The present invention relates to a shear leg crane and transportation vessel for handling of one or more heavy and large objects.

Shear leg crane vessels are generally known and generally include a floating hull, often embodied as a barge. In a common design a single shear leg crane is mounted on the hull, the crane being of the non-slewing type. The crane has a single shearleg jib with two rigidly interconnected jib legs that are each pivotally connected at a lower end thereof via a horizontal axis pivot to an associated jib leg stand that is structurally integrated with the hull of the vessel. The known shearleg crane has a main hoist assembly including at least one main hook, one or more main hoist cables and one or more main hoist winches. The main hook is suspended by the one or more main hoist cables from the shear leg jib. A luffing assembly is commonly associated with the shearleg jib and comprises one or more luffing cables and one or more luffing winches. The luffing assembly and the shearleg jib are embodied such that the shearleg jib has an angular operating range for performing hoisting activities with the main hoist assembly. This operating range at least includes an

overboarding position, wherein the at least one main hook is operable to perform hoisting operations with a heavy object suspended therefrom with said at least one main hook - when seen in vertical projection - in a position outside the bow or stern of the hull. Whilst such known shearleg cranes are satisfactory with respect to their crane function, and can be embodied to have a very significant lifting capacity, e.g. more than 1000 tonnes, the known shearleg crane vessel lack versatility.

It is an object of the present invention to provide measures that allow for an increased versatility of a shearleg crane vessel.

In an object of the present invention to provide a shearleg crane vessel that can both perform a transport function of one or more large and heavy objects, as well as perform lifting operations involving said one or more large and heavy objects.

It is an object of the present invention to provide a shearleg crane vessel that can be advantageously employed in a shipbuilding method, wherein one or more heavy objects are both transported by the shearleg crane vessel as well as hoisted in order to be placed on a vessel under construction, e.g. a floating production and storage vessel (FPSO).

It is an object of the present invention to provide an improved shipbuilding method wherein use is made of the inventive shearleg crane and transportation vessel.

The invention achieves one or more of the above objects by providing a shearleg crane and transportation vessel according to claim 1. The hull of the vessel can be embodied as a sea-going vessel, but can also be embodied as a barge, e.g. to be used primarily within a harbour, near a shipyard, etc.

The vessel can e.g. be used in pipelaying operation offshore, e.g. when loading and unloading heavy and large pipelaying reels from a pipelaying vessel.

The vessel is able to transport a heavy and large object, or several such objects, on its flush and planar cargo deck, as well as to pick up (or lower onto) such an object from its cargo deck. In a practical embodiment the flush cargo deck area has a length of at least 50 meters and a width of at least 20 meters.

In a preferred embodiment the vessel is provided with skidding equipment, e.g. with one or more skid rails that can be fitted on the cargo deck or are integrated therein and with one or more hydraulic jacks that can be locked onto a rail to perform a skidding of a heavy and large object over the cargo deck, e.g. from a central region of the cargo deck towards a position near the axial end where the shearleg crane is present, allowing the crane to handle the object. In view of the capacity of the shearleg crane when overboarding a heavy and large object, it is desirable for the pivot axis of the jib to be located rather close (when seen in vertical projection) to the respective bow or stern side of the vessel. In a practical embodiment the shear leg pivot axis, when seen in vertical projection, is spaced between 5 and 15 meters from an axial overboarding end of the flush cargo deck area. On the other hand, in order to be able to pick up a heavy and large object from the cargo deck with the shearleg crane, it is desirable to have the cargo deck have a significant length between said "overboarding side" of the hull and the same pivot axis. In a preferred embodiment of the inventive vessel a cargo deck area extension device is provided that is adapted to temporarily extend the flush cargo deck area at the side where the crane is able to pick up a heavy object from the cargo deck area.

The temporary extension is envisaged primarily to allow a large object to be placed at the overboarding side of the cargo deck - and then at least part of its weight supported by the deck extension device - in a position where it can be adequately handled by the main hoist of the shear leg crane. Once the object is actually suspended from the main hoist hook or hooks, it is envisaged that the extension device is removed or retracted or similar, so that the respective side of the vessel can be brought close against an item onto which the lifted object is to be placed.

Preferably the deck extension device provides for a continuous deck surface having a width at least equal to the width of the adjoining end of the cargo deck area formed by the hull of the vessel.

Preferably the deck extension device provides for an extension of the length of the cargo deck area with at least 5 meters.

Preferably the deck extension device is adapted to support a weight of at least 100 tonnes.

For example in a shipbuilding method it is envisaged that one or more large and heavy modules are placed on a ship under construction, e.g. to construe a floating production, storage, and offloading ship, commonly known under the acronym FPSO. In such a ship the hull is mainly used for temporary storage of hydrocarbons, and on the deck there is a topside with an installation for processing the hydrocarbons. For the construction of an FPSO the topsides to be placed on the hull of the ship is often composed of several modules, e.g. each module weighing between 1000 and 3000 tonnes. Such modules are made on shore, e.g. at a construction yard in an indoor facility. These modules then needed to be transported to the location of the hull of the ship, usually at a ship yard and then lifted onto the deck of the ship. It is not uncommon for the deck to be 30 meters above waterline at said stage.

The invention envisages that the inventive shearleg crane is used and that one or more modules are moved onto the cargo deck of the shearleg crane vessel, e.g. using

multiwheeled vehicles, preferably directly from the onshore construction yard. The vessel then sails (a short or even long distance) to the ship under construction, e.g. at a ship yard. A module is then, if not already in said position, moved over the flush cargo deck to the pick up position in order to be picked up by the main hoist of the shearleg crane. As explained, in a preferred embodiment, the cargo deck can be temporarily extended at said side of the vessel by the extension device. Once the module has been picked up by the main hoist and is free of the cargo deck, the extension device can be removed, retracted or otherwise, so that the crane vessel can now be brought with its respective bow or stern closely to or against the hull of the ship under construction. The crane then brings the module above the desired position on the hull of the ship under construction, and lowers the module onto its place. This ship building method, preferably with use of temporary extension of the cargo deck, is considered to be more efficient than the common prior art approach wherein such modules are first placed onto a separate cargo barge, then picked up from said cargo barge by a shearleg crane vessel, the cargo barge then sailed away and finally the shearleg vessel placing the object onboard the ship under construction.

The inventive method and shear leg crane vessel are also considered advantageous over the approach disclosed in US2005013667 (Technip-Coflexip) wherein complicated lifting equipment is proposed for FPSO construction, which equipment can hardly be put to use for other tasks.

In a preferred embodiment the cargo deck area extension device includes one or more mobile deck extension elements, that are movable or displaceable between a stored or retracted position on the one hand and an operative position on the other hand, wherein - in the operative position - the one or more mobile deck extension elements for one or more cargo deck area portions that are flush with the cargo deck area.

In a preferred embodiment the cargo deck extension device allows for extension of the length of the cargo deck area with at least 10 meters, preferably at least 15 meters.

In an embodiment the mobile deck extension elements are pivotal deck elements, that are hinged to the hull about a horizontal axis at an axial end of the hull and which in operative position form an extension of the cargo deck area. For example the pivoting is performed by associated hydraulic jacks or by a cable and winch assembly.

In an embodiment the pivotal deck elements are not only hinged to the hull, but also have a further hinge axis spaced from the hull, so that the deck elements can be folded, e.g. for storage.

In a possible embodiment the deck extension elements comprises removable or axially displaceable cantilever elements that in operative position extend as cantilevers from the hull. Removing of cantilever elements is less preferred as it requires additional lifting equipment. An axially displaceable version can e.g. be skidded between its retracted and operative position. In a preferred embodiment the axial ends of the cargo deck area coincide with the bow and the stern of the hull respectively such that the cargo deck area extends over the entire length of the vessel. This e.g. allows mooring the vessel with its end that is the most remote from the shearleg crane against a quay at the construction side, or a harbour quay near the construction site of the module(s), and then transfer the module(s) onto the cargo deck, e.g. using multiwheeled vehicles. The modules may then be moved all the way to the other end, where the overboarding with the shearleg crane takes place, over the flush cargo deck, e.g. by skidding or using said same multiwheeled vehicles if desired.

In a preferred embodiment the shear leg crane is embodied such that an heavy and large object having a width (seen at right angles to the vessels length) and a height of 15 x 15 meters, preferably of 20 x 20 meters, can pass slidingly, e.g. skidded, over the flush cargo deck area underneath the shear leg in an operating position of the shear leg crane.

Preferably the jib leg stands are spaced at least 20 meters apart, preferably more than 30 meters.

In a practical embodiment the jib legs are rigidly interconnected by a traverse beam near the lower end of the legs, said transverse beam extending at an elevated position above the cargo deck area, e.g. at least 15 meters, so as to have an unobstructed passage for said one or more objects underneath said transverse beam.

In a practical embodiment the jib stand have such a height that the horizontal axis of the shearleg jib extends at least 10 meters above the cargo deck area. This enhances the overboarding capacity of the crane vessel, e.g. considering the height of the hull of an FPSO vessel onto which modules are to be placed.

In a practical embodiment the luffing assembly includes a pivotal back stay boom, that is at its lower end pivotally connected to the jib stands and pivotal about an axis that is parallel to the pivot axis of the shear leg jib, and an associated a back stay cable assembly is provided with one or more back stay cables and one or more back stay cable winches, said back stay cable assembly connecting the back stay boom to the hull of the vessel, and wherein the luffing assembly further includes one or more luffing cables and one or more luffing cable winches, wherein said luffing cables extend between a top end of the back stay boom and the shear leg jib.

In an embodiment thereof the back stay boom has two rigidly interconnected back stay boom legs, each back stay boom leg having a lower end pivotally connected to an associated jib leg stand carrying the pivot of a leg of the shearleg jib.

In a practical embodiment the back stay boom is inverted V-shaped with the top ends of the legs converging into a top end section of the back stay boom.

In a practical embodiment the legs of the back stay boom are rigidly interconnected near their lower ends via a transverse truss. Preferably winches are mounted on said truss, so as to not occupy space on or even below the upper deck of the vessel. Advantageously the one or more main hoist winches of the shearleg crane are mounted on said transverse truss. The one or more back stay cable winches and/or the one or more luffing cable winches may also be mounted on said transverse truss of the back stay boom. Preferably all main hoist, back stay cable, and luffing winches are mounted on said truss.

In a practical embodiment the back stay cable assembly comprises two groups of one or more back stay cable runs, the groups extending from the top end section of the back stay boom downwards in an inverted V-arrangement when seen in axial view of the upper deck, each group extending along an imaginary line crossing the level of the upper deck at a position alongside a longitudinal side of the flush cargo deck area and outside of said cargo deck area.

In an embodiment the vessel includes at least one multiple storied superstructure rising above the upper deck, said superstructure being structurally integral with the hull and having multiple levels housing at least crew quarters and possibly also a bridge, said superstructure being arranged along a longitudinal side of the flush cargo deck area, outside of said cargo deck area. In a preferred embodiment thereof the cargo deck area extends over the entire length of the hull of the vessel, so from the bow to the stern, e.g. allowing to transfer an object onto the cargo deck area via the bow when the vessel is docked with its bow against a quay, the shearleg crane being arranged at the stern of the vessel. In a preferred embodiment the vessel has ballast tanks and a ballast system to allow suitable ballasting of the vessel. In an embodiment the hull of the vessel is a dual draft hull having a ballast system with one or more ballast tanks in the hull to allow for controlled variation of the draft of the vessel. Herein the hull has a narrow lower section having first width over a first height from keel level to a widening level, and a top section, extending at least over a portion of the length of the hull, that has a larger width than the narrow lower section, extending from the widening level upwards, e.g. towards the upper deck level, wherein the ballast system is adapted to ballast the vessel to have a relatively shallow draft level in a transit mode, so that the wide top section is above water level, while the vessel is traveling, and to ballast the vessel to a relatively deep draft level in a lifting mode such that the widening level is below water level, at least when the vessel is substantially stationary and the shear leg crane is operated.

The invention also relates to a method for transporting and hoisting of one or more heavy and large objects, wherein use is made of a vessel according to the invention. The invention also relates to a method for construction of a ship, e.g. a FPSO ship, wherein one or more modules are to be installed on a hull of the ship, wherein use is made of a vessel according to the invention. In a preferred embodiment a module is placed on the cargo deck area, the vessel is sailed to a site where the module is to be placed on some other item (e.g. a hull of a ship under construction), the module is moved over the cargo deck area to its pick up position for the shearleg crane (e.g. therein passing generally underneath the shearleg crane pivot axis), the cargo deck area possibly being extended to accommodate the module at said position, the module being picked up by the shearleg crane and placed onto the item whereon the module is installed. In a practical embodiment the ship construction method involves the steps of:

- placing one or more modules on the cargo deck area of the vessel, e.g. at a construction yard, e.g. using one or more multiwheeled vehicles,

- sailing the vessel with the one or more modules to the location of the hull of the ship,

- arranging a module on the cargo deck at the pick up position for the shearleg crane of the vessel, e.g. by skidding said module to said position - generally passing underneath the shearleg crane,

- picking up the module from the cargo deck with the shearleg crane,

- bringing the module into an overboarded position above the desired position of the module on the ship under construction, and lowering the module onto said position. When use is made of a vessel including a deck extension device for temporarily extending the cargo deck area beyond the respective overboarding end of the vessels hull, the method preferably comprises the additional steps of:

- extending the cargo deck by providing said deck extension device in operative position prior to bringing the module in its pick up position for the shearleg crane,

- bringing the module in its pick up position, said module then being at least partly supported by said deck extension device,

- removing or retracting the deck extension device from its operative position after the module has been picked up by the shearleg crane, thereby allowing to bring the vessel with its respective side closer to the hull of the ship under construction than with the deck extension device present.

The invention will now be explained with reference to the drawings. In the drawings:

fig. 1 shows schematically in side view an example of a vessel according to the invention during the installation of a large and heavy object on a hull of a ship,

fig. 2 the vessel of figure 1 from the stern with the cargo deck extension device omitted for clarity,

fig. 3 in a view on the bow the hull with crew accommodation and bridge at the bow as well as the outline of the back stay boom,

fig. 4 the vessel of figure 1 in top view,

fig. 5 the stern portion of the vessel of figure 1 with the large and heavy object suspended from the shearleg crane above the cargo deck extension device in deployed mode, fig. 6 illustrates the operation of an example of the cargo deck extension device at the overboarding end of the vessel.

With reference to the figures now a shear leg crane and transportation vessel 1 for handling of one or more heavy and large objects will be discussed, as well as preferred and optional features thereof.

The vessel 1 has a floating hull 2, here a monohull, with a bow and a stern.

As is possible the hull 2 is of the dual draft type wherein the hull of the vessel has a ballast system with one or more ballast tanks in the hull (not shown) to allow for controlled variation of the draft of the vessel. As can best be seen in figures 2 and 4 in this example the hull has a narrow lower section 2a having first width over a first height from keel level to a widening level, and a top section 2b, extending at least over a portion of the length of the hull, that has a larger width than the narrow lower section, extending from the widening level upwards, e.g. towards the upper deck level. The ballast system is adapted to ballast the vessel to have a relatively shallow draft level in a transit mode, so that the wide top section is above water level, while the vessel is traveling, and to ballast the vessel to a relatively deep draft level in a lifting mode such that the widening level is below water level, at least when the vessel is substantially stationary and the shear leg crane is operated.

The vessel is equipped, here at the bow of the vessel, with a multistoried superstructure 5 housing crew accommodation and the bridge.

The vessel 1 is provided with a propulsion system, here including azimuthable thrusters 6, allowing the vessel to sail across the sea, ocean at a transit speed.

The vessel 1 is equipped - here near the stern of the hull - with a single non-revolving shearleg crane 10 with a single shearleg jib 11 having two rigidly interconnected jib legs that are each pivotally connected at a lower end thereof via a horizontal axis pivot to an associated jib leg stand 12 that is structurally integrated with the hull of the vessel.

In the embodiment shown here, the lower ends of the jib are not directly connected to the jib stands 12, but are connected to the neighboring legs of the back stay boom 60, which are in turn each pivotable connected via horizontal axis 17 pivot to an associated jib leg stand 12, so as to provide an indirect connection between the jib and the stand, also within the scope of the invention. A direct pivotal connection of the jib to the stand 12 is also possible if desired.

The shearleg crane 10 has a main hoist assembly including at least one main hook 13, one or more main hoist cables 14 and one or more main hoist winches 15. The main hooks are suspended by said one or more main hoist cables from the shear leg jib 1 1.

The shearleg crane includes a luffing assembly associated with the shearleg jib 11 and comprising one or more luffing cables and one or more luffing winches, the luffing assembly and the jib being embodied such that the shearleg jib has an angular operating range for performing hoisting activities with the main hoist assembly. In figure 1 the jib is shown in multiple operating positions, including an overboarding position and a position where the crane 10 picks up a large and heavy object from the cargo deck area of the vessel.

In the overboarding position the at least one main hook 13 is operable to perform hoisting operations with a heavy object suspended therefrom with said at least one main hook - when seen in vertical projection - in a position outside the stern of the hull.

The exemplary embodiment of the luffing assembly will be discussed in more detail below.

The vessel has an upper deck including an elongated flush cargo deck area 20. The cargo deck area 20 is adapted to receive and support thereon one or more heavy and large objects 25, 26. In the example shown here a large pipelaying reel 25, e.g. weighing more than 1000 tonnes when loaded with pipeline to be laid on the seabed, is shown, as well as modules 26. These modules 26 are shown to illustrate as an example the size of objects that can be arranged on the cargo deck area and moved towards the stern end of said deck area in order to be picked up by the crane 10.

The cargo deck area 20 is planar to allow for unimpeded movement of a heavy and large object over said cargo deck area, e.g. by skidding. The cargo deck area has opposed longitudinal sides as well as opposed axial ends, here one axial end coinciding with the stern side of the hull, the other axial end being located near the rear side of the superstructure 5.

The jib leg stands 12 are each located along a longitudinal side of the flush cargo deck area 20, outside of said cargo deck area 20, and each rise above the upper deck. The shearleg jib 1 1 is pivotal about a horizontal axis 17 that is transverse to the upper deck and raised above the flush deck area 20. This horizontal axis is spaced - when seen in vertical projection - from each of the opposed axial ends of the flush cargo deck area 20, here - closer to the stern than to the bow end of the area 20 as the overboarding takes place at the stern.

The operating range of the shear leg crane 10 includes a deck lift position, shown in figure 1 as the near vertical positions of the jib 1 1 , wherein the shear leg jib 1 1 is vertical or near vertical and wherein the at least one main hook 13 is operable to perform hoisting operations with a heavy and large object (here reel 25) suspended therefrom with said at least one main hook - when seen in vertical projection - in a position above the flush cargo deck area 20. As explained in the introduction, the pivot axis 17 is preferably located not too far from the overboarding end of the hull, in order to obtain an attractive overboarding reach of the crane. In order to avoid that this places an undesirable limitation on the size (in particular in longitudinal direction) of the object that can be picked up from the area 20 by the crane 10, this vessel is equipped with a cargo deck area extension device 30 that is adapted to extend the flush cargo deck area 20 at the side where the crane is able to pick up an heavy object from the cargo deck area.

In general the cargo deck area extension device 30 includes one or more mobile deck extension elements, that are movable or displaceable between a stored or retracted position on the one hand and an operative position on the other hand, wherein - in the operative position - the one or more mobile deck extension elements form one or more cargo deck area portions that are flush with the cargo deck area. The cargo deck extension device forms a load bearing cargo deck extension, so that the weight of a heavy and large object handled by the vessel can at least be partly supported by the extension device. For example the extension device is able to support a load thereon of at least 100 tonnes (in the centre of the extension device).

In the embodiment shown in the figures it is envisaged that the mobile deck extension elements are pivotal deck elements 31 , that are hinged to the hull 2 about a horizontal axis 32 at an axial end, here the stern, of the hull and which in operative position form an extension of the cargo deck area. This can best be seen in figures 5 and 6, where arrow A indicates the operative position. In the embodiment shown the deck elements are foldable, here two deck element parts 31 a, 31 b are interconnected at a hinge line 33 parallel to the axis 32.

Operation of the pivotal deck elements 31 here is depicted as embodied with one or more cables 35 and one or more associated winches 36.

In figure 6 it is shown that the folding of the deck elements 31 reduces their size which is advantageous for (temporary) storage. It is illustrated that the deck elements could be stored in vertically downward position, extending along the stern of the hull, or in vertically raised position. Other positions are also possible.

In a non-shown embodiment the deck extension elements comprises removable or axially displaceable cantilever elements that in operative position extend as cantilevers from the hull. The shear leg crane 10 is embodied such that a heavy and large object, e.g. module 26, having a width and a height of 15 x 15 meters can pass slidingly, e.g. skidded, over the flush cargo deck area 20 underneath the shear leg crane 10 in an operating position of the shear leg crane. In the shown embodiment the modules 26 are shown as cubic members having a width, height and length of 21 meters. It is noted that in reality modules will not have a cubic shape, and can have in fact vastly different shapes. The cubes are only shown to outline the size of modules that one can handle with the depicted vessel.

As is preferred there is no transverse girder extending horizontally between the jib legs stands, so each stand 12 is erected as a solitary column from the hull of the vessel. Any transverse girder would diminish the height of objects that can be passed over the cargo deck area 20 towards the stern.

In this embodiment, the stands 12 are erected above the wider portion of the dual draft type hull of the vessel.

As is preferred, especially in combination with free-standing jib leg stands 12, the jib legs 11 are rigidly interconnected by a traverse beam 28 near the lower end of the legs, said transverse beam extending at an elevated position above the cargo deck area, e.g. at least 15 meters, here more than 25 meters with the jib 11 in near vertical position, so as to have an unobstructed passage for said one or more objects 26 underneath said transverse beam.

As is preferred the jib stands 12 have such a height that the horizontal axis of the shearleg jib extends at least 10 meters above the cargo deck area, here more than 20 meters. This is advantageous when the object handled by the crane 10 has to be placed on a rather high item, such as ships hull 50.

The luffing assembly that establishes the angular motion and position of the jib 11 here includes a pivotal back stay boom 60, here embodied as an A-frame with two rigidly interconnected back stay boom legs 61 and a transverse truss 62 near the lower end of each leg 61. Each back stay boom leg 61 has its lower end pivotally connected to an associated jib leg stand 12 carrying the pivot of a leg of the shear leg jib 1 1. In figure 3 these stands 12 are not shown. In figure 1 the back stay boom 60 is shown in two positions.

The back stay boom 60 is pivotally connected to the jib stands 12 and pivotal about an axis that is parallel to the pivot axis of the shear leg jib 11. A back stay cable assembly is provided with one or more back stay cables 62 and one or more back stay cable winches 63. The back stay cable assembly connects the back stay boom 60 to the hull of the vessel 1. The luffing assembly further includes one or more luffing cables 70 and one or more luffing cable winches 71 The luffing cables 70 extend between a top end of the back stay boom 60 and the shear leg jib 11.

As can be seen in this embodiment of the boom 60 the top ends of the legs 61 converge into a top end section 64 of the back stay boom 60.

The transverse truss 68 not only serves to connect the legs 61 near their lower end, but also serves as a support for the one or more main hoist winches of the shearleg crane which are mounted on said transverse truss. This provides for an attractive layout of the cables and also allows to keep the upper deck level clear from the large winches that are commonly employed as main hoist winches. As is preferred, these winches have a drum onto which the cable is wound; preferably two main hoist winches are employed.

In the embodiment shown here, the back stay cable assembly comprises two groups of one or more back stay cable 62 runs, the groups extending from the top end section 64 of the back stay boom 60 downwards in an inverted V-arrangement when seen in axial view of the upper deck. Each group extends along an imaginary line crossing the level of the upper deck at a position alongside a longitudinal side of the flush cargo deck area and outside of said cargo deck area. As an optional feature, each back stay cable group 62 does not extend to the level of the upper deck, but is connected to the upper end of a rigid beam 65 that pivotally connected to the hull of the vessel at its lower end, outside the deck area 20. As is shown in figure 1 , this beam can be brought in a more or less horizontal position. This position is assumed in the process of lowering the crane 10, e.g. for passing a bridge.

In the process of reducing the height of the crane 10 for the passage of a bridge or the like it is envisaged that the jib is first brought into its near vertical position. The main hook 13 is then fastened to the hull 2 of the vessel. In this situation, the back stay boom is lowered (pivoted forward), in which step - in this embodiment - the beam(s) 65 assume the more horizontal position. The beam 65 (or the lower end of the group of back stay cable runs 62) is then secured to the hull, so that the back stay 60 is secured in its position. As an alternative, or in cooperation therewith, the backstay is secured in this position via a beam 80. With the backstay boom secured in its lowered position, the luffing assembly is operated to pivot the jib rearward, so that its effective height is reduced till it can pass below the bridge.

To ensure that the near vertical jib is stable in said position, it is envisaged that additional beams are provided in the crane. A removable linkage beam 80 (or pair of such beams 80) allows to connect the back stay boom 60 to the hull 2 in an operative position of the back stay boom (indicated with B in figure 1). A second beam 82 extends from the back stay boom 60 towards the jib 1 1 , here held in said position by a further beam 83 on the back stay boom. The stern end of the second beam 82 provides an abutment for the jib 1 1 in near vertical position.

It will be appreciated that the modules 26 can be loaded onto the cargo deck area 20 by the vessel 1 being more with its stern against a quay, and the modules 26 being moved onto the deck area 20.

When the modules are to be handled by the crane 10, a module can be placed in pick up position. In order to provide for a stable support of the module 26 prior to pick up by the crane, the deck extension device 30 is employed to lengthen the deck area at the

overboarding end of the vessel, here the stern.

The crane 10 can then pick up the module from the deck area 20, and lift it onto the item on which the module is to be installed.

Often it will be desirable to bring the vessel 1 with the lifted module 26 close to the item onto which the module is to be installed in order to have as much lifting capacity available. This can be done by removing or retracting the deck extension device, here by folding the deck elements downward as shown in figure 1. This operation can be performed once the module 26 is suspended from the crane 10. With the deck extension out of the way, the stern of the vessel 1 can be brought close to or against the item onto which the module is installed, as is shown in figure 1 for the hull 50.

The vessel 1 may advantageously be employed in a method for construction of a ship, e.g. a FPSO ship, wherein one or more modules 26 are to be installed on a hull of the ship. As is shown in figure 1 the vessel can also be used for other activities, e.g. for loading an unloading large pipelaying reels 25 from a pipelaying vessel, preferably said reel 25 having a skid frame allowing to skid the reel over the cargo deck area 20. In a ship construction, e.g. FPOS construction, method, the following steps may be followed:

- placing one or more modules 26 on the cargo deck area 20 of the vessel 1 , e.g. at a construction yard, e.g. using one or more multiwheeled vehicles,

- sailing the vessel 1 with the one or more modules 26 to the location of the hull of the ship,

- arranging a module 26 on the cargo deck at the pick up position for the shearleg crane of the vessel, e.g. by skidding said module to said position - generally passing underneath the shearleg crane,

- picking up the module 26 from the cargo deck with the shearleg crane,

- bringing the module 26 into an overboarded position above the desired position of the module on the ship under construction, and lowering the module onto said position.

The method, as is preferred, also involves the additional steps of:

- extending the cargo deck area 20 by providing said deck extension device 30 in operative position prior to bringing the module 26 in its pick up position for the shearleg crane,

- bringing the module 26 in its pick up position, said module then being at least partly supported by said deck extension device,

- removing or retracting the deck extension device 30 from its operative position after the module has been picked up by the shearleg crane, thereby allowing to bring the vessel with its respective side closer to the hull of the ship under construction than with the deck extension device present.

Reference numeral 90 in figure 1 indicates a crane operator cabin that is supported by the back stay boom 60. As is preferred this cabin also is equipped as a secondary bridge, allowing to maneuver the vessel from said cabin 90 as well during hoisting operations. From the figure 1 the skilled person will already appreciate that the shearleg crane can, if desired, be fitted with additional hoisting equipment, e.g. one or more auxiliary jibs to extent the reach of the jib, auxiliary hoisting hook(s) and associated winches, etc. as generally known in the art.