which the mast is to be installed.

The wind turbine assembly and installation vessel 60 being provided with an upend device 61 enables a method according to the second aspect of the invention, i.e. a method for assembly and installation of a wind turbine on an offshore wind turbine foundation, using a vessel comprising a storage deck, a mast upend device and a wind turbine assembly crane.

The method comprises the following steps.

- Transporting on the storage deck of the vessel a wind turbine mast and a nacelle separate from the mast, preferably multiple wind turbine masts and nacelles separated from the masts, to a wind turbine installation site where the wind turbine foundation is arranged, with the wind turbine mast in a horizontal transport position.

- Placing the wind turbine mast, in a horizontal position, on an upend arm of the upend device, wherein the upend arm extends between a bottom end and a top end, and along the wind turbine mast.

- Upending the wind turbine mast, from the horizontal position into a vertical assembly position, by pivoting the upend arm using an upend arm drive.

- Supporting the mast in the assembly position, preferably vertically above the deck of the vessel, using the upend arm.

- Lifting a nacelle from the deck, using a crane mounted on the vessel, preferably using the installation crane, onto the top end of the wind turbine mast supported in the assembly position by the upend arm, and connecting the nacelle to the wind turbine mast. - Connecting the wind turbine installation crane to the assembly of mast and nacelle, preferably without blades attached to a hub of the nacelle.

- Releasing the mast from the upend device and operating the installation crane to position the mast above the wind turbine foundation, and lowering the mast on the wind turbine foundation.

- Disconnecting the installation crane form the wind turbine mast.

Reference signs

01 crane

02 nacelle

03 wind turbine mast

04 floating foundation

05 crane base

06 crane housing

07 slew bearing

08 vertical slew axis

09 boom

10 vessel

11 hoisting wire first hoisting assembly

12 hoisting wire second hoisting assembly

13 hoisting wire third hoisting assembly

14 load connector first hoisting assembly

15 load connector second hoisting assembly

16 load connector third hoisting assembly

17 boom luffing assembly

18 base end boom

19 head end boom

20 left support arm

21 left crown block

22 right support arm

23 right crown block

24 mast receiving space

25 boom luffing wire

26 base end left support arm

27 base end right support arm

28 floating foundation

29 jib

30 legs of the boom

31 cross beams of the boom

32 transvers structures

33 front side boom

34 backside boom

35 boom pivot axis

36 jib pivot axis 37 jib luffing wire

38 luffing wire spacers

39 jib stop

40 boom stop

41 storage deck vessel

42 upend tracks

43 upend trolley

44 bottom end wind turbine mast

45 top end wind turbine mast

46 upend location mast on deck of vessel

47 foundation gripper

48 suppressor arms

49 floating foundation connector

50 supports for suppressor arms

51 mast mounted wire guide hoisting wires

52 fastening points bottom end wind turbine mast

53 floating foundation engagement device

54 Suppressor structure

55 column of the floating foundation

60 wind turbine assembly and installation vessel

61 upend device

62 mast

63 floating hull

64 storage deck

65 wind turbine installation crane

66 upend device

67 nacelle

68 top end mast

69 deck mounted support frame

70 upend arm

71 drive

72 bottom end mast

73 bottom end upend arm

74 top end upend arm

75 mast support

76 mast restraint 77 track

78 drive arms

79 cart

80 mast support cradles

81 deck

82 A-shaped frame

83 legs A-shaped frame

84 cross beams A-shaped frame

85 connector section at bottom end mast

101 crane

102 nacelle

103 wind turbine mast

104 floating foundation

105 crane base

106 crane housing

107 slew bearing

108 vertical slew axis

109 boom

110 vessel

111 hoisting wire first hoisting assembly

112 hoisting wire second hoisting assembly

113 hoisting wire third hoisting assembly

114 load connector first hoisting assembly

115 load connector second hoisting assembly

116 load connector third hoisting assembly

117 boom luffing assembly

118 base end boom

119 head end boom

120 left support arm

121 left crown block

122 right support arm

123 right crown block

124 mast receiving space

125 boom luffing wire

126 base end left support arm

127 base end right support arm

128 floating foundation 129 jib

130 legs of the boom

131 cross beams of the boom

132 transvers structures

133 front side boom

134 backside boom

135 boom pivot axis

136 jib pivot axis

137 jib luffing wire

138 luffing wire spacers

139 jib stop

140 boom stop

141 storage deck vessel

142 upend tracks

143 upend trolley

144 bottom end wind turbine mast

145 top end wind turbine mast

146 upend location mast on deck of vessel

147 foundation gripper

148 suppressor arms

149 floating foundation connector

150 supports for suppressor arms

151 mast mounted wire guide hoisting wires

152 fastening points bottom end wind turbine mast

Claims

C L A I M S

1. Crane (1) for the assembly and installation of offshore wind turbines, wherein the crane is movable into an assembly configuration (fig.1 ), for mounting a nacelle (2) on an upright mast (3), and into an installation configuration (figs.2-4), for mounting the mast, e.g. provided with the nacelle, on a foundation (4), the crane comprising:

- a crane base (5);

- a crane housing (6);

- a slew bearing (7), wherein the slew bearing is provided between the crane base and the crane housing, to enable the crane housing to slew about a vertical slew axis (8);

- a boom (9), wherein the boom extends between a base end (18) and a head end, wherein the boom is at the base end pivotable mounted to the crane housing about a horizontal boom pivot axis (35); and

- a jib (29), connected to the boom at or near the head end of the boom such as to be pivotable relative to the boom about a horizontal jib pivot axis (36); wherein the boom has at the head end a left support arm (20) supporting a left crown block (21) for a first hoisting wire (11) of a first hoisting assembly (11,14) of the crane and a right support arm (22) supporting a right crown block (23) for a second hoisting wire (12) of a second hoisting assembly (12,15) of the crane, wherein the first and second hoisting assemblies are configured for hoisting a mast of a wind turbine and respectively comprise a first and second winch and a first and second load connector (14,15); wherein the support arms extend from the boom to define between them a mast receiving space (24), and the first and second crown blocks are arranged on the respective support arms to be spaced apart with the mast receiving space between them, to enable the mast to be supported by the first and the second hoisting assembly in the mast receiving space; wherein a hoisting wire (13) of a third hoisting assembly (13,16) of the crane departs from a head end of the jib remote from the jib pivot axis for hoisting a nacelle, the third hoisting assembly further comprising a third winch and a third load connector (16); wherein the boom is pivotable about the horizontal boom pivot axis between:

- a hoisting position (figs.2-4) thereof, for supporting the mast of the wind turbine in the mast receiving space; and - a clearance position (fig.1 ) thereof, in which the boom is retracted relative to the hoisting position; the jib is pivotable relative to the boom about the horizontal jib pivot axis between

- a hoisting position (fig.1 ) thereof, for mounting the nacelle, and

- a clearance position (figs.2-4) thereof, in which the jib is retracted relative to the hoisting position thereof; and wherein the crane is movable into the assembly configuration by pivoting the boom into the clearance position thereof and the jib into the hoisting position thereof, to enable the nacelle of the wind turbine to be placed onto a top end of the mast by means of the third hoisting assembly, and movable into the installation configuration by pivoting the boom into the hoisting position thereof and the jib into the clearance position thereof, to enable the mast of the wind turbine to be supported in the mast receiving space by the first and second hoisting assembly with a top end (45) of the mast higher than the head end of the boom.

2. Crane according to claim 1 , wherein the support arms extend in front of the boom to define laterally between them the mast receiving space forwards of the head end of the boom and the horizontal pivot axis of the jib, and the first and second crown blocks are arranged on the respective support arms on respective lateral sides of the mast receiving space.

3. Crane according to any one or more of claims 1-2, wherein the installation configuration is such as to enable the mast to be supported in the mast receiving space with a nacelle on top of the top end (45) of the mast clear from the jib.

4. Crane according to any one or more of the preceding claims, wherein the support arms are configured and arranged such that these are in the assembly configuration clear from the mast, e.g. extend backwards from the mast.

5. Crane according to any one or more of the preceding claims, wherein the jib does in the assembly configuration of the crane not extend above the mast receiving space.

6. Crane according to any one or more of the preceding claims, wherein the support arms of the boom are integral parts of the boom, i.e. form a continuation of the construction of the boom.

7. Crane according to one or more of the preceding claims, wherein the boom pivot axis is parallel to the jib pivot axis.

8. Crane according to claim 7, wherein the crane furthermore comprises a jib luffing winch and an associated jib luffing wire (37), and wherein the luffing wire extends between the jib luffing winch and the jib, to enable pivoting of the jib relative to the boom between the hoisting position and the clearance position of the jib.

9. Crane according to any one or more of the preceding claims, further comprising a luffing assembly (17) comprising a boom luffing winch and an associated boom luffing wire (25), wherein the boom luffing winch is mounted on the crane housing and the boom luffing wire extends between the boom luffing winch and the boom.

10. Crane according to any one or more of the preceding claims, wherein the left and the right support arm are at a top end provided with transverse structures (32), the transverse structures extending away from the boom at a frontside (33) and at a backside (34) thereof, wherein the transverse structures support the crown blocks at the front side of the boom and are connected with the boom luffing wires at the back side of the boom, the transverse structures providing the boom with a hammerhead shape when seen in side view.

11. Crane according to any one or more of the preceding claims, wherein the boom is provided with a jib stop (39), which jib stop is configured to stop the jib in the clearance position thereof when it is being moved into the clearance position thereof.

12. Crane according to any one or more of the preceding claims, wherein the boom is provided with a jib actuator, e.g. one or more cylinders to push the jib or one or more winches to pull the jib, for moving the jib out of the clearance position thereof and towards the hoisting position thereof.

13. Crane according to one or more of the preceding claims, wherein the boom is provided with a jib lock, for securing the jib relative to the boom in the clearance position.

14. Crane according to any one or more of the preceding claims, wherein the boom pivot axis and the jib pivot axis define a plane, and wherein the jib, or at least the free end of the jib, is on a first, e.g. front, side of this plane when the crane is in the assembly position, and is on an opposite, second, e.g. back, side of this plane when the crane is in the installation position.

15. Crane according to any one or more of the preceding claims, wherein the jib can be pivoted forwards relative to the boom such as to provide the crane with a knuckleboom configuration, for lifting objects close to the deck surface, for example for moving objects between the vessel and a supply vessel.

16. Crane according to any one or more of the preceding claims, wherein the boom, when the crane is in the assembly configuration in which the boom is in the hoisting position, is in a substantially vertical position, i.e. is substantially parallel to a slew axis of the slew bearing of the crane.

17. Crane according to any one or more of the preceding claims, wherein the crane housing is provided with a boom stop (40), which boom stop is configured to stop the boom in the clearance position thereof when the boom is being moved into the clearance position thereof.

18. Crane according to any one or more of the preceding claims, wherein the crane housing is provided with a boom actuator, e.g. one or more cylinders to push the boom or one or more winches to pull the boom, for moving the boom out of the clearance position and towards the hoisting position thereof.

19. Crane according to any one or more of the preceding claims, wherein the crane is provided with a boom lock, for securing the boom relative to the crane housing in the clearance position of the boom.

20. Crane according to any one or more of the preceding claims, wherein the boom has a length in the range of 75 to 80 meters, preferably has a length of about 78 meters, and/or has a width of over 18 meters, for example has a width of about 20 meters, and wherein the support arms preferably have a length of over 15 meters, for example have a length of about 20 meters.

21. Crane according to any one or more of the preceding claims, wherein the jib has a length of at least three quarters, i.e. at least 75% the length of the boom, preferably has a length of at least four fifth, i.e. at least 80%, of the length of the boom.

22. Crane according to any one or more of the preceding claims, wherein the crane comprises, preferably the first hoisting assembly and the second hoisting assembly each comprise, a heave compensation mechanism to compensate for sea induced vertical movement of a load supported by the first and second hoisting assembly relative to a foundation, preferably relative to a floating foundation.

23. Vessel (10), preferably a semisubmersible vessel, provided with a crane according to any one or more of the claims 1-22, wherein the vessel has a storage deck (41) for transport of wind turbine components, preferably has a storage deck for supporting a wind turbine mast having a length of at least 100 meters in a horizontal position, wherein the deck height of the top end of the boom of the crane, when the crane is in the assembly position, is less than the deck height of the wind turbine mast supported in the upright position on the deck of the vessel, such as to enable the first and second hoisting assemblies to hoist the mast with the top end thereof extending above the top end of the boom.

24. Vessel according to claim 23, wherein the vessel comprises a foundation gripper (47), for engaging a floating foundation and for reducing movements in the horizontal plane of the floating foundation relative to the vessel, preferably for substantially eliminating movements relative of the floating foundation relative to the vessel in the horizontal plane.

25. Vessel according to claim 23 or claim 24, wherein the vessel is provided with at least one suppressor arm, wherein the suppressor arm is configured to project from the vessel in a floating foundation engagement position, the suppressor arm being provided with a floating foundation engagement device for engaging with a floating foundation, preferably for engaging with a floating foundation connector mounted on the floating foundation, and for exerting a downward force, i.e. a force directed in the z-direction, onto said floating foundation to reduce, preferably eliminate, vertical movement of the floating foundation relative to the vessel.

26. Method for assembling and installing an offshore wind turbine, wherein the method comprises using a crane according to one or more of the claims 1-22 mounted on a vessel, or using a vessel according to one or more of the claims 23-25.

27. Method according to claim 26, wherein the method furthermore comprises:

- positioning the crane in the assembly configuration, - preferably using the crane in the assembly configuration to up end a wind turbine mast, or alternatively, using a mast upend device to upend a wind turbine mast without assistance of the crane;

- using the crane in the assembly configuration to mount a nacelle on the upended wind turbine mast;

- positioning the crane in the installation configuration; and

28. Method for mounting an offshore wind turbine, or part thereof, on a floating foundation from a floating vessel provided with a wind turbine installation crane comprising a hoisting assembly, wherein the crane preferably is a crane according to one or more of the claims 1- 22, and the vessel preferably is a vessel according to one or more of the claims 23-25, wherein the vessel is provided with a foundation gripper (47) for engaging a floating foundation and to subsequently reduce movement of that foundation relative to the vessel in the xy plane, i.e. in the horizontal plane, preferably while allowing for movement in the z direction, i.e. in the vertical direction, wherein the method comprises the steps:

- positioning the vessel adjacent the floating foundation;

- providing the foundation gripper with xy compensation, i.e. actively moving the foundation gripper to eliminate movement of the foundation gripper relative to the floating foundation in the xy plane;

- engaging the floating foundation with the foundation gripper, preferably engaging a foundation connector (49) mounted on the floating foundation with the foundation gripper, while providing the foundation clamp with xy compensation;

- ending the xy compensation of the foundation gripper and starting with xy damping, i.e. reduce the movement of the floating foundation relative to the vessel in the xy plane; and

- increasing the xy damping to further reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the xy plane, and preferably fully connect the foundation gripper with the floating foundation; wherein the vessel is furthermore provided with at least one suppressor arm (48), wherein the suppressor arm is configured to project from the vessel in a floating foundation engagement position, the suppressor arm being provided with a floating foundation engagement device for engaging a floating foundation, preferably for engaging a suppressor coupling provided on the floating foundation, e.g. a suppressor coupling provided on a floating foundation connector mounted on the floating foundation, and for exerting a downward force, i.e. a force directed in the z-direction, onto said floating foundation, wherein the method furthermore comprises the steps:

- ending the z compensation and starting with damping the movement of the floating foundation relative to the vessel in the z direction;

- removing ballast water from the floating foundation, preferably from a column of the floating foundation onto which the wind turbine is to be mounted, preferably by pumping the ballast water from the floating foundation into ballast tanks of the vessel, preferably ballast tanks located near or at the crane supporting the wind turbine, to create an upward force of the floating foundation against the suppressor arm, wherein the upward force preferably is similar or larger than the gravitational force of the wind turbine supported by the crane; - landing the wind turbine on the floating foundation, optionally while providing the wind turbine with z-compensation using the hoisting assembly of the crane, i.e. using the hoisting assembly to reduce, preferably eliminate, sea state induced movement of the wind turbine relative to the floating foundation; and

29. Method according to claim 28, wherein the floating foundation is provided with a floating foundation connector (49) and the wind turbine mast is provided with a wind turbine mast connector which floating foundation connector and wind turbine mast connector are configured to cooperate to provide a quick connection, i.e. a connection without bolting, between the floating foundation and the wind turbine mast, and wherein the method further comprises: by landing the wind turbine on the floating foundation establishing a quick connection such that the wind turbine mast and the floating foundation move in unison.

30. Method according to claim 29, wherein the foundation connector is provided with an abutment surface for engagement by the floating foundation engagement device of the suppressor arm.

31. Method according to claim 29 or claim 30, wherein the floating foundation connector and the wind turbine mast connector are provided with click fingers and one or more click finger engagement edges for establishing the quick connection between the floating foundation connector and the wind turbine mast connector.

32. Method according to any one or more of the claims 29-31 , wherein the floating foundation connector and the wind turbine mast connector are provided with guides for aligning the floating foundation connector relative to the wind turbine mast connector about the z axis, while landing the wind turbine mast on the floating foundation.

33. Method according to one or more of the claims 28-32, wherein the mass of the water removed from the floating foundation is at least similar, preferably larger than the mass of the wind turbine supported by the wind turbine installation crane above the floating foundation, e.g. the mass of the water is about 21 mt, such that the floating foundation pushes upwards against the abutment surface with a force similar to or larger than the gravitational force of the wind turbine supported by the crane.

34. Method according to one or more of the claims 28-33, further comprising the step of transferring the total weight of the wind turbine, i.e. the wind turbine mast and the nacelle mounted on the wind turbine mast, onto the floating foundation, only after establishing the quick connection.

35. Method for assembly and installation of a wind turbine on an offshore wind turbine foundation, using a vessel comprising a storage deck, a mast upend device and a wind turbine assembly crane, the method comprising: transporting on the storage deck of the vessel a wind turbine mast and a nacelle separate from the mast, preferably multiple wind turbine masts and nacelles separated from the masts, to a wind turbine installation site where the wind turbine foundation is arranged, with the wind turbine mast in a horizontal transport position; placing the wind turbine mast, in a horizontal position, on an upend arm of the upend device, wherein the upend arm extends between a bottom end and a top end, and along the wind turbine mast; upending the wind turbine mast, from the horizontal position into a vertical assembly position, by pivoting the upend arm using an upend arm drive, supporting the mast in the assembly position, preferably vertically above the deck of the vessel, using the upend arm; lifting a nacelle from the deck, using a crane mounted on the vessel, preferably using the installation crane, and onto the top end of the wind turbine mast supported in the assembly position by the upend arm, and connecting the nacelle to the wind turbine mast; connecting the wind turbine installation crane to the assembly of mast and nacelle, preferably without blades attached to a hub of the nacelle; releasing the mast from the upend device and operating the installation crane to position the mast above the wind turbine foundation, and lowering the mast on the wind turbine foundation; and disconnecting the installation crane form the wind turbine mast.

36. Method according to claim 35, wherein the method further comprises mounting blades to a hub of the nacelle, using a blade installation crane, which blade installation crane preferably is mounted on the wind turbine foundation.

37. Method according to claim 35 or claim 36, wherein the method further comprises mounting a blade installation crane on the wind turbine foundation, preferably using the wind turbine installation crane.

38. Method according to one or more of the claims 35-37, wherein the upend arm extends between a bottom end and a top end, and wherein the upend arm at the bottom end is pivotable mounted to the support frame and wherein moving the upend arm is done by pivoting the arm relative to the support frame.

39. Method according to one or more of the claims 35-38, wherein the upend arm comprises:

- a mast restraint, mounted to the upend arm at or near a top end thereof, for restraining the mast in the lateral direction, and wherein placing the wind turbine mast, in a horizontal position, on an upend arm of the upend device, further comprises receiving the mast in the mast support and the mast restraint and thus engaging the mast at a bottom end thereof and at a location away from the bottom end but also away from the top end of the mast.

40. Method according to one or more of the claims 35-39, wherein the drive of the upend device comprises one or more drive arms, wherein the one or more drive arms are with one end pivotable connected to the upend arm and with an opposite end linked to a track, e.g. a skid track or rack, and wherein moving the upend arm comprises moving the opposite end along the track.

41. Wind turbine assembly and installation vessel, for assembly and installation of a wind turbine on an offshore wind turbine foundation, wherein the vessel comprises:

- a floating hull; - a storage deck, for transporting wind turbine components, e.g. multiple masts and nacelles wherein the nacelles are separated from the masts, to a wind turbine installation site where a wind turbine foundation is arranged;

- an upend device, for upending the mast, i.e. for moving the wind turbine mast from a horizontal position into an assembly position, and for supporting the wind turbine mast above deck in the assembly position to enable a crane, preferably the installation crane, to mount a nacelle onto a top end of the mast; wherein the upend device comprises;

- a deck mounted support frame;

- a drive for upending the upend arm, e.g. one or more hydraulic cylinders, skid arms, etc. for moving the upend arm and to thus enable the upend device to upend a mast without assistance of the crane.

42. Vessel according to claim 41, wherein the upend arm extends between a bottom end and a top end, and wherein the upend arm at the bottom end is pivotable mounted to the support frame.

43. Vessel according to claim 41 or claim 42, wherein the upend arm comprises:

44. Vessel according to one or more of the claims 41-43, wherein the drive of the upend device comprises one or more tracks, e.g. skid tracks or racks, and one or more drive arms per track, and wherein the one or more drive arms are with one end pivotable connected to the upend arm and with an opposite end linked to a cart, e.g. a skid cart or a pinion drive, for moving that end along the track.

45. Vessel according to one or more of the claims 41-44, wherein the storage deck is provided with multiple mast support cradles, for supporting masts in a horizontal transport position, such that the center of gravity of the wind turbine mast is located close to the deck of the vessel to facilitate transport by vessel, and parallel to each other on the storage deck.

46. Vessel according to one or more of the claims 41-45, wherein the upend device only engages a lower part of a wind turbine mast to be upended, such that an upper part, preferably at least one third, of the mast extends above the upend device, when the upend device supports the mast in the assembly position.

47. Vessel according to one or more of the claims 41-46, wherein the upend device is mounted on the storage deck, such that the upend arm is parallel to masts that are stored on the storage deck, when the arm is in a lowered position for receiving a mast in a horizontal position.

48. Vessel according to one or more of the claims 41-47, wherein the upend device is configured to engage the lower end of the wind turbine mast, preferably at least a lowest one third of the wind turbine mast, while the upper end of the mast, preferably at least an upper most one third of the wind turbine mast, extends above the upend device when supported in the assembly position.

49. Vessel according to one or more of the claims 41-48, wherein the upend arm comprises an A-shaped frame, the A-shaped frame comprising two legs and multiple cross beams connecting the legs, and preferably a mast restraint and a mast support are connected to the A-frame at a top end and at the bottom end thereof, respectively.

50. Vessel according to one or more of the claims 41-49, wherein the mast restraint is ring shaped and comprises one or more pivotable doors incorporated in the ring shape, wherein the one or more pivotable doors enable the ring shape to be opened for receiving the mast within inside the ring shaped restraint.

51. Vessel according to one or more of the claims 41-50, wherein the mast restraint is pivotable connected to the upend arm, such that the restraint can be pivoted between an active position, in which it extends perpendicular to a longitudinal axis of the upend arm, and a passive position, in which it extends parallel to the longitudinal axis of the upend arm.

52. Vessel according to one or more of the claims 41-51 , wherein the support arm is configured to be coupled with a mast section, e.g. a mast connector section, to support the mast when in the assembly position and to restrain movement of the mast in a lateral direction, i.e. in a direction perpendicular to a longitudinal axis of the mast.

53. Use of a vessel according to one or more of the claims 41-52 in a method according to one or more of the claims 35-40.

54. Assembly comprising a vessel according to one or more of the claims 41-52, a wind turbine mast, nacelle, and wind turbine connector mounted to a bottom end of the mast, wherein the wind turbine connector and a mast support of the upend device are configured to cooperate, to enable a simple and robust connection between the upend device, preferably the support of the upend arm of the upend device, and the mast.

55. Suppressor structure configured to be mounted on, or mounted on, a vessel for controlling movement of a floating foundation relative to the vessel, to enable mounting an offshore wind turbine, or part thereof, on the floating foundation from the floating vessel, wherein the suppressor structure comprises at least two suppressor arms that are each configured to project from the vessel in a floating foundation engagement position, in which position the suppressor arms are positioned on opposite sides of a column of the floating foundation, onto which column the wind turbine is to be mounted, and wherein the suppressor arms are provided with a floating foundation engagement device for engaging the floating foundation, preferably for engaging a suppressor coupling provided on the floating foundation or on a floating foundation connector mounted on the floating foundation, and for exerting a downward force, i.e. a force directed in the z-direction, onto said floating foundation to reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the z direction.

56. Suppressor structure according to claim 55, wherein the suppressor structure comprises an engagement device drive for providing the engagement device with z compensation, i.e. for actively moving the engagement device, or the end of the suppressor arms supporting the engagement device, to eliminate movement of the engagement device relative to the floating foundation in the z direction,

57. Suppressor structure according to claim 56, wherein the engagement device drive is furthermore configured to dampen the movement of the floating foundation relative to the vessel in the z direction, when the engagement device engages the floating foundation, to reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the z direction and preferably to thus fully connect the suppressor arm with the floating foundation.

58. Suppressor structure according to one or more of the claims 55-57, wherein the suppressor structure is configured for moving the beams in an x- and y-direction relative to a deck of the vessel the suppressor structure is mounted on, to enable the suppressor beams, and the foundation engagement device, to move with the floating foundation in the x and y direction, preferably wherein the range of movement in the x-direction and y-direction is at least 2m preferably is at least 3m, for example is 6m.

59. Suppressor structure according to claim 58, wherein the suppressor structure comprises an x-y drive for moving the suppressor beams, and thus the foundation engagement device, in the x- and y-direction,

60. Suppressor structure according to claim 59, wherein the x-y drive is configured to enable passive movement of the suppressor beams, and thus of the foundation engagement device, in the x- and y-direction, the movement of the floating foundation causing the passive movement of the suppressor beams and thus of the foundation engagement device.

61 . suppressor structure according to one or more of the claims 55-60, wherein the suppressor structure comprises a suppressor arms control system and one or more sensors to monitor the movement of the foundation relative to the vessel.

62. Suppressor structure according to one or more of the claims 55-61 , wherein the support structure is configured to dampen movement of the floating foundation in the x- and y- direction relative to the vessel, e.g. comprises one or more damping cylinders and/or an x-y drive configured to dampen movement of the suppressor beams in the x- and y- direction.

63. Suppressor structure according to one or more of the claims 55-62, wherein the foundation engagement device comprises a ring shaped frame for engaging the floating foundation around a mount for attaching the mast of the wind turbine to the floating foundation.

64. Suppressor structure according to claim 63, wherein the ring shaped frame is provided with one or more pivotable doors incorporated in the ring shaped frame, wherein the one or more pivotable doors enable the ring shaped frame to be opened for receiving the mount for attaching the mast and/or the mast inside the ring shaped frame, and to allow for moving the mount for attaching the mast and/or the mast of the wind turbine into and out of the ring shaped frame in a lateral direction relative to the ring shaped frame.

65. Suppressor structure according to one or more of the claims 55-64, wherein the suppressor arms are configured for engaging a suppressor coupling provided on the floating foundation, e.g. a suppressor coupling provided on a floating foundation connector mounted on the floating foundation.

66. Suppressor structure according to one or more of the claims 55-65, wherein the suppressor beams each have a mass of at least 800mt preferably have a mass of at least 900 mt, for example have a mass of 1000mt.

67. Vessel comprising a suppressor structure according to one or more of the claims 55-66.

68. Vessel according to claim 67, wherein the suppressor structure is mounted on the vessel with the two suppressor arms positioned on opposite sides of the crane, for engaging a floating foundation.

69. Method for controlling movement of a floating foundation relative to a floating vessel to enable mounting an offshore wind turbine, or part thereof, on the floating foundation from the vessel, wherein the vessel is provided with a wind turbine installation crane for landing the wind turbine, or part thereof, on the floating foundation, and with a suppressor structure for exerting a downward force, i.e. a force directed in the z-direction, onto the floating foundation. wherein the suppressor structure comprises at least two suppressor arms that are each configured to project from the vessel in a floating foundation engagement position, in which position the suppressor arms are positioned on opposite sides of a column of the floating foundation, onto which column the wind turbine is to be mounted, and wherein the suppressor arms are provided with a floating foundation engagement device for engaging a floating foundation, preferably for engaging a suppressor coupling provided on the floating foundation or on a floating foundation connector mounted on the floating foundation, and for exerting a downward force, i.e. a force directed in the z-direction, onto said floating foundation to reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the z direction, wherein the method comprises the steps:

- positioning the vessel adjacent the floating foundation;

- increasing the z damping to further reduce and preferably eliminate the movement of the floating foundation relative to the vessel in the z direction and preferably thus fully connect the suppressor arms with the floating foundation.

70. Method according to claim 69, wherein the method furthermore comprises:

- moving the wind turbine, or part thereof, from a position above the deck to a position above the floating foundation, preferably while using a ballast system of the vessel to keep the vessel even keel, and supporting the wind turbine above the floating foundation using the wind turbine installation crane; - removing ballast water from the floating foundation, preferably from the column of the floating foundation onto which the wind turbine is to be mounted, to create an upward force of the floating foundation against the suppressor arms, wherein the upward force preferably is similar to or larger than the gravitational force of the wind turbine supported by the crane;

- landing the wind turbine on the floating foundation; and

71. Method according to claim 69 or claim 70, wherein the method, prior to engaging the floating foundation with the engagement device, furthermore comprises:

- ending the xy compensation of the foundation engagement device and starting with xy damping, i.e. dampen the movement of the floating foundation relative to the vessel in the xy plane; and

- increasing the xy damping to further reduce and to preferably eliminate the movement of the floating foundation relative to the vessel in the xy plane, and preferably fully connect the foundation engagement device with the floating foundation.