HK1027541B - Movement absorbing transferring system - Google Patents

Description

Motion absorbing conveyor system

The present invention relates to a motion absorbing conveyor system for transporting persons and/or objects between a floating vessel and a platform, such as a production platform, according to the preamble of claim 1. The invention also relates to a method of forming a moveable connection between a floating vessel and a platform.

There are many different devices for transporting people and cargo between floating vessels and offshore platforms. These types of transfer systems are particularly desirable because of the relative motion between the floating vessel and the platform. Previously, a basket suspended from a crane boom was used, which basket was hoisted by a winch equipped with a weight balancing system. Such hoistable baskets however imply a great risk in terms of safety, since relative movements between the vessel and the platform easily cause the baskets to impact the vessel or the platform with significant forces. Another risk is that the basket tips over when landing, causing people and/or goods to fall. A working walkway is also used between the platforms, thus forming a rigid connection between these platforms. However, these working walkways are not suitable for transporting people between the platform and the floating vessel when the relative motion is severe.

Examples of the prior art are shown in NO145131, NO151579, NO157255, US3008158, US4011615 and US 4169296. For example, US4169296 shows the use of a ball joint between the outer end of the working walkway and the platform. NO145131 for example shows the use of pull down cables to pull the outer end of the working walkway to the platform. However, none of these publications suggest the possibility of using a pull down cable in combination with a ball joint. Moreover, all known constructions have the disadvantage that the working walkway is self-supporting. It is not possible to transport cargo of any significant weight or size along the working walkway connection.

Therefore, there is a great need for a safer transport system that provides a safe and movable connection between a floating vessel and a platform, while at the same time being suitable for transporting cargo between two platforms. Thus, the invention provides a motion absorbing conveyor system as defined in the characterizing portion of claim 1. Further, a method is provided as claimed in the characterizing part of claim 6.

The invention is described in detail below with reference to the attached drawing figures, wherein:

figure 1 is a side view of the conveyor system as a whole,

fig. 2 shows a cross-sectional view of the transport system in a turret of a vessel, one end of which supports the working walkway,

figure 3 shows the outer end of the conveying system,

figure 4 shows the conveyor system in an inoperative position on a vessel,

FIG. 5 is a side view of the conveyor system in vertical and horizontal directions at different positions where the distance between the platform and the vessel changes,

figure 6 is a top view of the delivery system in a different position,

figure 7 illustrates a method of connecting a conveyor system to a platform,

figure 8 shows a device for emergency disconnection of a conveying system,

fig. 9-47 illustrate another alternative embodiment of the present invention, which is the presently preferred embodiment,

figure 9 shows the main components of the device,

fig. 10a, b and c show the inner part of the conveying system,

figure 11 shows an articulated boom which is shown,

figure 12 shows the outer end of the boom with the frame,

figure 13 shows a frame with a coupling device,

figure 14 shows a coupling device which is shown,

figures 15a and b show a quick release mechanism,

fig. 16a, b and c show a base,

figures 17a and b show a detail of the coupling device,

figures 18a, b and c show a bearing housing,

figures 19-34 show the connection steps of the delivery system,

figures 35-38 show the general disconnection steps,

FIGS. 39-43 show the steps of an emergency disconnect, an

Fig. 44-47 show the steps of disconnecting and stowing the working walkway.

Figure 1 shows a motion absorbing conveyor system 1 of the present invention, mounted on a vessel 2. The transport system 1 is mainly composed of a column 3, a tower 5, a working walkway 6, a boom 7 and a frame 8, which are arranged on the deck 4 of the vessel 2.

Figure 2 details column 3 and column 5. The tower 5 is rotatably connected to the column 3 such that the tower 5 is rotated at least about 360 degrees relative to the column 3, the column 3 being permanently mounted on the deck 4 of the vessel 2. To achieve this rotational capability, a conventional swivel link 9 is provided between the tower 5 and the column 3. The boom 7 is rotatably mounted in a joint 10 on the tower. Thus, the boom 7 can swing in a vertical plane. A winch (not shown) is connected to the boom 7 by means of a wire rope 11 (see fig. 1) so that the outer end of the boom 7 can be hoisted in the vertical plane. The working walkway 6 is also rotatably connected to the tower 5 by a joint 12, thus also allowing the working walkway 6 to swing in the vertical plane.

The outer end of the conveyor system 1 is shown in fig. 3. A frame 8 is connected to the boom 7 and the outer end of the working walkway 6. The frame 8 comprises a first leg 13 and a second leg 14, both legs being rotatably connected to the boom 7 by means of a joint 15. The legs 13 and 14 define an open area 16 therebetween. The frame 8 surrounds the working walkway 6 and is rotatably connected thereto by a joint 17. A ball is provided on the underside of the frame 8. The ball 18 is designed to be received in a ball seat 19, which ball seat 19 is securely mounted on, for example, the deck of a platform 20.

Between the boom 7 and the frame 8 there is also a hydraulic actuator 21, which hydraulic actuator 21 is designed to cause a forced swinging of the frame 8 with respect to the boom 7. A sliding crane or travelling winch 22 is provided in a guide 23 on the underside of the boom 7, which can be moved along the boom 7 from its outer end to its inner end. A hook 24 is connected to the trolley 22 by means of a wire 24a, which makes it possible to transport cargo between the vessel 2 and the platform 20. Thanks to the open space 16 in the frame 8 and the corresponding open space 25 in the tower 5, the trolley crane and the hook 24 are allowed to move along the boom 7 on the working walkway 6 unhindered.

The working walkway 6 comprises at least two parts 6a and 6b, one of the parts 6a being telescopically received in the other part 6 b. The two parts 6a and 6b form a frame giving full protection to the people on the passage 6. The working walkway 6 is either completely closed like a pipe or contains openings. An access ladder 26 provides access from the deck 4 through the top of the column 3 to the working walkway 6. On one side of the platform, the outer end of the working walkway 6 is very close to the platform deck, so that a ladder is not normally required on that side. Alternatively, however, a set of small ladders may be provided on the deck of the platform, or a step which can be lowered may be provided at the outer end of the working walkway 6.

In fig. 4, the transport system is shown in an unused state, in which the boom 7 and the working walkway 6 are swung to a rest position on the vessel 2. In the non-use state the working walkway 6 is selectively detached and removed from the tower 5 and the frame 8, and the frame 8 can either be swung inwards against the boom 7 or removed, so that the column 3, the tower 5 and the boom 7 function as a common crane.

Fig. 5 shows the transport system in different states depending on the particular positioning of the vessel 2 relative to the platform 20. Due to the ball joint, the working walkway 6 and the frame 8 can be rotated in three directions relative to the platform 20 about the ball joints 18, 19. In fig. 5a the inner end of the working walkway is located 1 meter below the standard position and at a distance of 6.5 meters from the platform compared to the standard position. The movement away from and towards the platform is mainly accomplished by the telescopic action of the working walkway 6. In fig. 5b the inner end of the working walkway 6 is located 2.5 metres above the standard position and is located 5.5 metres from the platform than the standard position. Fig. 5c and 5d show the two extreme positions of the transport system, fig. 5c showing the vessel 1 in the position furthest from the platform 20 and lowest below the platform 20, and fig. 5d showing the vessel 2 in the position highest and shortest relative to the platform 20. Here, the distance of the vessel from the platform can vary by about 20 meters, while at the same time the transport system is not excessively deformed. The wave height from top to bottom reached 13 meters without twisting the conveyor system.

FIG. 6 shows the conveyor system as viewed from above; in fig. 6a the transport system is in a nominal position and fig. 6b shows four different extreme positions. As is apparent from fig. 6b, the transport system can be rotated over a fan angle of 90 degrees or more without excessive elongation. The vessel may also change position by 180 degrees relative to the platform.

In fig. 3, the maximum rotation range of the transport system 1 is indicated by the angle V.

The method of providing a movable connection between the vessel 2 and the platform 20 is described below with reference to fig. 7. In fig. 7a the outer end of the work walkway 6 is moved to a position substantially above the ball seat 19 on the platform 20. To place the ball on the tee, the tower 5 is rotated and, by means of the actuator 21, the frame 8 is swung to position the ball in the correct position. The cable 27, which passes through a hole 28 in the ball 18, descends towards the platform 20. The cable 27 may be secured in a receptacle 29 in the tee 19, either by remote control or manually by a person on the platform 20. When the winch holding the boom 7 is put into operation at constant pressure and the slewing motor and brake are switched off, which controls the rotation of the tower 5 and the actuator 21 of the frame 8, the winch is activated to apply tension to the cable 27, thereby pulling the ball 18 down towards the ball seat 19. Once the ball 18 and tee 19 are in contact, the winch supporting the boom 7 is released, allowing the ball 18 to settle in the tee 19, and to be depressed by the weight of the boom 7, frame 8 and work walkway 6 to bear against the ball 18.

When the winch for the boom 7 is put into operation and the winch for the wire rope 27 is released until the ball 18 is sufficiently lifted from the ball socket 19 to an extent such that the wire rope 27 is disengaged from the ball socket 19, the process of disengagement is reversed. The boom 7 and the working walkway 6 may then be swung over the vessel 2.

Figure 8 shows an emergency procedure for disconnection. In this case, the winches for the boom 7 are activated simultaneously when the vessel is driven in a direction away from the platform 20. The telescopic connection between the work walkway sections 6a and 6b extends the work walkway 6 until it reaches its end position and the ball 18 is separated from the tee 19 due to the combined effect of the boom 7 lifting the outer end of the work walkway 6 and applying a force outwards on the work walkway 6. When the emergency procedure is initiated, the connection between the cable 27 and the tee 19 is broken.

With reference to fig. 9 to 47, a system with an articulated boom is described below. The torsional forces of the articulated boom on the column during connection and disconnection are significantly reduced. In addition, there are space saving features when the boom is mounted on deck during transport.

Fig. 9 shows the main components of the system, which includes a column 30, a boom 31, a frame 32 and a working walkway 33. The boom is a two-part structure having an inner part 34 and an outer part 35, the inner and outer parts 34, 35 being connected together at a joint B by a hinge mechanism 36.

Fig. 10a-10c show a column 30 with a suspension and hoisting device 37 for a boom 31. As mentioned above, the boom is hinged, only the innermost section 34 being shown here. The boom 31 is lifted by a wire rope hoist system 37 starting at the top of the column 30. The boom 31 is suspended by a two-axis support system 38 within the column 30. The boom 31 rotates about a transverse horizontal axis a (fig. 10a) during elevation and is free to rotate about a longitudinal axis a1 (fig. 10 b).

The column 30 is mounted on a support on the deck of the vessel and is able to rotate about a vertical axis a2 (fig. 10 c). A rotary actuator 39 is mounted in connection with the bearing block 40; they may be disconnected or they may control the rotational movement of the post 30.

Fig. 11 shows a boom 31 with a hinge mechanism 36 at joint B. A hydraulic cylinder 41 mounted on top of the boom 31 controls its bending and limits the maximum swing. When the cylinder 41 is retracted, the boom 31 is straightened and its movement is mechanically restricted, so that the lower edges of the two boom portions 34, 35 form a straight line.

Fig. 12 shows the connection between the outer portion 35 of the boom 31 and the frame 32. The frame 32 is articulated at an axis C to the boom portion 35, and rotation of the frame 32 is controlled by a hydraulic cylinder 42, the cylinder 42 being mounted between a top 43 of the frame 32 and a bracket 44 of the boom 31.

Fig. 13 and 14 show the frame 32 with the bearing block 49 and the coupling 45. The frame 32 and the coupling 45 are free to oscillate with respect to each other about a horizontal axis D, which extends through two journal bearings 46, as shown in fig. 14, which journal bearings 46 are mounted on two arms 48 on a bearing housing 49, the journal bearings 46 engaging legs 47 of the frame 32. The pivot bearing 50 mounted between the bearing housing 49 and the coupling 45 defines a vertical axis D1 about which the frame 32 with the bearing housing 49 rotates D1.

Referring now to fig. 15a and 15b, 16a-c, 17a and 17b and 18a-c, the elements in the landing system for platform attachment are made up of the following main components: the quick release mechanism 51 (see fig. 15a-b) has a base 52 (see fig. 16a-c) with a locking ball 53, a coupling 45 (see fig. 17a-b) with a pull-down cylinder 54 and a bearing housing 49 (see fig. 18a-c) for the frame 32.

The quick release mechanism in fig. 15a-b consists of a housing 55, a locking pawl 56 and a trip device 57. The trip device 57 is connected to the vessel and is controlled by mechanical or electronic remote control. Two such quick-release mechanisms 51 are provided on the platform, the quick-release mechanisms 51 being quick-welded to the platform on each side of a base 52, the base 52 having a locking ball 53 (see figures 16a, b and c).

The base 52 is composed of the following components: a circular shell 58, the circular shell 58 having an inner conical guide surface 59; a locking ball 53, the locking ball 53 having an inner vertical hole 60 for pulling in a wire rope; a horizontal hole 61, the horizontal hole 61 is used to lock the pull-in cable and the rivet pin 62. The locking pawl 56 locks the pin 62 so that the base 52 is secured to the platform deck.

Fig. 17a shows a vertical section through the coupling 45 with the pull-down cylinder 54, and fig. 17b shows a bottom view thereof. In fig. 17a, a circular end cap 75 with a top flange 63 for inserting the pull-down cylinder 54 and a ground flange 64 at the bottom and an outer flange 65 of the pivot bearing can be seen. Eight dogs 66 are suspended from the lower end of a cylindrical rod 67.

The detents 66 are internally spherical and externally conical. The skirt 68, which is correspondingly conical on the inside, is vertically movable by means of an actuator 69, which actuator 69 is mounted on a flange 70, and which flange 70 in turn is mounted on the cylindrical rod 67. At the lower part of the skirt 68, the detents 66 are held together under the influence of external forces and are thus lockable around the ball 53 (see fig. 16 a). The rod 67 is provided with a longitudinal through hole 71 for drawing the cable therethrough, and the rod 67 is mounted in a piston 72, the piston 72 being vertically movable in the cylinder 54. The rod 67 passes through a top flange 73 of the cylinder 54 and has an outer nut 74 screwed thereon.

Fig. 18a-c show the support housing 49 of the frame 32, which consists of a circular shell 49 and a rotary bearing block 76, the circular shell 49 having arms 48 bearing the bearings 46 for mounting the legs 47 of the frame 32. The bearing block 76 is bolted to the flange 65 (see fig. 17a) so that it moves with the frame 32.

Establishing a bridge between the vessel and the platform according to the following steps:

the base 52 as shown in fig. 1b is pre-locked on the platform deck by means of a quick release mechanism 51 as shown in fig. 15 and by locking of the locking pawl 56 around a pin 62. As shown in fig. 24, the ship is put in place and the wire ropes 77 are fixed in advance to the base 52 on the platform. The cable 77 is threaded into the through hole 60 in the ball 53 and the through hole 71 in the cylindrical rod 67 and is mounted on the winch V (see fig. 19). This can be done on the deck of the vessel when the boom 31 is bent and the frame 32 is fully down, then when the actuator 42 is switched off, the inner part 34 of the boom 31 is raised to the maximum upright position, while the outer part 35 of the boom 31 remains bent and the frame 32 is lowered to a vertical position.

Winch V pulls on cable 77 and frame 32 is pulled towards a mechanical brake on boom portion 35, so that pulling in this direction straightens boom 31 (see fig. 20). The actuator 41 is now activated and the boom 31 straightens out so that the coupling 45 is fixed to the base 52 of the platform (see figure 21).

The boom hoist actuator 78 and the boom sub actuator 41 maintain a constant force while the winch V continues to pull the coupling 45 toward the base 52 on the platform (see fig. 22). Fig. 23a, 23b and 24 show the angular and positional deflection allowed by the coupling 45 during pull-in. Fig. 25 and 26 show an inward turn in the base 52, directed outwardly of the coupling 45, which secures the center of the detent 66 against the ball 53. Fig. 27 shows the coupling 45 lowered onto the ball 53 and held in place by the traction of the cable 77.

Actuating actuator 79 in coupling 45 pushes skirt 69 forward and dogs 66 are fixedly connected to base 52 (see figure 28).

At the same time, the boom sub actuator 78 and the frame actuator 42 are disconnected and the boom actuator 41 begins to lower the outer boom portion 35 on the boom 31 (see FIG. 29). The pull-down cylinder 54 in the coupling 45 is actuated by applying pressure to the underside of the piston 72 (fig. 17a), and the pull-down cylinder 54 pulls the end cap 75 downward so that the landing flange 68 (fig. 17a) abuts the base 52 (see fig. 30). The pulldown cylinder 54 pulls the landing flange 68 toward the seat 80 in the base 52 so that the coupling 45 with the bearing housing 49 and the frame 32 are straight up to the vertical position (see fig. 31 and 32) while the inner portion 34 of the boom 31 is lowered to the operating position (see fig. 31) and the boom lift actuator 38 is fully released so that the boom 31 hangs freely within the column 30 and the frame 32 (see fig. 33).

The nut 74 is tightened manually, and the pressure of the lower cylinder 34 is exhausted, thereby being mechanically anchored (see fig. 34).

The following is the general disconnection step: the boom lift actuator 78 is actuated so that the inner portion 34 of the boom 31 is raised, a constant force on the boom joint actuator 41 is applied (see fig. 35), the coupling 45 is released (see fig. 36), the coupling 45 is lifted unimpeded when the boom 31 is in the fully upright position (see fig. 37 and 38), and the boat is driven to exit immediately.

The following is a quick disconnect in case of emergency: the boom lift actuator 78 is driven so that the inner portion 34 of the boom 31 is lifted, a constant force on the boom joint actuator 41 is applied (see fig. 39 and 40), and the pawl 56 in the quick release mechanism 51 is released (see fig. 41). The boom lift actuator 41 raises the boom 31 while the vessel is driven off the platform and, when the base 52 is off the platform, a constant force is applied on the frame actuator 42 to dampen the rotation of the frame 32 (see fig. 42). The boom 31 is bent so as to drive the conveyor system into a stowed position on deck (see figure 43).

In the above description, the working walkway 33 is not shown in order to avoid unnecessarily complicating the drawing. After the connection between the vessel and the platform through the boom 31 and the frame 32, the working walkway 33 can be guided up and down by using the hoisting and transport system 81. Fig. 44-47 show the working walkway 33 disconnected, and when connected, it can be connected in the same manner but in the reverse order.

As shown in fig. 44, the working walkway 33 is suspended at its inner end 82 from the post 30 and at its outer end 83 from the frame 32. When the working walkway 33 is to be disconnected, its outer end 83 is connected to a trolley or travelling winch 84, which trolley or travelling winch 84 is adapted to move along the boom 31. The working walkway 33 is lifted and disconnected from the frame 31 and the trolley hoist 84 is retracted to move the working walkway 33 towards the column 30 (see figure 45).

When the working walkway 33 is fully retracted, the trolley 84 is driven further and its attachment point within the working walkway rolls along the working walkway 33 until the trolley 84 is moved to the end position of the post 30. During this time the outer end of the working walkway 33 is lowered onto the deck of the ship (see fig. 46). Finally, the inner end of the working walkway 33 is also lowered onto the deck.

Claims (13)

1. A motion absorbing transfer system (1) for transporting persons and/or objects between a floating vessel (2) and a platform (20), such as a production platform, wherein the vessel (2) and the platform (20) are relatively movable, the system (1) comprising a boom (7, 31), the boom (7, 31) being provided with an articulation joint, the articulation joint being connected to one of the vessel (2) and the platform (20); and a working walkway (6, 33) of variable length having an articulated joint connected to the same one of the vessel (2) and the platform (20); and a frame (8, 32) connecting the ends of the boom (7, 31) and the working walkway (6, 33) opposite the said joint, there being one of a ball seat (19, 45) and a ball (18, 53) on the other of the vessel (2) and the platform (20), the other of the ball seat (19, 45) and the ball (18, 53) being adapted to engage with the said one of the ball seat (19, 45) and the ball (18, 53) at the outer end of the working walkway (6, 33) or at the lower end of the frame (8, 32), the said one of the ball seat (19, 45) and the ball (18, 53) being located on the said other of the vessel (2) and the platform (20) such that the ball/ball seat connection is adapted to move relative to one another in three axial directions between the vessel (2) and the platform (20),

characterised in that the ball (18, 53) and/or the ball seat (19, 45) includes a through hole (28, 60) for a pull down cable (27, 77) which is connectable with said other of the ball seat (19, 45) and the ball (18, 53) for pulling the travelator down towards said other of the vessel (2) and platform (20).

2. A motion absorbing transfer system (1) for transporting persons and/or objects between a floating vessel (2) and a platform (20), such as a production platform, wherein the vessel (2) and the platform (20) are relatively movable, the system (1) comprising a boom (7, 31), the boom (7, 31) being provided with an articulation joint, the articulation joint being connected to one of the vessel (2) and the platform (20); and a working walkway (6, 33) of variable length having an articulated joint connected to the same said one of the vessel (2) and the platform (20); and a connecting device (8, 32) connecting the ends of the boom (7, 31) and the working walkway (6, 33) opposite said articulation, one of the vessel (2) and the platform (29) being provided with a device for firmly coupling the working walkway to the same said one of the vessel (2) and the platform (20),

characterised in that the means for securely coupling the working walkway to said one of the vessel (2) and the platform (29) comprises a ball seat (19, 45) and a ball (18, 53), said one of the ball seat (19, 45) and the ball (18, 53) being arranged at the lower end of the connecting means (8, 32) and said other of the ball seat (19, 45) and the ball (18, 53) being arranged on said one of the vessel (2) and the platform (20), the ball (18, 53) being arranged to engage with the ball seat (19, 45) whereby the ball/ball seat connection is capable of accommodating relative movement in three axes between the vessel (2) and the platform (20), the ball (18, 53) and/or the ball seat (19, 45) comprising a through hole (28, 60) for a pull-down cable (27, 77) in order to pull the working walkway down towards said other of the vessel (2) and the platform (20), the pull down cable may be connected to the other of the tee (19, 45) and the ball (18, 53), and the connection means is a frame hingedly coupled to the boom.

3. A motion absorbing transfer system (1) for transporting persons and/or objects between a floating vessel (2) and a platform (20), such as a production platform, wherein the vessel (2) and the platform (20) are relatively movable, the system (1) comprising a boom (7, 31), the boom (7, 31) being provided with an articulation joint, the articulation joint being connected to one of the vessel (2) and the platform (20); and a working walkway (6, 33) of variable length having an articulated joint connected to the same said one of the vessel (2) and the platform (20); and a connecting device (8, 32) connecting the ends of the boom (7, 31) and the working walkway (6, 33) opposite said articulation, one of the vessel (2) and the platform (29) being provided with a device for firmly coupling the working walkway to the same said one of the vessel (2) and the platform (20),

characterised in that the means for securely coupling the work walkway to said one of the vessel (2) and the platform (29) comprises a ball seat (19, 45) and a ball (18, 53), said one of the ball seat (19, 45) and the ball (18, 53) being arranged at the outer end of the work walkway (6, 33) or at the lower end of the connecting means (8, 32) and said other of the ball seat (19, 45) and the ball (18, 53) being arranged on said one of the vessel (2) and the platform (29), the ball (18, 53) being arranged to engage with the ball seat (19, 45) whereby the ball/ball seat connection is adapted to move relatively in three axial directions between the vessel (2) and the platform (20), the ball (18, 53) and/or the ball seat (19, 45) comprising a through hole (28, 60) for a pull down cable (27, 77) in order to pull the work walkway down towards said other of the vessel (2) and the platform (20), the pull down cable may be connected to the other of the tee (19, 45) and the ball (18, 53) and the connection means is a frame, the boom having a travelling crane movable along the length of the boom.

4. A conveyor system as claimed in claim 1, 2 or 3, characterized in that the frame (8, 32) comprises two legs (13, 14; 47) which are rotatably connected to the boom (7, 31) and extend from each side of the boom (7, 31) and which enclose the working walkway (6, 33) on both sides, the legs (13, 14; 47) defining an opening (16) between them through which opening (16) a sliding trolley (22, 84) moving along (7, 31) can be moved.

5. A conveyor system as claimed in claim 4, characterised in that the ball (18, 53) and ball seat (19, 45) are relatively towed by means of a positive tow force directed downwards, a constant tow force being applied using a winch to counter the tow force directed downwards.

6. A conveyor system according to claim 5, characterized in that the frame (8, 32) is forcibly rotated relative to the boom (7, 31) by means of an actuator (21, 42).

7. A conveyor system as claimed in claim 1, 2 or 3, characterized in that the boom (31) is articulated.

8. A conveyor system as claimed in claim 1, 2 or 3, characterized in that the working walkway (6, 33) is designed to be retracted to the retrieval position by means of a trolley (22, 84), the trolley (22, 84) being adapted to lower the working walkway onto the deck of the vessel (20).

9. A delivery system according to claim 1, 2 or 3, characterised in that it includes a coupling means to secure the ball (53) to the ball seat (45).

10. A method of forming a moveable connection between a floating vessel (2) and a platform (20), wherein a boom (7, 31) supporting the working walkway (6, 33) and connected to one of the vessel (2) and the platform (20) is swung into a position, in which position one of the ball seat (19, 45) and the ball (18, 53) is located substantially above the other of the ball seat (19, 45) and the ball (18, 53) at the outer end of the work walkway (6, 33), the other of the tee (19, 45) and the ball (18, 53) being located above the other of the vessel (2) and the platform (20), characterised in that a pull down cable (27, 77) is connected between the ball (18, 53) and the ball seat (19, 45), the ball (18, 53) and the ball seat (19, 45) being drawn towards each other and the ball (18, 53) falling within the ball seat (19, 45).

11. A method of forming a moveable connection between a floating vessel (2) and a platform (20), in which a boom (7, 31) supporting a work walkway (6, 33) and connected to one of the vessel (2) and the platform (20) is swung into a position in which one of a ball seat (19, 45) and a ball (18, 53) is located substantially above the other of the ball seat (19, 45) and the ball (18, 53) at the outer end of the work walkway (6, 33), the other of the ball seat (19, 45) and the ball (18, 53) being located above the other of the vessel (2) and the platform (20), characterised in that a pull down cable (27, 77) is connected between the ball (18, 53) and the ball seat (19, 45), the ball (18, 53) and the ball seat (19, 45) are relatively towed, and the ball (18, 53) is seated in the ball seat (19, 45), the working walkway is telescopic and a trolley crane movable along the length of the boom is suspended from the outer end of the working walkway (6, 33) until it is retrieved and landed on the vessel (2) or platform (20).

12. A method according to claim 10 or 11, characterised in that a frame (8, 32) is connected to the outer end of the boom (7, 31) and comprises one of a ball socket (19, 45) and a ball (18, 53), the frame being coupled to the other of the ball socket (19, 45) and the ball (18, 53), and the work walkway (6, 33) is suspended within the frame (8, 32).

13. A method as claimed in claim 10 or 11, characterised in that a winch with constant traction is used to secure the boom (7, 31), the boom (7, 31) being suspended above the other of the tee (19, 45) and ball (18, 53), and the winch is not loaded when the ball (18, 53) is dropped into the tee (19, 45), whereby the weight of the boom (7, 31) and working walkway (6, 33) is either assisted by a clamping device, thereby securing the ball (18, 53) and tee (19, 45) together.