NL2026416B1

NL2026416B1 - Crane vessel with a crane for hoisting wind turbine components

Info

Publication number: NL2026416B1
Application number: NL2026416A
Authority: NL
Inventors: Stavenuiter Wilco
Original assignee: Tetrahedron B V
Priority date: 2020-09-04
Filing date: 2020-09-04
Publication date: 2022-05-04
Also published as: WO2022050840A1

Abstract

The invention relates to a crane vessel comprising a crane with an elongate boom and a jib that projects from the boom, a hoisting block, an aft hoisting tackle with a variable first hoisting length and a forward hoisting tackle with a variable second hoisting length between the jib and the hoisting block, and hoisting cable manipulators for manipulating the hoisting cables of the hoisting tackles, wherein the hoisting block comprises, an aft load suspension for a first load, and a forward load suspension for a second load that is further away from the boom, spaced apart from the aft load suspension.

Description

P138835NL00 Crane vessel with a crane for hoisting wind turbine components

BACKGROUND The invention relates to a jack-up crane vessel or semi-submersible crane vessel or mono-hull crane vessel comprising a hull with a deck, and a crane on the hull for hoisting a load outside the deck.

Crane vessels of this kind are used for building offshore wind turbines, wherein turbine components, such as a tower, a nacelle, and a rotor with a hub and multiple blades are hoisted high above the waterline. The known crane vessels have a crane that comprises a slewing crane base and a long boom that is rotatable connected with the crane base at the boom heel. The boom is raised and lowered by means of a luffing hoist tackle above the boom that is hauled in or paid out by a winch.

Known large offshore wind turbines typically have power of 8 Megawatt and require a lifting height for its components of 140 meters above the waterline. Offshore wind turbines are continuously scaled up, wherein a power of 15 Megawatt is envisaged in the near future.

SUMMARY OF THE INVENTION As a scale up of offshore wind turbines is envisaged, significant higher lifting heights {for the turbine components are required. These high lifts are executed close to the top of the luffing boom while the boom is operated in a steep angle, whereby the load position becomes very close to the boom. This may cause a boom clearance problem, wherein the boom clearance is the space between the load and the boom. The nacelle is heavy and compact, but when looking to a rotor lift or single blade lift, the boom clearance becomes critical.

In principle, the required boom clearance for the rotor or a single blade at high lifting heights can be reached by scaling up the crane but this is limited by the capacity of the entire vessel. Alternatively a so called auxiliary hoist is installed onto a boom extension, but again this causes a higher self-weight-load on the crane and basically results in a heavier crane again.

It is an object of the present invention to provide a crane vessel of the kind as described, having a crane that can meet the future boom clearance at large lifting heights without causing significant limitations as described before.

According to a first aspect, the invention provides a jack-up crane vessel or semi-submersible crane vessel or mono-hull crane vessel comprising a hull with a deck, and a crane on the hull for hoisting a load outside the deck, wherein the crane comprises a slewing crane base that is rotatable around a vertical slewing axis, an elongate boom having a longitudinal boom axis, a distal boom tip and a proximate boom heel, wherein boom is rotatably connected to the crane base for luffing the boom with respect to the crane base around a horizontal luffing axis, a Jib that projects from the boom tip under a jib angle, wherein the jib comprises multiple aft hoisting sheaves with a common aft hoisting sheave rotation axis, and multiple forward hoisting sheaves with a common forward hoisting sheave rotation axis that ís in a projection parallel to the slewing axis further away from the boom, spaced apart from the aft hoisting sheave rotation axis over a first distance,

a hoisting block that comprises multiple aft block sheaves with a common aft block sheave rotation axis, multiple forward block sheaves with a common forward block sheave rotation axis that is in the projection parallel to the slewing axis further away from the boom, spaced apart from the aft hoisting sheave rotation axis over a second distance, an aft load suspension for a first load, a forward load suspension for a second load that is in the projection parallel to the slewing axis further away from the boom, spaced apart from the aft load suspension, an aft hoisting cable that 1s reeved between the aft hoisting sheaves and the aft block sheaves with multiple aft falls forming an aft hoisting tackle with a variable first hoisting length between the aft hoisting sheave rotation axis and the aft block sheave rotation axis, a forward hoisting cable that is reeved between the forward hoisting sheaves and the forward block sheaves with multiple forward falls forming a forward hoisting tackle with a variable second hoisting length between the forward hoisting sheave rotation axis and the forward block sheave rotation axis, an aft hoisting cable manipulator for manipulating the aft hoisting cable, and a forward hoisting cable manipulator for manipulating the forward hoisting cable.

The vessel according to the invention has a crane with a hoisting block that is suspended from the Jib by means of the aft hoisting tackle and the forward hoisting tackle that are spaced apart from each other in the direction away from the vertical slewing axis. The first load suspension and the second load suspension are spaced apart from each other in the same direction. This enables the crane to be optimized for hoisting different loads with different clearance distances to the boom, wherein can be chosen whether for example a load 1s effectively hoisted substantially by the forward hoisting tackle while hanging with good clearance with respect to the boom, or that a heavier but more compact load is divided over both the forward hoisting tackle and the aft hoisting tackle while hanging closer to the boom. In particular for the second case, less capacity is required for the aft hoisting tackle as a part of the load is carried by the forward hoisting tackle.

In an embodiment are the aft hoisting cable manipulator and the forward hoisting cable manipulator configured or controlled to keep the first hoisting length edual to the second hoisting length or to maintain a constant difference between the first hoisting length and the second hoisting length, whereby a parallelogram configuration with constant angles can be maintained between the rotation axes of the sheaves.

In an embodiment is the first distance is equal to the second distance.

In an embodiment is in the projection parallel to the slewing axis, the aft load suspension located between the aft block sheave rotation axis and the forward block sheave rotation axis.

In an embodiment thereof is in the projection parallel to the slewing axis, the aft load suspension located closer to the aft block sheave rotation axis than to the forward block sheave rotation axis.

In an embodiment is in the projection parallel to the slewing axis, the aft load suspension located on an aft distance to the aft block sheave rotation axis and on a forward distance to the forward block sheave rotation axis.

In an embodiment thereof is the ratio between the aft distance and the forward distance equal to the ratio between the hoisting capacity of the forward hoisting tackle and the hoisting capacity of the aft hoisting tackle.

In an embodiment 1s the ratio between the aft distance and the forward distance 1:2.

In an embodiment a higher hoisting capacity for the aft hoisting cable is implemented by the amount of aft falls that is larger than or differs from the amount of forward falls.

Alternatively, or combined therewith, the cable 5 strength of the aft hoisting cable is higher than or differs from the cable strength of the forward hoisting cable.

In an embodiment is the forward load suspension located between the aft block sheave rotation axis and the forward block sheave rotation axis.

In a particular embodiment is in the projection parallel to the slewing axis, the forward load suspension located at the forward block sheave rotation axis.

In an embodiment are the centers of the sheave rotation axes located in the same vertical plane parallel to the slewing axis.

In an embodiment is the first distance a fixed first distance.

In an embodiment is the second distance a fixed second distance.

In an embodiment comprises the crane a boom luffing installation for driving the rotation of the boom around the horizontal luffing axis.

In an embodiment the jib angle is 45-90 degrees.

In an embodiment has the crane vessel at the aft load suspension and at the forward load suspension a hoisting height as from the water line of at least 100 meters, preferably at least 140 meters, more preferably at least 180 meters.

In an embodiment has the crane vessel at the aft load suspension and at the forward load suspension a hoisting capacity of at least 100 tons, preferably at least 200 tons, more preferably at least 300 tons.

In an embodiment is the crane vessel configured for hoisting the load with the longitudinal boom axis under a boom angle with respect to the slewing axis of 2-30 degrees.

According to a second aspect, the invention provides a method for hoisting a load with a jack-up crane vessel or semi-submersible crane vessel or mono-hull crane vessel comprising a hull with a deck, and a crane on the hull for heisting a load outside the deck, wherein the crane comprises a slewing crane base that is rotatable around a vertical slewing axis,

an elongate boom having a longitudinal boom axis,

a distal boom tip and a proximate boom heel, wherein boom is rotatably connected to the crane base for luffing the boom with respect to the crane base around a horizontal luffing axis,

a Jib that projects from the boom tip under a jib angle, wherein the jib comprises multiple aft hoisting sheaves with a common aft hoisting sheave rotation axis, and multiple forward hoisting sheaves with a common forward hoisting sheave rotation axis that ís in a projection parallel to the slewing axis further away from the boom,

spaced apart from the aft hoisting sheave rotation axis over a first distance,

a hoisting block that comprises multiple aft block sheaves with a common aft block sheave rotation axis, multiple forward block sheaves with a common forward block sheave rotation axis that is in the projection parallel to the slewing axis further away from the boom, spaced apart from the aft hoisting sheave rotation axis over a second distance, an aft load suspension for a first load, a forward load suspension for a second load that is in the projection parallel to the slewing axis further away from the boom, spaced apart from the aft load suspension,

an aft hoisting cable that is reeved between the aft hoisting sheaves and the aft block sheaves with multiple aft falls forming an aft hoisting tackle with a variable first hoisting length between the aft hoisting sheave rotation axis and the aft block sheave rotation axis,

a forward hoisting cable that is reeved between the forward hoisting sheaves and the forward block sheaves with multiple forward falls forming a forward hoisting tackle with a variable second hoisting length between the forward hoisting sheave rotation axis and the forward block sheave rotation axis, an aft hoisting cable manipulator for manipulating the aft hoisting cable, and a forward hoisting cable manipulator for manipulating the forward hoisting cable, wherein in the method the load is suspended from the aft load suspension or from the forward load suspension, wherein while hoisting the load, the aft hoisting cable manipulator and the forward hoisting cable manipulator keep the first hoisting length equal to the second hoisting length or maintain a constant difference between the first hoisting length and the second hoisting length.

In an embodiment thereof reach the aft load suspension and the forward load suspension from which the load is suspended a hoisting height as from the water line of at least 100 meters, preferably at least 140 meters, more preferably at least 180 meters.

In an embodiment is the load that is suspended from the aft load suspension or from the forward load suspension at least 100 tons, preferably at least 200 tons, more preferably at least 300 tons.

In an embodiment is during the hoisting the longitudinal boom axis under a boom angle with respect to the slewing axis of 2-30 degrees.

The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which: Figure 1 is a side view of a crane vessel having a crane with a boom, a jib and a hoisting block according to an embodiment of the invention, in a jacked-up state and with the boom in an operational raised position; Figures 2A-2C are side views of the boom, the Jib and the hoisting block of the crane of figure 1 in three orientations respectively; Figure 3 is an isometric view of the hoisting block of the crane according to figures 1 and 2A-2C; and Figures 4 and 5 are two schematic views of hoisting cable configurations for the crane according to figures 1-3.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a self-elevating jack-up crane vessel 10 that is raised or jacked up above a sea 1 with a water line 2. In this embodiment the crane vessel 10 is self-propelled, but alternatively the crane vessel 10 is towed by tugs. The crane vessel 10 comprises in this embodiment a rectangular hull 11 having a bow 12, a stern 13 and a large deck 18. The crane vessel 10 comprises a steering house 16, and in this example four upright legs 20 that are guided through jacking houses 19 having a not shown internal drive to lower and raise each of the legs 20 in direction A as known per se to raise the hull 11 above the sea 1. During sailing all legs 20 are raised and extend with their top side high above the deck 18 and the steering house 16.

The crane vessel 10 comprises a crane 30 according to an embodiment of the invention, above a crane foundation 22 on the hull 11. In this example the crane foundation 22 coincides with one of the jacking houses 19, above the rear starboard side Jacking house 19. The crane vessel 10 with the crane 30 is designed to handle and hoist large wind turbine components, such as a tower 5 or parts thereof, a nacelle 6 with an internal generator, and a rotor 9 with a hub 7 and blades 8 to build an offshore wind turbine 4 at an offshore installation site. The wind turbine components may be shipped on the deck 18 to the installation site, but alternatively a feeder barge is used to ship the wind turbine components to the crane vessel 10. Depending on the specific circumstances the rotor 9 may be hoisted pre-assembled in one hoisting operation, or the components thereof are hoisted in consecutive hoisting operations.

As shown in figure 1 the crane 30 comprises a steel slewing crane base 31 that in this example is rotatingly mounted to the crane foundation 22 for rotation of the entire crane 30 around its vertical slewing or rotation axis Z.

The crane base 31 comprises a slew platform 32 and a rigid base frame 33 on the slew platform 32. The base frame 33 comprises two upward back box girders 35 and two cross box girders 37 that are at their top end connected with the respective upward back box girders 35 to form rigid triangular frame configurations that are at their top end connected with a not shown transverse back box girder.

The crane 30 comprises an elongate boom 50 with a longitudinal boom axis L. The boom 50 comprises at its bottom end a boom heel 53 that is rotatably connected to the slew platform 32 for luffing or rotation of the boom 50 in direction D around a horizontal luffing axis or rotation axis X to adjust the boom luffing angle a. The horizontal rotation axis X extends transverse to the vertical rotation axis Z. The boom axis L extends in a notional boom luffing plane or boom rotation plane that is substantially parallel to the vertical rotation axis Z.

The crane 30 comprises a boom luffing installation 40 for driving the luffing or rotation of the boom 50 around the horizontal rotation axis X. The boom luffing installation 40 comprises boom luffing tackles that extend between the respective meeting ends of the upward back box girders 35 and the boom tip 55 of the boom 50.

At the installation site the wind turbine components are hoisted and installed aside the deck 18 by means of the crane 30. At present, offshore wind turbines typically have a power of 3 Megawatt. While the power of offshore wind turbines is continuously scaled up, a power of 15 Megawatt is envisaged in the near future. These offshore wind turbines require a high hoisting height above the waterline for the turbine components. In order to handle the large and heavy wind turbine components at these heights, the crane 30 minimally has a hoisting capacity of 100 tons and a hoisting height of 100 meters above the water line 2, preferably minimally a hoisting capacity of 900 tons and a hoisting height of 180 meters above the water line 2. For the tower 5 and the nacelle 6 a typical hoisting capacity of 900 tons is required. For the lift of a single blade 8 under a non-horizontal angle a typical hoisting capacity of 250 tons is required due to the added blade lifting gear such as blade yokes. For the pre- assembled rotor 9 a typical hoisting capacity of 400 tons is required, wherein a larger horizontal clearance with respect to the crane boom 50 is required to prevent collision therewith.

The crane 30 may optionally be configured as a so called crane around the leg, wherein the crane base 31 can rotate around one of the legs 20 of the jack-up crane vessel 10. The crane boom 50 may have parallel, spaced apart boom sections and/or jib sections so that in a lowered, horizontal position wherein the boom 50 is supported by a boom rest 21, the boom 50 can be stored around one of the legs 20.

The invention is not limited to a crane 30 on a jack-up crane vessel 10 as shown in figure 1. A jack-up rig with the crane 30 is considered a crane vessel according to the invention. The crane 30 may alternatively be installed on a semi-submersible crane vessel or on a monohull crane vessel for performing the same kind of offshore hoisting operations as described above.

As shown in figures 1 and 2A-2C, the crane 30 comprises an upper block or jib 70 that extends from the boom 50 at the tip 55 thereof under a fixed jib angle y. In this example the Jib 70 comprises an elongate Jib box girder 71 that has an aft Jib end 72 that is fixedly connected to or merges into the boom tip 55, and a forward jib end 73 opposite to the aft jib end 72. The Jib box girder 71 extends from the boom tip 55 substantially in the notional boom rotation plane. The Jib 70 comprises multiple aft hoisting sheaves 74 that serve as an aft load suspension at the jib box girder 71 near the aft jib end 72, and multiple forward holsting sheaves 75 that serve as a forward load suspension at the jib box girder 71 at or near the forward jib end 73.

The crane 30 comprises a hoisting block 78 that is suspended from the jib 70. As best shown in figures 2A- 2C and 3, the hoisting block 78 comprises in this example an elongate hoisting girder 79 that has an aft girder end 80, and a forward girder end 81 opposite to the aft girder end 80. The hoisting block 78 comprises multiple aft block sheaves 82 at the aft girder end 80 and multiple forward block sheaves 83 at the forward girder end 81.

As best shown in figures 2A-C, the crane 30 comprises an aft hoisting tackle 101 that comprises an aft hoisting cable 76 that is reeved through the aft hoisting sheaves 74 and the aft block sheaves 82. The crane 30 comprises a forward hoisting tackle 102 that comprises a forward hoisting cable 77 that is separate from the aft hoisting cable 76 and that is reeved through the forward hoisting sheaves 75 and the forward block sheaves 83.

The hoisting block 78 comprises an aft load suspension 84 with an aft hook 85 that is arranged at the hoisting girder 79 between the aft block sheaves 82 and the forward block sheaves 83, in this example along the hoisting girder 79 at an aft distance Ll to the rotation axis of aft block sheaves 82 and at a forward distance L2 to the rotation axis of the forward block sheaves 83. In this example the forward distance 12 is twice the aft distance Ll. The hoisting block 78 comprises a forward load suspension 86 with a forward hook 87 that is arranged at the hoisting girder 79 at or near the forward girder end 81 and/or the rotation axis of the forward block sheaves 83.

It is to be understood that the aft hook 85 and the forward hook 87 may be embodied as a single saddle hook or C-hook, or as a double saddle hook or ramshorn-hook, oar as a multi-saddle hook or four-prong hook for attaching a load thereto, for example by means of hoisting slings.

The aft hoisting sheaves 74, the forward hoisting sheaves 75, the aft block sheaves 82, the forward block sheaves 83, the first hook 84, and the second hook 85 are arranged substantially in a common plane that is parallel to the notional boom rotation plane, and that preferably substantially coincides with the notional boom rotation plane. A notional vertical aft force axis R extends along the aft hoisting tackle 101 through the rotation axis of the aft hoisting sheaves 74 and the rotation axis of the aft block sheaves 82. A notional vertical forward force axis S extends along the forward hoisting tackle 102 through the rotation axis of the forward hoisting sheaves 75 and the rotation axis of the forward block sheaves 83. A notional jib axis P extends along the Jib 70 through the rotation axis of the aft hoisting sheaves 74 and the rotation axis of the forward hoisting sheaves 75. A notional block axis Q extends along the hoisting block 78 through the rotation axis of the aft block sheaves 82 and the rotation axis of the forward block sheaves 83. The aft hoisting tackle 101 has a variable first hoisting length HI between the rotation axis of the aft hoisting sheaves 74 and the rotation axis of the aft block sheaves 82. The forward hoisting tackle 102 has a variable second hoisting length H2 between the rotation axis of the aft hoisting sheaves 75 and the rotation axis of the aft block sheaves

83.

The aft load suspension 84 and the forward load suspension 86 effectively engage onto the hoisting girder 79 on the block axis Q. The first distance between the rotation axis of the aft hoisting sheaves 74 and the forward hoisting sheaves 75 is equal to the second distance between the rotation axis of the aft block sheaves 82 and the forward block sheaves 83, and during hoisting the first hoisting length H1 is kept equal to the second hoisting length H2, whereby the hoisting tackles 101, 1902 the jib 70 and the hoisting block 78 form at the rotation axes a parallelogram arrangement with constant angles.

As schematically shown in figures 1 and 2A-2C, the crane 30 optionally comprises a block fixation 57 that is in this example embodied as a hook that can hook into the hoisting block 78. The block fixation 57 can fixate the hoisting block 78 with respect to the boom 50 in preparation to the lowering of the boom 50 into its lowered, horizontal position on the boom rest 21 in which the crane vessel 10 can sail to another location. Alternatively, the hoisting block 78 can be stored on the deck 18 or be tied down to the deck 18 by fixating a sling from the aft hook 85.

Figure 4 schematically shows the relevant parts that are related to the configuration of the aft hoisting tackle 101 and the forward hoisting tackle 102. The crane 30 comprises an aft hoisting cable manipulator 92 with a driven aft hoisting cable drum 93 for manipulating, in particular hauling in and paying out, the aft hoisting cable 76, and a forward hoisting cable manipulator 94 with a driven forward hoisting cable drum 95 for manipulating, in particular hauling in and paying out, the forward hoisting cable 77. The cable manipulators 92, 94 are for example located on the slew platform 32. The aft hoisting tackle 101 has a reeving in which the aft hoisting cable 76 has multiple aft falls 88 between the jib 70 and the hoist block 78, and a corresponding amount of aft hoisting sheaves 74 and aft block sheaves 82. The forward hoisting tackle 102 has a reeving in which the forward hoisting cable 77 has multiple forward falls 89 between the jib 70 and the hoist block 78, and a practically corresponding amount of forward hoisting sheaves 75 and forward block sheaves 83. In this example, the amount of aft falls 88 is twice the amount of forward falls 89, whereby the strength per cable 76, 77 is equal.

So in this example the strength along the aft force axis R is double of the strength along the forward force axis S.

Figure 5 shows an alternative configuration for the aft hoisting cable 76 of which only the deviating parts are discussed hereafter.

In this configuration the aft hoisting cable manipulator 92 comprises two driven aft hoisting cable drums 93 for manipulating both ends of the aft hoisting cable 76. Optionally the aft hoisting cable 746 comprises two sections that each extend between one of the aft hoisting cable manipulators 92 and an equalizer 99. As the amount of aft falls 88 is in this example twice the amount of the forward falls 89, this enables all drums 93, 95 to be rotated simultaneously as very schematically indicated by the common drive shaft 97 to maintain the parallelogram arrangement between the jib 70 and the hoist block 78. In practice the simultaneous rotation of the cable drums 93, 95 is for both configurations performed by manual or electronic control of the rotation of the hoisting cable drums 93, 95. The individual control of the rotations also enables the crane 30 to temporarily cancel the parallelogram, for example to lower the hoisting girder 79 horizontally above the deck 18 to enable the hoisting slings to be hooked onto the hoisting hooks 85, 87. As best shown in figures 2A-2C, the forward load suspension 86 of the crane 30 is arranged at or near the notional vertical forward force axis S whereby the forward hoisting tackle 102 hoists practically the entire load on the forward load suspension 86 while the aft hoisting tackle 101 just runs along with it simultaneously to maintain the parallelogram configuration.

In the crane 30 according to the invention the aft load suspension 84 is arranged between the notional vertical aft force axis R and the notional vertical forward force axis S.

In this example the forward distance L2 is twice the aft distance L1, whereby the aft hoisting tackle 101 with the double amount of falls 88 hoists twice as much of the load on the aft load suspension 84 than the forward hoisting tackle 102. The tension force in the aft hoisting cable 76 is thereby practically equal to the tension force in the forward hoisting cable 77. Alternatively, the difference in hoisting capacity is achieved by deviating cable strengths for the respective hoisting cables 76, 77, or combined with deviating amounts of falls.

Thereby the ratio between the aft distance Ll and the forward distance L2 is equal to the ratio between the amount of forward falls 89 multiplied by the strength of the forward hoisting cable 77, and the amount of aft falls 89 multiplied by the strength of the aft hoisting cable 76. As a practical example, the crane 30 can hoist 300 tons on the forward load suspension 86 that is carried by the forward hoisting tackle 102, or 900 tons on the aft load suspension 84 of which 1/3 or 300 tons is again carried by the forward hoisting tackle 102 while 2/3 or 600 tons is carried by the aft hoisting tackle 101. As a practical extension on this example, the crane 30 can hoist in between 900 tons and 300 tons in between the forward load suspension 86 and the aft load suspension 84, for example 600 tons can be carried at half of the forward distance 12, of which 1/2 or 300 tons is again carried by the forward hoisting tackle 102 while 1/2 or 300 tons is carried by the aft hoisting tackle 101. This can be physically arranged by lifting gear below the forward load suspension 86 and the aft load suspension 84, or alternatively by positioning another load suspension on the hoisting block 78 in between the present load suspensions 84, 86.

As a practical example, the boom angle « is 2-30 degrees, whereby the boom 50 stands almost upright to obtain the minimal hoisting height of 100 meters above the water line 2. The actively maintained parallelogram configuration ensures that the hoisted load remains straight below the jib 70 without penduling or searching for an equilibrium, Due to the particular positioning of the load suspensions 84, 86 with respect to the hoisting tackles 101, 102 along the hoisting block 78, the forward load suspension 86 can be used for the less heavy components of the wind turbine 4 that needs to be hoisted with sufficient clearance with respect to the almost upright oriented boom 50, such as the pre-assembled rotor 3 or its components. The aft load suspension 84 can be used for the much heavier components of the wind turbine 4 that can be hoisted closer to the almost upright oriented boom 50 while maintaining a minimal clearance, such as the tower 5 and the nacelle 6.

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the scope of the present invention.

Claims

CONCLUSIONS

A jack-up crane or semi-submersible crane vessel or monohull crane vessel comprising a hull having a deck, and a crane on the hull for lifting a load beyond the deck, the crane comprising a rotatable crane base which is rotatable relative to the hull about a vertical axis of rotation, an elongated boom having a boom longitudinal axis, a boom distal top and a proximal boom heel, the boom being rotatably connected to the crane base for luffing the boom relative to the crane base about a horizontal windward axis, a Jib projecting at a jib angle from the boom top, the jib having multiple rear hoist sheaves with a common rear hoist sheave rotation axis, and multiple front hoist sheaves with a common front hoist sheave rotation axis which in a projection parallel to the axis of rotation is further away from the boom, spaced from the rear hoist sheave rotation axis by a first distance, a lifting block provided with a plurality of breech blocks lifting with a common rear block disc rotation axis, multiple front block discs with a common front block disc rotation axis projected parallel to the axis of rotation—further from the boom, away from the rear block disc rotation axis over a second distance, a rear-load suspension for a first load, a front-load suspension for a second load projected further away from the boom parallel to the axis of rotation, remote from the rear-load suspension, a rear hoisting rope restrained between the rear hoist pulleys and the rear block sheave with multiple rear traps to form a rear hoist hoist with a variable first lifting length between the rear hoist sheave rotation axis and the rear block sheave rotation axis, a pre-hoisting rope that is reeved between the pre-lifting sheaves and the pre-block sheaves with multiple pre-lifting

traps to form a front hoist hoist having a variable second lifting length between the front chock sheave rotation axis and the front block sheave rotation axis, a rear hoist rope manipulator for manipulating the rear hoist rope, and a front hoist rope manipulator for manipulating the front hoist rope.

A crane vessel according to claim 1, wherein the aft hoist rope manipulator and the forward hoist rope manipulator are arranged or controlled to maintain a first hoist length equal to the second hoist length or to maintain a constant difference between the first hoist length and the second hoist length.

A crane vessel according to any one of the preceding claims, wherein the first distance is equal to the second distance.

A crane vessel according to any one of the preceding claims, wherein in the projection parallel to the axis of rotation the aft load suspension is placed between the aft block sheave rotation axis and the forward block sheave rotation axis.

A crane vessel according to any one of the preceding claims, wherein in the projection parallel to the rotational axis the aft load suspension is placed closer to the aft block sheave rotational axis than to the forward sheave rotational axis.

A crane vessel according to any one of the preceding claims, wherein in the projection parallel to the axis of rotation the rear load suspension is placed at a rear distance from the rear block sheave rotation axis and at a front distance from the front block sheave rotation -ash.

A crane vessel according to claim 6, wherein the ratio between the aft distance and the forward distance is equal to the ratio between the lifting capacity of the front hoist and the lifting capacity of the rear hoist.

A crane vessel according to claim 6 or 7, wherein the ratio between the aft distance and the forward distance is 1:2.

A crane vessel according to any one of the preceding claims, wherein the number of aft halyards is greater than or different from the number of forward halyards.

A crane vessel according to any one of the preceding claims, wherein the rope strength of the aft hoist rope is greater than or different from the rope strength of the forward hoist rope.

A crane vessel according to any one of the preceding claims, wherein in the projection parallel to the axis of rotation the front load suspension is located between the rear block sheave rotation axis and the front block sheave rotation axis.

A crane vessel according to any one of the preceding claims, wherein in the projection parallel to the rotational axis the wfor-load suspension is placed at the fore-block sheave rotational axis.

A crane vessel according to any one of the preceding claims, wherein the centers of the disk rotation axes are located in the same plane parallel to the rotation axis.

A crane vessel according to any one of the preceding claims, wherein the first distance is a fixed first distance.

A crane vessel according to any one of the preceding claims, wherein the second distance is a fixed second distance.

A crane vessel according to any one of the preceding claims, wherein the crane comprises a boom splitter installation for driving the rotation of the boom about the horizontal windward axis.

A crane vessel according to any one of the preceding claims, wherein the jib angle is 45-90 degrees.

A crane vessel according to any one of the preceding claims, which has a lifting height of at least 100 metres, preferably at least 140 metres, more preferably at least 180 metres, in the aft-load suspension and in the front suspension from the waterline.

A crane vessel according to any one of the preceding claims, which has a lifting capacity of at least 100 tons, preferably at least 200 tons, more preferably at least 300 tons at the rear-load suspension and at the front suspension.

A crane vessel according to any one of the preceding claims, arranged for hoisting the load with the jib longitudinal axis at a boom angle with respect to the axis of rotation of 2-30 degrees.

A method of lifting a load with a jack-up crane vessel or semi-submersible crane vessel or monohull crane vessel comprising a hull having a deck, and a crane on the hull for lifting a load beyond the deck, the crane having a rotatable crane base rotatable with respect to the hull about a vertical axis of rotation, an elongate boom having a boom longitudinal axis, a distal boom top and one and a proximal boom heel, the boom being rotatably connected to the crane base for luffing the boom relative to the crane base about a horizontal windward axis, a jib projecting at a jib angle from the boom top, the Jib having multiple rear lifting sheaves with a common rear lifting sheave rotation axis, and multiple front lifting sheaves having a common front hoist sheave rotation axis projecting parallel to the rotation axis further away from the boom, spaced from the rear sheave rotation axis by a first distance, a hi js block incorporating multiple breech blocks with a common breech block sheave rotation axis, multiple front sprocket sheaves with a common front block sheave rotation axis projected parallel to the rotation axis further away from the boom, on distance from the rear disc axis of rotation a second distance, a rear-load suspension for a first load, a front-load suspension for a second load projected parallel to the axis of rotation further away from the boom, at a distance of the rear load suspension,

a rear hoist rope reeved between the rear hoist pulleys and the rear block sheaves with multiple rear traps to form a rear hoist hoist with a variable first lift length between the rear hoist sheave rotary axis and the rear block sheave rotary axis shaft, a pre-hoist rope retched between the pre-hoist pulleys and the pre-hoist pulleys with multiple occurrences to form a pre-hoist hoist with a variable second lifting length between the pre-hoist sheave rotary axis and the pre-block sheave rotary axis axle, a rear hoist rope manipulator for manipulating the rear hoist rope, and a front hoist rope manipulator for manipulating the front hoist rope, wherein in the method the load is suspended from the rear load suspension or the front load suspension , wherein during the lifting of the load the rear lifting rope manipulator and the front lifting rope manipulator keep the first lifting length equal to the second lifting length or maintaining a constant difference tu s the first lifting length and the second lifting length.

A method according to claim 21, wherein the rear-load suspension and the front suspension reach a lifting height of at least 100 metres, preferably at least 140 metres, more preferably at least 180 metres, from the waterline.

A method according to claim 21 or 22, wherein the load suspended from the rear load suspension or the front suspension is at least 100 tons, preferably at least 200 tons, more preferably at least 300 tons.

A method according to any one of claims 21-23, wherein the boom longitudinal axis is at a boom angle relative to the rotational axis of 2-30 degrees during hoisting.

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