NL2006280C2

NL2006280C2 - Vessel comprising a stabilizing system.

Info

Publication number: NL2006280C2
Application number: NL2006280A
Authority: NL
Inventors: Anton Coppens
Original assignee: Seaway Heavy Lifting Engineering B V
Priority date: 2011-02-22
Filing date: 2011-02-22
Publication date: 2012-08-24
Also published as: WO2012115508A1

Description

VESSEL COMPRISING A STABILIZING SYSTEM 5 Field of the invention

[0001] The invention relates to a vessel comprising a hull having a length L of at least 35m, a width W of at least 10m, and along at least one side a stabilizing member that in its operational position is suspended from the vessel below water level via a flexible, 10 elongate suspension member that is attached on one side to the vessel and on another side to the stabilizing member.

Background of the invention 15 [0002] From W02005/035355 an offshore vessel is known having on port side and on starboard side two submerged hollow tubes suspended along the vessel via chains, cables or ropes. The tubes are ballasted and provide a stabilizing function by reducing roll and pitch motions of the vessel. By the known system the amplitude of the roll motion is reduced and the natural roll period is increased by about 1 second. The 20 known stabilizing system has as a disadvantage that the ballastable tanks have a relatively low submerged weight, such that the damping effect on the vessel motion is not optimal. Furthermore, in the known system the cables from which the ballastable tubes are suspended may become slack upon downward heave movements of the vessel, resulting in large snatch forces when the vessel suddenly heaves upwards. The 25 damping effect of the known stabilizing system is not easily adaptable to prevailing sea states and can not easily be deactivated.

[0003] Another patent that describes a stabilizing system is US5144904, which describes a stabilizing apparatus for stabilizing boats comprising a weighted concave 30 body which is suspended from the boat and which is formed as a grid defining openings through the body and a flexible flap in the concavity of the body, the flap blocking the openings when the body rises in the water due to rolling of the boat so as to inhibit rolling and the flap moving away from the openings to permit the apparatus to rapidly 2 fall as the boat rolls in the opposite direction. A pair of bodies are provided on opposite sides of the boat to inhibit rolling in both directions.

Again, this stabilizing system has as a disadvantage that the concave bodies have a relatively low submerged weight, such that the damping effect on the vessel motion is 5 not optimal. Also, this system reduces the roll motions only for upward movement.

[0004] Furthermore, hinging damping plates are known from US5095839. This patent describes an apparatus for stabilizing a vessel to drastically reduce the rolling and/or pitching of floating vessels, platforms, or the like. At least one stabilizer is suspended 10 by a bridle secured from a vessel so as to be submerged in the water. The stabilizer is formed having a pair of hingedly connected wing members, so-called with regard to their shape which is formed by a sequence of longitudinal sections associated by dimension and angle to provide a differential convexity over their breadth. This wing shape has an open span during an upward movement and is closed during a downward 15 movement. This system is only effective during upward movements and cannot be easily deactivated in increasing sea states, with high risk of breaking the bridle members.

[0005] It is therefore an object of the present invention to provide a vessel stabilizing 20 system that effectively reduces vessel roll and pitch motions while avoiding large snatch loads in the suspension members.

[0006] It is a further object of the invention to provide a vessel stabilizing system for a crane vessel that can be easily deployed and removed at sea, and with which the 25 window of operation is increased.

[0007] It is again an object of the invention to provide a vessel stabilizing system that can be easily adapted to prevailing sea states.

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Summary of the invention

[0008] Hereto the vessel according to the invention is characterised in that that the stabilizing member comprises a plate-shaped body having a width of at least 5% of the 5 width W, a length of at least 10 % of the length L and a weight below water of at least 25 ton, preferably at least 50 ton.

[0009] By using a heavy plate shaped-body, having a shape with a relatively large surface area, an effective damping is achieved by the water displacement (drag) of the 10 plate-shaped body upon heave movements of the vessel whilst the large weight of the plate-shaped body insures that the flexible elongate suspension members (cables, chains, wire rope or combinations thereof) remain taut at all times such that large snatch loads are prevented. Large plates may also increase the roll added inertia, increasing the natural roll period of the vessel with more than 2 seconds, outside the 15 most common wave periods. This results in a considerable reduction in vessel roll motions for waves with periods below the natural roll period.

[0010] One embodiment of a vessel according to the invention comprises a crane and along at least one of its sides a carrier projecting transversely to a vessel side wall, the 20 suspension member comprising a lifting part for releasable attachment to the crane and an engagement member for releasably engaging with the carrier, wherein the crane is adapted to lift the suspension member from a deck position to its over board operational position and to lower the suspension member such that the engagement member is engaged with the carrier.

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[0011] By use of the crane on the vessel, which can for instance be a heavy crane with a lifting capacity of 5000 ton or more for lifting large offshore structures such as platform components, and described in W02007/069897, the large plate-shaped bodies can be lifted from a storage position on deck or in the hull of the vessel to their 30 operational outboard submerged position via the lifting part. The lifting part can for instance comprise an eye, hook or shackle on the suspension member, which can engage with the hook of the crane. After the engagement member, for instance in the form of a spreader bar, has been connected to the carrier at the side of the vessel and 4 the plate-shaped body is hanging below water level, the hook of the crane can be released and the crane can be used for lifting objects at sea under stabilized vessel conditions. In this manner the crane tip motions can be reduced such as to be within 1° around the equilibrium position and the window of operation of the crane is increased 5 to include larger sea states which may result in a workability increase of between 15% and 60 % depending on the location.

[0012] The engagement member may comprise a spreader bar and a least two flexible elongate suspension members near the ends of the bar. The plate-shaped body is 10 hanging from the spreader bar by the suspensions members such as steel cables, chains, pipes, synthetic ropes or combinations thereof. The carrier may comprise a support cradle which is open at the top for receiving the spreader bar which can be introduced therein via the crane.

15 [0013] The plate-shaped body may comprise a weight attachment member for receiving an additional weight from the crane after the plate-shaped body has been placed in its operational position. In this way the stabilizing weight is increased while reducing the load on the crane during installation of the stabilizing member.

20 [0014] In a preferred embodiment of a vessel according to the invention, the plate shaped body defines a closed projected surface on a horizontal plane through which water flow is blocked. The vessel comprises a control device and an actuator at or near the plate-shaped body for changing the closed projected surface area in dependence on the actual or forecasted sea state. By selectively opening and closing of holes in the 25 plate-shaped body or by changing its angle relative to a horizontal plane via the actuator, the drag of the plate-shaped body can be adjusted from on board of the vessel. In this way the stabilizing member can be fine-tuned to match specific activities on the vessel, prevailing sea states and weather conditions so as to provide an optimal motion stabilizing effect.

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[0015] The actuator may, in one embodiment, comprise a first cable extending from a tilting device on the suspension member to a first side of the plate-shaped body and a second cable extending from the tilting device to the second side of the suspension 5 member and a third cable connected to the tilting device or to the plate-shaped body and to a winch situated on the vessel for changing the orientation of the plate-shaped body such that the plate-shaped body is tilted around a longitudinal axis. The tilting device may comprise a tri-plate to a first point of which the suspension cable is 5 attached and from the second and third point of which cables run to sides of the plateshaped body. The second or third point of the tri-plate may be connected to a winch on deck of the vessel via a tilting cable, tensioning of which will cause the one cable to go slack and the plate-shaped body to tilt from a horizontal to a more vertically oriented state.

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[0016] Another way to modify the closed projected surface of the plate-shaped body is achieved by dividing the plate-shaped body into two sections that are hingeably connected one to the other along a longitudinal center line of the plate-shaped body, the actuator effecting a hinging movement of the sections.

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[0017] In an alternative embodiment, the plate-shaped body comprises at least one aperture covered by movable hatch member. The actuator effects a movement of the hatch member to at least partly cover or uncover the aperture. In this way the water resistance of the plate-shaped body with respect to vertical motions can be adjusted in 20 simple manner.

[0018] In order to de-activate the plate-shaped body, it may be lowered onto the sea bed, but preferably the suspension member is connected to a lifting device, such as a crane or a winch, on the vessel for lifting the plate-shaped body from its operational 25 position situated below keel level, to an inoperational position in which the plateshaped body is situated near the hull of the vessel, for instance in a storage compartment near a side of the vessel, or to an inoperational position in which the plate-shaped body is stored on deck.

30 [0019] In an alternative embodiment, the plate-shaped body in the inoperational position is placed in a vertical orientation along the side of the vessel. The plate-shaped body may for instance be situated inside of a wing tank.

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[0020] In another embodiment, the suspension members may comprise a rigid frame of a jack-up type having an upper end that is movably attached to the vessel, a lower end being attached to the stabilizing member, wherein a plate-shaped body is attached to the lower end of the frame and projects transversely from the frame. The damping 5 members may be raised or lowered by extending or retracting the frames. Two or more of these may be provided on either side of the vessel, near the bow, midships and aft.

[0021] Furthermore, it is advantageous to have the suspension member be connected to a lifting device on the vessel for lifting the plate-shaped body from its operational 10 position situated below keel level, to an inoperational position in which the plateshaped body is situated near the hull of the vessel.

[0022] Also, the vessel can advantageously be provided with two or more stabilizing members situated along one of the vessel sides. By doing this, the amount of stabilising 15 force can be relatively easily influenced. Furthermore, by doing this it, is possible to adjust the roll axis of the vessel.

[0023] The plate-shaped body can advantageously be suspended from at least three lifting points. This ensures that the position of the plate-shaped body in the water is 20 relatively stable.

[0024] For fine-tuning the water resistance, the plate-shaped body may have a number of apertures, each covered by flexible hinge element that is on a clamping side of the opening attached to the body and is on another side freely movable relative to the 25 opening. Upon upward and/or downward movement the spring-biased flaps are moved from the apertures such that water can pass there through. In this manner the damping effect of the plate-shaped body can be tailored to be best adapted to the prevailing sea state.

30 [0025] For easy adjustment of the weight of the plate-shaped body, it is advantageous that this body comprises hollow compartments filled with removable solid ballast weights such as steel slabs, concrete, or gravel or any other material with a density larger than water.

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[0026] The vessel may also be provided with one or more stabilizing members that are situated along the sides of the vessel, such that the area of the stabilizing members results in an increase in the natural roll period of the vessel of more than 2 seconds.

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Brief description of the drawings

[0027] A number of embodiments of a vessel comprising a stabilizing member 5 according to the invention will by way of non-limiting example be described in detail with reference to the accompanying drawings. In the drawings:

[0028] Figure 1 shows a schematic front view of a vessel according to the invention provided with a stabilizing member having a plate-shaped body and a detail on an 10 enlarged scale of a hang-off frame;

[0029] Figure 2 shows a schematic front-, side- and plan view of a crane vessel according to the invention provided along one of its sides with a number of stabilisation members; 15

[0030] Figures 3a-3d show the different stages of changing the trim of a stabilizing member according to the invention by tilting of the plate-shaped body;

[0031] Figures 4a and 4b show a schematic front view of a vessel according to the 20 invention with a stabilizing member comprising a safety release mechanism in an operational and in an released position, respectively;

[0032] Figure 4c shows a schematic front view of a side of a vessel according to the invention with a stabilizing member comprising a hatching mechanism for changing the 25 water resistance of the stabilization member;

[0033] Figures 5a and 5b show a front view and a side view respectively of a vessel according to the invention having a stabilising member provided with a plate-shaped body including a folding mechanism for folding the plate-shaped body; 30

[0034] Figures 6a and 6b show a view on an enlarged scale of an embodiment of a stabilizing member according to figures 5a and 5b, with an adjustable folding mechanism, in an operational state and in a folded state, respectively; 9

[0035] Figures 7a and 7b show a schematic, close-up view of another embodiment of the stabilizing member according to figures 5a and 5b having an alternative folding mechanism, in an operational state and in a folded state, respectively; 5

[0036] Figure 8 shows a schematic, close-up view of a plate-shaped body provided with a flexible hinge element;

[0037] Figure 9 shows a schematic, close-up view of a plate-shaped body provided 10 with a movable hatch member;

[0038] Figures 10a-lOd shows the sequence of deployment of a stabilizing member according to the invention in a schematic front view, the stabilizing member being stored in a wing tank; 15

[0039] Figures 11a and lib show a front view and a side view, respectively, of a further embodiment of a vessel provided with a stabilizing member according to the invention having a plate-shaped body, the plate-shaped body being attached to movable columns; 20

[0040] Figures 12a and 12b show a schematic front view and a side view of a vessel according to the invention wherein the plate-shaped body of the stabilizing member is attached to a movable frame; 25 [0041] Figure 13 shows a cross-sectional view of a plate-shaped body of a stabilizing member according to the present invention that is provided with removable weights; and

[0042] Figures 14a-14f show cross-sectional views of different embodiments of a plate-30 shaped body of a stabilizing member according to the invention provided with hollow compartments.

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Detailed description of the invention

[0043] Figure 1 shows a front view of a vessel 1 that is along a side wall 8 of its hull 2 provided with a stabilizing member 3. The stabilizing member 3 comprises a plate- 5 shaped body 5, for instance a flat body 5 as shown, that is suspended below water level 13 from a steel or synthetic cable, a chain, a steel pipe or synthetic rope (or combinations thereof) 4. The vessel 1 has a width W that can range from 10m to 50m or more. The length L of the vessel (see fig. 2) is between 35m and 350m whereas the height of the hull 2 can be between 4m and 50m, the vessel having a displacement of at 10 least 1500 ton. The vessel 1 is along its side wall 8 provided with a carrier 7, such as a hang-off frame 7 as shown, that projects transversely from the side wall 8. In the hang-off frame 7 an engagement member 10, such as a spreader bar 10 as shown, of the stabilizing member 3 is supported. The elongate, flexible suspension member 4 is hanging off from the spreader bar 10 such that it is clear from the side wall 8, by for 15 instance a distance of at least 1 m. The flat body 5 is attached to the lower end of the suspension member 4. The width Wp of the flat body 5 can range from 3 m to 15m and is for instance about 7 m, so that the body 5 projects a few m below the hull 2 of the vessel 1. The height h of the body 5 is for instance between 50 cm - 3 m, for instance about 1 m. The length Lp (see fig. 2) of the flat body 5 may range from 10 m to 50 m, 20 for instance 35 m. The weight of the flat body 5 under water is at least 50 ton, for instance 300 ton. The flat body 5 is to be provided with three lifting points 28 for it to be stably positioned underwater.

[0044] A fender 42 is shown fixed around the suspension member 4, situated halfway 25 between the spreader bar 10 and the stabilization member 3. The fender protects the suspension member 4 when it touches the bilge keel 43 or the vessel’s hull 2 due to vessel roll motions.

[0045] Figure 2 shows a schematic side view and a top view of a crane vessel 1 30 comprising a crane 6 and provided along its length with two flat bodies 5, 5’. Each body 5, 5’ is connected to a respective spreader bar 10, 10’ via two spaced-apart suspension members 4, 4’. The spreader bars 10, 10’ are supported by a respective hang-off frame 7 that projects transversely from a side wall 8 of the vessel 1, when the 11 stabilizing system 3 is in its overboard operational position B. The hang-off frame 7 may comprise two or more spaced-apart cradles having a bracket which is open at its top side, to allow the spreader bar 10 to be introduced into the cradle from the top by the crane 6. The spreader bars 10-10” are each provided with a slings 9 releasably 5 engaging with a hook 44 of the crane 6, such that the crane 6 can lift the spreader bar 10 from a deck position A to the overboard operational position B.

[0046] After the stabilizing members 5 are all placed in position and the crane hook 44 is released, the crane 6 can lift objects while the deflections of the crane tip due to roll 10 and pitch motions are minimized. By selecting the position of the stabilizing members 3, 3’ along the length L of the vessel and the distribution of the stabilising members on the port and starboard sides of the vessel, the roll axis or roll centre, around which the vessel 1 moves can be shifted such as to be optimal for reducing motions of the tip of the crane 6, depending on the position of the crane while lifting and installing heavy 15 loads.

[0047] Figure 3a shows a side view of the flat body 5 provided with a tilting device, comprising a tri-plate 19. A fixed part cable 18 extends from the tri-plate 19 to a first side of the flat body 5. A tilting cable 20 extends from another side of the flat body 5 20 along a sheave 36 (see the enlarged detail of fig. 3c) to a tilting winch 45 situated on the vessel 1. The cable 20 freely runs along the sheave 36 on the tri-plate 19. The end of a hoisting cable 21 is fixed to the tri-plate and extends from a hoisting winch 46 situated on the vessel 1. By operation of the hoisting winch 46 connected to the hoisting cable 21, the flat body 5 can be raised or lowered to the desired depth below 25 water level. By operation of the tilting winch 45 connected to the tilting cable 20, the orientation of the flat body 5 is changed in such a way that the flat body 5 is tilted around a longitudinal axis perpendicular to the plane of the drawing. This tilting operation changes the area of the closed projected surface P of the body 5, i.e. the projection of the flat body 5 on the horizontal plane through which water flow is 30 blocked. Overloading of cables 18, 20 and 21 is thus avoided.

[0048] The tilting winch 45 may be connected to a control unit 16 receiving input from a terminal or console 47 about the desired angular position of the flat body 5. This data 12 may be manually inputted into the control unit 16 by an operator, e.g. based on weather forecasts, or can alternatively be derived from a sensor that measures roll and/or pitch and/or heave movements of the vessel 1 or which provides a control signal that depends on the wave height.

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[0049] Figures 4a and 4b show a front view of the vessel 1 comprising an emergency release mechanism 37a, 37b in the operational state and in the released state, respectively. The flat body 5 is suspended from a chain 4 that is attached to the spreader bar 10. On one side, the flat body 5 is connected via a releasable safety pin 10 37a that can be released by means of a control member 37b, which can be an electrical umbilical, a hydraulic or pneumatic duct, a pull cable or a radio or sonar transmission channel. Actuation of the safety pin 37a may be effected under control of the control unit 16, depending on the tension measured in the chain 4, the sea state or other control parameters. It is also possible to manually actuate the safety pin 37a via the control unit 15 16. Release of the safety pin 37a causes the body 5 to swing to a substantially vertical position such that it has a minimal water resistance and it can be easily lifted inboard by pulling in the chain 4 or it can remain in its vertical, inactive position below water level.

20 [0050] Figure 4c shows a schematic front view of a side of a vessel 1 according to the invention with a stabilizing member 3 comprising a hatching mechanism 60 for changing the water resistance of the stabilization member 3. The hatching mechanism 60 as shown has two hingeable hatches 59, 62 positioned in the flat body 5. The hatches 59, 62 can be placed in a closed position and an open position, as shown by the 25 dashed lines. In the open position the hatches 59, 62 are in a substantially transverse position with respect to the flat body 5. In the closed position the hatches 59, 62 are substantially aligned with the flat body 5. Water flow through the flat body 5 is prevented in the closed position. It is also thinkable that the hatches 59, 62 are put in an intermediate position, being a position somewhere in between the closed and open 30 positions. The positioning of the hatches 59, 62 is controlled by hatch control cables 56 and 57. In figure 4c hatch control cable 57 is connected to the left hatch 62, whereas hatch control cable 56 is connected to the right hatch 59. Hatch control cable 56 runs over a sheave 58 all the way to the hatch control winch 55. Analogously, hatch control 13 cable 57 runs over a sheave 61 to the hatch control winch 55. Preferably, additional sheaves 63, 64 are positioned near the intersection of the deck 11 and the vessel side wall 8 for providing additional guidance to the hatch control cables 56, 57. Furthermore, figure 4c shows that the spreader bar 10 in figure 4c comprises an I-beam.

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[0051] Figures 5a and 5b show a frontal view and a side view, respectively of a vessel 1 provided with a flat body 5 with a folding mechanism for folding a hingeable flat body 5 along its longitudinal center line around a hinge 48 that in figure 5a is situated perpendicular to the plane of the drawing. A set of tilt control cables 29 for folding and 10 unfolding of the body 5 is attached to the hinge 48 and a winch 22 on the deck of the vessel 1. By folding and unfolding of the body 5, the damping effect can be adapted to prevailing weather conditions. The winch 22 may be operated manually or under control of the control unit 16 depending on pre-set parameters relating to weather conditions and/or vessel motions and/or sea states.

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[0052] Figures 6a and 6b show in detail the flat body 5 with a first embodiment of a folding mechanism, in an unfolded and folded state respectively. It shows a fixed part cable 18 extending from the tri-plate 19 to a connection point situated on longitudinal centre line of the flat body 5. Furthermore, it shows a tilting cable 20 extending from a 20 first hingeable section I of the flat body 5, along a sheave 36’ on the tri-plate 19 to the winch 22 on the vessel 1. The cable 20 freely runs over the sheave 36 on the tri-plate 19. The suspension member 4 comprises a hoisting cable 21 extending from the hang-off frame 7 on the vessel 1 to the tri-plate 19. The cable 21 may be connected to a separate winch on the vessel. A second tilting cable 33, extends from a second 25 hingeable section II of the flat body 5 to either the same winch 22 or to another winch on the vessel 1 and runs over a second sheave 36 on the tri-plate 19. The flat body 5 may be raised and lowered with respect to the vessel 1 via the cable 21. By operating the winch 22 connected to the tilting cable 20 and to the second tilting cable 33, the sections I and II of the flat body 5 move towards each other around the hinge 48. This 30 hinging operation changes the area P of the projection of the flat body 5 on the horizontal plane through which water flow is blocked, so the damping effects of the body 5 are adjusted.

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[0053] Figures 7a and 7b show a schematic, close-up view of a flat body 5 with the folding mechanism of figures 5a, 5b, the folding being shown in two stages. More specifically, figures 7a and 7b show a first cable 34 extending from the tri-plate 19 to a hingeable section I of the flat body 5. A second cable 35 extends from the tri-plate 19 5 to another hingeable section II of the flat body 5. The flat body is suspended from the hang-off frame 7 by the suspension member 4 comprising a hoisting cable 21 extending from the spreader bar 10 or from a winch situated on the vessel 1, to the tri-plate 19. Using a winch on the vessel attached to the cable 21 the flat body 5 can be lowered, or when the winch is operated in the opposite direction, can be lifted upwards. A tilting 10 cable 38 is shown in figure 7b connecting the flat body at the longitudinal centre line to the winch 22 on the vessel 1. On operation of the winch 22, the longitudinal centre line of the body 5 can be raised and lowered, causing the sections I and II of the flat body 5 to move away from each other or to move towards each other. When operating the winch 22 in the upward direction the sections I and II of the body 5 are folded 15 outwards. The hinging operation changes the area of the projected surface P, of the flat body 5 on the horizontal plane through which water flow is blocked, such that the damping effects of the body and the forces in the suspension members 4 are adjusted.

[0054] Figure 8 shows a schematic, close-up view of a flat body 5 provided with a 20 flexible hinge element 30. The flat body 5 is, provided with an aperture 23. The aperture 23 is covered by a flexible hinge element 30. On a clamping side 51of the aperture the hinge element 30 is attached to the flat body 5, for instance by means of a bolted connection. The amount of overlap between the flat body 5 and the hinge element 30 can be used to adjust the flexibility of the hinge element 30. By choosing 25 the flexibility of the hinge element 30, the water resistance of the flat body 5 against downward movement, and the moment at which the hinge 30 opens to allow water to pass through the aperture 23 can be adjusted, such that the damping effect of the flat body can be fine-tuned and slack in the suspension members at high sea states can be avoided. The flexible hinge element 30 furthermore reduces forces in suspension lines 30 4 for downwards heave motions or upward motions of the flat body 5.

[0055] Figure 9 shows a schematic, close-up view of another embodiment of a flat body 5 provided with a movable hatch member 24. A weight 52 is attached to the 15 movable hatch member 24. Upon downward heave motions of the vessel, a hatching movement is initiated, wherein the movable hatch member 24 uncovers the aperture 23, such that the body 5 can rapidly descend and slack of the suspension members is avoided. By adjusting the weight 52, the movability of the movable hatch member 24 5 can be influenced and the damping and anti-slackening effect can be fine-tuned.

Figures 10a-10e show a schematic front view of a vessel 1 with a flat body 5, the vessel further being provided with a storage compartment, such as a wing tank 39, for storing the flat body 5. The hull 2 of the vessel 1 is near a side wall 8 provided with a wing 10 tank 39. The vessel 1 is further equipped with a winch 40, for lifting a flat body 5, being in a substantially vertical position, from an operational position below keel level to an inoperational position in which the flat body 5 is situated near the hull 2 of the vessel 1. In the inoperational position the flat body 5 is stored in the wing tank 39. Figures 10b-10d show the different stages of deployment of the stabilizing member 3 15 by lowering the flat body and tilting it from a vertical to a horizontal position by using the tri-plate 19, in the manner as illustrated in figures 3a-3d. The flat body 5 can optionally be provided with a low-drag part at its lower end, which closes off the wing tank in the inoperational position and minimizes sailing resistance of the vessel.

20 [0056] Figures 11a and 1 lb shows a schematic front view and side view respectively of a vessel 1 provided with a stabilization member 3, comprising a flat body 5, the flat body 5 being attached to movable columns 27. An upper end of the movable columns 27 is movably attached to the vessel 1. A lower end of the stabilization member 3 is attached to the movable columns 27. A movable column 27 can for instance comprise a 25 rigid frame which is driven by a rack and pinion system as generally known in the art of offshore jack-up platforms.

[0057] Figures 12a and 12b show a schematic front view and side view respectively of a vessel 1 provided with a stabilization member 3 comprising a flat body 5, the flat 30 body 5 being attached to a movable column 27 comprising a rigid frame. The vessel of figures 12a and 12b shows four of such columns 27. A flat body 5 is attached to a lower end of the columns 27. The columns 27 are provided with additional flat bodies 5’ between their lower ends and their upper end near the hull 2 of the vessel 1. The flat 16 body 5 at the lower end of a column 27 can be folded outwardly, away from a column 27, in order to become operational, and inwardly, towards a column 27 to become inoperational again. Additional flat bodies 5 ’ can be added to a column 27 for reducing vessel 1 motions even more.

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[0058] Figure 13 shows a schematic, cross-sectional view of a flat body 5 provided with removable weights 32. The flat body 5 is provided with water openings 41 for allowing flow of water through the flat body 5. The additional weights 32 can e.g. comprise iron ore, gravel or steel slabs fastened on the body 5 via fastener means 53.

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[0059] Figures 14a-14f show different schematic, cross-sectional views of embodiments of a flat body 5 suitable for use as stabilizing member. From top to bottom it shows a massive beam, an array of hollow pipes, interconnected I-beams, abutting pipes, a pile with stiffeners and a completely flooded barge.

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Reference numerals 1. Vessel 2. Hull 5 3. Stabilizing member 4. Suspension member 4 ’ 5. Flat body 5’ 6. Crane 7. Hang-off frame 10 8. Vessel side wall 9. Slings 10. Spreader bar 10’, 10” 11. Deck 12. Bar 15 13. Water level 14. Support cradle 15. Weight attachment member 16. Control device 17. Actuator 20 18. Fixed part cable 19. Tri-plate 20. Tilting cable 21. Hoisting cable 22. Winch 25 23. Aperture 24. Hatch member 25. Lifting device 26. Elongate suspension member 27. Movable column 30 28. Lifting point 29. Control cables 30. Flexible hinge element 31. Hollow compartment 18 32. Removable solid ballast weight 33. Second tilting cable 34. First cable 35. Second cable 5 36. Sheave 37a. Releasable safety pin 37b. Control member 38. Tilting cable 39. Wing tank 10 40. Winch 41. Water opening 42. Fender 43. Bilge keel 44. Hook 15 45. Tilting winch 46. Hoisting winch 47. Console 48. Hinge line 49.

20 50.

51. Clamping side 52. Weight 53.

54.

25 55. Hatch control winch 56. Hatch control cable 57. Hatch control cable 58. Sheave 59. Right hatch 30 60. Hatching mechanism 61. Sheave 62. Left hatch 63. Sheave 19 64. Sheave 65.

I = first section 5 II = second section L = length of vessel W = width of vessel A = deck position 10 B = overboard operational position C = longitudinal centre line P = closed projected surface X = longitudinal axis K = operational position (below keel) 15 H = inoperational position (near hull)

Claims

A vessel (1) comprising a hull (2) with a length L of at least 25 m, a width W of at least 10 m, and along at least one side a stabilizing member (3), which in an operational position below water level on the vessel ( 1) hangs by means of a flexible, elongated hanging member (4, 4 ') connected on one side to the vessel (1) and on another side with the stabilizing member (3), characterized in that the stabilizing member (3 ) comprises a plate-shaped body (5) with a width of at least 5% of the width W, a length of at least 10% of the length L and a weight of at least 50 tonnes below the water level, preferably at least 100 tonnes, the plate-shaped body (5) free from the seabed in its operational position.

2. Vessel (1) as claimed in claim 1, wherein the vessel (1) comprises a crane (6) and along at least one of its sides a support member (7) protruding transversely with respect to a side wall (8) of the vessel ( 1), wherein the hanging member (4, 4 ') comprises a hoisting part (9) for releasably connecting to the crane (6) and an engaging member (10) for releasably engaging the supporting member (7), the crane (6) being adapted to hoist the hanging member (4, 4 ') from a deck (11) position (A) to an operational position (B) and to lower the hanging member (4, 4') such that the engaging member (10 ) engages the support member (7).

3. Vessel (1) according to claim 2, wherein the hoisting part (9) comprises a rod (12) and at least two elongated hanging members (4, 4 ') near the ends of the rod (12), wherein the supporting member (7) comprises a support scaffold (14) open at a top for receiving the rod (12).

4. Vessel (1) as claimed in claim 2 or 3, wherein the plate-shaped body (5) comprises a weight connection member (15) for receiving an additional weight from the crane (6) after the body (5) is in the operational position placed.

Vessel (1) according to one of the preceding claims, wherein the plate-shaped body (5) comprises a closed projection surface (P) on a horizontal surface through which water flow is blocked, the vessel (1) a control member (16) and an actuator (17) on the plate-shaped body (5) for changing the surface of the closed projection surface (P) depending on the sea condition.

Vessel (1) according to claim 5, wherein the actuator (17) comprises a first cable (18) extending from a tilting device (19) on the hanging member (4) to a first side of the plate-shaped body (5), a second cable (20) extends from the tilting member (19) to a second side of the hanging member (4) and a third cable (21) is connected to the tilting member (19) and a winch (45) on the vessel (1) ) for changing the orientation of the tilting device (19) so that the plate-shaped body (5) is tilted about a longitudinal axis (X).

7. Vessel (1) as claimed in claim 5, wherein the plate-shaped body (5) comprises two parts (I; II) pivotally connected along a longitudinal axis of the plate-shaped body (5), the actuator (17) having a pivotal movement effectuates the parts (I; II).

Vessel (1) according to claim 5, wherein the plate-shaped body (5) comprises at least one opening (23), which is covered by a movable hatch member 20 (24), the actuator (17) moving the hatch member (24) ) effects at least in part covering or discovering the opening (23).

9. Vessel (1) as claimed in any of the foregoing claims, wherein the hanging member (4, 4 ') is connected to a hoisting device (25) on the vessel (1) for hoisting the plate-shaped body (5) from the operational position. below keel level to an inoperational position, in which the plate-shaped body (5) is located near the hull (2) of the vessel (1).

10. Vessel (1) according to claim 9, wherein the plate-shaped body (5) is placed in the inoperational position in a vertical direction along the side of the vessel (1).

Vessel (1) comprising a hull (2) with a length L of at least 35 m, a width W of at least 10 m, and along at least one side two spaced apart stabilizing members (3) which in their operational position are below the water level of the vessel (1) hanging by means of a respective elongated hanging member comprising a rigid frame (27) with an upper end movably connected to the vessel (1), and a lower end connected to the stabilizing member (3), wherein a plate-shaped body (5) is connected to the lower end of the frame (27), which extends transversely to the frame (27), the plate-shaped body (5) hanging free from the seabed in its operational position.

12. Vessel (1) according to claim 11, wherein the hanging member (4, 4 ') is connected to a hoisting device (25) on the vessel (1) for hoisting the plate-shaped body (5) from the operational position below keel level , to an inoperational position in which the plate-shaped body (5) is located near the hull (2) of the vessel (1).

Vessel (1) according to one of the preceding claims, wherein two or more stabilizing members (3) are located along one of the vessel (1) sides.

Vessel (1) according to one of the preceding claims, wherein the plate-shaped body (5) is suspended from at least three hoisting points (28). 20

Vessel (1) according to one of the preceding claims, wherein the plate-shaped body (5) comprises a number of openings (23), each opening being covered by a flexible hinge element (30) which is on a clamping side (51) of the opening (51). 23) is connected to the body (5) and is freely movable on another side with respect to the opening (23).

Vessel (1) according to one of the preceding claims, wherein the plate-shaped body (5) comprises hollow compartments (31) filled with removable fixed ballast weights (32).