The present invention relates to a marine vessel, e.g. a jack-up type vessel, having a crane and a method of operation of such a marine crane vessel.

It is commonly known to use marine crane vessels for offshore hoisting purposes, such for the installation and/or maintenance of offshore wind turbines. Other applications are, for example, hoisting activities related to offshore platforms for oil and/or gas production, e.g. for decommission such offshore platforms.

Current offshore wind turbines require a foundation, e.g. in the form of a monopile. The wind turbine is then installed on the monopile, either in one piece or in several pieces.

Many known offshore wind turbine installation vessels are of the jack-up type, with extendible jack-up legs and with a crane for installation of the wind turbine. In a known design, the crane is an around-the-leg crane.

In order to make efficient use of wind energy, the trend is to increase the diameter of the rotor of the wind turbine and to have the hub high above the water. Wind turbine blades of 60 - 90 meters in length or even longer may be very common in the near future. The hub of the wind turbine, and therefore the height of the mast, also is ever increasing. For example, the hub may be at 100 meters above the sea, or even higher. This also increases the size and weight of all other components of the turbine installation including the nacelle, hub, generator, blades, mast, and/or the foundation.

The trend therefore is towards cranes on such a vessel with an increased reach and lifting capability, so generally a longer and stronger boom, allowing for hoisting operations at great height.

During transfer of the vessel, it is advantageous, even necessary, to position the boom in a parking position.

It is an object of the present invention to provide a marine vessel with a crane having a boom allowing for an advantageous parking routine and parking position. This aim is achieved by a vessel operated according to the method of claim 1. In the invention, the vessel has a boom rest that is arranged on the hull spaced from the slew bearing and is adapted to rest the main boom section of the boom thereon in a parking position of the boom. Further a fastening assembly is provided which is configured to fasten the object suspension device relative to the hull of the vessel, said fastening assembly being spaced further from the slew bearing than the boom rest.

The method comprise a boom parking routine wherein the boom is brought from a hoisting position into the parking position, wherein said boom parking routine comprises:

a. bringing the boom in a raised intermediate position wherein the boom main section is remote from the boom rest and the jib sheave assembly is vertically above the fastening assembly;

b. paying out the hoist cable and thereby lowering the object suspension device suspended from the hoisting cable below the jib sheave assembly, said lowering being continued until the object suspension device reaches the fastening assembly,

c. fastening the object suspension device to the fastening assembly,

d. lowering the main boom section towards the boom rest by means of the luffing assembly combined with hauling in the hoist cable, and possibly also combined with operating the variable length stay mechanism, so that the tip end of the jib member is pulled towards the fastening assembly, until the main boom section rests on the boom rest in the parking position of the boom.

This approach allows for a long boom that allows to meet the industry demand, which boom is then also relatively heavy, whilst assuring a reliable and effective parking of the boom.

In an embodiment, the vessel further comprises a jib tip end support device in proximity of the fastening assembly for the object suspension device, wherein the boom parking routine comprises bringing the tip end of the jib member into load bearing engagement with the jib tip end support device, so that in the parking position of the boom a part of the weight of the boom rests on the boom rest and a part of the weight of the boom rests on the jib tip end support device. This allows to avoid undue load on the boom rest and/or on the main boom section where it is supported by the boom rest.

In an embodiment, the fastening assembly, and possibly also the jib tip end support device, are located closer to the slew bearing than the upper end of the main boom section in the parking position thereof on the boom rest, so that the jib member extends from the inner end thereon inwards relative to the main boom section. This, for instance, may allow for a crane having a long boom. For example, a marine vessel with a relatively smaller, shorter, hull can be provided with a crane having a relatively long boom.

In an embodiment, use is made of an automated control device that is configured and programmed to perform automatically the steps a., b., and d. of claim 1.

In an embodiment, the jib section has a second jib strut oriented at an angle from a first jib strut and configured to engage on the variable length stay mechanism, so as to maintain a lever action of the variable length stay mechanism about the pivot axis of the jib section, e.g. when the first jib strut becomes generally aligned with the main boom section, e.g. during the parking routine.

In an embodiment, the vessel is a marine jack-up type vessel comprising:

- a buoyant hull,

- at least three, preferably four or six, jack-up legs,

- a plurality of elevating units, each associated with a respective jack-up leg, adapted to move the respective jack-up leg vertically relative to the hull and to bring the vessel in an operational position wherein the legs engage the seabed and the hull is above water level.

In an embodiment, the crane is a leg encircling crane comprising a foot fixed to the hull, wherein the slew bearing is supported on the foot and extends about a jack-up leg of the vessel, and wherein the revolving superstructure is supported by said slew bearing.

In an embodiment, the main boom section comprises a pair of boom legs, which are connected at said upper end to each other via a head structure of the main boom section, e.g. said head structure supporting a whip hoist member extending beyond said main boom section in a central plane of the main boom section, and wherein said jib is pivotally connected to said head structure of the main boom section.

In an embodiment, in the boom parking routine, the main boom section is aligned with a jack-up leg of the vessel and is lowered over said jack-up leg so that in the parking position the boom legs of the main boom section are on opposite sides of said jack-up leg.

In an embodiment, the jib member comprises a triangular jib member frame, said jib sheave assembly being mounted at a tip end of said triangular jib member frame, wherein a base of the triangular jib member frame is pivotally connected to the head structure of the main boom section. In an embodiment, the jib structure comprises a jib strut frame having a pair of radial jib strut members each extending radially from a respective transverse end portion of the head of the main boom section and being pivotally connected to the head of the main boom section.

In an embodiment the method further comprises a hoisting step, wherein the crane is used to lift an object at an offshore location, e.g. a component of an offshore wind turbine.

The present invention also relates to a marine vessel as disclosed herein.

The present invention also relates to a marine vessel according to claim 11 , wherein the boom is movable, in a boom parking routine, from a hoisting position into the parking position, wherein said boom parking routine comprises:

a. bringing the boom in a raised intermediate position wherein the boom main section is remote from the boom rest and the jib sheave assembly is vertically above the fastening assembly;

b. paying out the hoist cable and thereby lowering the object suspension device suspended from the hoisting cable below the jib sheave assembly, said lowering being continued until the object suspension device reaches the fastening assembly,

c. fastening the object suspension device to the fastening assembly,

d. lowering the main boom section towards the boom rest by means of the luffing assembly combined with hauling in the hoist cable, and possibly also combined with operating the variable length stay mechanism, so that the tip end of the jib member is pulled towards the fastening assembly, until the main boom section rests on the boom rest in the parking position of the boom.

In an embodiment, the vessel further comprises a jib tip end support device in proximity of the fastening assembly for the object suspension device, wherein the boom parking routine comprises bringing the tip end of the jib member into load bearing engagement with the jib tip end support device, so that in the parking position of the boom a part of the weight of the boom rests on the boom rest and a part of the weight of the boom rests on the jib tip end support device.

In an embodiment, the fastening assembly, and possibly also the jib tip end support device, are located closer to the slew bearing than the upper end of the main boom section in the parking position thereof on the boom rest, so that the jib member extends from the inner end thereon inwards relative to the main boom section. In an embodiment, the vessel comprises an automated control device that is configured and programmed to perform automatically the steps a., b., and d. of claim 11.

In an embodiment, the vessel is a marine jack-up type vessel comprising:

- a hull,

- at least three jack-up legs,

- a plurality of elevating units, each associated with a respective jack-up leg, adapted to move the respective jack-up leg vertically relative to the hull and to bring the vessel in an operational position wherein the legs engage the seabed and the hull is above water level.

In embodiments, the main boom section comprises a pair of boom legs, which are connected at said upper end to each other via a head structure of the main boom section, e.g. said head structure supporting a whip hoist member extending beyond said main boom section in a central plane of the main boom section, and wherein said jib is pivotally connected to said head structure of the main boom section.

In embodiments, in the boom parking routine, the main boom section is aligned with a jack up leg of the vessel and is lowered over said jack-up leg so that in the parking position the boom legs of the main boom section are on opposite sides of said jack-up leg.

In embodiments, the jib member comprises a triangular jib member frame, said jib sheave assembly being mounted at a tip end of said triangular jib member frame, wherein a base of the triangular jib member frame is pivotally connected to the head structure of the main boom section.

In embodiments, jib structure comprises a jib strut frame having a pair of radial jib strut members each extending radially from a respective transverse end portion of the head of the main boom section and being pivotally connected to the head of the main boom section.

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

Fig. 1 shows a side view of a jack-up type marine vessel according to the invention;

Fig. 2 shows a part of the boom of the crane of fig. 1 on a larger scale,

Fig. 3 shows a plan view of the vessel of fig. 1 with the boom in parking position,

Fig. 4 shows the vessel of figure 1 in side view with the boom in parking position,

Fig. 5 shows a part of the figure 4 on a larger scale,

Fig. 6 shows a part of figure 3 on a larger scale, Fig. 7 shows the vessel of figure 1 , with the boom during execution of the parking routine, Fig. 8 shows a leg and the crane of the vessel of figure 1 in a perspective view,

Fig. 9 shows a leg and the crane of the vessel of figure 1 in another perspective view.

In the figures, an exemplary jack-up type marine vessel 1 is shown, comprising a buoyant hull 2. The hull 2, in this example, has an accommodation and bridge structure 4 at the bow, here with a helideck. Aft of the structure 4 the vessel has a main deck 3.

In figures 4, 5, 6, 7 a part of structure 4 has been left out for clarity.

The hull 2 comprises a plurality, here four, vertical leg openings 5 through the hull. These leg openings are spaced about the hull.

Jack-up legs 6a,b,c,d extend through the hull 2, each via a respective leg opening 5.

Each of the legs 6a-d is movable in a vertical direction with respect to the hull 2 by means of an elevating unit 7 is positioned at the vertical leg opening. The elevating units 7 are adapted to lift the hull 2 free of the water surface when the legs 6a-d engage the seabed.

The vessel 1 comprises a crane 20, here a leg-encircling crane, also referred to in the industry as an around-the-leg crane 20.

A foot 10 is fixed to the hull. Here the leg 6a extends through the foot 10.

A slew bearing 15 is supported on the foot 10 and extends about a jack-up leg 6a of the vessel 1.

The crane 20 has a revolving superstructure 21 that is supported by the slew bearing 15.

The crane further comprises a boom 30 that is pivotally mounted to the revolving

superstructure 21 about a horizontal pivot axis 22.

The boom 30 comprises:

- a main boom section 35 comprising a lower end 36 that is pivotally mounted about pivot axis 22 to the superstructure 21 and an upper end 37,

- a jib section 40 that is mounted pivotally about a pivot axis P to the upper end 37 of the main boom section 35. In the figure 1 , which is to scale as are the other figures, the tip end of the jib section 43 is shown at a height of 150 meters above the deck 3.

The jib section 40 comprises:

- a jib member 41 , e.g. having a length of between 15 and 35 meters, an inner end 42 of which is pivotally mounted about pivot axis P to the upper end 37 of the main boom section 35, said jib member 41 having a tip end 43, and

- a jib strut 45 having an inner end 46 that is secured to the inner end 42 of the jib member and having an outer end 47, and

- a jib stay 48 extending between the outer end of the jib strut and the jib member, here the tip end 43 thereof.

As shown here, the jib strut 45, or first jib strut as multiple jib struts at differing angles may be possible, is generally perpendicular to the jib member 41.

As preferred, the jib stay 48 is a fixed length jib stay, e.g. formed by one or more cables or rods.

A jib sheave assembly 50 is mounted on the jib member, here in proximity of the tip end thereof.

A variable length stay mechanism 60 is provided between the main boom section 35 and the jib strut 45.

In the depicted embodiment, an as optional for the crane, a second jib strut 45b is provided oriented at an angle from the first jib strut 45 that is further away from the jib member 41. It is envisaged that said second jib strut 45b engages on the variable length stay mechanism 60, so as to maintain a lever action of the mechanism 60 about the pivot axis P, when the first jib strut 45 becomes generally aligned with the main boom section 35, e.g. during the parking routine. The first and second jib struts 45, 45b may be fixed to another, e.g. by connector frame 45c.

The crane 20 has a luffing assembly comprising a luffing winch 70 mounted to the superstructure 21 and a luffing cable 72 extending between the luffing winch 70 on the superstructure and the main boom section 35, preferably the upper end 37 thereof; The crane 20 has a hoist winch 80, a hoist cable 82, and an object suspension device 85. The hoist cable 82 extends from the hoist winch 80, along the jib sheave assembly 50, to the object suspension device 85 suspended from the cable 82 below the assembly 50.

As preferred the cable 82 extends in a multiple falls arrangement between the sheave assembly 50 and the device 85, that is then also provided with a sheave assembly.

As shown here, in embodiments, the device 85 comprises a crane hook 86, e.g. a multi prong crane hook.

For example, as shown here, the crane has a capacity to lift at least 800 tonnes.

The vessel 1 has a boom rest 90, here in proximity of leg 6b, e.g. at both sides of the leg 6b, that is arranged on the hull 2 at a location spaced from the slew bearing 15 and adapted to rest the main boom section 35 of the boom thereon in a parking position of the boom.

The vessel has a fastening assembly 100 that is configured to fasten the object suspension device 85 relative to the hull 2 of the vessel, e.g. on a front deck 12 thereof as shown here.

The fastening assembly 100 is spaced further from the slew bearing 15 than the boom rest 90, here the assembly 100 is forward, so further to the bow, than the boom rest 90.

The boom 30 is movable, in a boom parking routine, from a hoisting position into a parking position by means of a boom parking routine.

The boom parking routine comprises:

a. bringing the boom 30 in a raised intermediate position, wherein the boom main section 35 still is remote from the boom rest 90 and the jib sheave assembly 50 is vertically above the fastening assembly 100;

b. paying out the hoist cable 82 and thereby lowering the object suspension device 85 suspended from the hoisting cable 82 below the jib sheave assembly 50, said lowering being continued until the object suspension device 85 reaches the fastening assembly 100, c. fastening the object suspension device 85 to the fastening assembly 100,

d. lowering the main boom section 35 towards the boom rest 90 by means of the luffing assembly combined with hauling in the hoist cable 82, and possibly also combined with operating the variable length stay mechanism 60, so that the tip end 43 of the jib member 41 is pulled towards the fastening assembly 100, until the main boom section 35 rests on the boom rest 90 in the parking position of the boom. As shown here, the vessel further comprises a jib tip end support device 120 in proximity of the fastening assembly 100 for the object suspension device 85. The device 120 may be integrated with the assembly 100 when desired.

In an embodiment the boom parking routine comprises bringing the tip end 43 of the jib member 41 into load bearing engagement with the jib tip end support device 120, so that in the parking position of the boom 30 a part of the weight of the boom 30 rests on the boom rest 90 and a part of the weight of the boom rests on the jib tip end support device 120.

As shown here, e.g. in view of the length of the vessel relative to the length of the boom, it is preferable for the fastening assembly 100, and possibly also the jib tip end support device 120, to be located closer to the slew bearing 15 than the upper end 37 of the main boom section 35 in the parking position thereof on the boom rest, so that the jib member extends from the inner end thereon inwards relative to the main boom section.

In embodiments, as shown here, the upper end 37 of the main boom section is located beyond, that is forward of, the bow of the vessel in the parking position, with the tip end 43 being inboard of the hull of the vessel. As can be seen, this allows for a relatively long main boom section 35 of the crane, as well as a relatively lengthy jib member 41 , resulting a significant operational height of the crane. As can be seen, this structure is advantageous in combination with an over-the-leg crane, more preferably in combination with an over-the-leg parking position, as the parked boom then extends generally along one side of the jack-up type vessel. This, e.g. avoids undue interference of the parked boom with the

accommodation and bridge structure 4, e.g. with the helideck of said structure 4, e.g. as shown in figure 1.

In embodiment, as shown here, the jib member 41 extends rearward and downward relative to the upper end 37 of the boom section 35 in the parking position.

In embodiment, the vessel comprises an automated control device that is configured and programmed to perform automatically the steps a., b., and d. of the boom parking routine.

As shown here, in an embodiment, the main boom section 35 comprises a pair of boom legs 35a, b, which are connected at said upper end 37 to each other via a head structure 38 of the main boom section 35. As shown here, the head structure 38 may support a whip hoist member 39 extending beyond said main boom section 35 in a central plane of the main boom section.

The jib section 40 is pivotally connected to the head structure 38 of the main boom section 35.

It is also shown here that in the boom parking routine, the main boom section 35 is aligned with a jack-up leg 6b of the vessel and is lowered over said jack-up leg 6b so that in the parking position the boom legs of the main boom section are on opposite sides of said jack- up leg. This is known as an over-the-leg parking of the boom.

It is also shown here that the jib member 41 comprises a triangular jib member frame, wherein the jib sheave assembly 50 is mounted at a tip end 43 of the triangular jib member frame, and wherein a base of the triangular jib member frame is pivotally connected to the head structure 38 of the main boom section.

It is also shown here that the jib strut 45 comprises a jib strut frame having a pair of radial jib strut members 45a, b each extending radially from a respective transverse end portion of the head 38 of the main boom section and being pivotally connected to the head of the main boom section.