GB2045173A

GB2045173A - A rescue vessel

Info

Publication number: GB2045173A
Application number: GB8009362A
Authority: GB
Original assignee: GOETAVERKEN ARENDAL AB; Gotaverken Arendal AB
Current assignee: GOETAVERKEN ARENDAL AB; Gotaverken Arendal AB
Priority date: 1979-03-29
Filing date: 1980-03-20
Publication date: 1980-10-29
Also published as: NO800866L; NO148103B; SE7902799L; GB2045173B; NL8001619A; NO148103C; SE428910B

Abstract

A rescue vessel of the semi- submersible type is provided with a tower structure (15), which is vertically displaceable in relation to a deck (10) of the vessel, and which carries a rotatable and extendible communication ramp (19). The tower structure is preferably formed as a cylindrical pillar (16) mounted in one of the legs (11), which carry the deck (10). The communication ramp (19) is preferably rotatable along a limited sector of the periphery of the tower structure (15) only, the remainder of the periphery being used for vertical guides (33) serving an elevator (32). <IMAGE>

Description

SPECIFICATION A rescue vessel The present invention relates to a rescue vessel of the semi-submersible type for servicing stationary off-shore plants.

Experiences interalia from oil fields in the North Sea suggest that no suitable means for rescue work at exposed off-shore plants are available.

Ships and helicopters can only be used under certain weather conditions. Heavy seas will prevent a ship from reaching a platform, and cranes may be put out of action by fires. Storm and fog will limit, or even prevent the use of helicopters.

The transfer of skilled staff and necessary equipment to a platform, where an accident has occurred, as well as removal of injured persons therefrom may therefore be delayed. The final damages resulting from a minor incident may thus become aggravated.

The object of the present invention is to provide a rescue vessel, the applicability of which will not be limited due to local conditions such as heavy waves, storms and local fires.

According to the invention, a rescue vessel of the semi-submersible type for servicing stationary offshore plants comprises a tower structure vertically displaceable in relation to a deck of the vessel and carrying an axially extendible communication ramp, which is pivotable about the tower structure and carried thereby by means permitting movements in three degrees of freedom.

As will be evident from the following description, the invention allows the rapid establishment of a temporary but serviceable communication with a stationary platform.

The tower structure may comprise a pillar mounted into and displaceable in relation to a vertical leg supporting an edge portion of the vessel's deck, the end of the communication ramp adjacent to the tower structure being carried by a ball joint providing the three degrees of freedom, and the opposite end of the ramp being preferably provided with means facilitating a sliding or rolling movement in relation to a support.

The communication ramp may be mounted for pivotal movement within a limited sector of the periphery of the tower structure, the remaining portion of the periphery having guides for an elevator movable the full length of the tower structure. A control gondola containing means for operating the communication ramp as well as manoevering the vessel is preferably located well above the top of the tower structure.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of a rescue vessel according to the invention, in use, and Figure 2 shows on a larger scale, a detail arrangement along line II - II in Figure 1.

In Figure 1 reference numeral 10 denotes a deck of a vessel of the semi-submersible type. The deck is carried by vertical tubular legs 11,which are attached to the deck at its corners as well as midway at the longitudinal sides 12. The two rows of tubular legs are each supported by a pontoon 13. The latter may be operated at water surface level, or may be submerged by the introduction of water ballast. In submerged position the structure will not be noticeably influenced by wave movements, and the height of legs will ensure that the deck, also when the pontoons are submerged, will be out of reach of the waves.

The vessel is provided with a propulsion machinery of its own, and a satisfactory speed is attainable with the pontoons at surface position. Rotatable nozzle propellers 14 at the forward and rearward ends of each pontoon provide a good manoeverability also in a submerged condition.

The deck 10 carries a tower structure 15, which comprises a cylindrical pillar 16 supporting a small platform 17. The pillar is vertically displaceable in one of the main legs 11 of the vessel, by means of arbitrary machinery, known per se.

In Figure 1 a rack and pinion mechanism is indicated. A number of toothed racks 18 are mounted externally upon the shell of the pillar 16, and co-operate with pinions (not shown in Figure 1) arranged within the leg 11. Alternatively so-called climbing jacks can be used.

A communication ramp 19 suited as a gangway and for transportation purposes, is mounted at the platform 17, and comprises two tunnel-shaped components 20,21, of which the outer one, 20, is telescopically displaceable in relation to the inner component 21, which is mounted at the tower structure. The necessary movements are brought about by means of pressure fluid rams 22 and facilitated by roller means 23. The arrangement is schematically illustrated in Figure 2.

The tower platform 17 is rotatably mounted at pillar 16. Known arm permits different ways of operation. Figure 2 shows a motor 24 (electric or hydraulic) fixedly mounted within the leg, which co-operates with a central pinion 25 at the platform.

Wheels 26 carry the platform in relation to a top part 16a of the pillar.

The communication ramp 19 is mounted at the platform 17 by means of a device 27 permitting rotation in three degrees of freedom, for instance a ball joint. The opposite end of the ramp is provided with a roller support 28.

Carrying wires 29 run between a king-post 30 at platform 17 (see Figure 1) and the outward end of the inner tunnel member 21, and are operable to maintain the ramp in a substantial radial direction from the platform, and level therewith.

When establishing a temporary connection for rescue work at a stationary platform (a portion of which is denoted by 31 in Figure 1), the pillar 16 is moved upwards so that the platform 17 is brought up above the deck of platform 31. A suitable orientation and extension of ramp 19 is made when the deck 10 of the rescue vessel has been brought as close as possible to the platform 31, whereupon the pillar is lowered so the distal end of the ramp rests upon the platform deck.

Movements of the ramp 19 transversely to its longitudinal axis, as well as tilting movements in relation thereto, which would impede disembarkation and acess, are mainly eliminated by the flexible joint 27 at the lower platform.

The ramp is mounted for pivotal movement within a limited sector of the periphery of the tower structure, and in order to maintain a continuous connection between the ramp and the deck 10, an elevator 32 is provided at the tower structure. The elevator runs in guides 33 which extend along the full length of the pillar 16, and will thus communicate the tower platform 17 with deck 10, independently of the occasional position of the tower 15.

A control gondola 34 having means for governing the various functions at the tower structure, as well as the nozzle propellers 14, is mounted well above the tower platform 17. An operator can thus visually follow all occurrences during the engagement of ramp 19 with the platform 31.

When the tower structure is not used, pillar 16 is lowered into the leg 11 with the elevator at its top position at the tower platform 17, and with the contracted ramp 19 resting upon deck 10, as is indicated by broken lines in Figure 1.

Different constructional solutions are of course possible within the scope of the appended claims.

The ramp may thus be mounted upon a trolley movable along rails at the periphery of the tower platform, or at an annular element.

Claims

1. A rescue vessel of the semi-submersible type for servicing stationary off-shore plants, comprising a tower structure vertically displaceable in relation to a deck of the vessel, and carrying an axially extendible communication ramp, which is pivotable about the tower structure and carried thereby by means permitting movements in three degrees of freedom.

2. A rescue vessel as claimed in Claim 1, wherein the tower structure comprises a pillar mounted into and displaceable in relation to a vertical leg supporting an edge portion of the vessel's deck.

3. A rescue vessel as claimed in either Claim 1 or Claim 2, wherein the end of the communication ramp adjacent to the tower structure is carried by a ball joint providing the three degrees of freedom, and the opposite end of the ramp is provided with means facilitating a sliding or rolling movement in relation to a support.

4. A rescue vessel as claimed in Claim 3, wherein the communication ramp is mounted for pivotal movement within a limited sector of the periphery of the tower structure, the remaining portion of the periphery having guides for an elevator movable the full length of the tower structure.

5. A rescue vessel as claimed in any one of the preceding Claims, wherein a control gondola, containing means for operating the communication ramp as well as manoevering the vessel, is located well above the top of the tower structure.

6. A rescue vessel of the semi-submersible type for servicing stationary off-shore plants, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.