The present invention relates to an offshore lifting tool and a method for lifting an object, for instance offshore wind turbine components, e.g. a tool and method for lifting and upending a monopile or mast of an offshore wind turbine.

When lifting offshore components on a floating vessel, it is common to utilize a vessel-mounted or integrated lifting device and a lifting tool releasably connectable thereto, which lifting tool is configured for coupling to the component. Generally the lifting device is a crane, the lifting tool with the coupled object being suspended from one or more hoisting cables of the crane, one or more winches being provided to pay out or haul in the respective hoist cables. The use of such lifting tools include the transfer or lifting of the components e.g. between a jack-up vessel or quay and a floating vessel, e.g. a feeder vessel, and/or between floating vessels. Particular lifting tools are used for wind turbine components with vessel-mounted or integrated lifting devices, e.g. in the installation, maintenance or demolition of offshore wind turbines.

Combined with such lifting tools, in line passive heave compensators are often utilized to reduce the impact of significant load variations on the lifting tool that are possible during offshore heavy lifting or transfer, generally due to the variable motions of the lifting point and/or the component induced by waves, wind and currents. These in line passive heave compensators are interposed between a lifting point at the top of the lifting range, e.g. a crown block of a crane, and a lifting tool. For example, an in line passive heave compensator is interposed between a hoisting block and the lifting tool, e.g. between a hook underneath the hoisting block and the lifting tool.

In line compensators are capable of reducing the dynamic forces in the lifting wire or hoist wire caused by the motion of the sea from or on the object, to the lifting point. They generally employ a mixture of hydraulic and pneumatic dampers to help compensate for such load variations and are operable between the lifting point, e.g. the crown block of a crane, and the object. They rely upon the maintenance of the predetermined fluid pressure in the cylinder and piston mechanism, while permitting relative telescopic movement to occur between the cylinder and piston portions of the mechanism.

During use with a lifting tool, an in line passive heave compensator cancels out at least part of, preferably substantially all of, the downwards heave motion of the coupled object. Thereby, the heave motions of the lifting device are substantially not transferred to the coupled object and the object can be vertically positioned by a lifting and lowering operation of the lifting device substantially without being influenced by heave motions. The lifting device can thus be operated without simultaneously compensating heave motions. Therefore a lifting device without heave compensating equipment can be used. In case of a crane with a hoisting block, the hoisting cables are advantageously kept free from compensating movements by the lifting device, reducing the accompanying wear of the cables caused by the heave compensating back and forth movements thereof over guiding sheaves and/or winches.

These in line passive heave compensators generally comprise an upper fixation point associated with a hydraulic cylinder for connection with the hoist cables, e.g. via a hoisting block or a hook, and a lower fixation point associated with the piston rod for connection to the load, e.g. a hook or a specific lifting tool. At least one accumulator is provided, having a moveable separator to divide the accumulator between a variable volume gas chamber above the separator, and a variable volume oil chamber below the separator. The oil chamber is in communication with an oil chamber in the hydraulic cylinder. The gas chamber is connected to a bank of pressurized gas reservoirs. The pressure of the gas can be controlled, e.g. set at a desired level, by a gas pressure controller such as to control the hydraulic pressure within the cylinder.

Heave motion of the vessel causes the piston to oscillate within the cylinder of the compensator. Hereby the distance between the hoisting point and the load is lengthened and shortened, thus cancelling at least a part of the heave motion. The accumulator can be provided on the compensator itself, or on the vessel, the accumulator being connected to the compensator via an umbilical.

For example, the company Ernst-B. Johansen AS supplies units under the trademark ‘Cranemaster’ as passive heave compensators, which are self-contained units charged with an internal gas pressure and oil volume. For instance when the lifting device is a crane, the ‘Cranemaster’ is interposed between a hook underneath a hoisting block and the tool.

As another example, the company Seaqualize develops a passive heave compensation device with a small active component for use between a crane hook and a lifting tool for wind turbine components. US9718652 and US7934561 disclose in line heave compensators. US3714995 and W02005038188 disclose the use of in line passive heave compensators on a drilling rig. Here the passive heave compensators are interposed between a travelling block and a lifting tool in the form of a hook.

When lifting wind turbine components, for instance when upending a monopile or mast thereof from a horizontal to a vertical location on a vessel, it is known to suspend an in line passive heave compensator between a hook, e.g. a hook underneath a hoisting block, and a specific lifting and upending tool engaging a longitudinal end of the monopile or mast.

Examples of upending and lifting tools are disclosed in DE202009006507U1 , figures 9d and 9e, in W02020020821 , WO2014084738, and WO2016184905, and in WO2018139918, NL2024947 and in NL2025102 by the applicant. These upending and lifting tools are configured to be suspended from one or more hoisting cables, e.g. from a crane hook of a crane, and are in particular envisaged for upending and lifting of a monopile of an offshore wind turbine. The tools of WO2018139918, NL2024947 and NL2025102 may however also be applied for retaining, lifting and/or upending other objects, e.g. other piles, e.g. for fixing a jacket-type foundation to the seabed, for mooring, etc. or for upending other wind turbine components, e.g. like the mast, or a jacket-type foundation.

The current practice of using an in line passive heave compensator in combination with a lifting tool is however not satisfactory in multiple respects.

The use of an in line passive heave compensator between the hoisting point, e.g. a crown block of a crane, and a lifting tool, e.g. between a hoisting block and the tool, e.g. between a hook underneath the hoisting block and the tool, leads to the compensator occupying a certain part of the hoisting height. This disadvantageously reduces the effective hoisting range of the lifting device.

Furthermore, the use of a passive heave compensator between the hoisting block and a lifting tool, e.g. between a hook underneath the hoisting block and the tool, increases the height between the hoisting block and the tool, which may complicate the interconnection of the tool and the hoisting block, compromising both safety and required time of this interconnection. Furthermore, the stability and control of the load may be reduced, as a greater distance from the hoisting block may result in a larger amplitude of possible (pendulous) motions relative thereto, hampering an accurate positioning of the load. Furthermore, the use of an in line passive heave compensator may complicate or alter the characteristics of a pendulum motion of the load, as it may add pivots at the upper and lower fixation point thereof. This may reduce the stability and control of the load, hampering an accurate positioning of the load. A further drawback is the time consumption involved with connecting the compensator.

It is an object of the invention to provide an alternative to an in line passive heave compensator used in combination with a lifting tool.

It is an object of the invention to provide in line passive heave compensation while lessening the entailed reduction of effective hoisting range of the lifting device when using a lifting tool, in particular the hoisting height occupied underneath a hoisting block of a crane.

It is an object of the invention to provide in line passive heave compensation while lessening the entailed reduction of stability of the object and improves the control in positioning the object when using a lifting tool.

These objects are at least in part achieved by a lifting tool according to claim 1 , and methods according to claims 14 and 15.

According to a first aspect thereof, the invention provides an offshore lifting tool for lifting an object. This object is for example a component of an offshore wind turbine, for example a monopile, a mast, a transition piece, or a jacket type component. The lifting tool is configured to be suspended from a lifting device on a floating vessel. According to common practice, this lifting device is for example a crane mounted on or integral with the vessel, the lifting tool therein being suspended from one or more hoisting cables of the crane. For instance, the lifting tool is configured to be suspended from a pair of hoisting cables suspended from a crane hook of the crane. This crane hook may be suspended underneath a hoisting block of the crane. When suspended, the tool can be lifted, e.g. hoisted, and lowered by the lifting device as is known in the art.

The lifting tool comprises an attachment member by means of which the tool is connectable to the lifting device such as to suspend the tool from the lifting device. For instance the attachment member is configured to suspend the tool from one or more, e.g. a pair, of hoisting cables, comprising for example one or more stationary guides or rotary sheaves through which the cables may be run, one or more eyelets, etc. The lifting tool further comprises a coupling part that is configured for coupling the object with the lifting tool. The coupling part may in a simple form be a crane hook, e.g. a Ramshorn hook. The coupling part may be an operable coupling part for coupling the object, for instance in the form of a gripper, for instance for gripping and retaining a component of an offshore wind turbine. In an embodiment the coupling part is embodied as the operable coupling part of the upending and lifting tool of NL2024947, and is pivotal around a horizontal pivot axis relative to the attachment member, so that the lifting tool is a lifting and upending tool for an offshore wind turbine component. In other embodiments wherein the lifting tool is a lifting and upending tool for an offshore wind turbine component, the coupling part is embodied as any of the coupling parts of other prior art upending and lifting tools, being pivotal around a horizontal pivot axis relative to the attachment member. In an embodiment the coupling part is a yoke, for instance for retaining a component of an offshore wind turbine, e.g. a rotor thereof, or parts of a rotor thereof, e.g. a blade or a generator.

The lifting tool further comprises an extensible structureand a passive heave compensator.

The extensible structure interconnects the attachment member and the coupling part. The extensible structure comprises an upper part, connected to the attachment member and comprising an upper fixation point, and a lower part, connected to the coupling part and comprising a lower fixation point. The upper and lower part are movable relative to one another in a longitudinal direction to allow for longitudinal extension and shortening of the extensible structure. With this extension and shortening, a longitudinal distance between the fixation points is increased and decreased, respectively.

The passive heave compensator mounted between the lower fixation point and an upper fixation point of the extensible structure, such as to form an integral part of the tool. The passive heave compensator is configured to, upon upwards heave motion of the lifting device, enable extension of the extensible structure such that the longitudinal distance between the upper and lower fixation points increases. By this extension of the extensible structure, at least a part of the upwards heave motion of the lifting device is cancelled out for the coupling part of the lifting tool. The passive heave compensator is configured to upon downwards heave motion of the lifting device, enable shortening of the extensible structure such that the longitudinal distance between the upper and lower fixation point decreases, which cancels out at least a part of the downwards heave motion of the lifting device for the coupling part of the tool. Preferably, the passive heave compensator is configured to enable extension and shortening of the extensible structure to an extent which cancels out all of the upwards and downwards heave motion of the lifting device. As is known in the art, this configuration is achieved by establishing a suitable stiffness of the passive heave compensator, which determines the effective elasticity of the extension and shortening in response to the heave motions.

When coupled to an object, the extension and shortening of the extensible structure thus, advantageously, cancels out at least part of, preferably substantially all of, the downwards heave motion of the coupled object. Thereby, the heave motions of the lifting device are substantially not transferred to the object and the object can be vertically positioned by a lifting and lowering operation of the lifting device substantially without being influenced by heave motions.

The lifting tool according to the invention thus exhibits the functionality of in line passive heave compensation. Therefore, when using the lifting tool according to the invention in lifting an object on a floating vessel, the use of a separate in line passive heave compensator between the lifting tool and the hoisting point to provide in line heave compensation is obviated. By integrating an extensible structure in the lifting tool, the invention enables that the upper and lower fixation point of an in line passive heave compensator are fixed to associated upper and lower fixation points of the tool itself. Thereby it enables the compensator to be integrated in the tool, instead of being provided in line with the hoisting tool.

By the integration of the compensator in the tool as enabled by the extensible structure of the lifting tool, and thus obviating a separate compensator in line with the tool, any pivoting at the fixation points of a separate compensator in line with the tool is eliminated. As such, the lifting tool according to the invention may eliminate the reduction of stability of the object entailed by this pivoting, and improve control in positioning the coupled object. Similarly, the stability and control of the lifting tool not being coupled to the object may be improved, which may aid in positioning the lifting tool while coupling it to the object.

By the obviating a separate compensator and the associated fixation points in line with the tool, the accompanying reduction of effective hoisting range of the lifting device may advantageously be lessened. When provided underneath a hoisting block of a crane, the height of the hoisting block relative to the object to be lifted is reduced - which may facilitate the controlled positioning of the tool relative to the object during coupling.

Furthermore, obviating a separate compensator advantageously saves the time and effort involved with a separate connection thereof to the lifting device. In some lifting tools, a certain height is necessarily provided between the coupling part and the attachment member in order to enable the specific functionality of the tool. For instance lifting and upending tools for elongate objects, e.g. wind turbine components, in which the coupling part is pivotal upwards relative to the attachment member around a horizontal pivot axis towards the attachment member, provide a certain height above the pivotal connection with the coupling part. This height covers at least the vertical extension of the coupling part when pivoted upwards, in order to enable the coupling part to pivot underneath the attachment member, for example such that with the center of gravity always being located underneath the attachment member, the coupling part can be pivoted upwards by a right angle. With such lifting tools, the extensible structure can be provided at least in part within the necessary height between the coupling part and the attachment member, so that the lifting range gained by the integration of the passive heave compensator in the tool relative to the provision of a separate compensator in line with the tool is advantageously increased by this part of the necessary height. Thus the necessarily provided height of the tool is effectively used for providing heave compensation - in the case of lifting and upending tools, without compromising its other function of enabling the pivoting of the coupling part. In embodiments of the lifting tool wherein the complete extensible structure can be covered by the necessarily provided height, which is the case in common lifting and upending tools, the lifting height gained by the integration of the passive heave compensation in the tool may be the whole height of the thereby obviated separate in line compensator.

In an embodiment, the lifting tool has an arm supporting the coupling part. The extensibe structure is integrated in this arm. The arm furthermore supports the attachment member. The arm may be connected to or integral with the coupling part. For example, the lifting tool comprises multiple arms with multiple extensible structures. In a preferred embodiment the lifting tool has one single arm with the attachment member and the extensible structure along its longitudinal extension. It is envisaged that the attachment member is provided at the upper side of the arm, the coupling part and/or the connection of the arm therewith, at the lower side, and the extensible structure between the attachment member and the coupling part and/or the connection therewith, along a longitudinal portion of the arm, e.g. extending substantially vertically.

In an embodiment the coupling part is pivotal around a horizontal pivot axis relative to the attachment member. In an embodiment wherein the arm is present, the coupling part is connected to the arm such as to be pivotal around the horizontal pivot axis. In an embodiment the coupling part is pivotal around a horizontal pivot axis upwardly into a horizontal position and downwardly into a vertical position. In this embodiment, when the coupling part is pivoted upwards, the vertical extension of the coupling part in the horizontal position, covers at least a part of the height of the tool above the horizontal pivot axis. As discussed, a larger height above the pivot axis leads to a larger potential height gain by the integration of the compensator in the tool. The lifting tool may comprise one or more pivot actuators which are operable between and connected to the coupling part and the arm and configured to pivot the coupling part relative to the arm around the horizontal pivot axis between the horizontal position and the vertical position of the coupling part. This pivotability is provided in known lifting and upending tools, wherein the actuators are generally in the form of one or more hydraulic cylinders between the arm and the coupling part.

In an embodiment the arm comprises an upper part and a lower part, respectively comprising a lower section and upper section, which sections are telescoping relative to one another to together form the extensible structure. The lower section of the upper part comprises the lower fixation point of the extensible structure and the upper section of the lower part comprises the upper fixation point of the extensible structure.

The passive heave compensator comprises one or more hydraulic heave compensation cylinders, e.g. two hydraulic cylinders arranged at opposed lateral sides of the extensible structure, e.g. at opposed lateral sides of the arm, when present. Each hydraulic heave compensation cylinder has a piston and is connected to a gas buffer. The piston, for instance the free end thereof, is fixed to the extensible structure at the upper or lower fixation point thereof, and a wall of the cylinder, for instance a longitudinal center portion or end portion of the wall, is fixed to the extensible structure at the lower or upper fixation point of the extensible structure, respectively. It is also possible to fix the piston and the wall of the cylinder to respectively the upper and lower fixation point, however the first mentioned configuration corresponds to the convention for in line passive heave compensators. Fixing the cylinder(s) to the respective fixation points at more inwards locations thereof, e.g, halfway the cylinder(s) and/or halfway the piston(s), and/or providing the fixation points makes the cylinder extend longitudinally further outwards from the fixation points, so that the extensible structure may be made shorter with the same length of the compensator, which may in embodiments lead to a larger lifting range gain. A shorter extensible structure may also be achieved by providing more horizontally juxtaposed cylinders of shorter length.

In an embodiment, the lifting tool comprises the gas buffer. The gas buffer may for example be fixed to the extensible structure, for example to the lower or upper part of the arm, when present. In another embodiment the gas buffer is provided externally from the tool, for example on the lifting device or on the deck of the vessel to which the lifting device is mounted or which it is integral with. The gas buffer is therein e.g. connected to the cylinder(s) via an umbilical.

In an embodiment the coupling part, the extensible structure, e.g. the arm with the integrated extensible structure, and the passive heave compensator are integral parts of the tool, which are fixedly interconnected or integral with each other.

In an embodiment the lifting tool is a lifting tool for a component of an offshore wind turbine, for example an elongate component such as mast, a monopile, or a transition piece. Therein the coupling part of the tool comprises multiple mobile engaging members, adapted to in a coupling position thereof engage a longitudinal end of the wind turbine component such as to couple the elongate component with the tool.

In an embodiment, the engaging members comprise mobile friction clamp members and/or mobile latching members.

Mobile friction clamp members are adapted to in the coupling position frictionally engage an inner surface and/or outer surface of the longitudinal end and one or more clamping actuators that are at least adapted to move the friction clamp members from a retracted position into the coupling position. Mobile friction clamp members are known from e.g., WO2014084738, WO2018139918, NL2024947 and NL2025102.

Mobile latching members are adapted to in the coupling position latch onto the longitudinal end, e.g. underneath a radially inward flange thereof, when present, and one or more latching actuators adapted to move the latching members from a retracted position into the coupling position. Mobile latching members are disclosed in WO2016184905, WO2018139918, WO2018139918

W02020020821 discloses mobile engaging members which are combined latching and friction members. In WO2018139918 the coupling part comprises both friction clamp members and latching members - NL2025102 also discloses a tool combining both.

The coupling part may further comprise one or more guiding members. Guiding members are configured for guiding the tool into a position relative to the longitudinal end in which moving the latching and/or friction members to the coupling position couples the component to the tool, aiding in the relative positioning of the tool prior to coupling. To this end the guiding members engage the upper end while positioning the tool in the vicinity of the longitudinal end, such as to limit the movement of the tool in directions away from an inserted position of the tool in which the longitudinal end may be coupled to the tool by moving the engaging members to the coupling position. Such guiding members are known from W02020020821 , wherein these guide the tool by their resiliency, and NL2024947, wherein these are actively operable.

In an embodiment, the lifting tool is a lifting and upending tool for an elongate component of an offshore wind turbine, e.g. a mast, a monopile, or a transition piece. Therein the coupling part of the lifting and upending tool is pivotal into a horizontal position and a vertical position. The lifting and upending tool comprises one or more pivot actuators, for example one or more hydraulic cylinders, operable between and connected to the coupling part and the arm and configured to pivot the coupling part relative to the arm around the horizontal pivot axis between the horizontal position and vertical position of the coupling part.

The coupling part of the lifting and upending tool is configured to, e.g. by the arrangement of the engaging members, in a horizontal position of the coupling part, engage the longitudinal end when the elongate component is in a horizontal orientation, such as to couple the elongate component with the hoisting tool. The coupling part is furthermore configured to retain the coupled elongate component during lifting of the longitudinal end by means of the lifting device thereby upending the elongate component from a horizontal orientation into a vertical orientation thereof, while allowing the coupling part to pivot from its horizontal position to its vertical position.

In an embodiment the lifting and upending tool comprises a locking mechanism, e.g. a controllable member for maintaining a position of the pivot actuators, e.g. a mechanical blocking element, or e.g. in the case the pivot actuators are hydraulic cylinders, valves of the cylinders controllable to close off the hydraulic fluid flow, configured to retain the coupling part in its horizontal position while positioning the coupling part relative to the longitudinal end and while moving the engaging members to the coupling position thereof.

In an embodiment the arm of the lifting and upending tool comprises a longitudinal portion, which comprises the extensible structure, and one or more perpendicular or slanted portions. The longitudinal portion and the perpendicular or slanted portions are arranged such that in the horizontal position of the coupling part, the longitudinal portion extends horizontally offset from the attachment member and the center of gravity of the lifting tool, e.g, completely horizontally offset from the coupling part, when the coupling part is in the horizontal position, such that - given that the center of gravity being located underneath the attachment member in any position of the coupling part relative to the arm - the coupling part can be pivoted upwards by a right angle. For example the arm has one single slanted portion extending above the longitudinal portion. For example the upper part of the arm, when present, comprises the slanted portion.

The integration of the passive heave compensator in the lifting tool furthermore advantageously enables that the lifting tool may be connected directly to an upper tool connector of the lifting device, instead of to a lower fixation point of the obviated in line compensator. Thereto the lifting tool comprises a lower tool connector configured for releasable connection with the upper tool connector of the lifting device. The lifting tool being provided with such lower tool connector, makes it an exchangeable lifting tool, which may advantageously easily be interchanged with other tools to be suspended from the lifting device and comprising a corresponding lower tool connector. This may save time and effort in an offshore lifting operation, e.g. in an installation or maintenance operation for wind turbines.

WO2018139931 and W02020055249 disclose two types of such lower tool connectors, each being configured for connection to a specific upper tool connector of a lifting device: the lower tool connector of WO2018139931 is a female connector configured for connection with a male upper tool connector of the lifting device, and that of W02020055249 is a male tool connector configured for connection with a female upper tool connector. WO2018139931 and W02020055249 disclose a range of lifting tools being provided with such lower tool connector, e.g. an upending and lifting tool for an elongate offshore component.

W02020055249 also discloses an female-to-male adapter configured to make tools provided with a female lower connector compatible with a female upper connector.

The upper tool connector of WO2018139931 is suspended directly from hoisting cables. In W02020055249 the upper tool connector is supported inside a hoisting block of the crane. In embodiments of the lifting device provided with the upper tool connector, in particular the lifting device of W02020055249, the use of a hook underneath the hoisting block is obviated. Accordingly, the provision of a matching lower tool connector to the lifting tool according to the invention may further benefit the hoisting range when such lifting device is used.

In an embodiment of the lifting tool according to the invention, the lifting tool is an exchangeable lifting tool and the attachment member comprises a lower tool connector, configured for releasable connection with an upper tool connector of the lifting device. The lifting device may be a crane as discussed above, and the upper tool connector may therein be supported in or integral with a hoisting block of the crane accommodating the hoisting cables.

Preferably, the lifting tool is provided with the arm as discussed herein, and the lower tool connector forms the upper end of the arm. For example the lower tool connector is a male tool connector configured for releasable connection with a female upper tool connector. For example the male lower tool connector comprises a shank having a shoulder adapted to latch above multiple mobile tool retainers inside a central passage of the female upper tool connector upon insertion of the shank into said passage, as disclosed e.g. in W02020055249.

In an embodiment, the lifting tool is embodied as a female-to-male adapter, the attachment member comprising a male lower tool connector and the coupling part being embodied as a female upper tool connector. In another embodiment the lifting tool is embodied as a male-to- female adapter, the attachment member comprising a female lower tool connector and the coupling part being embodied as a male upper tool connector.

In known applications, in-line heave compensation is also obtained with an additional active heave compensator, wherein the oscillations of the piston(s) relative to the cylinder(s) of the compensator are governed by a unit supplying pressurised fluid (gas or hydraulic liquid) in a controlled manner to one or more variable volume chambers within the compensator based upon one or more input signals obtained by one or more suitable sensors - for example a vertical vessel motion sensor, e.g. acceleration sensor, a (cable) force sensor, a compensator piston position sensor, and so on. The energy source for the active part of the compensator, e.g. a battery pack, is for instance provided directly on the compensator. Alternatively an energy source may be provided elsewhere on the vessel, e.g. on the upper deck, and connected to the compensator via an umbilical. The passive heave compensator according to the invention may have such an added active component to increase the performance.

As is known in the art, the capacity of the passive heave compensator of the lifting tool can increased as desired by increasing the amount of the hydraulic cylinders in parallel. The stroke of the compensator can be increased by increasing the amount of hydraulic cylinders in series. Additional accumulators can be added to further improve the operating performance for extreme conditions. The invention furthermore relates to a method for lifting an object on a floating vessel wherein use is made of the lifting tool as described herein. For example, the object is a component of an offshore wind turbine.

The invention furthermore relates to a method for lifting an object on a floating vessel, wherein use is made of the lifting tool as described herein and a lifting device, for example a crane mounted on or integral with the vessel. The method comprises the steps of:

1a) connecting the attachment member to the lifting device thereby suspending the lifting tool from the lifting device, e.g. from one or more hoisting cables of the crane, e.g. a pair of hoisting cables suspended from a crane hook of the crane,

2a) operating the coupling part thereby coupling the object to the lifting tool, and

3) lifting and/or lowering the object.

During steps 2a) and 3), the method comprises extending and shortening the extensible structure by means of the passive heave compensator thereby respectively cancelling out at least a part of the upwards and downwards heave motion of the lifting device for the coupling part of the lifting tool, and thereby of the coupled object.

In an embodiment, the method is devoid of any step of interconnecting the coupling part, the extensible structure, e.g. the arm, and the passive heave compensator of the lifting tool.

In an embodiment the method further comprises, between steps 1a) and 2b), the further step of:

1 d) positioning the lifting tool relative to the object.

During step 1 d), the method comprises extending and shortening the extensible structure by means of the passive heave compensator thereby respectively cancelling out at least a part of the upwards and downwards heave motion of the lifting device for the coupling part of the lifting tool.

In an embodiment, use is made of a lifting and upending tool for an elongate component as described herein, e.g. an elongate component of an offshore wind turbine. Therein the elongate component is initially in a horizontal orientation. In this embodiment the method comprises, prior to step 1 d), the further step of:

1 b) operating the pivot actuators of the tool thereby pivoting the coupling part into the horizontal position thereof. In this same embodiment, step 1d) involves positioning the coupling part relative to the longitudinal end of the elongate component into a position in which the engaging members can engage the longitudinal end, and step 2a) involves moving the engaging members to the coupling position thereof. Step 3) involves lifting the longitudinal end thereby upending the elongate component from its horizontal orientation to a vertical orientation thereof, while allowing the coupling part to pivot from its horizontal position to its vertical position.

In an embodiment wherein the lifting and upending tool further comprises the locking mechanism as described herein, the method may comprise between steps 1b) and 1d), the further step of:

1c) operating the locking mechanism, such as to retain the coupling part in its horizontal position during steps 1d) and 2a), and comprise between steps 2a) and 3), the further step of:

2b) releasing the locking mechanism such as to allow said pivoting of the coupling part during step 3).

In an embodiment wherein use is made of a lifting tool comprising the lower tool connector as described herein, step 1a) of the method involves connecting the lower tool connector to an upper tool connector of the lifting device, and the method further comprises, prior to step 1a), a use of another lifting tool with a corresponding lower tool connector, and a subsequent disconnection of the lower tool connector of the other lifting tool from the upper tool connector of the lifting device such as to disconnect the other tool from the lifting device.

In an embodiment wherein use is made of a lifting tool comprising the lower tool connector as described herein, step 1a) of the method involves connecting the lower tool connector to an upper tool connector of the lifting device, and the method further comprises, after step 3), a connection of a corresponding lower tool connector of another lifting tool to the upper tool connector of the lifting device such as to suspend the other tool from the lifting device, and a subsequent use of the other lifting tool.

The invention furthermore relates to an offshore lifting tool for lifting an object, for suspension from a lifting device on a floating vessel, comprising a coupling part for coupling the object with the lifting tool, an attachment member for connecting the tool to the lifting device, and an extensible structure interconnecting the attachment member and the coupling part via upper and lower parts thereof that are mutually longitudinally movable to allow for longitudinal extension and shortening of the extensible structure, wherein a passive heave compensator interconnecting the upper and lower part forms an integral part of the tool and is configured to upon upwards and downwards heave motion of the lifting device enable respectively extension and shortening of the extensible structure thereby cancelling out the heave motion of the lifting device for the coupling part of the tool. The above discussed embodiments may be applied to this lifting tool as well and are therefore not repeated here.

The invention will now be described in reference to the appended figures. Therein, figures 1a-b illustrate in two side views an embodiment of the lifting tool according to the invention along with a longitudinal end of an elongate offshore wind turbine component in respectively a shortened and extended position of the extensible structure, figure 1c illustrates in a side views the same embodiment along with the same longitudinal end in an extended position of the extensible structure, figure 2a illustrates in a side and front view the upper part of the arm of the same embodiment, figure 2b illustrates in a side and front view the lower part of the arm of the same embodiment, figure 2c illustrates in two side views a cylinder of the passive heave compensator of the same embodiment, figure 2d illustrates in a back view the gas buffer of the same embodiment, figures 3a-b illustrate the parts of figures 2a-c in the same views together in respectively the same shortened and extended position of the extensible structure as in figures 1a-b, figures 4a-b illustrate the same embodiment in a perspective view being suspended from a lifting device and coupled to the same elongate offshore wind turbine component in respectively the same shortened and extended position of the extensible structure, figures 5a-b illustrate the same embodiment in another perspective view being suspended from the lifting device and coupled to the same elongate offshore wind turbine component in respectively the same shortened and extended position of the extensible structure, figure 6a-b illustrate another embodiment according to the invention, figure 7 illustrates another embodiment according to the invention.

In figures 1-5, an embodiment of an offshore lifting tool 1 according to the invention is illustrated. In figures 1-3, the lifting tool 1 is shown without being engaged to any object. In figures 4 and 5, the lifting tool 1 is shown while lifting an object 50, namely an elongate component 50 of an offshore wind turbine.

The lifting tool 1 is configured to be suspended from a lifting device 100 on a floating vessel. In figures 4-5, the lifting device is embodied as a crane 100, which is mounted on or integral with the vessel (not shown). The lifting tool 1 is suspended from a pair of hoisting cables 103 of the crane, which hoisting cables 103 are suspended from a crane hook 101 of the crane 100 underneath a hoisting block 104 of the crane 100.

The lifting tool 1 comprises a coupling part 2 that is configured for coupling the object 50 with the lifting tool 1 . In this case the coupling part 2 is embodied as a specific gripper which is operable for engaging the elongate component 50 in order to couple the component 50 to the lifting tool 1. In figures 4-5, the lifting tool 1 is shown while engaging the elongate component 50 during lifting of the elongate component 50 by the crane 100.

The lifting tool 1 further comprises an attachment member 31 , by means of which the lifting tool 1 is connectable to the crane 100 such as to suspend the lifting tool 1 from the crane 100.

The lifting tool 1 comprises an extensible structure 32 which is extensible and shortenable between the attachment member 31 and the coupling part 2 in at least the vertical direction.

In figures 1a, 1c, 2c (left part), 3a, 4a, and 5a, the extensible structure 32 is in a shortened position thereof. In figures 1b, 2c (right part), 3b, 4b, and 5b the extensible structure 32 is in an extended position thereof.

The lifting tool 1 further comprises a passive heave compensator 4 which is fixed to the extensible structure 32 at lower fixation points 33 and upper fixation points 34 of the extensible structure 32 such as to form an integral part of the lifting tool 1.

The compensator 4 is configured to, upon upwards heave motion of the crane 100, enable extension of the extensible structure 32 such that the longitudinal distance d, and therefore the height difference h, between the upper and lower fixation point 33,34 increases. Thus, the compensator 4 enables the extensible structure 32 to move from the shortened position shown in figures 1a, 1c, 2c (left part), 3a, 4a, and 5a to the extended position shown in figures 1b, 2c (right part), 3b, 4b, and 5b when the crane 100 moves upwards as in its heave motion. This makes the coupling part 2 of the lifting tool 1 move downwards relative to the crane 100 by the same amount as the crane 100 moves upwards. Thereby, the compensator 4 cancels out the upwards heave motion of the crane 100 for the coupling part 2 of the lifting tool 1.

Upon downwards heave motion of the crane 100, the compensator 4 enables shortening of the extensible structure 32 such that the longitudinal distance d, and therefore the height difference h, between the upper fixation points 34 and lower fixation points 33 decreases. Thus, the compensator 4 enables the extensible structure 32 to move from the extended position shown in figures 1b, 2c (right part), 3b, 4b, and 5b to the shortened position shown in figures 1a, 1c, 2c (left part), 3a, 4a, and 5a when the crane 100 moves downwards as in its heave motion. This makes the coupling part 2 of the lifting tool 1 move upwards relative to the crane 100 by the same amount as the crane 100 moves downwards. Thereby, the compensator 4 cancels out the downwards heave motion of the crane 100 for the coupling part 2 of the lifting tool 1.

The lifting tool 1 comprises an arm 3 supporting the coupling part 2 from the crane 100. The arm comprises the attachment member 31 and the extensible structure 32. The arm 3 forms part of a frame of the lifting tool 1.

The coupling part 2 is connected to the arm 3 of the lifting tool such as to be pivotal around the horizontal pivot axis 2a relative to the attachment member 31 of the arm 3.

The coupling part 2 is pivotal upwardly into a horizontal position, shown in figure 1c, and downwardly into a vertical position, shown in figures 1a-b in the same view, and in figures 3a- b, 4a-b, 5a-b in other views.

The lifting tool 1 comprises a pivot actuator which is operable between and connected to the coupling part 2 and the arm 3 and configured to pivot the coupling part 2 relative to the arm 3 around the horizontal pivot axis 2a between the horizontal position and the vertical position of the coupling part 2. This actuator is omitted in the figures for the sake of clarity. However it can easily be envisaged that the actuator may, as is known in the art, be embodied as a hydraulic cylinder. The piston and cylinder wall of the cylinder are therein connected to respectively the arm 3 and the coupling part 2 or vice versa. The arm 3 comprises an upper part 35 and a lower part 36, respectively comprising a lower section 35I and upper section 36u. These sections 35l,36u are telescoping relative to one another to together form the extensible structure 32. The lower section 35I of the upper part 35 comprises the lower fixation points 33 of the extensible structure 32 and the upper section 36u of the lower part 36 comprises the upper fixation points 34 of the extensible structure 32.

The passive heave compensator 4 as provided in the lifting tool 1 is in principle known in the art. The compensator comprises two hydraulic heave compensation cylinders 41 at opposed lateral sides of the arm 3. Each hydraulic heave compensation cylinder 41 has a piston 43 with a separator separating a gas chamber from a liquid chamber. The cylinder 41 is connected to a bank of pressurized gas reservoirs 45. The piston 43 is with its free end 44 thereof fixed to the extensible structure 32 at the lower fixation points 33 via a ring member 46. A wall 42 of the cylinder 41 is with a longitudinal center portion thereof fixed to the extensible structure 32 at the upper fixation point 34.

Heave motion of the crane 100 causes the piston 43 to oscillate within the cylinder 41 of the compensator 4. Hereby the distance between the hoisting point and the object 50 is lengthened and shortened, thus cancelling at least a part of the heave motion. The lifting tool 1 comprises the gas reservoirs 45. The bank of gas reservoirs 45 is fixed to the extensible structure 32, namely to the lower part 36 of the arm 3.

The coupling part 2, the extensible structure 32, e.g. the arm 3, and the passive heave compensator 4 are integral parts of the tool 1 , which are fixedly interconnected.

Figures 2a-d illustrate the upper part 35, the lower part 36, the cylinder 41 , and the gas buffer 45 separately. In figure 3a, these parts are shown as present in the hoisting tool 1 , when the extensible structure is in the shortened position. The cylinder 41 is shown separately to the left of the figure, to illustrate that the cylinder 41 is extended in this position of the extensible structure 32. In figure 3a, the parts 35, 36, 41 and 45 are shown in the same manner, but this time when the extensible structure is in the extended position. The cylinder 41 is shortened in this position of the extensible structure 32.

The lifting tool 1 is a lifting and upending tool for an elongate component 50 of an offshore wind turbine, e.g. a mast, a monopile, or a transition piece. The coupling part 2 of the tool comprises multiple mobile engaging members 21 adapted to in a coupling position thereof, engage a longitudinal end 51 of the elongate wind turbine component 50 such as to couple the elongate component with the tool.

The engaging members 21 comprise three mobile latching members 21 adapted to in the coupling position latch onto the longitudinal end 51 , underneath a radially inward flange 53 thereof, and three latching actuators 22, in the form of cylinders, adapted to move the latching members 21 from a retracted position into the coupling position. In figures 1a-c, the latching members 21 are in the retracted position, so that the lifting tool 1 has a radial contour that fits within the inner circumference of the flange 53, so that the tool 1 is movable into and out of the longitudinal end 51. In the figures the lifting tool 1 is shown being inserted into the longitudinal end 51 , in a position relative to the flange 53 in which extension of the cylinders

22 moves the latching members 21 to the coupling position, in which these latch underneath the flange 53.

The engaging members 21 further comprise two actively operable guiding members 23, not visible in figures 1a-b but shown most clearly in figures 4a-b and 5a-b. The guiding members

23 are embodied as in NL2024947, and are configured for guiding the tool 1 into the position relative to the longitudinal end 51 shown in figures 1a-c, in which moving the latching members 21 to the coupling position couples the component 50 to the tool 1, thus aiding in the relative positioning of the tool 1 prior to coupling.

As shown in figure 1 c, by the arrangement of the latching members 21 , the coupling part 2 is configured to in a horizontal position of the coupling part 2, engage the longitudinal end 51 when the elongate component 50 is in a horizontal orientation, such as to couple the elongate component 50 with the lifting tool 1.

The coupling part 2 is configured to retain the coupled elongate component 50 during lifting of the longitudinal end 51 by means of the crane 100 thereby upending the elongate component 50 from the horizontal orientation of figure 1c into a vertical orientation thereof, shown in figures 1a-b, 4a-b, and 5a-b, while allowing the coupling part 2 to pivot from its horizontal position to its vertical position.

The lifting tool 1 comprises a locking mechanism, formed by valves of the cylinder forming the pivot actuator (not shown). The valves are controllable to close off the hydraulic fluid flow. Thereby the locking mechanism is configured to retain the coupling part 2 in its horizontal position while positioning the coupling part 2 relative to the longitudinal end 51 and while moving the latching members 21 to the coupling position thereof. The arm 3 comprises a longitudinal portion 37, which comprises the extensible structure 32. The upper part 35 of the arm 3 has a slanted portion 38 extending above the longitudinal portion 37. The longitudinal portion 37 and the slanted portion 38 are arranged such, that in the horizontal position of the coupling part 2, the longitudinal portion 37 extends substantially vertically and horizontally offset from the attachment member 31 and the center of gravity of the lifting tool 1 when the coupling part 2 is in the horizontal position. In particular, the longitudinal portion extends completely horizontally offset from the coupling part 2. With the center of gravity being located centrally within the coupling part, the result is that the coupling part 2 can be pivoted upwards from the vertical position of figures 1a-b into the horizontal position of figure 1c by a substantially a right angle, i.e. 90 degrees. This is visible from a comparison between figures 1a-b and 1c.

In other embodiments, the lifting tool is an exchangeable lifting tool. An example of such an exchangeable lifting tool is shown in figure 6a, wherein parts of the embodiment of figures 1-5 are visible as well. Therein, the coupling part 2 of the tool is embodied here as a Ramshorn hook, but it may in other embodiments also be another tool such as a gripper or a yoke. The attachment member 31 comprises a lower tool connector 5. This lower tool connector 5 is configured for releasable connection with an upper tool connector 105 of the crane 100. Here, the tool connectors 5,105 are embodied as in W02020055249, and the upper tool connector 105 is alike in W02020055249 supported in the hoisting block 104 of the crane 100 accommodating the hoisting cables 103 as shown in figure 6b.

The lower tool connector 5 forms the upper end of the arm 3 of the hook. The lower tool connector 5 is a male tool connector and the upper tool connector a female tool connector. The male lower tool connector 5 comprises a hollow shank having a shoulder adapted to latch above multiple mobile tool retainers inside a central passage of the female upper tool connector upon insertion of the shank into said passage. This is illustrated for this embodiment in figure 6b, and disclosed in more detail in W02020055249.

In this embodiment the passage of the female upper tool connector 105 enables the lower part 36 of the arm 3 to extend and shorten inside the passage in order to maximize the hoisting height. In this embodiment, the gas buffer 45 is not fixed to the extensible structure 32, but present on the crane 100 and to be connected inside the hollow shank to the cylinder 41 via an umbilical. Other embodiments are envisaged wherein the extensible structure is below the passage of the upper tool connector 105, e.g. wherein the gas buffer 45 is fixed to the extensible structure 32. Figure 7 illustrates another embodiment wherein the lifting tool is an exchangeable lifting tool. The lifting tool is similar to the lifting tool illustrated in figures 5a-b. The lifting tool is coupled to an elongate offshore wind turbine component and is illustrated with the extensible structure in the extended position. The coupling part 2 is embodied as a specific gripper which is operable for engaging the elongate component 50 in order to couple the component 50 to the lifting tool.

Similar to the embodiment illustrated in figure 6, the attachment member comprises a lower tool connector 5 that is configured for releasable connection with an upper tool connector 105 of the crane. Again, the tool connectors 5,105 are embodied as in W02020055249, and the upper tool connector 105 is alike in W02020055249 supported in a hoisting block of the crane accommodating hoisting cables, for example as shown in figure 6b.

The lower tool connector 5 forms the upper end of the upper part of the arm 3 of the lifting tool. The lower tool connector 5 is a male tool connector and the upper tool connector 105 is a female tool connector. The male lower tool connector 5 comprises a hollow shank having a shoulder adapted to latch above multiple mobile tool retainers inside a central passage of the female upper tool connector upon insertion of the shank into said passage.