Marine escape systems are used to evacuate people from elevated fixed marine platforms such as oil rigs or high-sided ships. Such platforms and ships will be referred to collectively as "marine structures". One form of such a system includes a chute and one or more inflatable liferafts that are stored on a marine structure and, when required, deployed from the structure with the chute providing a passage from the structure to an inflated liferaft.

One proposal for such a system is shown in US patent 5,765,500. This system has a group of inflatable life rafts, including a reception raft and evacuation rafts, and a chute in the form of a stocking for transferring people from a ship to the life rafts. The life rafts are held deflated on a frame that can be lowered from a ship into the water where the life rafts inflate on the water and the frame continues beneath the water to stabilise the reception raft and the stocking via wires that pass from the frame to the ship through the reception raft and the stocking. The stocking leads to the reception raft so providing a pathway for people from the ship to the reception raft and thence to the life rafts.

The need to inflate the reception raft prevents the stocking from being connected to the reception raft and requires the stocking to be prevented from extending fully while the reception raft inflates. Once inflation of the reception raft is completed, the stocking is extended onto the reception raft. This delays the full deployment of the system into a usable condition and requires control of the deployment of the stocking, both of which are undesirable in an emergency evacuation.

According to a first aspect of the invention, there is provided a marine escape system for evacuating a marine structure comprising a chute, a buoyant non-inflatable platform and at least one inflatable life raft that are deployable from a packed disposition on the structure to a disposition in which the chute leads from the structure to the platform floating on the water and the platform leads to the inflated at least one life raft so providing a passage for people from the structure to the at least one liferaft.

By having a buoyant non-inflatable platform, the chute can be deployed fully immediately and evacuation can commence while the life raft is inflating.

It is also a problem that one end of the chute is fixed relative to the structure and the other end moves with the life raft and this can lead to twisting of the chute that, it turn, may make descent through the chute difficult.

According to a second aspect of the invention, there is provided a marine escape system for evacuating a marine structure comprising a chute, a platform and at least one inflatable life raft that are deployable from a packed disposition on the structure to a disposition in which the chute leads from the structure to the platform floating on the water and the platform leads to the inflated at least one life raft so providing a passage for people from the structure to the at least one liferaft, the platform being formed by inner and outer parts that are relatively rotatable to allow, on deployment, the life raft to swing relative to the chute.

In this way, any tendency of the life raft to twist the chute is mitigated.

The following is a more detailed description of an embodiment of the invention, by way of example, reference being made to the accompanying drawings, in which:-

Figure 1 is a schematic view of a marine structure with a marine escape system partially deployed over the side of the structure, the system including a housing, a chute, a platform and an uninflated life raft,

Figure 2 is a similar view to Figure 1 but showing the liferaft inflated,

Figure 3 is a perspective view from above and to one side of the platform and uninflated life raft of Figure 1, with the chute omitted for clarity,

Figure 4 is a perspective view from below and to one side of the platform of Figure 2, Figure 5 is a front elevation of the platform and uninflated life raft of Figures 3 and 4, Figure 6 is a plan view from above of the platform and uninflated life raft of Figures 3, 4 and 5,

Figure 7 is a side elevation of the platform and uninflated life raft of Figures 3 to 6, showing in broken line two bearing roller assemblies within the platform,

Figure 8 is a cross-section on the line A-A of Figure 6,

Figure 9 is a perspective view of one of the bearing roller assemblies of Figure 6,

Figure 10 is a detail view of a part of the platform of Figures 1 to 9 showing a spigot for mounting a pole for supporting a fence on the platform, Figure 11 is a similar view to Figure 10 showing the pole mounted on the spigot and attached to the spigot by a spring clip,

Figure 12 is a side elevation of the housing of Figure 1 with side panels removed for clarity, Figure 13 is a plan view from above of the housing of Figure 12, also with the side panels removed for clarity, and

Figure 14 is and end elevation of the housing of Figures 9 and 10 also with the side panels removed for clarity.

Referring first to Figures 1 and 2, the escape system comprises a housing 10, a chute 11, a platform 12, an inflatable life raft 13 and a stabilising system including a weight 14 and wires 15.

The chute 11 is of known type and may, for example, be as shown in W09722514 or NO 134291. Such a chute 11 comprises an outer generally tubular sleeve 15 with an entrance at an upper end 16 and an exit at the lower end 17. The interior of the chute 11 is provided with a formation or formations such as panels 60 that arrest the passage of a person through the chute 11 so that a person can descend through the chute 11 at a safe speed from the entrance to the exit. The platform 12 is buoyant and non-inflatable. Referring next to Figures 3 to 8, the platform 12 is formed in two parts - an inner part 18 and an outer part 19. Each part 18, 19 may, for example, be formed from a glass reinforced plastics material and may be filled with a foamed plastics material to prevent sinking in the case of damage. The inner part 18 is, as seen in Figures 3 and 8, generally cylindrical with a flat upper surface 20 and a flat lower surface 21 interconnected by a curved side wall 22. The side wall 22 is formed by upper and lower frusto-conical sections 22a, 22b (see Figure 8) whose greater diameter ends meet at the equator of the inner part 18. The outer part 19 has generally semi-circular upper and lower surfaces 23, 24, as seen in Figures 3 to 8, interconnected by a curved side wall 25a and a straight front wall 25b. A passage 28 extends between the upper and lower surfaces 23, 24 and receives the inner part 18 (see Figure 8).

The inner part 18 is positioned in the passage 28 and mounted for rotation relative the outer part 19 by two bearing roller assembles 25, one of which is shown in Figure 9. Each assembly 26 comprises flat metal strip 29 formed into a closed circle. Eight roller mountings 30 depend from one surface of the strip 29 at equiangular positions around the strip 29. Each mounting 30 comprises a base 31 and two spaced flanges 32 that carry a respective ends of a roller 33 so that the roller 33 is mounted for rotation about an axis slightly inclined to the axis of the strip 29.

As seen in Figures 7 and 8, a first assembly 26 is mounted at one end of the passage 28 and a second assembly 26 is mounted at the other end of the passage 28. The roller mountings 30 and the associated rollers 33 extend along the passage 28 and are located between the outer part 19 and the inner part 18 with the rollers 33 of the first assembly 26 angled to engage engaging the upper frusto conical side surface 22a of the inner part 18 and the rollers 33 of the second assembly 26 inclined to engage the lower frusto-conical side surface 22b of the inner part 18, as seen in Figure 8. In this way, the rollers 33 and the surfaces 22a, 22b position the inner part 18 within the outer part 19 and permit the inner part 18 to rotate relative to the outer part 19 about an axis that is normal to the upper and lower surfaces 20, 21, 23, 24 of the inner and outer parts 18, 19. The strips 29 overlie the associated ends 20, 21 of the inner part 18 to limit axial movement of the inner part 18 in the passage 28. The upper surface 20 of the inner portion 18 and the upper surface 24 of the outer portion 19 form a contiguous upper surface to the platform 12 with this upper surface extending around and outside the cross-sectional area of the chute 11.

The lower end 17 of the chute 11 carries a mounting ring 34 seen in Figure 3. The mounting ring is fixed to the upper end 20 of the inner part 18 of the platform 12 so that the lower end of the chute 11 is fixed to the platform 12 and located relative to the platform 12.

The curved edge of the upper surface 23 of the outer part 19 is surrounded by a mesh guard

35 that is supported by poles 36. Referring to Figures 10 and 11, the periphery of the upper surface 23 of the outer part 19 is provided with a succession of spaced spigots, one of which is shown at 61 in Figure 10. The poles 36 are hollow and, as seen in Figure 11, the lower ends of the pole 36 can be pushed over respective spigots 61 and be attached to the spigot by a spring clip 62 that passes through registering holes 63, 64 in the spigot 60 and the pole

36 to erect the poles 36 and hence erect the guard 35. The free ends of the guard 35 are carried by a plate 37 (see Figure 3 and Figure 4) that is hinged to the straight edge 38 of the upper surface 24 of the outer part 19.

The life raft 13 in a packed condition is carried by the outer part 19 and located below the plate 37 against the straight side wall 25b, as seen in Figures 3 to 8). The liferaft is connected to the plate 37 by a quick release system. The life raft 13 is inflatable by an inflation system (not shown). The life raft 13 is of known type with, as seen in Figure 2, a floor 40 surrounded by inflatable tubes 41 and provided with inflatable arches 42 that support a canopy 43. The life raft 13 is connected to the platform 12 by the quick release connection so that the exit to the chute 11 is adjacent to and facing an entrance (not shown) to the life raft 13.

The stabilising system has wires 15 that extend between the support 10 and the weight 14. The weight 14 is in the form of a perforated metal grid (see also Figure 1) that, prior to deployment, rests against the lower surface 24 of the outer part 19 of the platform 12 (as seen in Figures 3 to 8). The wires 15 are arranged in a circular pattern and pass through successive guide rings arranged at axially spaced positions on the chute 11. The wires 15 then extend through respective sleeves 43 in the inner part 18, whose ends are seen in Figures 3 and 6, before attaching to the weight 14, as seen schematically in Figure 1.

In use, the chute 11, the platform 12, the life raft 13 (deflated), the weight 14 and the wires 15 are packed into the housing 10. Referring next to Figures 12, 13 and 14, the housing 10 is formed by a framework of members 51 defining an enclosure of generally rectangular cross- section. The housing has a forward part 52 and a rear part 53. The forward part 52 contains the collapsed chute 11, the platform 12, the packed deflated liferaft 13 and the weight 14. The wires 15 extend from the weight 15 through the platform 12 and the chute 11, as described above, then over pulleys 54 to a winch 55 in the rear part 53. In the position shown in Figures 9, 10 and 11, the winch 55 holds the collapsed chute 11, the platform 12, the packed deflated liferaft 13 and the weight 14 in the undeployed position shown. The housing 10 may be carried anywhere on a marine structure shown schematically at 44 in Figure 12, which may , for example, be a ship or a fixed marine platform. The housing 10 may be located inboard of the structure and, when required for use, moved to the position shown in Figure 1 and in Figure 9 where an open base forward part 52 of the housing 44 overlies the water

To deploy the system, the winch 55 is actuated to unwind the wires 15 and the weight 14 descends with the platform 12 so extending the chute 11. On reaching the water 45, the weight 14 continues into and under the water 45 but the platform 12 and the life raft 13 float on the water surface, as seen in Figure 1. The chute 11, since it is connected to the inner part 18 of the platform 12, extends along the side 46 of the structure 44 to the platform 12. The winch 55 is then halted. As soon as the life raft 13 reaches the water 45, it inflates automatically using a known system that initiates inflation when water is detected, as seen in Figure 2. The weight 14 and the wires 15 stabilise the chute 11 and the platform 12.

A first person enters the entrance to the chute 11 at the support 10 and descends through the chute 11 to the exit. At the exit, the first person will move onto t the plate 37 in front of the exit and then erects the guard 35 to the position shown in Figures 4 and 5 via the spigots 61. The person can then walk over the plate 37 and enter the life raft 13. Subsequent people pass from the structure to the life raft 13 in the same way. Once the life raft 13 is full, it can be released from the platform 12 by means of the quick release arrangement and move away from the structure 44 either under its own power or by being towed. The ability of the outer part 19 of the platform 12 to rotate relative to the inner part 18 about an axis normal to the upper surface of the platform 12 and generally co-axial with the axis of the chute 11 allows the system to accommodate the life raft 13 swinging relative to the chute 11 and the structure 44 without twisting the chute 11. This may obviate the need for bowsing lines. The use of a buoyant but non-inflatable platform 12 allows immediate deployment of the platform 12 and allows the chute 11 to be permanently connected to the platform 12. This lowers evacuation times and increases the safety of evacuation. The area of the upper surface of the platform 12 outside the cross-section of the chute 11 allows an area for people exiting the chute 11 to collect before passing to the life raft 13 while other people exit the chute 11.

There are a number of important variations that may be made to the marine evacuation system described above with reference to the drawings.

The relatively rotatable inner and outer parts 18, 19 of the platform 12 may be useful even when the platform 12 is inflatable. In addition, the use of a buoyant non-inflatable platform 12 has the advantage of quick deployment even when it is formed in one-piece without the relatively rotatable inner and outer parts 18, 19.

The weight 14 could take any form. Although only one non-powered life raft 13 is shown, there will usually be a n umber of such life rafts 13 clustered around the platform 12 and accessed via the life raft 13 connected to the platform 12. The life raft or life rafts could be powered.

The platform 12 need not be shaped as described above. It could be any convenient shape.