Offshore operations, such as offshore wind turbine installation are generally performed using marine vessels comprising a buoyant hull used for travelling to the offshore location. Depending on the requirements of the offshore operations and characteristics of the offshore location, offshore operations may be performed with vessels which are of a type wherein the hull floats during operations or with vessels which are of a jack-up type, wherein the hull is raised above the water during operations.

The invention relates to a jack-up vessel, the jack-up vessel comprising: a buoyant hull; a plurality of jack-up legs, each jack-up leg comprising one or more leg chords, each leg chord having at least one rack; a plurality of jacking assemblies, each jacking assembly being associated with a leg chord, each jacking assembly being configured to relatively move the associated leg chord the buoyant hull vertically; wherein each jacking assembly comprises: o a pinion group, comprising a plurality of pinions arranged vertically above each other, each pinion engaging a rack of a leg chord and being configured for transferring load between the hull and the leg chord resulting in a load distribution over the pinions within the pinion group; o actuators for actuating the pinions of the pinion group, each actuator being configured for actuating a respective pinion.

A jack-up vessel is known in the art, e.g. from US2009/0090191 and US2019/040598.

Jack-up vessels generally are designed to be used for performing a certain type of operations. In the past, this was often offshore drilling for oil or gas. Such designs are also envisaged within the scope of this invention. Recently jack-up vessels are increasingly used for installing components of an offshore wind turbine at a wind turbine installation site. In an embodiment, the jack-up vessel has a crane that is used for hoisting, e.g. of wind turbine components.

A jack-up vessel generally comprises a plurality of jack-up legs, often 3, 4, 5 or 6 legs, which can be moved vertically relative to the buoyant hull. In a travelling configuration, these jack-up legs extend upward from the hull. Upon reaching the offshore location, before the intended operation of the jack-up vessel is commenced, the jack-up vessel needs to be brought into an operational configuration. In this operational configuration, the jack-up legs have been lowered with respect to the hull to engage with the seabed and further operating the jack-up legs has caused the hull of the vessel to be raised into a stationary position above the water level. Optionally, bringing the vessel in the operational configuration thereof may further comprise a preloading operation of increasing the load on one leg at a time such that the load on the seabed exerted by that leg is temporarily higher, and repeating this for all legs. A so- called pre-drive operation may also be performed.

A jack-up leg comprises one or, more common, multiple leg chords. A jack-up leg is often formed as a truss structure. For example, a triangular truss structure may comprise three leg chords in a jack-up leg and a rectangular truss structure four leg chords in a jack-up leg. The jack-up legs further comprise racks, usually two racks per leg chord, e.g. one rack member connected to the chord that is provided with a rack at opposed vertical sides thereof.

Operation of the jack-up legs is performed by jacking assemblies, each jacking assembly being associated with a leg chord. Generally, one jacking assembly is associated with one leg chord. Each jacking assembly is configured to move the corresponding jack-up leg and the buoyant hull vertically relative with respect to each other.

A jacking assembly comprises a plurality of pinions and associated actuators, each actuator configured for actuating a respective pinion. The pinions are arranged in pinion groups, wherein pinions are arranged vertically above each other. Each pinion engages a rack of its associated leg chord and is configured for transferring, in the operational configuration, a part of the load of the hull to the leg chord, resulting in each pinion having an actual transferred load associated with the pinion. The number of pinions in a pinion group per rack may, for example, be 2, 3, 4, 5, 6, or 10 pinions per rack.

The jacking assemblies engage with the racks of a leg chord by means of the pinions to transfer loads from the jack-up assemblies to the legs and to move the jack-up legs with respect to the hull. A vertical movement of the jack-up legs is achieved by means of a rotational movement of the pinions, which is achieved by operating the actuators. The operation of the actuators is stopped when the respective jack-up leg is in a desired extended position. Once the jack-up legs are in the desired extended position, this position should be maintained, i.e. this position should be a stationary position. It is known to achieve this by using the actuators of the pinions for braking. For example, a brake is integrated with the drive motor of the actuator or is located in a transmission, e.g. a gear transmission, between the drive motor and the pinion.

In this stationary position, it is common practice to strive for an equal load distribution of the pinions of a pinion group. This equal load distribution then remains as long as the load on the jack-up leg is not changed substantially. When the load on the jack-up leg changes, this load distribution between pinions in a pinion group may then become unequal. For instance, when the load on a jack-up leg is increased due to a certain use, for instance a pre-loading operation or an operation of installing a wind turbine component using a crane of the vessel, this increase is not equally transferred to the all pinions in the pinion group. This is especially the case if brakes are applied to hold the pinions, which brakes are situated between the each pinion and the respective actuator. The change in leg load may cause that the lower pinions to need to transfer a higher load, while the upper pinions of the pinion group may see no increase or just a small increase in load. Consequently, the resulting load distribution is unequal over the pinions of the pinion group.

Alternatively or in addition to the load on a jack-up leg increasing due to a certain use of the vessel, e.g. a crane thereof, this load may also increase due to a change in environmental conditions. For instance, when a storm passes the offshore location, winds and/or swell may cause significant additional forces on the jack-up vessel, e.g. bending forces on the legs. These additional forces may not be equally distributed among all the legs. Consequently, the loads on some pinion groups may increase, causing (additional) unequal load distribution within the pinion groups and amongst the pinion groups, e.g. of one leg. In practice, the loads which the pinions have to endure during a so-called storm holding operation may be one of the most influential on the requirements on the design of the jack-up legs and jackingassemblies.

The aim of the invention is to provide an improved version of a jack-up vessel.

The aim is achieved according to the present invention by a jack-up vessel according to claim 1.

The inventive jack-up vessel comprises a control system configured to perform a routine comprising: receiving information about an intended use and/or future environmental conditions for the jack-up vessel determining, based on this information, a pre-operation load distribution for the plurality of pinions of the pinion group, in which pre-operation load distribution the loads over the pinions within this pinion group are unequally distributed, such that in an operational load distribution during the intended use and/or during the future environmental conditions, e.g. during the storm, the loads over the pinions within this pinion group are equally distributed; receiving the sensor signals indicative of the sensed load distribution for the plurality of pinions of the pinion group, and determining/ computing a difference between the preoperation load distribution and the sensed load distribution; emitting, in response to the difference, control signals to the actuators, such that the actuators are operated and the sensed load distribution of the pinion group is made to correspond to the pre-operation load distribution.

Due to the routine, the effect may be achieved that during the intended use and/or during the future environmental conditions, e.g. during the storm or when hoisting an object with a crane of the vessel, the loads over the pinions within the pinion group are equally distributed. To achieve this, the routine deliberately introduces an unequal distribution of the pinion loads ahead of the intended use and/or predicted future environmental conditions. Once the intended use takes place and/or the predicted environmental conditions become reality, the change in load on the leg has the desired effect that the pinion loads become equal, without operating the actuators to do so, in practical embodiments, without releasing the brakes that each hold a respective pinion.

In absence of the routine, as in the prior art approach discussed above, the change of load on the jack-up leg due to the use or the change in an environmental condition would lead to a significant unequal load distribution over the pinions in the pinion group, with some pinions, e.g. the lower pinion(s) being subject to a very high load.

For example, the future environmental conditions involve the prediction of a storm which requires the jack-up vessel to be brought into storm holding mode, also referred to as storm survival mode, wherein the hull is kept raised above the water with a storm survival air gap under the raised hull. For example, the intended use comprises a hoisting operation to be performed by a crane of the jack-up vessel, with the hull being kept raised above the water during the hoisting operation.

An effect of the invention is to avoid unequal load distribution over the pinions in a pinion group during an the intended use of the vessel, e.g. of a crane thereof, and/or during the (adverse) environmental conditions, e.g. during the passing of a storm.

The invention may serve to lower wear on the pinions, e.g. on the lower pinion(s) of a pinion group and/or allow the use of pinions and/or actuators for the pinions with a lower maximum load/power capacity.

Unequal load distribution leads to a non-optimal loading of pinions, which may lead to higher wear on some pinions and/or the need for pinions with a higher capacity than if this unequal loading would not be the case.

In embodiments, as is known in the art, one or more of the jacking assemblies each comprise a first pinion group engaging a first rack of the leg chord and a second pinion group engaging a second rack of the same leg chord, preferably the first and second racks being opposite one another. In these embodiments, the pre-operation load distributions may be determined symmetrically for the first and the second pinion group, i.e. the pre-operation load distribution of the first and second group are the same. The pre-operation load distribution may also be determined asymmetrically for the pinion groups of a jacking assembly. For example, the preoperation load distribution may be different for the first pinion group compared to the second pinion group. For example, during a storm the opposing first and second pinion groups may be expected to have a different operational load distribution as a result of the wind blowing in a certain wind direction, e.g. causing a predictable bending of the jack-up legs. For example, during intended use, e.g. hoisting a heavy object with the crane, the first and second pinion groups may be expected to have a different operational load distribution as a result of the side of the vessel where the load is hoisted, e.g. also causing bending of a jack-up leg(s).

In embodiments, the pre-operational load distribution for a pinion group may be determined depending on an expected load on the leg, e.g. on the basis of an expected bending of the leg due to the intended use and/or the predicted environmental conditions. For example, the expected operational load distribution for a first pinion group associated with a first leg chord may be different to the expected operational load distribution for a second pinion group associated with a second leg chord of the same leg which may result in different pre- operational load distributions. In embodiments, the pre-operational load distributions may be determined based on the leg, e.g. the position of the leg relative to the crane and/or other legs of the vessel.

As known in the art, in embodiments, the jacking assembly comprises a frame in which the plurality of pinions and actuators of the pinion group are arranged vertically above one another. For example, also as known in the art, the frame of each jacking assembly supports two pinion groups, wherein the two pinion groups each have a plurality of pinions arranged vertically above each other and associated actuators in order to engage two racks on a chord of a leg.

In embodiments, the pre-operation load distribution for the plurality of pinions of the pinion group is such that lower pinion(s) of the pinion group have lower loads thereon then higher pinion(s) of the same pinion group. In these embodiments, the lowest pinion of the pinion group may have the lowest load in the pre-operation load distribution and the load in the preoperation load in this distribution increases for each higher located pinion in the pinion group.

In embodiments, a load increase from the pre-operation load distribution to the operational load during the intended use and/or during the future environmental conditions for lower pinions of the pinion group is larger than for higher pinions of the same pinion group. In these embodiments, an increase in load between the pre-operation load distribution and the load distribution during the planned intended use and/or during the predicted future environmental conditions may be highest for the lowest pinion of the pinion group and the load increase may be lower for each higher located pinion of the pinion group.

In an embodiment, a hull connector structure is provided at a lower end of the frame of the jacking assembly, which hull connector structure connects the jacking assembly to the hull. In this arrangement, the load of the hull is effectively suspended from the lower end of the frame of the jacking mechanism.

In embodiments, a hull connector structure is provided at an upper end of the frame of the jacking assembly, which hull connector structure connects the jacking assembly to the hull. In this arrangement, the load of the hull effectively rests on the upper end of the frame of the jacking mechanism.

It will be appreciated, that the load distribution over the pinions in a pinion group is influenced by whether the hull connector structure is present at the lower end of the frame or at the upper end of the frame. Yet, the inventive concept is applicable in each of these variants. The embodiment wherein the hull rests on the jacking assembly may provide enhanced options to achieve an advantageous distribution than the other, traditional, suspension of the hull from the lower end of the frame.

For example, the hull connector structure is configured for a pin connection to the hull. For example, the hull connector comprises a pair of spaced part eye members, each receiving a connector pin therein to connect the hull connector structure to the hull, e.g. through one or more associated eye members on the hull. For example, an elastic bushing is provided in one or more eye members, for example made of a synthetic composite material incorporating solid lubricant(s), e.g. made of Orkot.

In embodiments, the pin connection of the frame of the jacking assembly may result in a pivotal connection of the jacking assembly to the hull. In such embodiment, and others, a stabilizing connector structure may be provided at the other end of the frame of the jacking assembly, generally to avoid undue pivoting of the assembly. This stabilizing connector structure may comprise one or more elastic members, e.g. when the hull connector structure also comprises one or more elastic members, e.g. the elastic bushing as described above.

In an embodiment, the hull connector structure is provided with a total load monitoring arrangement that is configured to sense to total load of the hull onto the frame of the jacking assembly. For example, deformation of an elastic member in the hull connector structure, e.g. of an elastic bushing fitted in an eye member, is measured to determine the total load of the hull onto the frame. In another example, strain gauges are provided for total load monitoring.

For example, the control system of the jack-up vessel may have a storm holding mode wherein the vessel is placed when a storm approaches the vessel.

In embodiments, the control system may be configured receive, e.g. automatically, the information about future environmental conditions, e.g. configured to perform the inventive routine in the process of bringing the vessel in a storm holding mode. For example, when the vessel is to be placed in storm holding mode, the control system uses this information to determine the pre-operation load distribution, e.g. selected from a list of predefined load distributions and/or based on calculations based on a modelling of the jack-up vessel and/or based on experimental/historical data related to the jack-up vessel or similar jack-up vessels. In embodiments of the control system, the pre-operation load distribution for the plurality of pinions of the pinion group is such that lower pinions of the pinion group have lower loads thereon then higher pinions of the pinion group.

In embodiments of the control system, a load increase from the pre-operation load distribution to load during the intended use and/or during the future environmental conditions for lower pinions of the pinion group is larger than for higher pinions of the pinion group.

In embodiments, the control system is configured to determine the pre-operation load distribution for each pinion group individually. For a jack-up vessel with 4 jack-up legs and 2 jacking assemblies per leg, 8 separate pre-operation load distributions are determined. It is conceivable that, for a certain operation, some or all of these pre-operation load distributions are the same.

In embodiments, the control system is configured to determine the pre-operation load distribution for the pinion groups of a jack-up leg. In other words, in this embodiment the preoperation load distribution is determined for all the pinion groups in a jack-up leg, i.e. the preoperation load distribution may be different for each jack-up leg, but not between pinion groups of a jack-up leg. Of course, it is also possible to determine the pre-operation load distribution for a set of legs, such as the starboard jack-up legs or the portside jack-up legs; or for the front jack-up legs and the rear jack-up legs.

For example, when the pre-loading operation is initiated, the pre-operation load distribution may be set automatically such that when the maximum loads corresponding to the intended use and/or conditions are reached, these maximum loads are distributed equally over pinions in a pinion group.

In another example, when weather is forecast that exceeds a threshold, a storm hold mode may be selected and characteristics of the expected weather may be the basis for determining the pre-operation load distribution. These characteristics may be wind direction, wind speed, and/or wind gusts, but they may also be characteristics of the sea such as swell height, swell direction, and/or other characteristics. These characteristics may be selected by an operator or retrieved automatically, e.g. from weather forecast data which can be accessed and interpreted by a computer.

The information about the intended use may be related to parameters of the installation location, such as parameters relating to the sea condition or the depth of the sea. After receiving information about the intended use and/or future environmental conditions, the control system determines a pre-operation load distribution for at least one pinion group, in which pre-operation load distribution the load within this pinion group is unequally distributed, such that in the intended use and/or during the future environmental conditions the load within this pinion group is equally distributed.

It will be clear that the pre-operation load distribution thus depends on the intended operation, and possibly also on characteristics of this intended operation. This may be set by an operator or it may be determined automatically.

In embodiments, the jack-up vessel further comprises a user interface, and the control system is configured for receiving the information about an intended use and/or future environmental conditions from an operator using the user interface.

By intentionally causing an unequal load distribution before an intended use takes place and/or before the predicted future environmental conditions actually occur, the effect of a resulting unequal load distribution - which would be present in absence of the invention - is (partially) ‘cancelled out’. The result is that during the intended operation, or at least during part of the intended operation, and/or during the future environmental conditions, the actual load distribution may be close to an equal load distribution.

In embodiments, the jack-up vessel is configured for installing components of a wind turbine at a wind turbine installation site, wherein the jack-up vessel further comprises a crane configured for hoisting said components; wherein the pre-operation load distribution is such that during hoisting the loads within a pinion group are equally distributed. At a wind turbine installation site, the crane of the jack-up vessel is operated for hoisting one or more components of a wind turbine. These components may initially be positioned on the jack-up vessel. Alternatively, these components may initially be positioned on or in a separate vessel. In both cases, the crane is operated for hoisting these components. During operation of the crane the loads transferred to the jack-up legs through the jacking assemblies may vary. For example, when the crane hoists a wind turbine component from a separate vessel, at least the load of the weight of this component is transferred to one or more jack-up legs, increasing one or more transferred loads. During the hoisting of a wind turbine component from an initial position on the jack-up vessel, the loads on one or more legs may increase, while the loads on other one or more legs of the vessel may decrease. During a hoisting operation, the loads transferred from a jacking assembly to a leg chord may not be evenly distributed between two or more pinions in a pinion group of a jacking assembly. For example, the load on the bottom-most pinion in a pinion group may be higher than the load on the top-most pinion this pinion group. It is desirable that the load on a pinion in a pinion group does not exceed a maximum allowable load corresponding to that pinion.

In embodiments, the pre-operation load distribution is calculated on the basis of a hoisting load of the crane. When the jack-up vessel is used to hoist a load, characteristics of this load may be the basis for determining the pre-operation load distribution. This may be set before the hoisting operation is commenced, for example based on initial location, intended location and total weight of the load to be hoisted. Alternatively or in addition, information obtained during the hoisting operation may be used to (re)determine the pre-operation load distribution. For example, when first hoisting a first wind turbine component, and subsequently hoisting a second wind turbine component, wherein the second wind turbine component has a higher weight than the first wind turbine component, the pre-operation load distribution in a nonhoisting configuration may be different. Additionally, one or more leg chords may have different pre-operation load distributions associated with it. For example, if it is foreseen that during the operation of the jack-up vessel one leg will transfer higher loads than one or more other legs, it may be desired that the load distribution in the pre-hoisting configuration differs for different legs, such that the load distribution achieved at a point in time during hoisting is close to an equal distribution for one or more jack-up legs.

Avoiding exceeding the maximum allowable load on a pinion may also or in addition be achieved by limiting the hoisting operation such that the highest load on a pinion in a pinion group is below the maximum allowable load for that pinion. When all pinions in a pinion group have a similar maximum allowable load, this means that other pinions in this pinion group are loaded below their maximum allowable load, which may not be considered efficient. Alternatively, a pinion group may comprise pinions with different maximum allowable loads, such that all pinions in a pinion group are loaded closer to their maximum allowable loads during the intended hoisting operation. This means that different pinions are required, which impacts maintainability and the number of spare parts to be retained.

It may be that the pre-operation load distribution in a pinion group is such that the load transferred by the uppermost pinion is a highest load, each subsequent lower pinion having a lower load than pinions above this subsequent lower pinion, the lowermost pinion having a lowest load. In this way, in the intended use, the uppermost pinion in a pinion group transfers a higher part of the load than the bottom-most pinion in this pinion group, and the amount per pinion may decrease from the uppermost pinion to the bottom-most pinion. For example, for a jacking assembly comprising five pinions in a pinion group, such a pre-operation load distribution may be that the relative amount of load transferred by the uppermost, second uppermost, middle, second-to-lowest, and lowest pinion, respectively, is 30%, 25%, 20%, 15%, and 10%.

The control system may be configured to compute a computed pre-operation load distribution. Such a computed pre-operation load distribution may, for example, be that the loads transferred in three pinions in a pinion group consisting of three pinions is 200 metric tonnes (mt), 300 mt, and 500 mt, respectively. Alternatively, such a computed pre-operation load distribution may be that these pinions transfer 20%, 30% and 50%, respectively, of the total load in this pinion group. This unequal pre-operation load distribution may be achieved by operating the associated actuators and sensing the load transferred in each pinion in a pinion group, or by measuring the loads in all but one pinion and computing the load in the remaining pinion.

The control signals based on the difference may be emitted based on an acceptable margin. For example, when the difference is zero, the control signal may be a zero value, indicating that no change is required. If the difference is nonzero, for example 0.5 mt, 1 mt, 20 mt or 100 mt, or 0.1% , 0.5%, 1%, 2%, 5% or 10%, the emitted control signal may reflect that change is required, and/or how much change is required. Alternatively, in the case of a nonzero acceptable margin, when a measure of the difference is smaller than this accepted margin the control system may emit a zero value for the control signal. This may be the case, for example, if the error in a pinion is 0.5% and the accepted margin if 1%; or when the error in a pinion is 10 mt and the accepted margin is 11 mt. The measure of the difference corresponding to the accepted margin may also be a combined measure, for instance that the sum of error values is lower than 100 mt or that the sum of the squared error values is below a number or that the average error value is less than 1%. Combinations of such measures may also be used.

The invention further relates to a method for operating a jack-up vessel, preferably a jack-up vessel according to one or more of the preceding claims, comprising the steps of: lowering jack-up legs for engagement with the seabed and raising a buoyant hull to a distance above water level; receiving information about an intended use and/or future environmental conditions; determining, based on this information, a pre-operation load distribution for a pinion group, in which pre-operation load distribution the loads within this pinion group are unequally distributed, such that in the intended use and/or during the future environmental conditions the loads within this pinion group are equally distributed; sensing the load distribution associated with a pinion group, and emitting sensor signals indicative of the sensed load distribution; a control system receiving the sensor signals indicative of the sensed load distribution, and determining/computing a difference between the pre-operation load distribution and the sensed load distribution; the control system emitting, in response to the difference, control signals to actuators such that the sensed load distribution of the pinion group corresponds to the preoperation load distribution.

The invention further relates to a method for operating a jack-up vessel for use such as: installing components of a wind turbine at a wind turbine installation site including hoisting said components, pre-drive operations, pre-load operations; the jack-up vessel comprising: a buoyant hull; a plurality of jack-up legs, each jack-up leg comprising one or more leg chords having racks; a plurality of jacking assemblies, each jacking assembly being associated with a leg chord, each jacking assembly being configured to relatively move the associated leg chord the buoyant hull vertically; wherein each jacking assembly comprises: o a pinion group, comprising a plurality of pinions arranged vertically above each other, each pinion engaging a rack and being configured for transferring load between the hull and the leg chord, resulting in a load distribution over the pinions within a pinion group; o actuators for actuating the pinions; o a sensor system; wherein the jack-up vessel further comprises a control system configured for receiving sensor signals from the sensor system and emitting control signals for actuating the actuators; the method comprising the steps of: receiving information about an intended use and/or future environmental conditions; determining, based on this information, a pre-operation load distribution for a pinion group, in which pre-operation load distribution the loads within this pinion group are unequally distributed, such that in the intended use and/or during the future environmental conditions the loads within this pinion group are equally distributed; sensing the load distribution associated with pinion group(s), and emitting sensor signals indicative of the sensed load distribution; the control system receiving the sensor signals indicative of the sensed load distribution, and determining/computing a difference between the pre-operation load distribution and the sensed load distribution; the control system emitting, in response to the difference, control signals to actuators such that the sensed load distribution of the pinion group corresponds to the preoperation load distribution.

In embodiments of the methods, the pre-operation load distribution for the plurality of pinions of the pinion group is such that lower pinions of the pinion group have lower loads thereon then higher pinions of the pinion group.

In embodiments of the methods, a load increase from the pre-operation load distribution to loads in the intended use and/or during the future environmental conditions for lower pinions of the pinion group is larger than for higher pinions of the pinion group.

In embodiments, the step of receiving information about an intended use and/or future environmental conditions comprises an operator interacting with a user interface. For example, the user interface may allow an operator to input future wind speed and wind direction, to select a pre-load operation, to enter sea depth or sea bottom characteristics, or to select a pre-programmed operation.

In embodiments, the information about future environmental conditions is received using telecommunication means. For instance, weather predictions may be supplied to the control system via a mobile network, a satellite downlink, or a wired connection.

In embodiments, the jack-up vessel is configured for installing components of a wind turbine at a wind turbine installation site, wherein the jack-up vessel further comprises a crane configured for hoisting the components of a wind turbine; wherein the pre-operation load distribution is such that during hoisting the loads within a pinion group are equally distributed.

The invention further relates to a control system for a jack-up vessel, the jack-up vessel being intended for offshore operations, wherein the control system is configured for receiving information about an intended use and/or future environmental conditions; determining, based on this information, a pre-operation load distribution for a pinion group, in which pre-operation load distribution loads within this pinion group are unequally distributed, such that in the intended use and/or during the future environmental conditions the loads within this pinion group are equally distributed; receiving a sensed load distribution associated with a pinion group, and determining/computing a difference between the pre-operation load distribution and the sensed load distribution; emitting, in response to the difference, control signals to actuators such that the sensed load distribution of the pinion group corresponds to the pre-operation load distribution.

In embodiments, the control system further comprises a user interface to receive information about an intended use and/or future environmental conditions, e.g. from an operator.

In embodiments, the information about future environmental conditions is received using telecommunication means.

In embodiments, the pre-operation load distribution is calculated on the basis of a hoisting load of a crane.

Details of the invention described above in relation to the device also relate to the method and the control device of the invention.

A second aspect of the invention relates to a jack-up vessel, e.g. for use such as installing components of a wind turbine at a wind turbine installation site including hoisting said components, e.g. the jack-up vessel having a crane, e.g. an around-the-leg crane, the jack-up vessel comprising:

- a buoyant hull;

- a plurality of jack-up legs, each jack-up leg comprising one or more leg chords having racks;

- a plurality of jacking assemblies, each jacking assembly being associated with a leg chord, each jacking assembly being configured to vertically move the associated leg chord relatively to the buoyant hull; wherein each jacking assembly comprises:

- a frame

- a pinion group comprising a plurality of pinions arranged vertically above each other, each pinion engaging a rack and being configured for transferring load between the hull and the leg chord, resulting in a load distribution over the pinions within a pinion group; - actuators for actuating the pinions, preferably each actuator configured for actuating a corresponding pinion; wherein the frame supports the pinion group and actuators , wherein a hull connector structure is provided at a lower end of the frame of the jacking assembly, which hull connector structure connects the jacking assembly to the hull, or wherein a hull connector structure is provided at an upper end of the frame of the jacking assembly, which hull connector structure connects the jacking assembly to the hull.

In the latter arrangement of the hull connector, the load of the hull effectively rests on the upper end of the frame of the jacking mechanism.

For example, the hull connector structure is configured for a pin connection to the hull. For example, the hull connector comprises a pair of spaced part eye members, each receiving a connector pin therein to connect the hull connector structure to the hull, e.g. through one or more associated eye members on the hull. For example, an elastic bushing is provided in one or more eye members, for example made of a synthetic composite material incorporating solid lubricant(s), e.g. made of Orkot.

In embodiments, the pin connection of the frame of the jacking assembly may result in a pivotal connection of the jacking assembly to the hull. In such embodiment, and others, a stabilizing connector structure may be provided at the other end of the frame of the jacking assembly, generally to avoid undue pivoting of the assembly. This stabilizing connector structure may comprise one or more elastic members, e.g. when the hull connector structure also comprises one or more elastic members, e.g. the elastic bushing as described above.

In an embodiment, the hull connector structure is provided with a total load monitoring arrangement that is configured to sense to total load of the hull onto the frame of the jacking assembly. For example, deformation of an elastic member in the hull connector structure, e.g. of an elastic bushing fitted in an eye member, is measured to determine the total load of the hull onto the frame. In another example, strain gauges are provided for total load monitoring.

The jack-up vessel of the second aspect of the invention may include one or more other technical details discussed herein, e.g. with reference to the claims.

The invention will be further elucidated in relation to the drawings, in which:

Fig. 1 is a side view of a jack-up vessel;

Fig. 2a is a side view of a jack-up vessel in an operational position; Fig. 2b is a side view of a jack-up vessel in an operational position during a hoisting operation;

Fig. 3a is a perspective view of a jack-up leg showing jacking assemblies;

Fig. 3b is a perspective view showing a jacking assembly;

Fig. 4 is a schematic representation of a sensor system and control system;

Fig. 5a is an illustration of load distribution with ‘Christmas Tree Behaviour’;

Fig. 5b is an illustration of a pre-operation load distribution;

Fig. 6a shows a side view of a gearbox for a pinion which is mounted in a resilient way by using resilient parts;

Fig. 6b shows a cross section of Fig. 6a, taken along the line Vlb-Vlb in Fig. 6a;

Fig. 6c shows a side view of the gearbox of Fig. 6a.

Fig. 7 shows the jacking assembly of figures 3a, b when mounted to the hull, Fig. 8 shows an alternative mounting of the jacking assembly to the hull.

Although the drawings illustrate a jack-up vessel performing an operation of installing components of a wind turbine at a wind turbine installation site, this does not mean that the invention is limited to this operation. The invention may also be applied to jack-up vessels used for other operations, for example a jack-up vessel drilling for natural resources such as oil. In practice, most jack-up vessels perform a pre-loading step and may be required to withstand environmental conditions such as storms.

In fig. 1 a jack-up vessel 1 for installing one or more components of a wind turbine at a wind turbine installation site is shown. The jack-up vessel is not in an operational position, but in a condition where it can travel to or from a wind turbine installation site. The jack-up vessel 1 includes a buoyant hull 5 and a crane 14. In an operational position of crane 14, not shown in fig. 1 , crane 14 is configured for hoisting one or more components 2, 3a, 3b, 4a, 4b of a wind turbine.

In this embodiment, wind turbine components 2, 3a, 3b, 4a and 4b are positioned on the buoyant hull 5 for transport to a wind turbine installation site. In other embodiments, some or all wind turbine components may be transported to the wind turbine installation site by other vessels.

The crane 14 is shown in a transport position. In embodiments, the vessel may include more than one crane, such as two, in which case both cranes are e.g. mounted on the same side of the buoyant hull 5. Jack-up vessel 1 includes a plurality of jack-up legs 6, 8. In this embodiment, jack-up vessel 1 includes four jack-up legs and four jacking assemblies. Jack-up legs 6 and 8 are shown; not shown are two other legs which are positioned, in this side view, behind legs 6 and 8. In other embodiments, the number of legs may be different, e.g. six. The legs may also be positioned at other locations than shown in fig. 1. For example, one or more legs may be positioned in the middle of buoyant hull 5. Two legs may be positioned at one end of buoyant hull 5 and the other legs at the opposite end.

Each jack-up leg comprises one or more leg chords. In fig. 1, each jack-up leg comprises three leg chords. Jack-up leg 6 includes leg chords 20, 21 and a third leg chord which is not shown in this side view. Jack-up leg 6 is shown in detail in fig. 3a.

Jack-up vessel 1 comprises a plurality of jacking assemblies 10, 11 , 12, 13, each jacking assembly being associated with a leg chord. In the embodiment shown in fig. 1, jacking assembly 10 is associated with leg chord 20, and jacking assembly 11 is associated with leg chord 21. Jacking assemblies 12 and 13 are associated with two chords of jack-up leg 8. Jacking assemblies associated with the third chords of jack-up legs 6 and 8 is not shown in this side view.

In this embodiment, jacking assemblies 10 and 11 are positioned at the same vertical position relative to buoyant hull 5. In other embodiments, jacking assemblies may be positioned at different vertical positions.

Jacking assemblies 10, 11 are configured to move the corresponding jack-up leg 6 vertically relative to the buoyant hull. Jacking assemblies 12, 13 are configured to move the corresponding jack-up leg 8 vertically relative to the buoyant hull.

In fig. 2a, jack-up vessel 1 is in an operational configuration of the jack-up vessel. This operational configuration is achieved by lowering jack-up legs 6, 8 for engagement with the seabed 16 and raising buoyant hull 5 to a distance above water level 15.

In this figure, legs 6 and 8 extend relative above and below buoyant hull 5. Crane 14 is in an operational configuration, such that a hoisting operation can be performed. Crane 14 may hoist one or more components to and from a wind turbine installation site. In this figure, no wind turbine component is being hoisted. This may be the case when jack-up vessel 1 has not yet started operation at the current site; alternatively, this may be the case when jack-up vessel 1 has finished hoisting of a wind turbine component, such as wind turbine component 4a. In this embodiment, wind turbine components 2 and 3b are positioned on buoyant hull 5. In other embodiments some or all wind turbine components may be positioned on other vessels. Wind turbine component 4a may also have been installed by a separate vessel, which may be a jack-up vessel or a different type of vessel, which is suitable for hoisting wind turbine component 4a.

In fig. 2b, jack-up vessel 1 is in the operational configuration and hoists wind turbine component 3b using crane 14, for example to an intended position 3b’ on wind turbine component 4a. This may be at the same wind turbine installation site as in fig. 2. Alternatively, this may be at a different wind turbine installation site. Wind turbine component 3b may have been hoisted from a position on buoyant hull 5, or from a different position, for example a position on a separate vessel.

Alternatively, the intended position of wind turbine component 3b may be a position on buoyant hull 5, or on a separate vessel. A wind turbine component 3b may have already been positioned on wind turbine component 4a, such as when wind turbine component 3b was incorrectly placed on wind turbine component 4a or when jack-up vessel 1 is used in a situation where for instance maintenance or decommissioning of a wind turbine requires hoisting wind a wind turbine component such as wind turbine component 3b.

In fig. 3a, leg 6 is shown in more detail. In this embodiment, leg 6 consists of three chords 20,

21 and 22, each chord having two racks. Rack 23 of chord 20 is visible, and rack 26 of chord

22 is visible. Both racks 24 and 25 arranged on chord 21 are visible. In this embodiment, chords 20, 21 and 22 are interconnected via a truss structure.

Also shown in fig. 3a are: jacking assembly 27, corresponding to leg chord 20, shown engaging with rack 23 and an opposed rack of corresponding leg chord 20; jacking assembly 28, corresponding to leg chord 21 , shown engaging with racks 24 and 25 of corresponding leg chord 21 ; and jacking assembly 29, corresponding to leg chord 22, shown engaging with rack 26 and an opposed rack of corresponding leg chord 22.

In embodiments, these jacking assemblies are arranged on buoyant hull 5, but for illustrative purposes, hull 5 is omitted in fig. 4. In this embodiment, jacking assemblies 27, 28 and 29 are configured in the same way, but in other embodiments, different jacking assemblies may be used for different chords, for different legs, or for both.

In fig. 3b, jacking assembly 28 is shown in more detail. Each jacking assembly comprises at least one pinion group. The number of pinion groups is generally equal to the number of racks. In this embodiment, jacking assembly 28 comprises two pinion groups, 34 and 35. Each pinion group comprises a plurality of, in this figure five, pinions 40 arranged vertically above each other.

Each pinion 40 engages a rack 24, 25 of its associated leg chord 21 and is configured for transferring a part of the load of the buoyant hull 5 to the leg chord 21 , resulting in each pinion 40 having a transferred load associated with the pinion.

In the shown embodiment, each pinion 40 is formed identical, but in other embodiments, different pinions may be comprised by jacking assemblies. In embodiments, pinions within a pinion group may be the same; alternatively, different pinions may be used within a pinion group, or for different pinion groups, or for different jacking assemblies, or for a combination thereof.

Jacking assembly 28 further comprises a plurality of actuators 30, each actuator configured for actuating a respective pinion 40. An actuator may actuate just one pinion, but it is also possible that an actuator actuates a plurality of pinions, e.g. 2 pinions at the same vertical position, or all pinions in one pinion group. In the shown embodiment, jacking assemblies also comprise a plurality of gearboxes 31 , brakes 32 and parallel parts 33.

Actuator 30 may be a hydraulic motor or an electric motor. In the embodiment shown, actuator 30 is an electric motor. In the case of an electric motor, actuation of a pinion 40 may be done directly coupled to actuator 30, or there may be a gearbox to provide the transmission from actuator 30 to pinion 40, such as a planetary gearbox 31. A parallel part 33 may also be included in the transmission.

Braking may be achieved by actuating actuator 30, or by actuating brake 32. Alternatively, brake 32 may be a failsafe brake, to be used in cases wherein using actuator 30 for braking does not give a sufficient result, such as when actuator 30 fails. Brake 32 may be embodied as a brake which brakes in a neutral position and is kept in a non-braking configuration by means of electric power, such that in case of a power failure, rendering actuator 30 inoperable, brake 32 is activated. In embodiments, brake 32 acts on the same shaft as the shaft on which actuator 30 acts.

In embodiments, gearboxes 31 are of the same type to keep the number of spares minimal. In embodiments, this also applies for actuators 30.

In Fig. 4, a sensor system 150 and a control system 152 are schematically represented. Pinions 140a and 140b engage with rack 125 of associated leg chord 121.

Sensor system 150 is configured for sensing the load distribution associated with a pinion group, and emitting sensor signals indicative of the sensed load distribution.

In this figure, one sensor system is associated with a pinion group. It is conceivable that a jack-up vessel comprises one sensor system for the entire jack-up vessel. It is also conceivable that each pinion, each pinion group, each rack, each chord, each jacking assembly, or each leg may have a sensor.

Sensor signals may be emitted to the control system 152 by a wire from a sensor to the control system, or there may be an intermediate component which combines one or more sensor signals and emits a signal to the control system. Such an intermediate component may also perform calculations.

Here, sensor system 150 comprises sensor 151a and 151b, sensing parameters representative of transferred loads associated with pinion 140a and pinion 140b, respectively. Pinion loads associated with pinions may be measured in many different ways, e.g. by load cells on the pinions or the pinion shaft. In a preferable embodiment they may be measured by integrated sensors at the pre-stages of the gearboxes 131a and 131b. This is a more practical location than the actual pinion or pinion shaft, because the actual pinion is in a harsher environment and more difficult to reach.

The jack-up vessel comprises a control system 152. Control system 152 receives the sensor signals indicative of the sensed load distribution from sensor system 150.

Control system 152 is configured for receiving information about an intended use and/or future environmental conditions. In embodiments, an operator may use user interface 154 to provide the control system with characteristics of the pre-load operation, the load to be hoisted, weather conditions, etc. Alternatively, this information may be received before the vessel is deployed and stored in the control system. Based on the received information, the control system determines a pre-operation load distribution, e.g. automatically. For example, in a hoisting operation, a characteristic of the load to be hoisted may be measured by a hoisting system in communication with the control system.

If during a pre-loading step the actual transferred loads are measured and a difference between one or more of these loads is determined to be higher than a desired amount, the pre-operation load distribution may be reactively determined such that the load distribution is more even across the pinions in a pinion group. In other words, after receiving information about the intended use and determining a pre-operation load distribution, feedback during the operation may be received after which the control system may determine a second preoperation load distribution. This may be determined at any point before or during operation and subsequently stored in the control system. At any point after storing this pre-operation load distribution it may be replaced by a different pre-operation load distribution. It is also possible that the control system is configured for storing a plurality of pre-operation load distributions, e.g. each time that a new pre-operation load distribution is determined, the previous pre-operation load distribution is added to a memory of possible load distributions, such that a previous pre-operation load distribution may be selected at any later point, for instance by the operator or automatically based on a characteristic that the control system detects.

In embodiments, control system 152 receives information about future environmental conditions using telecommunication means 153.

User interface 154 may provide the operator with information on the load distribution, for example the current load distribution, or information about integrity of the sensor system, i.e. whether the system detects that sensors in sensor system 150 are working properly or malfunctioning.

Control system 152 determines a difference between the pre-operation load distribution and the actual transferred load. It emits, in response to the difference, control signals to one or more actuators 130a, 130b, such that the pre-operation load distribution corresponds to the actual transferred loads. In embodiments, the one or more actuators 130a, 130b actuate their associated pinion 140a, 140b by using the respective gearbox 131a, 131b. It may suffice for one pinion to be actuated: for example, if the load on pinion 140a is higher than desired, and the load on pinion 140b is higher than desired, after actuating either actuator 130a or actuator 30b, the actual transferred loads may correspond to the pre-operation load distribution. Alternatively, it may be required or desired to actuate more than one actuator, for example all actuators in a pinion group. It is also possible to actuate a plurality of pinions at a certain vertical location, i.e. first actuating upper pinions, then middle pinions, etc.

Figs. 5a and 5b illustrate the effect of a load distribution for a leg chord 21 with two racks and for a jacking assembly 28 with two pinion groups 34,35, each pinion group comprising three pinions. Both figures show next to the pinions loads associated with the pinions as two horizontal bars. Each highest bar represents the load associated with the pinion before load is increased, each lowest bar represents the load associated with the pinion after load is increased. The behaviour illustrated in fig. 5a may be called ‘Christmas Tree Behaviour’. If the load on the jack-up leg increases while brakes are applied (e.g. during a pre-loading step, during storm conditions or during a hoisting operation of crane 14), the lower pinions might take more load than the upper pinion.

This can be counteracted by adjusting the load distribution before increasing the load on a leg to a pattern that gives an even distribution when the high leg load is applied. This can be achieved by adjusting the settings of a (re-)torque system. The resulting load distribution is shown in fig. 5b. The pre-operation load distribution before increasing load may be called a ‘Reverse Christmas Tree’. When load is applied, the loads associated with the pinions are equal, illustrated by the lower bars in fig. 5b.

The lower pinions in a pinion group will generally have the largest increases in load from the pre-operation load distribution to the loads in the intended use and/or during the future environmental conditions, in particular in embodiments wherein the hull is suspended from the jacking frame. In certain pre-operation load distributions, these pinions transfer a low load or approximately no load and have a large increase in load in the intended use and/or during the future environmental conditions.

It may however be desirable to achieve an even larger increase in load. In this case, in the pre-operation load distribution the loads of these pinions can be thought of as having a desired load corresponding to a value below zero, a ‘negative pre-operation load’ so to say. In other words, the slanted dashed line in Fig. 5b, when extrapolated to lower pinions, would cross the vertical axis. This can be achieved by positioning these pinions with respect to the rack so that they do not engage the rack in the pre-operation load distribution. In other words, a certain backlash or play is introduced, i.e. a clearance that the rack and/or the pinion can move before they engage each other. In this way, below a certain load on the rack these pinions transfer essentially no load, and above a certain load on the rack, these pinions will engage the rack and transfer part of the load on this rack.

It is also conceivable that a part, e.g. a respective pinion, its respective gearbox, a connection between the pinion and the gearbox, and/or a mounting part in the respective jacking assembly is provided as a resilient part. This resilience refers to the ability of this part to absorb energy when it is deformed elastically, and release this energy upon unloading. With a resilient part, when the load on the respective pinion is increased, a part of this load is absorbed by elastic deformation of the resilient part. This allows the total load that can be transferred by this pinion to be higher. Within a pinion group, one more pinions, such as the lowest pinion, may be provided as a resilient part. When more than one pinion are provided as a resilient part, it is conceivable that a lower pinion has a resilient part which can take more load than a higher pinion.

When a resilient part is provided for a pinion in a pinion group, the pre-operation load distribution is determined such that the combined effect of the pre-operation load distribution and the resilient part leads to the loads within this pinion group being equally distributed in the intended use and/or during the future environmental conditions. For example, the lowest pinion in a pinion group could be provided with a resilient part, such as a flexible mounting of the gearbox. The resilient part can absorb part of an increase in load. The pre-operation load for the lowest pinion would then be the load in the intended use and/or during the future environmental conditions, minus the part of the increase in load which is not absorbed by the resilient part.

In Fig. 6a, an actuator (not shown) actuates a pinion (not shown) through a gearbox 31, brake 32 and parallel part 33. Gearbox 31 is mounted to a housing 60. Also shown are axial mounting plates 61. In Fig. 6b a cross section of Fig. 6a is shown. Between the gearbox 31 and housing 60 a bearing 62 is provided, here comprising a bronze bushing. The bearing allows rotation of the gearbox 31 with respect to the housing 60. In Fig. 6c, axial mounting plates 61 have been omitted for clarity. Now multiple (8) flexible parts 63 of a flexible or resilient material are visible, e.g. rubber or a polymer, e.g. a fibre-reinforced polymer. These flexible parts are provided between the gearbox 31 and the housing 60. The presence of these flexible parts 63 provides resilience to and limits any rotation of the gearbox 31 with respect to the housing 60.

As already visible in figures 3a, 3b, and further shown in figure 7, the jacking assembly 28 has a frame 28a. This frame 28a supports two pinion groups, each with pinions at levels above one another. Each pinion is driven by an associated actuator, e.g. an electric motor with a reduction gearbox. Here the two pinion groups 34, 35, each have a plurality of pinions arranged vertically above each other in order to engage the two racks 24, 25 on the leg chord 21.

A hull connector structure 28b is provided at a lower end of the frame 28a of the jacking assembly 28. This hull connector structure 28b connects the jacking assembly 28 to the hull 5. In this arrangement, the load of the hull 5 is effectively suspended from the lower end of the frame 28a of the jacking assembly 28.

In another embodiment, as shown in figure 8, the hull connector structure 28b’ is provided at an upper end of the frame 28a’ of the jacking assembly 28’, which hull connector structure 28b’ connects the jacking assembly to the hull 5. In this arrangement, the load of the hull 5 effectively rests on the upper end of the frame 28a’ of the jacking assembly 28’.

It will be appreciated, that the load distribution over the pinions in a pinion group is influenced by whether the hull connector structure 28b, 28b’ is present at the lower end of the frame as in figure 7 or at the upper end of the frame as in figure 8. Yet, the inventive concept for load distribution over the pinions of a group is applicable to each of these variants.

It is illustrated, that the hull connector structure is configured for a pin connection to the hull. For example, the structure comprises a pair of spaced part eye members 28b1 , 28b2, 28b1’, 28b2, each receiving a connector pin 28d, 28d’ therein to connect the hull connector structure to the hull 5, here through one or more associated eye members on the hull. For example, an elastic bushing is provided in eye members 28b1, 28b2, 28b1’, 28b2 of the hull connector structure, for example made of a synthetic composite incorporating solid lubricant(s), e.g. made of Orkot.

It is shown that the pin connection of the frame 28a, 28a’ of the jacking assembly to the hull may result in a pivotal connection of the jacking assembly to the hull. In such embodiment, and others, a stabilizing connector structure 45, e.g. shown in figure 7 at the upper end, may be provided at the other end of the frame of the jacking assembly, generally to avoid undue pivoting of the assembly 28, 28’. This stabilizing connector structure may comprise one or more elastic members, e.g. when the hull connector structure also comprises one or more elastic members, e.g. the elastic bushing as described above.