Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
  • B63B35/003—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for for transporting very large loads, e.g. offshore structure modules
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
  • B63B35/40—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for for transporting marine vessels
  • B63B35/42—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for for transporting marine vessels with adjustable draught
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B17/02—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto
  • E02B17/027—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto steel structures
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B2017/0039—Methods for placing the offshore structure
  • E02B2017/0047—Methods for placing the offshore structure using a barge
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B2017/0052—Removal or dismantling of offshore structures from their offshore location
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B2017/0056—Platforms with supporting legs
  • E02B2017/0069—Gravity structures
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
  • E02B2017/0056—Platforms with supporting legs
  • E02B2017/0073—Details of sea bottom engaging footing
  • E02B2017/0086—Large footings connecting several legs or serving as a reservoir for the storage of oil or gas

Definitions

• the invention relates to a combination of a heavy lift vessel and a floating appendage structure for the installation and/or removal of large offshore structures.
• the underside of a top side or module support frame is generally the preferred location where the topside should be engaged for an installation procedure or a removal procedure in one piece.
• the underside of an installed topside on a jacket is generally positioned quite high above the water level in order to keep the topside out of reach of the waves in case of a storm.
• the preferred height of a topside which is to be scrapped is quite low, so the workers can easily and safely reach the topside. Therefore, at some point in time - preferably as soon as possible - it is desired to lower the topside during a removal operation.
• the desire to lower the topside also applies when a topside is scrapped directly from a removal vessel or barge.
• the same may apply, but in an opposite sequence. It may be preferable to build the topside at a low location and to install the topside quite high on the jacket.
• the Pioneering Spirit is not capable of varying its height in order to change the level of the topside, or only to a very limited extent.
• MPU heavy Heavy Lifter of MPU Offshore Lift ASA is a purpose built vessel which was only intended for the lift of (large) offshore platforms. Although fabrication had started, this was halted at an early stage and the project was eventually completely stopped. In general, lifting operations of heavy structures offshore are quite rare and these vessels remain idle for a large part of the time. This results in a need to earn back a large initial investment in a limited number of offshore operations, driving up the costs. Also, most designs require accommodation, propulsion and other equipment to be incorporated in the single purpose vessel. This further increases the initial investment.
• Appendages also called floating appendage structures
• W00160688A1 uses a combination of a semi- submersible vessel and an floating appendage structure which are coupled to one another.
• the floating appendage structure has a U-shape, when seen in top view.
• the GM lifter is considered to form the closest prior art for the present invention.
• the coupling between the (main) semi-submersible vessel and the floating appendage structure comprises a right and a left connection at deck level and a right and left connection at the level of the floater (and possibly over the complete height).
• a drawback of this solution is that the coupling between the floating appendage structure and the heavy lift vessel is put under heavy loads during operation. These large environmental loads (mainly hogging and sagging) will result in large bending moments in the combination. These bending moments need to be carried by the coupling.
• a further disadvantage of the GM-Lift Decommissioning and Installation Vessel is that a transfer operation of a topside from the GM-Lift Decommissioning and Installation Vessel to a barge or vice versa is quite difficult. This is related to the U-shape, which prevents a barge from traversing the GM-Lift Decommissioning and Installation Vessel.
• Appendage structures are also known in pipe-laying vessels, such as those disclosed in US3924415A and US3854297A.
• an appendage is disclosed which is hingedly attached to a pipe-laying vessel. The appendage can be partly sunk, to change its orientation with respect to the vessel. This provides a gradual transition for a pipe that is payed out from the vessel.
• an appendage structure is disclosed which comprises two parts, one of which is suspended from an A-frame and is hingedly attached to a vessel, and one part which has a variable buoyancy and is hingedly attached to the other part.
• the structure e.g. the topside
• the lifting vessel For a removal operation, the topside is typically transferred from the lifting vessel to a barge.
• All of the proposed solutions above display a restricted access of a barge underneath the structure which is lifted by the lifting vessel. This prevents the structure from being positioned in the most favourable position on the barge (lengthwise): centrally where the centre of buoyancy relatively lines up with the platform's centre of gravity as to minimise ballasting and thus maximise barge capacity.
• the load needs to be positioned eccentrically on the barge, i.e. near the front end or rear end of the barge. This creates large longitudinal bending moments on the vessel or barge.
• the eccentric position necessitates the use of large barges or purpose-built barges with large section moduli and resulting large barge depth to withstand the loads exerted.
• the invention provides a combination of a heavy lift vessel and an floating appendage structure which are interconnected by a hinge having a horizontal hinge axis, wherein:
• the heavy lift vessel comprises:
• the heavy lift vessel is configured to carry out heavy lift operations by itself, i.e. without the floating appendage structure
• the floating appendage structure is configured to lift a heavy structure at sea and comprises:
• the heavy lift vessel and the floating appendage structure are interconnected via the hinge, wherein the hinge allows a rotation of the floating appendage structure relative to the heavy lift vessel about the hinge axis, and
• a crane line suspension point of the at least one crane boom is positioned above the floating appendage structure, wherein the at least one crane is connected to the floating appendage structure, wherein at least one first crane line extends from the first crane line connector to the crane line suspension point of the at least one crane, wherein the floating appendage structure is a semi-submersible vessel, comprising:
• the combination comprises a passageway between the columns of the floating appendage structure and the heavy lift vessel or between the columns of the floating appendage structure
• passageway is constructed to position a barge, or substructure in said passageway between said columns when said columns intersect the waterline for:
• the combination according to the invention provides the capability of lifting operations of very heavy loads for relatively low capital costs, both CAPEX and OPEX. Also, use can be made of an already existing heavy lift vessel which only needs to be converted to a limited extent by adding a part of a hinge to the heavy lift vessel. A functionality similar to that of the bow section of the Pioneering Spirit can be achieved and possibly superseded by a suitable vessel by appending the floating appendage structure to said vessel. This provides great flexibility and a significant cost reduction when compared to the Pioneering Spirit and other vessels of similar functionality.
• a floating appendage structure in the form of a semi- submersible vessel was found to provide excellent characteristics during transfer operations at sea and in short transit. When ballasted to a draught in which the columns are in the water line, the floating appendage structure displays very calm behaviour.
• the combination comprises a passageway between the columns of the floating appendage structure and the heavy lift vessel or between the columns of the floating appendage structure.
• Providing a passageway allows favourable positioning of the floating appendage structure and makes float over operations for removal of topsides and other structures and installation of topside and other structures relatively easy.
• the passageway is configured for positioning:
• the at least one crane line is under pretension and exerts an upward force on the floating appendage structure, wherein the crane line under pretension limits the freedom of movement of the floating appendage structure relative to the heavy lift vessel.
• the pretension causes the heavy lift vessel and the floating appendage structure to move in tandem, with motion characteristics resembling the motion characteristics of a single rigid vessel.
• motion characteristics resembling the motion characteristics of a single rigid vessel.
• the heavy lift vessel comprises:
• floating appendage structure comprises:
• a first crane line connector which is positioned on a first side of the hull of the floating appendage structure
• first crane line is connected to the crane line suspension point of the first crane and to the first crane line connector and a second crane line is connected to the crane line suspension point of the second crane and the second crane line connector.
• first crane and the second crane provide added stability and rigidity to the overall combination.
• the first crane is positioned on the right side of the heavy lift vessel and the first crane line connector is positioned on a right side of the floating appendage structure
• the second crane is positioned on the left side of the heavy lift vessel and the second crane line connector is positioned on a left side of the floating appendage structure.
• the first and second crane when seen in top view define a crane axis, wherein the crane axis extends parallel to the hinge axis.
• the first and second crane when seen in top view are positioned on a same side or end of the heavy lift vessel as the vessel hinge part, said side or end being the right side, the left side the bow or the stern of the heavy lift vessel.
• the vessel hinge assembly comprises a first vessel hinge part and a second vessel hinge part which are positioned at a distance from one another, and wherein the appendage hinge assembly comprises a first appendage hinge part associated with the first vessel hinge part and a second appendage hinge part associated with the first vessel hinge part .
• the heavy lift vessel is a semi-submersible vessel, comprising:
• floaters in particular a right floater and a left floater
• ballasting system for varying the draught of the heavy lift vessel.
• Heavy lift vessels in the form of a semisubmersible vessel have the advantage of being less sensitive to waves when the columns are positioned in the water line.
• the columns have a relatively small water piercing surface area, which results in very calm behavior.
• the floating appendage structure when seen in top view the floating appendage structure has a right floater and a left floater. This has the benefit of low drag forces during transit mode.
• the at least one crane line in particular the first crane line and the second crane line, extend under an angle of less than 35 degrees to the vertical, in particular less than 20 degrees. In this way, horizontal forces between the heavy lift vessel and the floating appendage structure and the offlead load on the crane are limited.
• first vessel hinge part is connected to a first column of the heavy lift vessel and the second vessel hinge part is connected to a second, different column of the heavy lift vessel. It was found that this has the benefit of a very strong and rigid hinge.
• first vessel hinge part and the second vessel hinge part are connected to respectively a first side of the first column and to a second side of the second column, wherein the first side and second side face one another.
• the floating appendage structure when seen in top view, has a U- shape, H-shape or W-shape, the U-shape, H-shape, extended H-shape or W-shape having a right elongate part and a left elongate part and a cross-connection, the W-shape or extended H-shape further having an additional support element.
• the additional support element may be attached to a central floater of the floating appendage structure or to a transverse structure between the floaters.
• the floating appendage structure comprises an opening between the floaters at one end, and a transverse structure between the floaters at the opposite end, wherein the transverse structure is located higher than the floaters but lower than the upper ends of the columns of the floating appendage structure, and in particular about halfway the height of the columns of the floating appendage structure.
• the columns of the floating appendage structure define a passageway which traverses the floating appendage structure.
• the passageway may extend between a row of right columns and a row of left columns of the appendage structure.
• the passageway may extend in a longitudinal direction of the floating appendage structure.
• the passageway may in top view extend longitudinally on either side of a longitudinal midplane of the floating appendage structure.
• the passageway may extend from a first opening located between a front right column and a front left column of the floating appendage structure and a second opening located between a rear right column and a rear left column of the floating appendage structure.
• a barge or combination of barges can move completely through said passageway, thereby traversing the floating appendage structure when the floating appendage structure is ballasted at a deep draught.
• the barge or combination of barges cannot move completely through said passageway, but only enter the passageway from one end of the floating appendage structure. Entry into the passageway from the other side may be blocked by the transverse structure, for example because the transverse structure is positioned just below, just above or at the level of the water line under any or all draught conditions of the floating appendage structure. In other words, the passageway may have a dead end in some embodiments.
• the passageway extends in the longitudinal direction of the floating appendage structure and makes it easy to position a topside or other heavy structure centrally on the barge.
• the barge can travel into the passageway and be positioned with its center of buoyancy directly underneath the center of gravity of the topside.
• the vessel hinge assembly comprises a first hole and a second hole which are aligned, wherein the appendage hinge assembly comprises a first pin which is inserted in the first hole and a second pin which is inserted in the second hole. It was found that this type of hinge is very strong and reliable, which is essential for this application.
• first pin and second pin are rigidly interconnected by a beam or truss construction.
• first vessel hinge part and the second vessel hinge part each comprise a flat plate which positioned with one of the main faces thereof against a column and welded to a column at least at the circumference thereof, wherein the plate comprises the hole.
• the appendage hinge assembly is connected to the rest of the floating appendage structure via an open truss frame. This further limits the water piercing surface of the floating appendage structure when positioned with the columns in the water line. This further reduces motions of the floating appendage structure as a result of waves.
• the vessel hinge assembly is provided above the floater of the heavy lift vessel. This reduces drag, and make it possible to position the hinge above the floaters of the floating appendage structure.
• the vessel hinge assembly is provided at the level of the columns of the heavy lift vessel.
• the vessel hinge assembly is provided at the level of the deck structure of the heavy lift vessel.
• the floating appendage structure does not comprise: a propulsion system, a living quarters or a helicopter deck. In this way the floating appendage structure remains cost-effective.
• the columns of the floating appendage structure have a smaller water piercing surface than the columns of the heavy lift vessel. This reduces the motions of the floating appendage structure.
• one or more columns of the floating appendage structure are formed entirely or partially as a truss structure.
• one or more columns of the floating appendage structure comprise an upper part having a greater water piercing surface than a lower part of the column, wherein in particular the upper part is formed as a closed box and the lower part is formed as a truss structure.
• the upper ends of the columns of the floating appendage structure are interconnected by one or more beams which extend lengthwise of the floating appendage structure.
• first crane line connector and the second crane line connector define a connector axis which extends parallel to the hinge axis and in particular parallel to the crane axis.
• the at least one crane line connector when seen in top view is positioned at a distance from the hinge axis which is greater than 35 percent, in particular greater than 45 percent of a distance from the hinge axis to the opposite side or end of the floating appendage structure.
• the vessel hinge assembly is located at the bow or stern of the heavy lift vessel, and wherein the hinge axis extends orthogonal to a main longitudinal direction of the heavy lift vessel.
• the vessel hinge assembly is located at the right or left side of the heavy lift vessel and wherein the hinge axis extends parallel to a main longitudinal direction of the heavy lift vessel.
• the floating appendage structure comprises a plurality of cross- beams which rest on the upper end of the columns or on longitudinal beams which rest on the columns of the floating appendage structure, wherein the cross-beams extend over the open lifting area from a right side of the floating appendage structure to a left side of the floating appendage structure.
• the floating appendage structure comprises a hydraulic lift system configured to raise the cross-beams relative to the at least one hull of the floating appendage structure.
• the present invention also relates to a method of lifting a heavy structure at sea, the method comprising:
• the at least one crane line under pretension limits the freedom of movement of the floating appendage structure relative to the heavy lift vessel, wherein the at least one crane line under pretension causes the heavy lift vessel and the floating appendage structure to move in tandem, with motion characteristics resembling the motion characteristics of a single rigid vessel.
• the method provides substantially the same advantages as the combination.
• At least one barge when seen in top view at least one barge is positioned in a passageway between the columns of the floating appendage structure and the heavy lift vessel or between the columns of the floating appendage structure, in particular between the right columns and the left columns of the floating appendage structure under the heavy structure, and wherein the heavy structure is transferred from the barge onto the floating appendage structure or from the floating appendage structure to the barge.
• a topside is lifted from a jacket or other substructure by positioning a U-shaped, H-shaped, extended H-shaped or W-shaped part of the floating appendage structure around the jacket or other substructure and by subsequently deballasting the heavy lift vessel and the floating appendage structure together, thereby lifting the topside from the jacket or jacket, or
• a topside is installed onto a jacket by carrying the topside with the floating appendage structure and by positioning the U-shaped, H-shaped, extended H- shaped or W-shaped part of the floating appendage structure around the jacket or other substructure, and subsequently ballasting the heavy lift vessel and the floating appendage structure, thereby lowering the heavy lift vessel, floating appendage structure and the topside and placing the topside onto the jacket or other substructure.
• the floating appendage structure comprises a hydraulic lift system configured to raise the cross-beams relative to the at least one hull of the floating appendage structure, wherein for making the initial contact between the floating appendage structure and the heavy structure which is to be lifted the hydraulic system raises the cross-beams relative to the hull.
• a topside or other heavy structure is transferred from a barge to the floating appendage structure, and wherein:
• topside or other heavy structure is positioned centrally on the barge, o the floating appendage structure is ballasted to a deep draught,
• the barge including the topside or other heavy structure is positioned in the U- shaped, H-shaped, extended H-shaped or W-shaped part of the floating appendage structure, and
• topside or other heavy structure is transferred from the floating appendage structure to at least one barge or vessel, wherein: o the topside or other heavy structure is positioned on the floating appendage structure,
• the floating appendage structure including the topside or other heavy structure is pre-ballasted to a deeper draught,
• the floating appendage structure is ballasted, thereby increasing the draught of the floating appendage structure, wherein the floating appendage structure is lowered and places the topside or other heavy structure on the barge.
• the method comprises the subsequent steps of :
• the method comprises the steps of:
• the at least one crane line under pretension causes the heavy lift vessel and the floating appendage structure to move in tandem, with motion characteristics resembling the motion characteristics of a single rigid vessel
• floating appendage structure is connected to the jacket, gravity based structure or other substructure
• the jacket, gravity based structure or other substructure is raised by deballasting the heavy lift vessel and the floating appendage structure together, thereby raising the jacket, gravity based structure or other substructure, or the jacket, gravity based structure or other substructure is lowered by ballasting the heavy lift vessel and the floating appendage structure together, thereby lowering the jacket, gravity based structure or other substructure.
• the present invention further relates to a floating appendage structure configured to lift a heavy structure at sea, the floating appendage structure comprising:
• At least one appendage hinge assembly configured to be connected to a vessel hinge part of a heavy lift vessel and to form a hinge therewith
• At least one crane line connector mounted to the hull
• the floating appendage structure is configured to be interconnected via the hinge to the heavy lift vessel, wherein the hinge allows a rotation of the floating appendage structure relative to the heavy lift vessel about the hinge axis,
• floating appendage structure is a semi-submersible vessel, comprising:
• the combination comprises a passageway between the columns of the floating appendage structure and the heavy lift vessel or between the columns of the floating appendage structure
• passageway is constructed to position a barge or substructure in said passageway between said columns when said columns intersect the waterline for:
• Figure 1 shows an isometric view of the combination according to the invention.
• Figure 2 shows a top view of the combination according to the invention.
• Figure 3 shows a side view of the combination according to the invention.
• Figure 4 shows a rear or front view of the combination according to the invention.
• Figure 5 shows an isometric view of the combination according to the invention carrying a topside.
• Figure 6 shows a top view of the combination according to the invention carrying a topside.
• Figure 7 shows a side view of the combination according to the invention carrying a topside.
• Figure 8 shows a front view of the combination according to the invention carrying a topside.
• Figure 9A shows an isometric view of the floating appendage structure.
• Figure 9B shows a further isometric view of the floating appendage structure.
• Figure 9A shows yet a further isometric view of the floating appendage structure.
• Figure 10A shows an isometric view of the hinge.
• Figure 10B shows they another isometric view of the hinge, with the rest of the heavy lift vessel and the appendage vessel left out.
• Figure 11 shows a top view of the hinge.
• Figure 12A shows an isometric view of a part of the hinge.
• Figure 12B shows another isometric view of a part of the hinge.
• Figure 12C shows a top view of a part of the hinge.
• Figure 13A shows an isometric view of the installation or removal of a topside from a substructure.
• Figure 13B shows an isometric view of the uncoupled floating appendage structure carrying a topside.
• Figure 14 shows a front view of the uncoupled floating appendage structure carrying a topside.
• Figure 15 shows a side view of the uncoupled floating appendage structure carrying a topside.
• Figure 16 shows a top view of the uncoupled floating appendage structure carrying a topside.
• Figure 17 shows the same view as figure 13B, but with two barges positioned under the topside and under the cross-beams.
• Figure 18 shows a side view associated with figure 17.
• Figure 19 shows a top view associated with figure 17 and 18.
• Figure 20 shows a front view associated with figure 17 - 19.
• Figure 21 shows an isometric view of the floating appendage structure with two barges.
• Figure 22 shows a front view of the floating appendage structure with two barges.
• Figure 23 shows a side view of the floating appendage structure with two barges.
• Figure 24A shows a top view of another embodiment of the invention.
• Figure 24B shows a top view of yet another embodiment of the invention.
• Figure 25 shows a front view of the embodiment of figure 24.
• Figure 26 shows a top view of yet another embodiment of the invention
• Figure 27 shows a top view of again another embodiment of the invention.
• Figure 28 shows a top view of an embodiment of the invention wherein the floating appendage structure has a W-shape.
• Figure 29 shows a top view of an embodiment of the invention wherein the floating appendage structure has a J-shape.
• Figure 30A shows the floating appendage structure supporting a gravity based structure.
• Figure 30B shows the floating appendage structure supporting part of a jacket.
• Figure 30C shows a detail view of the attachment of the jacket to the floating appendage structure.
• a combination 10 of a heavy lift vessel 12 and a floating appendage structure 14 is provided.
• the heavy lift vessel 12 and the floating appendage structure 14 are interconnected via a hinge which will be discussed further below.
• the heavy lift vessel 12 is a semi-submersible vessel, comprising one or more floaters, in particular a right floater 56A and a left floater 56B and a deck structure 57.
• the heavy lift vessel 12 comprises multiple columns 58 which extend upward over a vertical distance from the at least one floater and which interconnect the floaters with the deck structure.
• the columns 58 are arranged in a right row 61 A and a left row 61 B.
• the columns define open areas 59 between the columns.
• the columns have a lower water piercing surface than the combined floaters.
• the heavy lift vessel comprises a ballasting system for varying the draught of the heavy lift vessel. Such ballasting systems are known per se for semi-submersible vessels.
• the heavy lift vessel 12 comprises at least one crane 15.
• the heavy lift vessel comprises two cranes, a first crane 15A and a second crane 15B.
• the second crane 15B is positioned at a distance from the first crane.
• the cranes have a rotatable turret which allows rotation of the crane about a respective vertical axis.
• Each crane 15A, 15B comprises a crane boom 20.
• the heavy lift vessel is configured to carry out heavy lift operations by itself, namely with the cranes 15A, 15B, and without the floating appendage structure 14.
• the heavy lift vessel comprises accommodation 31 , a helicopter deck 32, propulsion 33, and may comprise further equipment.
• the floating appendage structure 14 is configured to lift a heavy structure at sea and comprises a hull 22.
• the floating appendage structure 14 and in particular the hull 22 thereof may be of a semi-submersible type.
• the floating appendage structure 14 is a semi-submersible vessel, comprising one or more floaters, in this case a right floater 60A and a left floater 60B.
• the floating appendage structure 14 comprises multiple columns 62 which extend upward from the at least one floater over a vertical distance and define open areas 63 between the columns, and ballasting tanks which can be filled and emptied for varying the draught of the floating appendage structure.
• the left floater 60B of the appendage structure may be aligned or substantially aligned with the left floater 56B of the heavy lift vessel, and the right floater 60A of the appendage structure may be aligned or substantially aligned with the right floater 56A of the heavy lift vessel. This reduces drag in transit. If the heavy lift vessel is relatively wide, it also provides a relatively broad passageway 77, which is discussed in more detail below.
• the upper ends 90 of the columns 62 of the floating appendage structure are interconnected by one or more beams 92A, 92B which extend lengthwise of the floating appendage structure.
• the floating appendage structure does not have a“real” deck structure, because a central part is open for carrying out lifting operations.
• the pumps for the ballasting tanks and other equipment on board may be temporarily removable in order to lower the Capex.
• the columns 62 of the floating appendage structure 14 have a smaller water piercing surface than the columns of the heavy lift vessel. This improves the lift characteristics.
• the floating appendage structure 14 benefits from the stability of the heavy lift vessel when coupled to the heavy lift vessel.
• the floating appendage structure 14 does not comprise: a propulsion system, a living quarters or a helicopter deck.
• the floating appendage structure 14 relies on the heavy lift vessel for these aspects, which keeps the floating appendage structure 14 cost-effective
• the floating appendage structure 14 when seen in top view, has a U-shape having a right elongate part formed by the right floater and a left elongate part formed by the left floater and a cross-connection which will be discussed later.
• the floating appendage structure 14 may have an H-shape, extended H-shape or W-shape.
• the floating appendage structure comprises an opening 70 between the floaters at one end 72, and a transverse structure 74 between the floaters at the opposite end.
• the opening 70 is large enough such that a barge, jacket of gravity based structure fits through it.
• the floating appendage structure does not have a transverse connection at the level of the upper ends of the columns 62. This provides a passageway 77 for a barge to travel through when the floating appendage structure is ballasted at a deep draught.
• the floating appendage structure may also have a transverse connection at any level of the columns, such that the barge can only enter the passageway 77 from one side of the floating appendage structure.
• a jacket or gravity based structure can also be accommodated in the passageway.
• the floating appendage structure 14 comprises at least one crane line connector 24A, 24B is mounted to the hull 22.
• the first crane line connector 24A is positioned on a first side of the hull (in this case the right side) of the floating appendage structure and the second crane line connector 24B is positioned on a second side of the floating appendage structure (in this case the left side).
• the first crane line connector 24A and the second crane line connector 24B define a connector axis 93 which extends parallel to the hinge axis and in particular parallel to the crane axis 17, see fig. 2.
• the at least one crane line connector 24A, 24B is positioned at a first distance D1 from the hinge axis 45 which is greater than 35 percent, in particular greater than 45 percent, of a second distance D2 between the hinge axis 45 to the opposite end 95 of the floating appendage structure 14.
• One or more columns 62 of the floating appendage structure 14 may be formed entirely or partially as a truss structure.
• one or more columns 62 of the floating appendage structure 14 may comprise an upper part having a greater water piercing surface than a lower part of the column, wherein in particular the upper part is formed as a closed box and the lower part is formed as a truss structure.
• a crane line suspension point 26A, 26B of the at least one crane boom is positioned above the floating appendage structure.
• the at least one crane is connected to the floating appendage structure via at least one crane line 28A, 28B.
• Figure 1 - 4 show that each crane 15A, 15B is connected to the floating appendage structure via multiple crane lines.
• the at least one first crane line 28A extends from the first crane line connector 24A to the crane line suspension point 26A, of the first crane.
• the at least one second crane line 28B extends from the second crane line connector 24B to the crane line suspension point 26B of the second crane 15B.
• the at least one crane line in particular the first crane line 28A and the second crane line 28B, extend(s) under an angle a of less than 35 degrees to the vertical 19, in particular less than 20 degrees.
• the first crane 15A is positioned on the right side of the heavy lift vessel and the first crane line connector 24A is positioned on a right side of the floating appendage structure.
• the second crane 15B is positioned on the left side of the heavy lift vessel and the second crane line connector 24B is positioned on a left side of the floating appendage structure.
• first and second crane 15A, 15B When seen in top view the first and second crane 15A, 15B define a crane axis 17.
• the same combination 10 is shown, but this time carrying a topside 30.
• the combination 10 can lift a topside 30, but also other types of heavy structures, such as a jacket, a gravity based structure, a vessel, or another type of heavy structure which is to be lifted.
• the jacket or gravity based structure can be lifted from a seabed and also lowered onto a seabed.
• seabed in this context is to be interpreted broadly and can also be the bottom of a harbor, lakebed, concrete slab on which a jacket is positioned, or a template, fundament or other kind of support structure on a bottom of a body of water.
• the at least one crane line 28A, 28B is under pretension and exerts an upward force on the floating appendage structure 14.
• the crane line(s) 28A, 28B under pretension limits the freedom of movement of the floating appendage structure 14 relative to the heavy lift vessel 12.
• the pretension causes the heavy lift vessel and the floating appendage structure to move in tandem, with motion characteristics resembling the motion characteristics of a single rigid vessel.
• the skilled person will understand that in practice, some movement may occur between the floating appendage structure and the heavy lift vessel.
• the skilled person will understand that a single rigid vessel also deforms somewhat under the influence of the forces of wind and waves. Therefore, absolute rigidity does not occur.
• the floating appendage structure comprises a plurality of cross-beams 100 which rest on the upper ends 76 of the columns or on the longitudinal beams 92A, 92B which rest on the columns 62 of the floating appendage structure.
• the cross-beams 100 extend over the open lifting area 102 from a right side of the floating appendage structure to a left side of the floating appendage structure.
• the floating appendage structure comprises a hydraulic lift system 104 configured to raise the cross-beams 100, i.e. move the cross-beams up or down, relative to the at least one hull 22 (and relative to the columns 62) of the floating appendage structure. See the arrow 105 in figures 9B and 9C.
• the hinge 40 comprises a part on the side of the floating appendage structure 14. This part is called the appendage hinge assembly 42 and is configured to be connected to the vessel hinge assembly 44 and to form the hinge 40 therewith.
• the hinge 40 has a horizontal hinge axis 45.
• the heavy lift vessel 12 and the floating appendage structure 14 are interconnected via the hinge 40.
• the hinge allows a rotation of the floating appendage structure 14 relative to the heavy lift vessel 12 about the hinge axis 45.
• the crane axis 17 extends parallel to the hinge axis 45.
• the first and second crane 15A, 15B are positioned on a same end 48 of the heavy lift vessel 12 as the vessel hinge assembly 44, said end being the stern of the heavy lift vessel. It is noted that a heavy lift vessel often moves backwards, wherein the stern becomes the bow. For a heavy lift vessel, the stern and bow may be exchangeable.
• the hinge axis 45 extends orthogonal to a main longitudinal direction 99 of the heavy lift vessel.
• the vessel hinge assembly 44 comprises a first vessel hinge part 50A and a second vessel hinge part 50B which are positioned at a distance from one another.
• the first vessel hinge part 50A is connected to a first column 58.1 of the heavy lift vessel and the second vessel hinge part is connected to a second, different column 58.2 of the heavy lift vessel.
• the columns are numbered 58.1-58.8, the uneven columns 58.1 , 58.3, 58.5, 58.7 being located on the right side and the even columns 58.2, 58.4, 58.6, 58.8 being located on the left side.
• the first vessel hinge part 50A and the second vessel hinge part 50B are connected to respectively a first side 59.1 of the first column 58.1 and to a second side 59.2 of the second column 58.2, wherein the first side and second side face one another.
• the vessel hinge assembly 44 is provided above the floaters of the heavy lift vessel 12. In the shown embodiment, the vessel hinge assembly 44 is provided at the level of the columns 58 of the heavy lift vessel 12. Alternatively, the vessel hinge assembly 44 may be provided at the level of the deck structure of the heavy lift vessel.
• the appendage hinge assembly 42 comprises a first appendage hinge part 51 A associated with the first vessel hinge part 50A and a second appendage hinge part 51 B associated with the first vessel hinge part 50B.
• the transverse structure 74 may be located higher than the floaters but lower than the upper ends 76 of the columns 62 of the floating appendage structure, and in particular about halfway the height of the columns of the floating appendage structure. The transverse structure then restricts entry into the passageway 77 from one side of the floating appendage structure.
• the transverse structure 74 provides rigidity to the floating appendage structure and interconnects the floaters 60A, 60B.
• the transverse structure 74 also serves as a base frame which connects the appendage hinge assembly 42 to the floaters 60A, 60B.
• the transverse structure 74 may be located at the level of the floaters as indicated in the embodiment of figs. 4 and 8. However, this is not preferred, because at this level, the transverse structure 74 creates drag in transit mode. On the other hand, this allows a barge to enter into the passageway 77 from both sides of the floating appendage structure when it is ballasted to a deep draught.
• the vessel hinge assembly 44 comprises a first hole 80A and a second hole 80B which are aligned.
• the appendage hinge assembly 42 comprises a first pin 82A which is inserted in the first hole and a second pin 82B which is inserted in the second hole.
• the appendage hinge assembly 42 comprises a hydraulic system 47 (indicated in dashed lines in fig. 12B) for moving the pins 2A, 82B along the hinge axis from an inward to an outward position and vice versa as indicated with arrow 83. This allows coupling and uncoupling of the floating appendage structure. The inward position allows coupling and uncoupling. In the outward position of the pins, the floating appendage structure and the heavy lift vessel are coupled.
• the first pin 82A and second pin 82B are rigidly interconnected by a beam 85 or truss construction in order to take bending moments, notwithstanding the capability of inward and outward movement of the pins.
• the first vessel hinge part 50A and the second vessel hinge part 50B each comprise a flat plate 88A, 88B which is positioned with one of the main faces thereof against a column 58 and welded to a column at least at the circumference 89 thereof, wherein the plate comprises the hole 80.
• the appendage hinge assembly 42 is connected to the rest of the floating appendage structure via the transverse structure 74 which in this embodiment has the form of an open truss frame.
• the columns 62 of the floating appendage structure 14 define a passageway 77 which traverses the floating appendage structure.
• the passageway may extend between the row 61 A of right columns and the row 61 B of left columns of the appendage structure.
• the passageway may extend in a longitudinal direction of the floating appendage structure.
• the passageway may be located centrally and in top view extend longitudinally on either side of a longitudinal midplane of the floating appendage structure.
• the passageway 77 may have a width of at least 50 percent of the width of the appendage structure.
• the passageway may have a width of at least 50 percent of the width of the heavy lift vessel.
• the passageway may be at least 10 meters wide.
• the passageway extends from a first opening 78 located between a front right column 62.5 and a front left column 62.6 of the floating appendage structure 14 and a second opening 79 located between a rear right column 62.1 and a rear left column 62.2 of the floating appendage structure.
• a barge or combination of barges can move completely through said passageway, thereby traversing the floating appendage structure when the floating appendage structure is ballasted at a deep draught.
• the passageway may be blocked on one side by the heavy lift vessel.
• the presence of the passageway may be dependent on the draught of the appendage structure.
• the transverse structure 74 and/or the appendage hinge assembly 42 may be positioned just below, at or above the waterline and block the passageway on one side. Therefore, in that case in order for the passageway to be accessible from both ends of the floating appendage structure, the appendage structure will need to be positioned at a deep draught, allowing a barge to float over the appendage hinge assembly 42.
• the passageway When the appendage structure is at its deepest draught, the passageway may have a clearance (or draught) to the appendage hinge assembly 42 or to the transverse structure of several meters, e.g. 1-10 meters. Alternatively, the passageway may always be a dead end, irrespective of the draught of the floating appendage structure. A barge or combination of barges can then enter the passageway from one side of the floating appendage structure only.
• FIG. 24A, 24B, and 25 an alternative embodiment is shown, wherein the vessel hinge assembly is located at the right or left side of the heavy lift vessel and wherein the hinge axis 45 extends parallel to a main longitudinal direction 99 of the heavy lift vessel.
• the combination 10 moves in the transport direction T, but may also move in the opposite direction.
• the first and second crane 15A, 15B are positioned on a same side of the heavy lift vessel as the hinge axis, said side being the right side. Obviously the side can also be the left side.
• the opening 70 of the floating appendage structure is oriented in the same direction as the bow 110 of the heavy lift vessel.
• the heavy lift vessel comprises two cranes.
• the heavy lift vessel comprises a single crane 15.
• the appendage hinge assembly 42 of the hinge 40 is connected to the floater
• the floating appendage structure is asymmetric and has an L-shape instead of a U-shape, H-shape, extended H-shape or W-shape.
• the floating appendage structure has only a single floater. This embodiment may require two cranes 15A, 15B.
• the single crane 15 may also be used in a longitudinal configuration, i.e. wherein the crane 15 and the floating appendage structure 14 are positioned at the bow 110 or stern of the heavy lift vessel 12.
• the floating appendage structure has an additional support element (60C), yielding a W-shape.
• a floating appendage structure having an H- shape may also include an additional support element (60C), forming an extended H-shape comprising an H with an extension from the horizontal line connecting the two vertical lines of the H, with the additional support element (60C) forming the extension.
• a floating appendage structure comprising a single floater is shown, including an additional support element (60C).
• This embodiment has a J- shape.
• the passageway 77 is also present.
• the passageway is located between the floaters of the floating appendage structure from the opening 70 up to the additional support element 60C.
• the passageway is split in two passageway parts, with the two passageway parts located between a floater of the floating appendage structure and the additional support element (60C).
• the floating appendage structure is seen supporting a substructure, wherein the substructure is a gravity based structure 140 (fig. 30A) or a jacket 150 (fig. 30B).
• the gravity based structure is supported by cables 130 that are connected to the cross beams 100 and the substructure.
• the substructure is accommodated in the passageway 77, while part of the substructure extends below the floating appendage structure.
• the jacket may be supported in a similar way as the gravity based structure in fig. 30A, or by different means.
• portion in this context is obviously not intended to refer to a very small part of a jacket, gravity based structure or other substructure, such as a single beam. Instead, the term portion in this document is intended to mean a significant part of the substructure, more in particular a portion which is large enough to extend to underneath the floating appendage structure when carried by the floating appendage structure. This will be generally be a portion which is at least 20 percent, more in particular at least 30 percent, of the total gross tonnage of the substructure,.
• Fig. 30C shows a detail view of the attachment of the jacket 150 to the cross-beams 100.
• Collars 160 are welded to the legs 155 of the jacket.
• the collars 160 comprise castellation 165 to increase the weld length when compared to simple tubular collars.
• the cross-beams 100 comprise support elements 101 that engage with the collars 160 to support the jacket 150.
• the method of lifting a heavy structure 30 comprises:
• the at least one crane line under pretension limits the freedom of movement of the floating appendage structure relative to the heavy lift vessel.
• the at least one crane line 28 under pretension may cause the heavy lift vessel 12 and the floating appendage 14 structure to move in tandem, with motion characteristics resembling the motion characteristics of a single rigid vessel.
• At least one barge 120 is positioned between the right floater 60A and the left floater 60B of the floating appendage structure under the heavy structure and under the cross-beams 100.
• the heavy structure 30 or other heavy structure including the cross beams 100 is transferred from the barge 120 onto the floating appendage structure 14 or from the floating appendage structure 14 to the barge 120.
• the topside 30 or other heavy structure is positioned centrally on the barge. In top view the centre of gravity of the topside is close to the centre of buoyancy of the barge. This improves the stability and makes it possible to use a smaller, simpler and more cost-effective barge.
• the topside 30 When removing a topside, the topside 30 will initially be present on a jacket or other substructure at sea.
• the combination 10 travels to the location of the topside.
• the cross-beams 100 are installed on the floating appendage structure 14.
• the U-shaped part, H-shaped part, extended H-shaped part, L-shaped part, W-shaped part or J-shaped part of the floating appendage structure 14 is positioned around the jacket or other substructure. See figure 13A, where the substructure is a gravity based structure.
• the cross-beams engage the topside 30 and lift the topside 30 from the substructure.
• the floating appendage structure comprises a hydraulic lift system 104 configured to raise the cross-beams 100 relative to the at least one hull 22 of the floating appendage structure.
• the hydraulic system 104 raises the cross-beams 100 relative to the hull 22 for making the initial contact between the floating appendage structure and the heavy structure which is to be lifted.
• the hydraulic system 104 obviously havs a limited stroke.
• the ballast tanks are emptied, thereby raising the heavy lift vessel 12, the floating appendage structure and the topside 30 further.
• the combination 10 then travels to an inshore location.
• the conditions wave, wind
• the topside or other heavy structure is transferred from the floating appendage structure to at least one barge or vessel.
• the floating appendage structure 14 may be uncoupled from the heavy lift vessel 12. Next, the floating appendage structure 14 including the topside 30 or other heavy structure is ballasted to a shallow draught.
• One or more barges 120 is positioned under the topside and under the cross-beams 100. The barge can travel through the passageway 77.
• the floating appendage structure 14 is ballasted, thereby increasing the draught of the floating appendage structure.
• the floating appendage structure is lowered and the topside 30 or other heavy structure including the cross-beams 100 is placed on the barge 120. Scrapping may then take place from the barge. This obviates the need for an extra transfer operation, or the need for a reinforced quayside or the need for a deep draught quayside.
• the topside or other heavy structure may be transferred from the barge to a location on shore.
• the topside 30 When installing a topside 30, the topside 30 is generally built on shore and first transferred from shore to a barge 120.
• the topside 30 needs to be first transferred from the barge 120 to the floating appendage structure 14.
• the cross-beams are connected to the topside 30 on the barge.
• the cross-beams 100 may be moved underneath the topside 30 by a translational movement.
• the floating appendage structure 14 is ballasted to a deep draught. In this stage the floating appendage structure 14 may be uncoupled from the heavy lift vessel 12.
• the barge 120 including the topside 30 or other heavy structure is positioned in the U-shaped part of the floating appendage structure.
• the cross-beams 100 are already present and connected to the topside 30.
• the floating appendage structure 14 is deballasted, thereby decreasing the draught of the floating appendage structure, wherein the floating appendage structure lifts the topside or other heavy structure including the crossbeams 100 from the barge 120.
• the floating appendage structure 14 including the topside 30 is coupled to the heavy lift vessel 12 at the hinge 40.
• the combination 10 travels to the target location where a substructure, e.g. a jacket has previously been installed. During the travel, the crane lines 28 are pretensioned, thereby providing rigidity and stability to the floating appendage structure 14.
• the topside is transferred to the substructure.
• the topside 30 is installed onto a jacket by carrying the topside 30 with the floating appendage structure 14 and by positioning the U-shaped part, H-shaped part, extended H-shaped part, L-shaped part, W- shaped part or J-shaped part of the floating appendage structure 14 around the jacket or other substructure. See figure 13A.
• the heavy lift vessel 12 and the floating appendage structure 14 are ballasted, thereby lowering the heavy lift vessel, floating appendage structure 14 and the topside 30 and placing the topside onto the jacket or other substructure.
• cross-beams 100 are removed from the installed topside.
• the cross-beams may be withdrawn by a translational movement.
• the heavy lift vessel and floating appendage structure 14 then move away from the target location and travel back to an inshore location.
• the floating appendage structure After an installation of removal operation, the floating appendage structure is uncoupled at an inshore location, and the heavy lift vessel is directly ready to perform an entirely different operation on its own, without the floating appendage structure.
• the floating appendage structure can remain in an inshore location to wait for a next operation.
• the heavy lift vessel is only needed for the duration of the sailing and for the transfer operations.
• the floating appendage structure When removing a substructure such as a jacket 150 or a gravity based structure 140, the floating appendage structure is positioned such that the substructure is accommodated in the passageway 77.
• the substructure is connected to the cross-beams 100 by cables 130.
• de draught of the floating appendage structure may be subsequently reduced by deballasting.
• the cables 130 may be used to hoist the substructure by shortening their length between their attachment point 135 to the substructure and the cross-beams 100, for example by using winches mounted on the cross-beams or elsewhere on the floating appendage structure, or by using strandjacks.
• Installation of a substructure may be performed by positioning the floating appendage structure supporting the substructure over an intended installation location. Subsequently, the floating appendage structure may be ballasted to a deeper draught to lower the substructure onto the intended installation location. Additionally or alternatively to ballasting the floating appendage structure, the cables 130 may be used to lower the substructure by increasing their length between their attachment point 135 to the substructure and the cross-beams 100, for example by using winches mounted on the cross-beams or elsewhere on the floating appendage structure, or by using strandjacks.
• the heavy lift vessel will be capable of lift operations in excess of 15.000 mT. However, smaller sizes are in principle also possible.
• the columns of the heavy lift vessel may be closed. It is also possible that one or more of the columns of the heavy lift vessel are closed, whereas one or more other columns of the heavy lift vessel are open, and have a smaller water piercing surface.
• the columns of the heavy lift vessel may be embodied in the form of truss structures.
• the deck structure of the heavy lift vessel will typically be closed and may provide buoyancy.
• a deck structure with buoyancy can be combined with columns in the form of truss structures.
• a closed column combines both functionalities in a single structure. This potentially results in a weight saving, but is more difficult to tune/adapt for different
• the heavy lift vessel comprises:
• At least one crane (15; 15A.15B) comprising a crane boom (20), wherein the heavy lift vessel is configured to carry out heavy lift operations by itself, i.e. without the floating appendage structure, o at least one vessel hinge assembly (44),
• the floating appendage structure is configured to lift a heavy structure at sea and comprises:
• the heavy lift vessel and the floating appendage structure are interconnected via the hinge, wherein the hinge allows a rotation of the floating appendage structure relative to the heavy lift vessel about the hinge axis, and
• a crane line suspension point (26) of the at least one crane boom is positioned above the floating appendage structure, wherein the at least one crane is connected to the floating appendage structure, wherein at least one first crane line (28) extends from the first crane line connector to the crane line suspension point of the at least one crane.
• the at least one crane line is under pretension and exerts an upward force on the floating appendage structure
• the crane line under pretension limits the freedom of movement of the floating appendage structure relative to the heavy lift vessel.
• the pretension causes the heavy lift vessel and the floating appendage structure to move in tandem, with motion characteristics resembling the motion characteristics of a single rigid vessel.
• the heavy lift vessel comprises:
• floating appendage structure comprises:
• a first crane line connector which is positioned on a first side of the hull of the floating appendage structure
• a first crane line is connected to the crane line suspension point of the first crane and to the first crane line connector and a second crane line is connected to the crane line suspension point of the second crane and the second crane line connector.
• the vessel hinge assembly comprises a first vessel hinge part (50A) and a second vessel hinge part (50B) which are positioned at a distance from one another, and wherein the appendage hinge assembly comprises a first appendage hinge part associated with the first vessel hinge part and a second appendage hinge part associated with the second vessel hinge part.
• the heavy lift vessel is a semi-submersible vessel, comprising:
• floaters in particular a right floater (56A) and a left floater (56B), a deck structure (57),
• ballasting tanks which can be filled and emptied for varying the draught of the floating appendage structure.
• first vessel hinge part is connected to a first column of the heavy lift vessel and the second vessel hinge part is connected to a second, different column of the heavy lift vessel.
• first vessel hinge part (50A) and the second vessel hinge part (50B) are connected to respectively a first side of the first column and to a second side of the second column, wherein the first side and second side face one another.
• appendage structure when seen in top view, has a U-shape or H-shape, the U-shape or H-shape, having a right elongate part and a left elongate part and a cross- connection.
• appendage structure comprises an opening between the floaters at one end, and a transverse structure between the floaters at the opposite end, wherein the transverse structure is located higher than the floaters but lower than the upper ends of the columns of the floating appendage structure, and in particular about halfway the height of the columns of the floating appendage structure.
• the columns of the floating appendage structure define a passageway (77) which traverses the floating appendage structure, the passageway extending from a first opening located between a front right column and a front left column of the floating appendage structure and a second opening located between a rear right column and a rear left column of the floating appendage structure, wherein a barge or combination of barges can move completely through said passageway, thereby traversing the floating appendage structure when the floating appendage structure is ballasted at a deep draft.
• the vessel hinge assembly comprises a first hole (80A) and a second hole (80B) which are aligned
• the appendage hinge assembly comprises a first pin (82A) which is inserted in the first hole and a second pin (82B) which is inserted in the second hole.
• first vessel hinge part and the second vessel hinge part each comprise a flat plate which positioned with one of the main faces thereof against a column and welded to a column at least at the circumference thereof, wherein the plate comprises the hole .
• appendage structure does not comprise: a propulsion system, a living quarters or a helicopter deck.
• one or more columns of the floating appendage structure comprise an upper part having a greater water piercing surface than a lower part of the column, wherein in particular the upper part is formed as a closed box and the lower part is formed as a truss structure.
• first crane line connector and the second crane line connector define a connector axis which extends parallel to the hinge axis and in particular parallel to the crane axis.
• appendage structure comprises a plurality of cross-beams which rest on the upper end of the columns or on longitudinal beams which rest on the columns of the floating appendage structure, wherein the cross-beams extend over the open lifting area from a right side of the floating appendage structure to a left side of the floating appendage structure.
• appendage structure comprises a hydraulic lift system configured to raise the crossbeams relative to the at least one hull of the floating appendage structure.
• Method of lifting a heavy structure at sea comprising:
• the at least one crane line under pretension limits the freedom of movement of the floating appendage structure relative to the heavy lift vessel.
• a topside is lifted from a jacket or other substructure by positioning the U-shaped part of the floating appendage structure around the jacket or other substructure and by subsequently deballasting the heavy lift vessel and the floating appendage structure together, thereby lifting the topside from the jacket or other substructure, or
• topside is installed onto a jacket by carrying the topside with the floating
• appendage structure comprises a hydraulic lift system configured to raise the cross- beams relative to the at least one hull of the floating appendage structure, wherein for making the initial contact between the floating appendage structure and the heavy structure which is to be lifted the hydraulic system raises the cross-beams relative to the hull.
• a topside or other heavy structure is transferred from a barge to the floating appendage structure, and wherein:
• topside or other heavy structure is positioned centrally on the barge, o the floating appendage structure is ballasted to a deep draft,
• topside or other heavy structure is positioned on the floating appendage structure
• Floating appendage structure configured to lift a heavy structure at sea, the floating appendage structure comprising:
• At least one appendage hinge assembly configured to be connected to a vessel hinge part of a heavy lift vessel and to form a hinge therewith
• At least one crane line connector mounted to the hull
• the floating appendage structure is configured to be interconnected via the hinge to the heavy lift vessel, wherein the hinge allows a rotation of the floating appendage structure relative to the heavy lift vessel about the hinge axis.
• passageway (77) between the columns of the floating appendage structure and the heavy lift vessel or between the columns of the floating appendage structure, wherein the passageway is constructed to position a barge or jacket in said passageway between said columns when said columns intersect the waterline for transfer of the heavy structure from the floating appendage structure to the barge or to a jacket and/or for transfer of the heavy structure from the barge or jacket to the floating appendage structure.
• Floating appendage structure according to clause 44 or 45, further comprising any of the features of the dependent clauses 2-35 insofar as related to the floating appendage structure.
• the terms "a” or "an”, as used herein, are defined as one or more than one.
• the term plurality, as used herein, is defined as two or more than two.
• the term another, as used herein, is defined as at least a second or more.
• the terms including and/or having, as used herein, are defined as comprising i.e., open language, not excluding other elements or steps.

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• Engineering & Computer Science (AREA)
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• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Ocean & Marine Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)
• Load-Engaging Elements For Cranes (AREA)

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• 2018
  • 2018-10-19 NL NL2021841A patent/NL2021841B1/en active
• 2019
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