GB2138771A - Arrangement for the transfer of a passenger and/or freight unit to and from a rig or another installation at sea - Google Patents

Abstract

An arrangement for the transfer of a passenger and/or freight unit (container 16) to and from a rig (10) especially to and from a vessel (15) which is freely moveable on the surface of the sea in step with wave movements. Corresponding, cooperating gripping and holding means (32, 33) are arranged on said unit (16) or in connection with the hoisting and positioning device which is connected to the rig or the installation. The gripping and holding means (33) of the hoisting and positioning device are moveable in controlled paths of movement vertically and horizontally and preferably also rotatably mounted about a common vertical axis, via a support means (37) in a support platform (27) which is separately adjustable at different levels between the deck (13) of the rig (10) and the deck (15a) of the vessel, by means of a hoisting device (17) placed on the deck of the rig or the installation. The support platform (27) is in addition kept in place in a particular horizontal position relative to the rig means of guide or tensioning means (30, 31) connected to the rig at a level below the hoisting device. The arrangement may be used to launch or recover life saving equipment to or from the sea. <IMAGE>

Description

SPECIFICATION Arrangement for the transfer of a passenger and/or freight unit to and from a rig or another installation at sea The present invention relates to an arrangement for the transfer of a passenger and/or freight unit (container) to and from a rig or another installation at sea, especially to and from vessels which are freely moveable on the surface of the sea in step with wave movements of the sea, the corresponding, cooperating gripping and holding means being arranged on said unit (the container) or in connection with a hoisting and positioning device which is connected to the rig or the installation.

On transferring passengers or freight from a vessel which is freely moveable on the ocean surface in step with the wave movements of the seat, to a rig or another installation which is stationarily arranged on or in the sea, and the reverse, there have been problems with the transfer of passengers and freight, especially during unfavourable weather conditions with strong winds and/or strong wave movements. Firstly, big problems can be presented in holding the vessel in place in a desired precise position relative to the installation, as a consequence of drift produced by wind, ocean currents in the sea together with wave movements of the sea. Secondly, big problems can be presented in compensating for undulating movements of the vessel on the surface of the sea in step with the wave movements of the sea.A particular problem arises as a consequence of the relatively large height difference which is present between the deck of the installation and the deck of the vessel, since there can easily occur as a result large uncontrolled lateral displacements of the passenger and freight unit, especially in the transfer phase just by the deck of the vessel.

By means of relatively rigid, stationary constructions there can be obtained relatively accurate, controlled guide movements of the passenger and freight unit, but such rigid, stationary constructions find little favour in practice, since they exert large weight loadings on the rig or the installation and in addition can be obstructive to the possibility for movement of the vessel relative to the rig of the installation.

With the present invention the aim is a solution where one can achieve accurate,controlled guide movements for support devices of the passenger or freight unit via a support platform which can be adjusted for use at different levels or be held at an approximately defined height from the freight unit (ship, ocean surface), by a movement corresponding to the undulating movement of the ship relative to the rig, ali according to the conditions.

A particular objective are hoisting and positioning devices of light weight construction which hardly catch the wind, so that one can move the devices relatively rapidly with relatively little force, but nevertheless with sufficient precision under varying working conditions.

With the present invention an objective is also to launch or haul on board again lifeboats or like life-saving devices from the rig or installation.

The arrangement according to the invention is characterised in that gripping and holding means of the hoisting and positioning device are moveable, by means of a hoisting device placed on the deck of the rig or installation, in controlled paths of movement vertically and horizontally and preferably also rotatably mounted about a vertical axis, via a support means in a support platform which is separately and continuously adjustable at different levels between the deck of the rig or the installation and the deck of the vessel, so that the distance between these can be maintained at an optimum distance at any time, the support platform being in addition safeguarded in place in a particular horizontal position relative to the rig or the installation by means of guide or tensioning means connected to the rig or installation at a level below the hoisting device.It can be appropriate and in certain situations advantageous to allow the support platform to move, on loading and unloading, up and down, so that the support platform will be at an approximately permanent vertical distance (height) from the ship. Thereby one will be able to reduce the necessary movement of the gripping and holding means (the support means). This up/down movement of the support platform will be able to be guided with mini-processors or in another manner.

According to a preferred embodiment the arrangement is characterised in that the support platform is supported via two or more hosting wires via a travelling crab in support arms which project upwardly above and outside the deck of the rig or installation, in that the support platform is maintained by means of one or more tension-regulatable wire(s) with a certain tensile force in place in a particular horizontal position relative to the rig or installation, but permits a limited movement outwardly from said particular position against said tensile force, and in that the gripping and holding means of the hoisting and positioning device are connected with a link arm arrangement controlled by a pressure medium cylinder to a rotary disc which is rotatably mounted about the vertical axis of the support platform.

By means of the said two or more hoisting wires it is possible to adjust the support platform in a desired horizontally supported position even with a non-central loading of the platform from the support means, by means of the tension-regulatable wires one can ensure furthermore a stable horizontal position of the support platform, and by means of the pressure medium cylinder-controlled link arm arrangement and the rotary disc one can move the gripping and holding means of the hoisting and positioning device in an accurate manner relative to the support platform. In this way there is the possibility of being able to adjust the support platform roughly and to fine-adjust the gripping and holding means in different positions relative to the support platform in an accurately controlled manner.

Further features of the invention will be evident from the following description having regard to the accompanying drawings, in which: Fig. 1 shows an arrangement according to the invention, illustrated in a schematic view from the side.

Fig. 2 shows a part of the arrangement according to Fig. 1 seen from above.

In Fig. 1 there is indicated an oil rig 10 of a partially submerged type, there being indicated a lower float body 11 and an associated supporting column 1 2 together with a deck 1 3. The level of the sea is indicated at 14.

There is illustrated a ship 1 5 which is provided on the deck 1 spa with a sow of passenger and/or freight units in the form of containers 1 6 which are to be transferred one after the other from the ship 1 5 to the rig 10 by means of an arrangement according to the present invention.

The arrangement according to the invention comprises a boisting device 1 7 which in the illustrated embodiment is stationarily secured on the upper deck 1 3 of the rig 10. The device 1 7 comprises a pair of crane arms, of which only the one arm 19 is illustrated in the drawing. Between the arms 19 there is horizontally displaceable a travelling crab 20, which is displaceable between the outer position at the outer end of the arm 19 to an inner position at the inner end of the arm 19.

There is secured on the deck 1 3 a winch 21 with pulling wire 22 which passes over rotary pulleys 23 and 24 of the one arm 19, for the displacement of the travelling crab 20 between its said outer positions in the arms 1 9.

The arms 1 9 project a significant distance outside the deck of the rig 10, so that the container 1 6 can be raised with a good clearance upwardly to a position. outside the deck 18 and thereafter can be transported via the travelling crab 20 in a horizontal direction to a position on the deck 1 8 between the arms 19.

In the travelling crab 20 there is fastened via four casters 25 (a caster at each of four corners of the travelling crab) and four associated parallel hoisting wires 26 (only two shown in Fig. 1 of the drawing) a support platform 27 at four associated fixing points 28 (Fig. 2). The wires 26 are payed out and drawn in via respective drums on a common winch 29 and pulleys 29a in the arms 1 9.

The paying out and drawing in of the wires 26 can be controlled,besides, in a manner known per se by means of pilot control devices (not shown) which sense the movement of the ship 1 5 on the surface 14 of the sea, so that the support platform 27 can be subjected to a movement corresponding to the undulating movement of the ship relative to the rig.

A pair of holding wires 30 are guided by their respective winches 31 placed on respective sides of the hoisting device 1 7 (only the one wire 30 and the one winch 31 is shown in Fig. 1). The wires 30 pass in the position illustrated in Fig. 1 from the deck obliquely outwards and downwards towards the support platform 27. By means of the wires 30 the support platform can be maintained in place in a particular position outside the rig, provision being made for exerting a particular holding force in the wires 20 adjusted according to the level of the support platfform, that is to say adjusted according to the angle of attack between the wire 30 and the support platfform 27. Wire 30 is given out when said particular holding force is exceeded and is drawn in when said particular holding force falls below.The regulation of the holding force can take place according to a particular mode of operation established in advance, but in cases of strong winds or for other reasons the holding force can if necessary be regulated separately according to current conditions. By means of the wires 26 and the wires 30 the support platform 27 can be roughly adjusted in a relatively easy manner relative to rig 10 and ship 15.

The support platform 27 is provided with a holding means 32 which in a manner not shown further is adapted to engage and securely lock a corresponding holding means 33 on the passenger or freight unit or the container 16. The holding means 32 is supported pivotably mounted about a horizontal axis at the outer end of a pair of first parallel link arms 34. The link arms 34 are linked at the opposite end to a support shaft 35. The support shaft 35 is on opposite sides axially outside the respective link arm 34 linked to the one end of a respective arm of a pair of other parallel link arms 36. The link arms 36 are linked at their opposite end directly to a support means 37 in the support platform 27.

The link arms 34 can be raised and lowered about a shaft via a first pressure medium cylinder 38 which is inserted pivotably mounted between the one end of the support means 37 and a cross piece 39 between the arms 34, while the arms 36 can be correspondingly raised and lowered relative to the support means 37 via a second pressure medium cylinder 40 which is inserted pivotably mounted between the opposite end of the support means 37 and the shaft 35.

In the illustrated (Fig. 2), preferred embodiment the support means 37 is in the form of a rotary disc which is rotatably mounted about a vertical axis of the support platform 27.

It is possible according to the invention by means of the link arm arrangement 34-36 and the rotary disc 37 to finely adjust the holding means 32 relative to the support platform 27 angularly as well as spacedly relative to the vertical rotary axis of the rotary disc37 in the support platform 27. The movements of the holding means 32 relative to the support platform 27 can if necessary be remotely controlled from the ship or from the support platform by means of control devices known per se (not shown) which can be adjusted according to the undulating movements of the ship on the sea.

The device 1 7 including the support platform 27 and associated link arm arrangement 34-36 and rotary disc 37 for the holding means 32 can if necessary also be employed on the rig 10 for launching or for hauling in from the sea lifeboats or other life-saving appliances.

On the deck of the rig there can be arranged rail guides or similar arrangements (not shown further) for the transport of containers 16 (or life-saving appliances) to and from a storage location on the deck of the rig from and to the work area of the travelling crab 20 in the device 1 7.

Instead of the illustrated arrangement of rigid support arms 19 with travelling crab 20 there can be employed alternatively parallel derricks which can be swung about a common horizontal axis for lifting and lowering of the freight platform in step with the wave moments of the ocean.

Claims (3)

1. Arrangement for conveying units of cargo individually between an oceanic installation means and ocean-going means moveable on the surface of the sea in step with wave movements thereof and comprising means for hoisting and positioning a unit of cargo which includes a hoisting device for mounting on a deck of said installation means, a platform assembly supporting a device for holding said unit of cargo in clamping engagement therewith, said hoisting device being adapted via said platform assembly to move said holding device vertically and horizontally in controlled paths of movement and means connected to said installation means at a position below said hoisting device for maintaining said platform assembly in a predetermined horizontal position relative to said installation means by separate and/or continuous adjustment of said assembly at different levels between respective decks of said installation and oceangoing means.

2. An arrangement according to claim 1, wherein the hoisting device includes a pair of arms projecting upwardly above and outside the deck of the installation means and between which travelling crab means are mounted for reciprocating horizontal displacement from one extreme end of said arms to the other, the means for maintaining the platform assembly ina predetermined horizontal position includes tension-regulatable wiring to which a certain tensioning force is applied while said wiring permits limited movement against said force outwardly from said position, and the holding device is supported in said platform by a rotary disc which is rotatably mounted about a vertical axis of the latter, said holding device being connected to said disc via joint arm means controlled by pressure medium cylinder means.

3. Arrangements as claimed in claim 1 and substantially as described herein with particular reference to the accompanying drawings.