NL2024782B1

NL2024782B1 - Assembly of a vessel and a crane, a crane, and a heave compensation system

Info

Publication number: NL2024782B1
Application number: NL2024782A
Authority: NL
Inventors: Hartmans Tiemen; Cornelius Van Grieken Gerardus; Hendrik Gerssen Sietse
Original assignee: Kenz Figee Group B V
Priority date: 2020-01-29
Filing date: 2020-01-29
Publication date: 2021-09-10

Abstract

The invention relates to an assembly of a vessel and. a crane, wherein. the crane comprises a first and. a second hoist cable, a first winch and ea second winch to manipulate the respective hoist cables, and a heave 5 compensation system that comprises a manipulator, a first and a second manipulator sheave that are connectable to the manipulator, and. a first and. a second. stationary sheave, wherein. the respective hoist cables are reeved. from the winches, via. the stationary sheaves, via the Inanipulator lO sheaves, towards the boom, wherein the manipulator is configured to manipulate a displacement of the manipulator sheaves with respect to the stationary sheaves, and wherein the heave compensation system has a first hoisting mode in which the first and. second. manipulator sheaves are both 15 connected to the manipulator, and a second hoisting mode in which only the first manipulator sheave is connected to the manipulator.

Description

P137130NL00 Assembly of a vessel and a crane, a crane, and a heave compensation system

BACKGROUND The invention relates to an assembly of a vessel and a crane, more specifically an offshore installation vessel with an offshore crane, a crane for use in such an assembly, and a heave compensation system for use in such an assembly or for use in such a crane. Known offshore vessels comprise a hull with a deck and a crane pedestal on the deck that supports a crane. The crane has a slewing crane base that is rotatable with respect to the pedestal and the deck around a vertical slewing axis, a boom that is connected to the crane base, a hoist cable that is suspended from the boom, a main winch to manipulate the hoist cable, and a heave compensation system that compensates the hoist cable for relative motions between the vessel and an offshore platform or the seabed. The crane is used for hoisting loads from the deck of the vessel to the offshore platform or onto the seabed, wherein the crane and therewith the hoist cable typically has a maximum hoisting capacity of tens to hundreds of tons or more.

SUMMARY OF THE INVENTION A disadvantage of the known crane is that the heave compensated hoist cable and its associated equipment such as the crane hook are heavy and therefore hard to handle, especially when connecting a load to the hoist cable. As most of the loads, approximately eighty percent, that are hoisted by the crane weigh less than fifty percent of the maximum capacity of the hoist cable, most of the time loads are hoisted using a hoist cable that has overcapacity and that is not optimal for the particular hoisting job. Personnel operating the crane and connecting the loads to the hoist cable have to handle the heavy hoist cable and its associated equipment. This exposes the personnel to tough and potentially dangerous conditions.

It is an object of the present invention to provide an assembly of a vessel and a crane, a crane for use in such an assembly, and a heave compensation system for use in such an assembly or for use in such a crane that addresses at least one of the problems described above.

According to a first aspect, the invention provides an assembly of a vessel and a crane, wherein the vessel comprises a hull with a deck, and wherein the crane comprises a crane base arranged at the vessel, a boom that is connected to the crane base, a first hoist cable that is suspended from the boom, a second hoist cable that is suspended from the boom, a first winch to manipulate the first hoist cable, a second winch to manipulate the second hoist cable, and a heave compensation system, wherein the heave compensation system comprises a manipulator that is connected to the crane, a first manipulator sheave that is rotatably connectable to the manipulator for guiding the first hoist cable, a second manipulator sheave that is rotatably connectable to the manipulator for guiding the second hoist cable, a first stationary sheave that is rotatably connected to the crane for guiding the first hoist cable, and a second stationary sheave that is rotatably connected to the crane for guiding the second hoist cable, wherein the first hoist cable is reeved from the first winch, via the first stationary sheave, via the first manipulator sheave, towards the boom, and the second hoist cable is reeved from the second winch, via the second stationary sheave, via the second manipulator sheave, towards the boom, wherein the manipulator is configured to impose, manipulate or follow a displacement of the first and the second manipulator sheaves with respect to the first and the second stationary sheaves, and wherein the heave compensation system has a first hoisting mode in which the first manipulator sheave and the second manipulator sheave are both connected to the manipulator, and a second hoisting mode in which only the first manipulator sheave is connected to the manipulator, wherein the heave compensation system is configured to switch between the first hoisting mode and the second hoisting mode by connecting and disconnecting the second manipulator sheave.

The heave compensation system is configured to switch between the first hoisting mode and the second hoisting mode. In the first hoisting mode the assembly provides a crane having at least two heave compensated hoist cables. The combined hoisting capacity of the first hoist cable and the second hoist cable defines the maximum hoisting capacity of the crane. When lighter loads that are well below the maximum hoisting capacity, typically below fifty percent of the maximum hoisting capacity, of the crane are to be hoisted the heave compensation system can be switched to the second hoisting mode. In the second hoisting mode only the first hoist cable is connected to the heave compensation system and the second hoist cable is disconnected from the heave compensation system and is not used. As the first hoist cable has a hoisting capacity that is lower than the maximum hoisting capacity, the hoist cable and its associated equipment can be less heavy and more easy to handle compared to a hoist cable having the maximum hoisting capacity. As a result the personnel operating the crane and connecting the loads to the hoist cable are exposed to less tough and dangerous conditions thereby increasing the safety of the hoisting operation. As the majority of the hoisting operations may be performed in the second hoisting mode this potentially has a big influence on the overall safety of the hoisting operations performed by the assembly. It is to be understood that the use of the references first and second with respect to the hoisting cables and the sheaves are interchangeable.

Additionally, as the second hoist cable is not used when the heave compensation system is in the second hoisting mode, the second winch may be switched off. This results in a reduction of the power consumption of the crane in the second hoisting mode and therefore reducing the environmental impact of the crane.

Furthermore, by using one manipulator to compensate heave for at least two hoist cables, the heave compensation system may have minor to no influence on the synchronism of the hoist cables.

In an embodiment the manipulator is configured to actively control the displacement of the first and the second manipulator sheaves with respect to the first and the second stationary sheaves, which results in more accurate compensation of the vessel motions.

In an embodiment the heave compensation system comprises an equalizer that is connected to the manipulator and to which the first manipulator sheave and the second manipulator sheave are rotatably connectable, wherein the equalizer is arranged to adapt to a resultant force that is exerted on the manipulator by the first hoist cable and the second hoist cable, in order to align the manipulator with the resultant force. The direction of the resultant force may be different in the first hoisting mode as compared to the second hoisting mode. By aligning the manipulator with the resultant force fhe resultant force acts on the manipulator in substantially the working direction thereof which is favorable as to wear and tear of the manipulator.

In an embodiment the equalizer is hingeably connected to the manipulator to allow the equalizer to hinge with respect to the manipulator around a first equalizer hinge axis that is orientated transverse to the resultant force, when the heave compensation system is switched between the first hoisting mode and the second hoisting mode.

In this embodiment the equalizer is 5 connected to the manipulator by a first connector pin.

A pin connection is a simple and robust connection that allows the equalizer to adapt to the resultant force.

In an embodiment the manipulator 1s hingeably connected to the crane to allow the manipulator to hinge with respect to the crane around a manipulator hinge axis that 1s orientated transverse to the manipulator, when the heave compensation system is switched between the first hoisting mode and the second hoisting mode.

In this embodiment the manipulator is connected to the crane by a manipulator pin connection.

A pin connection is a simple and robust connection that allows the manipulator to adapt to the resultant force.

In an embodiment the first equalizer hinge axis and the manipulator hinge axis are orientated parallel to each other.

This allows the manipulator to align with the resultant force in a specified plane which makes the displacement of the manipulator more predictable.

In an embodiment the first manipulator sheave is hingeably connected to the equalizer to allow the first manipulator sheave to hinge with respect to the equalizer around a second equalizer hinge axis that is orientated transverse to the resultant force, when the heave compensation system is switched between the first hoisting mode and the second hoisting mode.

In this embodiment the first manipulator sheave is connected to the equalizer by a first equalizer pin that allows the equalizer to further adapt to the resultant force.

In an embodiment the second manipulator sheave is hingeably connected to the equalizer to allow the second manipulator sheave to hinge with respect to the equalizer around a third equalizer hinge axis that is orientated transverse to the resultant force, when the heave compensation system is switched between the first hoisting mode and the second hoisting mode. In this embodiment the second manipulator sheave 1s connected to the equalizer by a second equalizer pin that allows the equalizer to further adapt to the resultant force.

In an embodiment the heave compensation system comprises a sensor device to monitor the orientation of the equalizer with respect to the manipulator. The monitored data may be used to optimize the performance of the heave compensation system.

In an embodiment the crane is arranged to control at least one of the winches at least partly based on the monitored orientation of the equalizer, to control the synchronisation of the first hoist cable and the second hoist cable by the respective winches.

In an embodiment the heave compensation system comprises a manipulator sheave parking arrangement, wherein in the second hoisting mode the second manipulator sheave is parked in the manipulator sheave parking arrangement.

The second manipulator sheave is parked away from the moving trajectory of the first manipulator sheave to prevent collisions between the first manipulator sheave, the second manipulator sheave, the first hoist cable, and the second hoist cable.

In an embodiment the manipulator sheave parking arrangement is arranged to hinge the second manipulator sheave with respect to the crane. In this way the second manipulator sheave is hinged further away from the moving trajectory of the first manipulator sheave to better prevent collisions between the first manipulator sheave, the second manipulator sheave, the first hoist cable, and the second hoist cable.

In an embodiment the heave compensation system comprises a sheave bracket that comprises a cam, wherein the second manipulator sheave is rotatably mounted to the sheave bracket, and wherein in the second hoisting mode the cam is engaged by the manipulator sheave parking arrangement. By providing a cam to the sheave bracket the second manipulator sheave is easily engageable by the sheave parking arrangement. In an embodiment the manipulator sheave parking arrangement comprises a sheave parking arm that 1s at one end hingeably connected to the crane and that at the opposite end has a slot for catching the cam, wherein the sheave parking arm is arranged to hinge the second manipulator sheave with respect to the crane.

In an embodiment the manipulator comprises a hydraulic cylinder. The hydraulic cylinder is a simple and robust mechanical manipulator that is very well suited for use in an offshore environment.

In an embodiment the manipulator comprises a passive hydraulic cylinder. The passive hydraulic cylinder can compensate at least a portion of the resultant force that is exerted on the manipulator. This reduces the amount of power that is required for the heave compensation system to compensate the motions of the hoisted load.

In an embodiment the manipulator comprises an active hydraulic cylinder. The active hydraulic cylinder actively manipulates the length of the connected first and second hoist cable to compensate the motions of the hoisted load.

In an embodiment the heave compensation system is at least partially arranged inside the crane base which keeps the footprint of the crane on the deck of the vessel relatively low.

In an embodiment the manipulator is connected to the crane base. In an embodiment the manipulator is connected to the crane base near the bottom thereof. The crane base 1s a strong and stiff part of the crane, by connecting the manipulator to the crane base the generally high forces exerted on the heave compensation system are transferred to the crane in a proper manner.

In an embodiment the first stationary sheave and the second stationary sheave are rotatably connected to the crane base. In an embodiment the first stationary sheave and the second stationary sheave are rotatably connected to the crane base near the topside thereof.

In an embodiment the first winch and the second winch are located below the deck to reduce the overall footprint of the crane on the deck of the vessel.

In an embodiment the crane base 1s rotatable with respect to the deck around a slewing axis that is orientated transverse to the deck, and the first winch and the second winch are fixed with respect to the deck, wherein the crane comprises a spacer that is rotatable with respect to the deck and with respect to the crane around a spacer rotation axis that is orientated parallel to the slewing axis, wherein from the first winch and the second winch to the heave compensation system the first hoist cable and the second hoist cable are reeved along the spacer, wherein the spacer comprises a first spacer sheave that is rotatable around a first spacer axis that is orientated transverse to the slewing axis, and a second spacer sheave that is rotatable around a second spacer axis that is orientated transverse to the slewing axis, and wherein the first spacer sheave and the second spacer sheave guide the respective first hoist cable and the second hoist cable and space them apart from each other.

In the assembly according to the invention the first hoist cable and the second hoist cable may have parallel tracks. Especially when the respective first winch and second winch are located below the deck of the vessel the first and second hoist cable may have a long parallel track between the crane base and the winches. When the crane slews around the slewing axis the heave compensation system and the winches rotate with respect to each other and the first and second hoist cable that extend substantially parallel to the slewing axis may twist around each other. By running the first and second hoist cable respectively along the first spacer sheave and the second spacer sheave, the first hoist cable and the second hoist cable are kept spaced apart from each other. This prevents that the first and second hoist cable come into contact with each other and get damaged when the crane slews. In this way the safe slewing range of the crane is increased.

In an embodiment the first spacer sheave and the second spacer sheave space apart the first hoist cable and the second hoist cable at opposite sides of the first spacer axis or the second spacer axis. In an embodiment the first spacer axis and the second spacer axis coincide. In an embodiment the first spacer sheave and the second spacer sheave extend side by side. By guiding the hoist cables along opposite sides of the first spacer axis, the hoist cables clamp the spacer and when the crane slews the spacer will slew with the cables. This keeps the hoist cables better aligned with the spacer sheaves.

In an embodiment the spacer comprises a third spacer sheave that is rotatable around a third spacer axis that is orientated parallel to and that is spaced apart from the first spacer axis, wherein the third spacer sheave guides the first hoist cable, and wherein between the first spacer sheave and the third spacer sheave the first hoist cable passes between the first spacer axis and the third spacer axis. Through the spacing of the first hoist cable with respect to first and third spacer axes, the first hoist cable clamps the spacer irrespective of the tension in or the reeving of the second hoist cable.

In an embodiment the spacer comprises a fourth spacer sheave that is rotatable around a fourth spacer axis that is orientated parallel to and that is spaced apart from the second spacer axis, wherein the fourth spacer sheave guides the second hoist cable, and wherein between the second spacer sheave and the fourth spacer sheave the second hoist cable passes between the second spacer axis and the fourth spacer axis. Through the spacing of the second hoist cable with respect to second and fourth spacer axes, the second hoist cable clamps the spacer irrespective of the tension in or the reeving of the first hoist cable.

In an embodiment the third spacer axis and the fourth spacer axis coincide. In an embodiment the third spacer sheave and the fourth spacer sheave extend side by side.

In an embodiment the spacer 1s operatively connected with the crane to rotate with the crane in dependency of the slewing of the crane base with respect to the deck. In an embodiment the spacer is operatively connected to the crane by a gearing. In an embodiment the spacer 1s located halfway between the crane base and the winches, wherein the gearing comprises a two-to-one transmission. In an embodiment the crane comprises a spacer slewing actuator. These embodiments may aid in better control of the slewing motion.

According to a second aspect, the invention provides an assembly of a vessel and a crane, wherein the vessel comprises a hull with a deck, and wherein the crane comprises a crane base arranged at the vessel, a boom that is connected to the crane base, a first hoist cable that is suspended from the boom, a second hoist cable that is suspended from the boom, a first winch to manipulate the first hoist cable, a second winch to manipulate the second hoist cable, wherein the crane base is rotatable with respect to the deck around a slewing axis that is orientated transverse to the deck, and the first winch and the second winch are fixed with respect to the deck, wherein the crane comprises a spacer that is rotatable with respect to the deck and with respect to the crane around a spacer rotation axis that is orientated parallel to the slewing axis, wherein from the first winch and the second winch to the boom the first hoist cable and the second hoist cable are reeved along the spacer, wherein the spacer comprises a first spacer sheave that is rotatable around a first spacer axis that is orientated transverse to the slewing axis, and a second spacer sheave that is rotatable around a second spacer axis that is orientated transverse to the slewing axis, and wherein the first spacer sheave and the second spacer sheave guide the respective first hoist cable and the second hoist cable and space them apart from each other.

The assembly and its embodiments according to the second aspect of the invention relate to the aforementioned assembly and its embodiments according to the first aspect of the invention, and thus have the same technical advantages, which will not be repeated hereafter.

According to a third aspect, the invention provides a crane for use in an assembly according to the first aspect or the second aspect of the invention.

According to a fourth aspect, the invention provides a heave compensation system for use in an assembly according to the first aspect of the invention.

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 an isometric rear view of an assembly of a vessel and a crane according to an embodiment of the invention, wherein the crane comprises a crane base and a heave compensation system inside the crane base; Figure 2 shows the contours of the crane base of the crane as shown in figure 1 and the heave compensation system that is located inside the crane base in an isometric view; Figure 3 is a side view of the crane base and the heave compensation system as shown in figure 2;

Figures 4A-4E are perpendicular rear views of the heave compensation system in various hoisting modes; Figure 5 shows a schematic top view of a spacer for two heist cables of the crane, and; Figures 6A and 6B show respective schematic side views of an alternative spacer for two hoist cables of the crane.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows an assembly 1 of a vessel 2 and a crane 20 according to an embodiment of the invention. The vessel 2 comprises a hull 8 with a bow 3, a stern 4, a main cabin 5 at the bow 3, a deck 6 between the main cabin 5 and the stern 4, and a crane pedestal 7 on the deck 6 that supports the crane 20. The crane 20 is used for hoisting loads from the deck 6 of the vessel 2 to an offshore platform or onto the seabed. A typical application for the crane 20 may be to assemble subsea structures. The crane 20 in this example is an offshore knuckle boom crane.

The crane 20 comprises a slewing box shaped crane base 21 that is substantially hollow and that is constructed from steel plates. The crane base 21 is rotatably connected to the crane pedestal 7 via a circular slewing bearing or slewing ring 22 for slewing or rotating the crane base 21 with respect to the crane pedestal 7 around a vertical slewing axis S. The crane 20 furthermore comprises an elongated main boom 30, an elongated knuckle boom 50, a first hoist cable 23a and a second hoist cable 23b each with a crane hook 24a-b, and one auxiliary hoist cable 25 with an auxiliary crane hook 26. The first hoist cable 23a and the second hoist cable 23b are respectively connected to a first winch and a second winch, which are not shown and are, in this example, located below the deck 6, preferably below the crane base 21. The hoist cables 23a-b are guided substantially parallel to each other from the winches through the pedestal 7 and through the crane base 21 to the topside of the crane base 21, and from the topside of the crane base 21 substantially along the main boom 30 and the knuckle boom 50. The hoist cables 23a-b are suspended from the knuckle boom 50.

The main boom 30 comprises two main boom girders 31 that are substantially parallel with respect to each other in the longitudinal direction of the main boom 30 and two crossbars 32 that interconnect and space apart the main boom girders 31 transverse thereto. The main boom 30 comprises a main boom heel 33 at the proximal end thereof that is connected to a main boom suspension 27 at the crane base 21 by a pin-hole connection 35 between the respective main girders 31 and the crane base 21 to hinge around a horizontal first hinge axis P. The main boom 30 comprises a main boom tip 34 at the distal end thereof with two first hoist sheaves 36a-b and a first auxiliary hoist sheave 37 for the respective hoist cables 23a-b and auxiliary hoist cable 25. The crane 20 comprises a luffing arrangement 70 between the topside of the crane base 21 and the main boom tip 34 for luffing or hinging the main boom 30 with respect to the crane base 21 around the first hinge axis P. The knuckle boom 50 comprises two knuckle girders 51 that are substantially parallel with respect to each other in the longitudinal direction of the knuckle boom 50 and two round bars 52 that interconnect and space apart the knuckle girders 51 transverse thereto. The knuckle boom 50 is narrower than the main boom 30 to fit between the main boom girders 31. The knuckle boom 50 comprises a knuckle boom heel 53 at the proximal end thereof that is hingeably connected to the main boom 30 by a shaft connection 55 to hinge around a horizontal second hinge axis Q that is located approximately at three quarters of the main boom 30 length away from the main boom heel 33. The knuckle boom 50 comprises a knuckle boom tip 54 at the distal end thereof with two second hoist sheaves 56a-b and a second auxiliary hoist sheave 57 for the respective hoist cables 23a-b and the auxiliary hoist cable 25. The crane comprises a knuckle arrangement 80 between the main boom 30 and the knuckle boom 50 for knuckling, also known as hinging, the knuckle boom 50 with respect to the main boom 30 around the second hinge axis Q. The purpose of the knuckle boom 50 is to increase the reach and/or the height of the crane 20 with respect to the main boom tip 34. Figure 2 shows the outline of the crane base 21 of the crane 20. The crane 20 comprises a heave compensation system 100 that is arranged inside the hollow crane base 21. The crane base 21 offers space to house the heave compensation system 100. The crane 20 comprises two first guide sheaves 40a-b for the respective hoist cables 23a-b that are arranged inside the crane base 21 near the bottom thereof and that are each rotatably connected to the crane base 21 by a first sheave pin connection 41. The crane comprises two second guide sheaves 42a-b for the respective hoist cables 23a-b that are arranged between sheave suspension plates 28 at the topside of the crane base 21 and that are each rotatably connected to the sheave suspension plates 28 by a second sheave pin connection 43. The hoist cables 23a-b run substantially parallel with respect to each other and run through the slewing ring 22, via the first guide sheaves 40a-b, through the heave compensation system 100, and via the second guide sheaves 42a-b towards the first hoist sheaves 36a-b at the main boom Lip 34. The reeving of the hoist cables 23a-b along the heave compensation system 100 is explained in more detail further down below.

As shown in figures 2, 3 and 4A-E, the heave compensation system 100 comprises a manipulator 110 having a central manipulator axis A. The manipulator 110 comprises, in this example, a central passive hydraulic first cylinder 111 along the central manipulator axis A with a first barrel 112, a first padeye 113 at the bottom of the first barrel 112, a first piston rod 114, and a first rod padeye 115 at the end of the first piston rod

114. The manipulator 110 is hingeably connected to the crane base 21 near the bottom thereof by a manipulator pin connection 117 through the first padeye 113 of the first cylinder 111 to allow the manipulator 110 to hinge with respect to the crane base 21 around a manipulator hinge axis K that is orientated substantially transverse to the central manipulator axis A. The manipulator pin connection 117 is shown in a simplified version for clarity reasons only.

The manipulator 110 comprises a medium separator 116 that is fixedly attached to the first barrel 112 of the first cylinder 111. The medium separator 116 comprises a, not shown, internal free moving piston that divides an internal chamber into a hydraulic oil chamber that is fluidly connected to the first cylinder 111 and a gas chamber that is fluidly connected to a, not shown, volume of pressurized gas, preferably nitrogen. The medium separator 116 and the volume of pressurized gas together form an accumulator that ensures that the first cylinder 111 provides a substantially constant passive pulling force over the range of the stroke thereof.

The manipulator 110 comprises two active hydraulic second cylinders 120 that each have a second barrel 121 that is fixedly attached to the first barrel 112 of the first cylinder 111, and a second piston rod 122 with a second rod padeye 123 at the end thereof. The manipulator 110 comprises two active hydraulic third cylinders 130 that each have a third barrel 131 that is fixedly attached to the first barrel 112 of the first cylinder 111, and a third piston rod 132 with a third rod padeye 133 at the end thereof.

The first cylinder 111, the second cylinders 120 and the third cylinders 130 are all orientated substantially parallel with respect to each other. The second cylinders 120 are located at opposite sides of the first cylinder 111 and the third cylinders 130 are located at opposite sides of the first cylinder 111 next to the respective second cylinders 120. The respective second rod padeyes 123 are aligned with the adjacent third rod padeyes

133. The manipulator 110 comprises a connector 140 that connects the first rod padeye 115, the second rod padeyes 123 and the third rod padeyes 133. The connector 140 comprises two parallel triangular connector plates 141 that extend at opposite sides of the first rod padeye 115, the second rod padeyes 123 and the third rod padeyes 133. The connector comprises a first connector pin 142 that extend transverse to the connector plates 141, and two second connector pins 143 that extend transverse to the connector plates 141. The first connector pin 142 extends through the connector plates 141 and through the first rod padeye 115, and the respective second connector pins 143 extend through the connector plates 141 and the respective adjacent second rod padeye 123 and third rod padeye 133.

It is to be understood that the manipulator 110 may also be embodied such that it comprises only passive cylinders or only active cylinders.

The heave compensation system 100 comprises, in this example, a first manipulator sheave 150a and a second manipulator sheave 150b that are rotatably mounted in two respective sheave brackets 151a-b. The sheave brackets 15la-b each comprise two bracket plates 152 at opposite sides of the respective manipulator sheaves 150a-b, a bracket pin 153 that extends through the bracket plates 152 and through the centre of the manipulator sheave 150a-b, two stiffener plates 154 that connect and space apart the bracket plates 152 near one end thereof near the rim of the manipulator sheave 150a-b, and a bracket spacer 155 that connects and spaces apart the bracket plates 152 near a second end thereof near the rim of the manipulator sheave 150a-b at the opposite side of the bracket pin 153. As best shown infigure 4A the sheave brackets 151a-b comprises cams 156 that in this example protrude from each end of the bracket pins 153 outside the bracket plates 152.

The heave compensation system 100 comprises an equalizer 160 that is arranged between the manipulator 110 and the sheave brackets 151a-b.

The equalizer 160 comprises two triangular parallel equalizer plates 161 that extend at opposite sides of the first rod padeye 115 substantially parallel to the connector plates 141 of the connector 140 and to the stiffener plates 154 of the sheave brackets 151a-b.

The equalizer 160 is hingeably connected to the manipulator 110 by the first connector pin 142 that extends through the equalizer plates 161 to allow the equalizer 160 to hinge with respect to the manipulator 110 around a first equalizer hinge axis L that is orientated substantially transverse to the central manipulator axis A and substantially parallel to the manipulator hinge axis K.

As best shown in figure 4A the equalizer 160 comprises a removable first equalizer pin 162a and a removable second equalizer pin 162b that both extend transverse to and through the equalizer plates 161 and the stiffener plates 154 of the respective sheave brackets 151a-b.

The sheave brackets 15la-b are thereby hingeable with respect to the equalizer 160 to allow the sheave brackets 15la-b to hinge with respect to the equalizer 160 around a second equalizer hinge axis M and a third egualizer hinge axis N respectively.

The second and third equalizer hinge axes M, N are orientated substantially transverse to the central manipulator axis A, and substantially parallel to the manipulator hinge axis K and to the first equalizer hinge axis L.

The heave compensation system 100 may be provided with a not shown sensor device to monitor and/or measure the orientation of the equalizer 160, in particular the orientation thereof with respect to the manipulator 110 and/or with respect to the respective manipulator sheaves 150a-b.

The monitored and/or measured orientation of the equalizer 160 may be used to control the synchronisation of the first hoist cable 23a and the second hoist cable 23b by the respective winches and/or to compensate for elongation of the first hoist cable 23a and the second hoist cable 23b by the respective winches. The heave compensation system 100 comprises a first stationary sheave 170a and a second stationary sheave 170b that are arranged parallel to the second guide sheaves 42a-b between the sheave suspension plates 28 at the topside of the crane base 21, and that are each rotatably connected to the crane base 21 via the sheave suspension plates 28 by the second sheave pin connection 43.

The hoist cables 23a-b are reeved from the first guide sheaves 40a-b near the bottom of the crane base 21, via the stationary sheaves 170a-b at the topside of the crane base 21 back downwards, via the manipulator sheaves 150a-b back upwards to the second guide sheaves 42a-b at the topside of the crane base 21 and from there towards the main boom tip 34. Due to this reeving the stationary sheaves 170a-b, the manipulator sheaves 150a-b and the manipulator 110 are arranged in series. Therefore, the chain of the stationary sheaves 170a-b, the manipulator sheaves 150a-b and the manipulator 110 is subjected to a pulling force and the load path extends through this chain. This is advantageous as the loads can thus be introduced to the crane 20 in a direct manner via the manipulator pin connection 117. The structure of the crane 20 can thereby be designed more straightforward. Furthermore, the arrangement of the stationary sheaves 170a-b, the manipulator sheaves 150a-b and the manipulator 110 and the reeving of the the hoist cables 23a-b allows to connect the manipulator 110 to the crane base 21 distant from the stationary sheaves 170a-b. This reduces the angular rotation of the manipulator 110 with respect to the crane base 21 around the manipulator hinge axis K, and therewith reduces the angular rotation of the hoist cables 23a-b with respect to the stationary sheaves 170a-b. This may reduce wear and tear of the hoist cables Z3a-b.

The heave compensation system 100 comprises a first manipulator sheave parking arrangement 180a and a second manipulator sheave parking arrangement 180b, each having a pair of elongated sheave parking arms 181 that are at one end hingeably connected to the crane base 21 by a pin connection 182, and that have at the opposite end a slot 183 for catching or receiving the cams 156 of the bracket pins 153 of the sheave brackets 151a-b.

The manipulator sheave parking arrangements 180a-b comprise a parking arm spacer 184 that connects and spaces apart the sheave parking arms 181, and a parking arm cylinder 185 that is connected between the parking arm spacer 184 and the crane base 21 to hinge the manipulator sheave parking arrangements 180a-b with respect to the crane base 21. Wave induced motions of the vessel 2 may cause the crane 20 and therewith the crane hooks 24a-b to move with respect to the notional fixed world or the horizon.

In order to reduce or cancel out the relative motions of at least one of the crane hooks 24a-b the heave compensation system 100 is arranged to adjust the effective length of at least one of the respective hoist cables 23a-b between the winches and the respective crane hook 24a-b.

Therefore the manipulator 110 of the heave compensation system 100 imposes, manipulates or follows a displacement of at least one of the manipulator sheaves 150a-b with respect to the stationary sheaves 170a-b.

In this example the first cylinder 111 is configured to follow the displacement of the connector 140 and/or to manipulate the displacement of the connector 140 by passively exercising a pulling force on the connector 140 in a direction away from the stationary sheaves 170a-b to compensate at least a portion of the force that is exerted on the hoist cables 23a-b, for instance by a load that is hoisted by the crane 20. The second cylinders 120 are configured to actively push the connector 140 towards the stationary sheaves 170a-b in order to extend the effective length of the hoist cables 23a-b, and the third cylinders 130 are configured to actively pull the connector 140 away from the stationary sheaves 170a-b in order to reduce the effective length of the hoist cables 23a-b. The second cylinders 120 and the third cylinders 130 thereby impose a displacement of the connector 140. The first cylinder 111, the second cylinders 120 and the third cylinders 130 are connected to a not shown hydraulic powerpack and control system to directly power and control the motions of the manipulator 110.

The second cylinders 120 and the third cylinders 130 are matched in such a way that the displaced oil volumes over a same stroke length substantially coincide in order to ensure equal forces and flow rates of the second cylinders 120 and the third cylinders 130. A similar result may be obtained by using one or more integrated cylinders with a continuous piston rod on both sides of the piston, instead of the second cylinders 120 and the third cylinders

130.

As best shown in figures 4A, in this example the heave compensation system 100 has a first hoisting mode for hoisting heavy loads, in which both of the sheave brackets l151a-b with the manipulator sheaves 150a-b are connected to the manipulator 110 via the equalizer 160. As best shown in figure 4E the heave compensation system 100 has a second hoisting mode for hoisting less heavy loads, in which the first sheave bracket 15la is connected to the manipulator 110 wvia the equalizer 160 and the second sheave bracket 151b is parked in the second manipulator sheave parking arrangement 180b. In the first hoisting mode the heave compensation system 100 is operably connected to both hoist cables 23a-b and can reduce or cancel out the relative motions of both crane hooks 24a-b, and in the second hoisting mode the heave compensation system 100 is operably connected to the first hoist cable 23a and can reduce or cancel out the relative motions of the first crane hook 24a. In the second hoisting mode the second crane hook 24b is typically retracted towards and positioned near the boom tip 34 and the second winch is switched off. When the heave compensation system 100 is in the first hoisting mode the crane 20 has a higher hoisting capacity as compared to when the heave compensation system 100 is in the second hoisting mode. This means that loads that cannot be hoisted by the crane 20 in the second hoisting mode can be hoisted by the crane 20 in the first hoisting mode. Typically the first hoist cable 23a and the second hoist cable 23b will have the same hoisting capacity but other ratios may be applied to tune the crane 20 to the loads it is expected to hoist. It is to be understood that the heave compensation system 100 works analogous when in the second hoisting mode the second hoist cable 23b is operably connected to the heave compensation system 100 instead of the first hoist cable 23a. In practice in the second hoisting mode, the first hoist cable 23a and the second hoist cable 23b will be used alternately so that both hoist cables 23a-b wear substantially uniformly. In this respect the use of the references first and second with respect to the hoisting cables 23a,b and the components associated therewith are interchangeable.

As best shown in figures 4A and 4B, in the first hoisting mode of the heave compensation system 100 both sheave brackets 15la-b are connected to the equalizer 160 by the respective equalizer pins 162a-b. The first hoist cable 23a exerts a first cable force on the equalizer 160 along a first cable force axis B and the second hoist cable 23b exerts a second cable force on the equalizer 160 along a second cable force axis C, these cable forces result in a resultant cable force that is exerted on the equalizer 160 along a resultant cable force axis D. As the forces exerted by the hoist cables 23a-b are substantially equal, the equalizer 160 is caused into a straight position in which both equalizer pins 162a-b are at an equal distance to the central manipulator axis A at opposite sides thereof and at a substantially same distance from the manipulator 110 parallel to the central manipulator axis A. As a result the resultant cable force axis D and the central manipulator axis A are aligned and preferably coincide, which ensures a favourable load on the manipulator 110,

As best shown in figure 4B, in order to switch the heave compensation system 100 from the first hoisting mode to the second hoisting mode the two manipulator sheaves 150a-b are moved by the manipulator 110 towards the stationary sheaves 170a-b close to the manipulator sheave parking arrangements 180a-b.

As best shown in figure 4C the second manipulator sheave parking arrangement 180b is hinged by the parking arm cylinder 185 towards the corresponding second sheave bracket 151b until the slots 183 of the second manipulator sheave parking arrangement 180b catch or receive the cams 156 of the corresponding second sheave bracket 151b. The second manipulator sheave parking arrangement 180b with the engaged second sheave arrangement 151b is subsequently moved further towards the manipulator 110 to gradually transfer the force, which is exerted by the second hoist cable 23b on the equalizer 160, from the equalizer 160 to the second manipulator sheave parking arrangement 180b. As a result the equalizer 160 hinges into a tilted position in which the first equalizer pin 162a corresponding to the first sheave bracket 151a that is attached to the equalizer 160 is positioned along the central manipulator axis A, and the second equalizer pin 162b corresponding to the second sheave bracket 151b that is engaged by the second manipulator sheave parking arrangement 180a is at a distance from the central manipulator axis A. When the second manipulator sheave parking arrangement 180b carries the total force of the engaged second sheave bracket 151b, only the first sheave bracket 151a exerts a force on the equalizer 160 and therefore the resultant force acting on the equalizer 160 is equal to this force and therewith the first cable force axis B and the resultant cable force axis D coincide. As the manipulator 110 is hingeable with respect to the crane base 21 around the manipulator hinge axis K, the manipulator 110 hinges under the influence of the resultant force until it is in an orientation in which the central manipulator axis A is aligned with the resultant cable force axis D, which ensures a favourable load on the manipulator 110. As best shown in figure 4D subsequently the second equalizer pin 162b is extracted from the unloaded second sheave bracket 151b to disconnect the second sheave bracket 151b, that is engaged by the second manipulator sheave parking arrangement 180b, {from the equalizer 160. The extraction of the second equalizer pin 162b may be performed by hand or mechanically by, for instance, an automated pin pulling device. Thereafter the second manipulator sheave parking arrangement 180k with the engaged second sheave bracket 151b is hinged by the parking arm cylinder 185 towards the stationary sheaves 170a-b to provide sufficient clearance with respect to the manipulator 110 so that the manipulator 110 can freely move along the full range of its stroke. As best shown in figure 4E subsequently the first manipulator sheave 150a that is connected to the equalizer 160 is moved away from the stationary sheaves 170a-b by the manipulator 110. In order to switch the heave compensation system 100 from the second hoisting mode back to the first hoisting mode the above described procedure is performed in a reversed sequence. The outline of this procedure comprises the steps of moving the equalizer 160 towards the stationary sheaves 170a-b close to the manipulator sheave parking arrangements 180a-b, aligning the disconnected second sheave bracket 151b with the equalizer 160 by the second manipulator sheave parking arrangement 180b, inserting the second equalizer pin 162b to connect the second sheave bracket 151b, that is engaged by the second manipulator sheave parking arrangement 180b, to the equalizer 160, and moving the manipulator sheaves 150a-b away from the stationary sheaves 170a-b by the manipulator

110. It is to be understood that the heave compensation system 100 may also be embodied such that it functions with more than two hoist cables. Such a heave compensation system 100 has a manipulator sheave associated to each hoist cable. Each manipulator sheave is hingeably connectable to the equalizer 160, and therewith to the manipulator 110, by a removable equalizer pin. The equalizer 160 can adapt to the resultant force that is exerted thereon by the hoist cables that are operably connected to the equalizer 160 by hinging with respect to the manipulator sheaves and/or with respect to the manipulator 110. By adapting to the resultant force the equalizer 160 aligns the resultant force of the hoist cables with the manipulator 110, which ensures a favourable load thereon.

The crane 20 comprises a spacer 60 for the first hoist cable 23a and the second hoist cable 23b of the crane

20. The spacer 60 is schematically shown in figure 5. in a top view as seen when looking down along the vertical slewing axis S of the crane. The spacer 60 is in this example located inside the pedestal 7 of the crane 20 in the part thereof that has a circular cross section. In a substantially vertical direction along the hoist cables 23a-b the spacer 60 is located between the first guide sheaves 40a-b and the winches below the deck 6, preferably substantially halfway between the first guide sheaves 40a-b and the winches. The spacer 60 comprises a circular spacer shell 61 that is arranged substantially parallel with respect to the pedestal 7, a spacer shaft 62 that extends between two opposite sides of the spacer shell 61 and that is orientated substantially transverse to the slewing axis S. The spacer 60 comprises a first spacer sheave 63a and a second spacer sheave 63b for guiding the respective hoist cables 23a-b. The parallel first spacer sheave 63a and second spacer sheave 63b are rotatably connected to the spacer shaft 62 to respectively rotate around a first spacer axis F and a second spacer axis G that are orientated substantially transverse to the slewing axis S.

In this example the first spacer axis F and the second spacer axis G coincide and the first spacer sheave 63a and the second spacer sheave 63b extend side by side.

The spacer 60 is rotatably mounted to the pedestal 7 by a rotation bearing connection 64 that is schematically indicated by bearing balls 65 that are positioned between the spacer shell 61 and the pedestal 7. The spacer 60 is therefore rotatable in a spacer slewing direction H around a spacer rotation axis that is parallel to the slewing axis S. In this example the spacer rotation axis coincides with the slewing axis S.

The respective hoist cables 23a-b are guided from the first guide sheaves 40a-b, along the respective spacer sheaves 63a-b at opposite sides thereof with respect to the spacer axes F, G towards the winches. The spacer sheaves 63a-b space apart the respective hoist cables 23a-b at opposite sides of the spacer axes F, G and, as the direct paths of the hoist cables 23a-b between the first guide sheaves 40a-b and the winches below the deck 6 extend through the spacer axes F, G, the hoist cables 23a-b exert a force on the spacer sheaves 63a-b towards the spacer axes F, G. By these forces the respective hoist cables 23a-b effectively clamp the spacer 60.

When the crane 20 slews around the slewing axis S, the first guide sheaves 40a-b that are fixed to the crane base 21 slew with respect to the winches that are fixed to the vessel 2. At the spacer 60 the hoist cables 23a-b will also slew with respect to the pedestal 7. As the hoist cables 23a-b together clamp the spacer 60, a slewing force will be exerted on the spacer 60. The spacer 60 will slew with the hoist cables 23a-b in the spacer slewing direction H. The spacer 60 will slew approximately half as much as the crane 20 with respect to the pedestal 7. During slewing of the spacer 60 the hoist cables 23a-b are kept spaced apart by the spacer 60 and thereby prevents the hoist cables 23a-b from entangling with each other. In order to better control the slewing motion the crane 20 may be provided with a not shown spacer slewing actuator, for instance a rack and pinion system between the crane pedestal 7 and the spacer shell 61. Alternatively the spacer 60 may be operatively connected with the crane 20, for instance by a not shown gearing that is connected to the slewing ring 22 of the crane 20, preferably wherein the gearing comprises a two-to-one transmission.

When the crane 20 hoists a load in the second mode or when in the first mode the first hoist cable 23a and the second hoist cable 23b are loaded unevenly the tension in the first hoist cable 23a and the second hoist cable 23b differ from each other. As a result the hoist cables 23a-b exert different forces on the spacer sheaves 63a-b at opposite sides of the spacer axes F, G and the spacer 60 is forced to slew to find a new balance of forces. As a result the slewing motion of the spacer 60 may be somewhat unpredictable.

Figures 6A and 6B show respective schematic side views of an alternative spacer 260 for the first hoist cable 23a and the second hoist cable 23b of the crane 20. The spacer 260 comprises a circular spacer shell 261 that is arranged substantially parallel with respect to the pedestal 7, two pairs of triangular first spacer suspension plates 266 that extend from a first side of the spacer shell 261 towards the first guide sheaves 40a-b and substantially parallel to the slewing axis S, and two pairs of triangular second spacer suspension plates 267 that extend from an opposite second side of the spacer shell 261 towards the winches below the deck 6 and substantially parallel to the slewing axis S.

The spacer 260 comprises a first spacer sheave 263a and a second spacer sheave 263b for guiding the respective hoist cables 23a-b. The parallel first spacer sheave 263a and second spacer sheave 263b are rotatably connected between the first spacer suspension plates 266 of the respective pair of first spacer suspension plates 266 to respectively rotate around a first spacer axis F and a second spacer axis G that are orientated substantially transverse to the slewing axis S. In this example the first spacer axis F and the second spacer axis G coincide.

The spacer 260 comprises a third spacer sheave 26% and a fourth spacer sheave 269 for guiding the respective hoist cables 23a-b. The parallel third spacer sheave 26%a and fourth spacer sheave 269b are rotatably connected between the second spacer suspension plates 267 of the respective pair of second spacer suspension plates 267 to respectively rotate around a third spacer axis H and a fourth spacer axis J that are orientated substantially transverse to the slewing axis S. The third spacer axis H and the fourth spacer axis J are spaced apart from the first spacer axis F and the second spacer axis G in the direction of the slewing axis S. In this example the third spacer axis H and the fourth spacer axis J coincide.

The spacer 260 is rotatably mounted to the pedestal 7 by a rotation bearing connection 264 that is schematically indicated by bearing balls 265 analogous to the rotation bearing connection 64 of figure 5.

The respective hoist cables 23a-b are guided from the first guide sheaves 40a-b, along the respective first and second spacer sheaves 263a-b at opposite sides thereof with respect to the first and second spacer axes F, G, «crosswise towards and along the respective third and fourth spacer sheaves 269a-b at opposite sides thereof with respect to the third and fourth spacer axes H, J, and towards the winches. Between the first spacer sheave 263a and the third spacer sheave 269a the first hoist cable 23a passes between the first spacer axis F and the third spacer axis H, and between the second spacer sheave 263b and the fourth spacer sheave 269b the second hoist cable 23b passes between the second spacer axis G and the fourth spacer axis J. The first and second spacer sheaves 263a-b space apart the respective hoist cables 23a-b at opposite sides of the first and second spacer axes F, G, and the third and fourth spacer sheaves 26%a-b space apart the respective hoist cables 2Z3a-b at opposite sides of the third and fourth spacer axes H, J. The first and third spacer sheaves 263a, 206948 guide the first hoist cable 23a along opposite sides of the first and third spacer axes F, H. The direct path of the first hoist cable 23a between the first guide sheaves 40a-b and the winches below the deck 6 extends through the first and third spacer axes F, H. Through the spacing of the first hoist cable 23a with respect to the first and third spacer axes F, H, it exerts a first force on the first spacer sheave 263a towards the first spacer axis F, and it exerts a second force on the third spacer sheave 269a towards the third spacer axis in the opposite direction of the first force. By these forces the first hoist cable 23a effectively clamps the spacer 260. As the first force and the second force are equally large and oppositely directed there 1s a balance of forces acting on the spacer 260. Similarly, the second and fourth spacer sheaves 263b, 26%b guide the second hoist cable 23b along opposite sides of the second and fourth spacer axes G, J. Therefore the second hoist cable 23b clamps the spacer 260 in the same manner as the first hoist cable 23a clamps the spacer 260. Due to the arrangement of the spacer sheaves 263a-b, 26%a-b and the reeving of the hoist cables 23a-b the spacer 260 is in a stable equilibrium also when the tension of the first hoist cable 23a and the second hoist cable 23b differ from each other. As a result the slewing motion of the spacer 260 is more predictable as compared to the slewing motion of the spacer 60 of figure 5.

The spacer 260 slews with respect to the pedestal as a result of the slewing of the crane 20 and prevents the hoist cables 23a-b from entangling with each other in a similar fashion as the spacer 60 of figure 5.

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant Lo 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.

For instance the heave compensation system 100 is not limited to use in offshore knuckle boom cranes, the heave compensation system 100 can also be applied in most other types of offshore cranes or hoisting devices.

Claims

CONCLUSIONS

An assembly of a vessel and a crane, the vessel comprising a hull with a deck, the crane comprising a crane base provided on the vessel, a mast coupled to the crane base, a first hoist rope connected to the mast is suspended, a second hoist rope suspended from the mast, a first winch to manipulate the first hoist rope, a second winch to manipulate the second hoist rope, and a swell compensation system, the swell compensation system comprising a manipulator coupled to the crane, a first manipulator sheave rotatably coupleable to the manipulator to guide the first hoist rope, a second manipulator sheave rotatably coupleable to the manipulator to guide the second hoist rope, a first stationary sheave rotatably coupled to the crane for guiding of the first hoist rope, and a second stationary sheave rotatably coupled to the crane for guiding the two the hoisting rope, wherein the first hoisting rope is reeved from the first winch, via the first stationary sheave, via the first manipulator sheave, towards the mast, and the second hoisting rope is reeved from the second winch, via the second stationary sheave, via the second manipulator sheave toward the mast, the manipulator being configured to impose, manipulate or track a displacement of the first and second manipulator sheaves relative to the first and second stationary sheaves, and wherein the swell compensation system has a first lifting mode in which the first manipulator sheave and the second manipulator sheave are both coupled to the manipulator, and a second hoist mode in which only the first manipulator sheave is coupled to the manipulator, wherein the heave compensation system is configured to switch between the first hoist mode and the second hoist mode by coupling the second manipulator sheave and disconnect.

The assembly of claim 1, wherein the manipulator is configured to actively control the displacement of the first and second manipulator disks relative to the first and second stationary disks.

Assembly according to claim 1 or 2, wherein the swell compensation system comprises an equator which is coupled to the manipulator and with which the first manipulator disk and the second manipulator disk can be rotatably coupled, the equator being adapted to adapt to a resultant force which is applied to the manipulator by the first hoist rope and the second hoist rope to align the manipulator with the resultant force.

An assembly according to claim 3, wherein the equator is pivotally coupled to the manipulator to allow the equator to pivot relative to the manipulator about a first equator pivot axis oriented transverse to the resultant force when the swell compensation system is switched between the first lifting mode and the second lifting mode.

An assembly as claimed in any preceding claim, wherein the manipulator is pivotally coupled to the crane to allow the manipulator to pivot relative to the crane about a manipulator pivot axis oriented transversely to the manipulator when the swell compensation system is switched between the first lifting mode and the second lifting mode.

Assembly according to claim 4 or 5, wherein the first equator pivot axis and the manipulator pivot axis are oriented parallel to each other.

An assembly according to any one of claims 3-6, wherein the first manipulator disk is pivotally coupled to the equator to allow the first manipulator disk to pivot relative to the equator about a second equator pivot axis oriented transversely to the resultant force when the heave compensation system is switched between the first lifting mode and the second lifting mode.

An assembly as claimed in any one of claims 3 to 7, wherein the second manipulator disk is pivotally coupled to the equator to allow the second manipulator disk to pivot relative to the equator about a third equator pivot axis oriented transverse to the resultant force when the heave compensation system is switched between the first lifting mode and the second lifting mode.

An assembly according to any one of claims 3-8, wherein the swell compensation system comprises a sensor device for monitoring the orientation of the equator relative to the manipulator.

An assembly according to claim 9, wherein the crane is arranged to operate at least one of the winches based at least in part on the monitored orientation of the equator.

An assembly according to any one of the preceding claims, wherein the swell compensation system comprises a manipulator sheave parking device, wherein in the second hoisting mode the second manipulator sheave is parked in the manipulator sheave parking device.

An assembly according to claim 11, wherein the manipulator disk parking device is adapted to pivot the second manipulator disk with respect to the crane.

An assembly according to claim 11 or 12, wherein the heave compensation system comprises a sheave bracket comprising a cam, the second manipulator sheave is rotatably mounted to the sheave support, and wherein in the second hoisting mode the cam is engaged by the manipulator sheave parking device.

An assembly according to claim 13, wherein the manipulator disc parking device comprises a disc parking arm pivotally coupled to the crane at one end and having a cam engaging recess at the opposite end, the disc parking arm being arranged about the second manipulator disc. to pivot relative to the tap.

An assembly according to any one of the preceding claims, wherein the manipulator comprises a hydraulic cylinder.

An assembly according to claim 15, wherein the manipulator comprises a passive hydraulic cylinder.

17. Assembly according to claim 15 or 16, wherein the manipulator comprises an active hydraulic cylinder.

An assembly according to any one of the preceding claims, wherein the swell compensation system is provided at least partially within the crane base.

An assembly according to any one of the preceding claims, wherein the manipulator is coupled to the crane base.

An assembly according to any one of the preceding claims, wherein the manipulator is coupled to the crane base near the bottom thereof.

An assembly according to any one of the preceding claims, wherein the first stationary disc and the second stationary disc are rotatably coupled to the crane base.

An assembly according to any preceding claim, wherein the first stationary disc and the second stationary disc are rotatably coupled to the crane base near the top thereof.

An assembly according to any one of the preceding claims, wherein the first winch and the second winch are placed below the deck.

An assembly according to any one of the preceding claims, wherein the crane is rotatable relative to the deck about a pivot axis oriented transversely to the deck, and the first winch and the second winch are fixed relative to the deck, the crane having a includes spacer rotatable with respect to the deck and with respect to the crane about an axis of rotation oriented parallel to the pivot axis,

wherein from the first winch and the second winch to the swell compensation system, the first hoist rope and the second hoist rope are reeved along the spacer, the spacer comprising a first spacer disk rotatable about a first spacer axis oriented transverse to the pivot axis, and a second spacer disk rotatable about a second spacer axis oriented transversely to the pivot axis, and wherein the first spacer disk and the second spacer disk guide and space the respective first hoist rope and the second hoist rope from each other.

The assembly of claim 24, wherein the first spacer pulley and the second spacer pulley space the first hoist rope and the second hoist rope on opposite sides of the first spacer axis or the second spacer axis.

An assembly according to claim 24 or 25, wherein the first spacer axis and the second spacer axis correspond.

An assembly according to any one of claims 24-26, wherein the first spacer disk and the second spacer disk extend side by side,

An assembly according to any one of claims 24-27, wherein the spacer comprises a third spacer disc rotatable about a third spacer axis oriented parallel to and spaced from the first spacer axis, the third spacer disc guiding the first hoisting cable. and wherein between the first spacer sheave and the third spacer sheave the first hoisting rope passes between the first spacer shaft and the third spacer shaft.

An assembly according to any one of claims 24-28, wherein the spacer comprises a fourth spacer disc rotatable about a fourth spacer axis oriented parallel to and spaced from the second spacer axis, the fourth spacer disc guiding the second hoisting cable. and wherein between the second spacer sheave and the fourth spacer sheave the second hoisting rope passes between the second spacer shaft and the fourth spacer shaft.

An assembly according to claim 29, wherein the third spacer axis and the fourth spacer axis correspond.

An assembly according to claim 29 or 30, wherein the third spacer disk and the fourth spacer disk extend side by side.

An assembly according to any one of claims 24-31, wherein the spacer is operatively coupled to the crane to rotate with the crane in dependence on pivoting of the crane relative to the deck.

An assembly according to claim 32, wherein the spacer is operatively coupled to the crane by a gear transmission.

An assembly according to claim 32 or 33, wherein the spacer is located midway between the crane base and the winches, and wherein the spacer is operatively coupled to the crane with a two-to-one transmission.

An assembly according to any one of claims 24-34, wherein the tap comprises a spacer drive.

36. Assembly of a vessel and a crane, the vessel comprising a hull with a deck, the crane comprising a crane base provided on the vessel, a mast coupled to the crane base, a first hoist rope connected to the mast, a second hoist rope suspended from the mast, a first winch to manipulate the first hoist rope, and a second winch to manipulate the second hoist rope, the crane being rotatable relative to the deck about a pivot axis transverse to the deck is oriented, and the first winch and the second winch are fixed relative to the deck, the crane comprising a spacer rotatable relative to the deck and relative to the crane about an axis of rotation parallel to the pivot axis oriented, wherein from the first winch and the second winch to the swell compensation system the first hoist rope and the second hoist rope are reeved along the spacer, the spacer being provided with a first a spacer sheave rotatable about a first spacer axis oriented transversely to the pivot axis, and a second spacer sheave rotatable about a second spacer axis oriented transversely to the pivot axis, and wherein the first spacer shear and the second spacer sheave connect to the respective first hoist rope and guide the second lifting rope and keep it at a distance from each other.

An assembly according to claim 36, wherein the first spacer disk and the second spacer disk space the first hoist rope and the second hoist rope on opposite sides of the first spacer shaft.

An assembly according to claim 36 or 37, wherein the first spacer axis and the second spacer axis correspond.

An assembly according to any one of claims 36-38, wherein the first spacer disk and the second spacer disk extend side by side.

An assembly according to any one of claims 36-39, wherein the spacer comprises a third spacer disc rotatable about a third spacer axis oriented parallel to and spaced from the first spacer axis, the third spacer disc guiding the first hoisting cable. and wherein between the first spacer sheave and the third spacer sheave the first hoisting rope passes between the first spacer shaft and the third spacer shaft.

An assembly according to any one of claims 36-40, wherein the spacer comprises a fourth spacer disc rotatable about a fourth spacer axis oriented parallel to and spaced from the second spacer axis, the fourth spacer disc guiding the second hoisting cable. and wherein between the second spacer sheave and the fourth spacer sheave the second hoisting rope passes between the second spacer shaft and the fourth spacer shaft.

An assembly according to claim 41, wherein the third spacer axis and the fourth spacer axis correspond.

An assembly according to claim 41 or 42, wherein the third spacer disk and the fourth spacer disk extend side by side.

An assembly according to any one of claims 36-43, wherein the spacer is operatively coupled to the crane to rotate with the crane in dependence on pivoting of the crane relative to the deck.

An assembly according to claim 44, wherein the spacer is operatively coupled to the crane by a gear transmission.

An assembly according to claim 45, wherein the spacer is located midway between the crane base and the winches, and wherein the gear transmission comprises a two-to-one transmission.

An assembly according to any one of claims 36-45, wherein the tap comprises a spacer drive.

A tap for use in an assembly according to any one of the preceding claims.

A swell compensation system for use in an assembly according to any one of claims 1 to 35 or for use in a crane according to claim 48.

A spacer for use in an assembly according to any one of claims 36-47 or for use in a tap according to claim 48.

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