HK1017321B - Marine escape systems - Google Patents

Description

Marine escape system

The invention relates to a marine escape system.

Marine escape systems are used to evacuate personnel from offshore structures in the event of an accident. This structure may be a well rig or a vessel.

One form of marine escape system includes a gas-filled lifeboat into which people may enter to be evacuated. However, since the lifeboat is used on water and there is usually a considerable height difference (freeboard height) between the point on the structure where people are to be evacuated and the lifeboat, some form of passage is required between the two.

It is known to use chutes made of inflatable members extending from the point of evacuation to the lifeboat. The chute may extend directly onto the lifeboat or onto an inflated floating structure to which the lifeboat is tethered. Some vessels have freeboards up to 14-15 metres in height, so the chutes are quite long.

Recent shipwreck accidents have attracted considerable public attention, emphasizing the need to rapidly evacuate people from offshore structures in the event of an accident. As such, any vessel traveling at sea must be able to evacuate 400 people in 17 minutes and 40 seconds. In addition, there are requirements, such as that any marine escape system must be able to operate in climates where six-grade winds have a wave height of three meters, and must be able to be used for a considerable period of time while suspended alongside a vessel and sailing at sea.

Inclined chutes do not meet this requirement. As the chutes projecting from the sides of the vessel need to be stable to resist considerable lateral movement in inclement weather. In addition, to accommodate such climates, the chutes must be relatively strong, which can significantly increase the volume of the chutes.

Marine escape systems have also been proposed in which a pipe containing a helical chute is connected between the point of evacuation and the inflatable lifeboat. See, for example, WO-A-84/D2658, WO-A-94/01324 and US-A-3994366. Persons entering the passageway at the point of egress slide along a helical path within the passageway and exit the outlet at the lower end of the tube.

Pipes are more stable than chutes in the harsh weather against lateral movement. However, the pipe has a problem of adapting to the wave height, which, as mentioned above, changes the topsides height of the vessel by six meters or more.

It has previously been proposed to accommodate this by providing a tube of flexible material having a maximum length sufficient to accommodate the wave height. The pipe is hung from an evacuation point on the structure and excess length is deposited on the platform, and people are evacuated to the platform when the wave height is less than a maximum. The pipes will at least extend from the platform or be stacked onto the platform, as the distance between the platform and the evacuation point will vary. This is disclosed in WO-A-94/01324.

The problem with this arrangement is that a single outlet cannot be provided. To address this problem, it has previously been the practice to provide such pipes with a plurality of outlets spaced along the length thereof to enable evacuated persons to exit the outlet closest to the platform when they reach the platform. This is not satisfactory because personnel may come out too early or the position of the platform may change such that the selected outlet suddenly becomes unsuitable.

According to the present invention there is provided a marine escape system having a passageway for personnel having an inlet at one end and an outlet at the opposite end; at least one support is provided for the passageway between the inlet and the outlet, the support being suspended by at least one first elongate elastic member, at least one second elongate elastic member extending from the support to the outlet, the at least one second elongate elastic member being more elastic than the at least one first elongate elastic member, whereby a portion of the passageway between the outlet and the support will elongate and contract earlier than a portion of the passageway between the inlet and the support, the entire passageway being extendible and contractible to accommodate changes in the distance between the inlet and the outlet.

The wave height can be accommodated by varying the length of the tube between the inlet and outlet while maintaining a single outlet.

According to a second aspect of the invention there is provided an escape chute having an elongated tube extending generally vertically and a series of spaced apart elements within the tube which define with the tube a path for a person to pass through.

Some embodiments of the invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a side elevation view of a watercraft, schematically illustrating a marine escape system including two escape chutes leading from emergency exits to an inflatable lifeboat at sea;

FIG. 2 is a side elevational view of a portion of the escape chute;

fig. 3 is a perspective view of a portion of the escape chute of fig. 2;

fig. 4 is a cross-sectional view of the escape chute of fig. 2 and 3;

FIG. 5 is an elevational view of one side of another version of the right hand section of the escape chute;

FIG. 6 is a front elevational view of the right-hand section illustrated in FIG. 5;

FIG. 7 is an elevational view of the other side of the right-hand section of FIGS. 5 and 6;

FIG. 8 is a rear elevational view of the right-hand section illustrated in FIGS. 5 through 7;

FIG. 9 is a diagrammatic view of the outer wall of the right-hand section of FIGS. 5 through 8;

FIG. 10 is a diagrammatic view of the slide path assembly of the right-hand section of FIGS. 5 through 9;

fig. 11 is a partial cross-sectional view of the right-hand section of fig. 5 through 10, showing the slide path and outer wall in an extended state,

fig. 12 is a view similar to fig. 11, showing the outer wall in a flattened condition,

FIG. 13 is a view similar to FIG. 12, except that the entire right hand section and outer wall are shown in a flattened condition;

fig. 14 is an elevation view of one side of a right-hand section of another form of escape route;

FIG. 15 is a front elevational view of the right-hand section;

FIG. 16 is an elevation view of the other side of the left hand section;

FIG. 17 is a rear elevational view of the right-hand section of FIGS. 14 through 16;

FIG. 18 is a view similar to FIG. 14, except that the outer wall of the left-hand section of FIGS. 14 to 18 is shown in a flattened condition;

fig. 19 is an elevational view of one side of the bottom section of an alternative escape chute;

FIG. 20 is a front elevational view of the bottom section of FIG. 19;

FIG. 21 is an elevational view of the other side of the base section of FIGS. 19 and 20;

FIG. 22 is a rear elevational view of the bottom section of FIGS. 19 to 21, an

Fig. 23 is a view similar to fig. 19, except that the outer wall of the bottom section of fig. 19 to 22 is shown in a flattened condition.

Referring first to fig. 1, the escape system for a ship has two emergency exits 10 leading to respective escape chutes 11. Each escape chute terminates in a respective lifeboat 12 and two further lifeboats 12 are provided. It will be appreciated that the escape system for a ship is normally held in a vessel on the side of the ship and deployed in an emergency, in a manner to be described below.

Referring now to figures 2, 3 and 4, each escape chute 11 has a closed tube 13 in the form of a spiral of foldable material, such as fabric. The tube 13 may be provided with reinforcing strips 14 at intervals along its length to keep the tube 13 clear.

The tube 13 may be supported by a plurality of hoops 15 spaced along its length. There is a total of eleven cuffs 15 as shown in figure 2, but they may be increased or decreased as required. Each ferrule 15 is made of a rigid alloy or carbon fiber material. A typical ferrule diameter may be 2.3 meters.

As best seen in fig. 3 and 4, each ferrule is provided with six fixing points 16, spaced apart from each other at equal angular intervals on the periphery of the ferrule 15. The purpose of which will be explained below.

As can be seen from figures 2, 3 and 4, each ferrule 15 is positioned at a point along the length of the tube 13 at which the separation between the axis 17 of the tube 13 and the axis 18 of the ferrule is at a maximum. The tube 13 is held in this position by five flexible but inelastic elongate members 19 and seven flexible but elastic elongate members 20. The non-elastic element 19 may be a cord and the flexible element 20 is preferably made of an elastic elastomer material.

The non-elastic member 19 extends from equiangularly spaced points 21 on a peripheral portion of the tube 13 between two parallel planes, one passing through the tube axis 17 and the other passing through the ferrule axis 18, both of which planes are perpendicular to the ferrule radius extending between the ferrule axis 18 and the tube axis 17, so that said portion is the portion of the tube 13 facing the ferrule axis 18. In this way, the non-elastic member 19 fixes the maximum separation between the tube axis 17 and the ferrule axis 18, thereby preventing further approach of the tube 13 to the ferrule 15.

An elastic member 20 is also connected between the tube 13 and the ferrule 15. Two of the resilient members 20 extend outwardly from two diametrically opposed points 22 on the periphery of the tube 13 and lie in a plane containing the tube axis 17 and perpendicular to a radius extending from the ferrule axis through the tube axis. The remaining resilient members 20 are angularly spaced at equal angles between these two points 22 on the periphery of the tube 13.

The resilient member 20 thus allows the tube 13 to move to narrow the spacing between the tube axis 17 and the ferrule axis 18. At any time, however, the resilient members 20 are tensioned so that they provide a force tending to return the tube 13 to the position shown in figure 3, which would result in a helix angle of 30 ° for the coil 13.

The band and the band 15 are also interconnected by two flexible materials, a non-elastic flexible member 23 and an elastic flexible member 24.

The non-elastic member 23 extends downwardly from the top support 25 of the escape chute 11 to the sixth hoop 15 as shown in fig. 2. A total of six flexible members 23 are angularly spaced from one another about the hoops 14 and connect each hoop to one of the anchor points 16. In this way, the non-elastic flexible element 23 fixes the maximum distance between the first and sixth hoops.

The sixth strap 15 is connected to the associated lifeboat 12 by a resiliently flexible member 24. There are three different types of resiliently flexible members 24 which have different degrees of resilience. The first elastic members 24a are minimally elastic and extend between the sixth cuff and the eighth cuff. There are six flexible elements 24a which are attached to the fixing points 16 of the sixth, seventh and eighth hoops.

The second resiliently flexible member 24b is more resilient than the first resiliently flexible member 24 a. There are six such pieces that extend between the sixth cuff 15 and the tenth cuff 15 and are joined to the fixing points 16 of these cuffs.

A third resiliently flexible member is coupled between the tenth hoop and the associated lifeboat 12, which are more resilient than the second resiliently flexible member 24 b. There are six such pieces 24c which are attached to the attachment points 16 of the tenth and eleventh straps 15 and to the attachment points (not shown) on the lifeboat 12.

A typical first resiliently flexible element 24a may be 19mm in diameter and may extend over 4000mm under a load of about 7.5N. A typical second resiliently flexible element 24b may be 16mm in diameter and may extend over 4000mm under a load of about 5.5N. A typical third resiliently flexible element 24c may be 12.5mm in diameter and may extend over 4000mm under a load of 3.5N.

The outside of this structure may be enclosed by a fabric tube (not shown) of generally the same diameter as the ferrule 15.

Each outlet 10 is connected to a support 25 at the upper end of the escape chute 11. This leads the outlet from the vessel to the inlet at the upper end of the chute 11.

The lifeboat 12 is formed by an air tube 25 and covered by a fabric 27. The lifeboat is generally rectangular in plan view as shown in figure 1 and held together in a rectangular matrix. The lower end of each escape chute 11 is provided with an outlet in its associated lifeboat.

Before use, the lifeboat 12 is deflated and stored together with the chute 11 in a container mounted at the exit 10 on the boat. It will be appreciated that escape chute 11 requires very little space since individual hoops 15 can be stacked together when collapsed and the fabric of tube 13 can be easily collapsed. The parts 23, 24 can also be collapsed into a smaller space.

In the event of an emergency, the lifeboat 12 and escape chute 11 are ejected from the container and the exit 10 is opened. When they are deployed, the lifeboat 12 is inflated with a source of pressurized gas (not shown) in a conventional manner. The lifeboat 12 is provided with a water bag (not shown) which is filled with water when the lifeboat 12 is bumped into the sea surface. The weight of the lifeboat 12 and the length of the non-elastic member 23 and the elastic member 42 are chosen such that under calm sea and normal loading of the vessel the non-elastic member 23 is sufficiently extended and the elastic member 24 is under tension. As described above, typical elastic members 24 may provide an elongation therebetween of over 12000 mm. In this case it is possible to arrange for the elongation of the elastic element 24 to be 6000mm on a calm sea.

The elongation of the elastic member 24 increases the distance between the sixth hoop 15 and the associated lifeboat. This will increase the helix angle of the tube as shown in figure 2. This in turn straightens the tube so that the flexible resilient member 20 connecting the tube 13 to the cuff 15 extends to move the tube 13 towards the axis 18 of the cuff 15.

When so deployed, personnel can enter the entry port at one end of the tube 13, slide through the tube in a helical path and emerge within the lifeboat. Therefore, they are not exposed to the outside throughout the entire journey from the ship to the lifeboat.

The waves will move the lifeboat 12 up and down relative to the outlet 11 to increase and decrease the freeboard height of the boat. This is compensated by the elongation and contraction of the elastic member 24 and the elongation and contraction of the tube 13. The third elastic member 24c will first elongate, followed by extension of the second elastic member 24b, followed by extension of the first elastic member 24 a. The weight provided by the lifeboat 12 at the end of the tube 13 is sufficient to cause this elongation without lifting the lifeboat 12 above the sea surface. The position of the axis 17 of the tube 13 will also change, this change being compensated by the elastic element 20. When this occurs, the helix angle of the tube 13 will also change.

It will be appreciated that many variations of the marine life saving system described above with reference to the accompanying drawings are possible.

Two escape chutes 11 are not necessarily required, and one or three or more escape chutes may be used. Each escape chute need not necessarily terminate within the lifeboat 12 but may terminate on a floating platform to which the lifeboat is tethered.

In an alternative arrangement the pipe 13 may be split into two parallel pipes at some point along its length to allow persons evacuated from the vessel to descend from one pipe and then the other in a sequence.

The connection between the hoops need not be made with a flexible member 24, but may be made with any suitable extendable member.

Although the above described solution is only elastically extendable and retractable in a section from the sixth band 15 to the lifeboat 12, it is also elastically extendable and retractable over the entire length from the lifeboat to other bands 15 than the sixth band.

It will also be appreciated that the weight of the lifeboat 12 at the end of the escape chute 11 tends to keep the chute in a vertical position. This reduces the requirements with regard to any stability of the position of the escape chute 11 relative to the ship.

The evacuation path of the evacuees need not necessarily be helical, but could be by a helical chute open at the top, or by a tube arranged at intervals along its length with a series of alternately oppositely facing planes each inclined at an angle to the length of the tube. A person entering the pipe may slide down one ramp first and then turn to slide down the opposite ramp face on the opposite side, alternating until the end of the pipe is reached. In this case, the ramp may be made of a flexible material to accommodate the elongation and contraction of the tube.

Referring next to figures 5 to 22, alternative forms of escape chutes as shown in figure 1 will now be described.

In this embodiment, the escape chute is composed of three different sections, a left-hand section as shown in fig. 5 to 13, a right-hand section 31 as shown in fig. 14 to 18, and a bottom section 32 as shown in fig. 19 to 23. The right-hand and left-hand sections 30, 31 are alternately joined end-to-end to form a chute in a manner to be described in more detail below, while the bottom section 32 is joined at the end in a manner also to be described in more detail below.

Referring first to fig. 5 through 13, the left-hand compartment 30 is comprised of a compartment wall 33 (best seen in fig. 9) and a slide path 34 (best seen in fig. 10). The partition walls 33 are generally cylindrical and made of a waterproof fabric of high strength, as shown in fig. 9. As can be seen in fig. 5 to 8, the compartment wall 33 has an upper edge 35 on which is provided a series of circumferentially spaced sleeves 36. The compartment wall 33 also has a lower edge 31 on which is provided a similarly spaced sleeve 38. And a series of sleeves 39 extending around the compartment wall 33 intermediate the upper edge 35 and the lower edge 37 to form a passageway to be blocked around the compartment wall.

The function of the sleeves 36, 38 and the sleeve 39 will be explained below.

The partition wall 33 includes a slide path 34, as best seen in fig. 10, the slide path 34 is also made of a strong waterproof fabric.

The slide path 34 has a back 40 with a rounded upper edge 41 and a convexly curved side edge 42. The side of the back 40 opposite the side edge 42 is straight and the lower edge 44 of the back 40 opposite the upper edge 41 is also straight. The diverting surface 45 has one edge connected to the straight edge 43 of the back surface 40, and the plane in which the diverting surface 45 lies forms an obtuse angle with the plane of the back surface 40. The peripheral surface 46 is curved between the lower part of the outer edge 47 of the deflecting surface 45 and the lower part of the rear side edge 42. This forms a converging closed passage or pocket between the back surface 40, the diverting surface 45 and the peripheral surface 46. The passage terminates in an opening 48.

The slide path 34 is connected to the inside of the partition wall 33 in the following manner.

The upper edge 41 of the slide path 34 is positioned such that the apex of the upper edge 41 is adjacent the upper edge 35 of the compartment wall 33 when attached to the inner surface of the compartment. The connection then continues around the upper end edge 41, the side edges 42 and the outer edge 47 of the diverting surface 45 until near the level with the sleeve. In addition, the peripheral surface 46 has an upper edge 50 that is also connected to the inner or outer surface of the compartment, also generally at the level of the sleeve.

Thus, as seen in FIGS. 5 through 8, back 40 extends diagonally across compartment wall 33 between upper edge 35 and lower edge 37. As shown in fig. 7, the diverting surface 45 forms an obtuse angle with the back surface 40. Funnel outlet 49 extends downwardly beyond lower edge 37 of compartment wall 33. Thus, as shown in FIG. 13, the lower portion of the partition wall 33 can be crushed downward without affecting the state of the slide path. This purpose will be explained below.

The right-hand section 31 will now be described with reference to fig. 14 to 18. As shown in these figures, the right-hand section is largely identical to the left-hand section 30, and therefore common parts will not be described in detail but will be identified with the same reference numerals. The right-hand section 31 differs from the left-hand section 30 in that the slide path of the right-hand section 31 is rotated by 90 ° relative to the sleeves 36, 38 compared to the slide path 34 of the left-hand section 30. This allows the sleeves 36, 38 to form a channel in a manner to be described below.

The bottom section 32 is formed by an annular partition wall 55 having an upper edge 5b provided with a sleeve 56 identical to the sleeve 36 on the upper edge 35 of the partition wall 33 of the left-hand section 30. However, the intermediate wall 55 is provided with a sleeve 39, which is also free of a sleeve on its lower edge 58. The length of the partition wall 55 between the upper edge 56 and the lower edge 58 is longer than the length of the partition wall 33 of the left-hand partition 30 between the upper edge 35 and the lower edge 37 thereof. The partition wall 55 contains a slide path 59 identical to the slide path 34 in the left-hand section 30 and the slide path 59 is connected to the partition wall 55 in the same manner as the slide path 34 is connected to the left-hand section 30. Thus, as can be seen from figures 18 to 22, the funnel outlet 49 extends only a short distance above the lower edge 58 of the compartment wall 55. The back 40 may be perforated to allow water to drain through the back 40.

The chute is formed by left and right hand sections 30, 31 alternately connected together until the desired length is reached. The sections are arranged such that the back 40 of each slide path 34 is inclined at 90 deg. relative to the front and rear back 40. The tilting is performed successively in the same direction (clockwise or counterclockwise).

The compartments 30, 31 are interconnected by a hoop (not shown). The sleeve 38 on the lower edge 37 of one slide path 34 of the left or right hand section 30, 31 fits into the space between the sleeves 36 on the upper edge 35 of the next slide path 34 of the right or left hand section 31, 30, thus forming a continuous tubular passage within which the ferrule 52 connects the two sections. These hoops may be made of metal, for example.

The bottom section 32 is similarly connected to the lowermost left or right hand section 30, 31 by a ferrule 52 passing through the channel formed by the sleeves 36, 38.

The sleeve 39 between the upper and lower edges 35, 37 of each compartment wall 33 is also threaded with a ferrule 53. The function of these hoops 52, 53 is to keep the compartment walls 33, 55 open while allowing them to collapse.

The cuffs 52 on the upper and lower edges 35, 37 of the compartment walls (rather than the central cuff 53) are interconnected by elastic members arranged in the same manner as the elastic members connecting the cuffs 15 together in the embodiment described above in connection with figures 2 to 4. An escape chute thus formed is also connected between the ship and the lifeboat 12 in the same manner as the escape chute described above in connection with fig. 2 to 4.

This embodiment of the escape chute essentially forms a spiral path between the uppermost sections 30, 31 and the bottom section 32. Persons entering the uppermost sections 30, 31 initially sit on the back side 40 of the first slide path 34. When he slides down the back face 40, it engages the deflecting face 45, is twisted by the deflecting face 45 in the counter-clockwise direction and then, via the funnel outlet 49, engages the back face 40 of the next successive sector 30, 31, which is inclined by 90 ° to the back face 40 from which he just left. Both the function of the funnel outlet and the inclined arrangement of the back face 40 are such that the person descends slowly with a frictional engagement with the material of the sliding path and the restriction provided by the funnel outlet. Thus, after entering the escape chute, the person can follow a spiral path through the following sliding path 34 at a safe rate until reaching the bottom section. When a person leaves the floor section 32 through the funnel outlet 49 he can enter the lifeboat 12 as described above in connection with figures 1 to 4.

As the distance between the lifeboat 12 and vessel changes, these changes may be accommodated by collapsing and extending the chutes under the control of the flexible members 24 which progressively flatten the chutes upwardly from the floor space 32, as described above in connection with figures 1 to 4.

This collapsing of the walls 33, 55 does not cause the slide paths 34 to collapse the poles, due to the manner in which the slide paths 34 are connected to the partition walls 33, 55. When the escape chute is shortened in length, they simply fold over each other so that when a person leaves the funnel outlet of one section 30, 31, he can engage the back 40 of the next successive section 30, 31, except at a lower point than when the sections 30, 31 are fully extended.

It will be appreciated that many variations of this second form of escape chute are possible. The sliding path need not be as illustrated and may have any shape so long as it guides and controls the path of a person through the chute. The compartments 30, 31, 32 need not be connected by sleeves 36, 38 as described above, but may be connected by other suitable means. The partition walls 33, 55 are not necessarily continuous, and may be notched.

Claims (33)

1. A marine escape system comprising a passageway (11) for persons, having an entrance opening (10) at one end and an exit opening (12) at the opposite end, there being at least one support (15) for the passageway between the entrance opening and the exit opening, the support being suspended by at least one first elongate resilient member (24), at least one second elongate resilient member (24) extending from the support (15) to the exit opening, the at least one second elongate resilient member (24) being more resilient than the at least one first elongate resilient member (24), whereby a portion of the passageway (11) between the exit opening and the support (15) is extendible and contractible prior to extension and contraction of a portion of the passageway between the entrance opening and the support (15), said passageway being extendible and contractible to compensate for changes in the distance between the entrance opening and the exit opening.

2. A system according to claim 1, characterised in that a further support (15) is provided between the first said support (15) and the outlet (12), at least one second elongate resilient member (24) being connected between the first said support and the further support (15), and at least one third elongate resilient member extending from the further support (15) to the outlet (12) whereby the passageway (11) is initially extended and retracted between the outlet (12) and the further support (15), then between the further support (15) and the first said support (15), and finally between the first said support (15) and the inlet (10).

3. A system according to claim 1, characterised in that at least one first elongate elastic member (24) is connected between an upper support (15) and a first of said supports (15), said upper support (15) being at a distance from the inlet of the channel (11), and the connection between said inlet and said upper support (15) being non-elastic.

4. A system according to claim 3, wherein the connection between said inlet and said upper support comprises at least one elongate non-resilient member (23).

5. A system according to any of claims 1 to 4, wherein the or each support is formed by a collar (15) extending around the passage.

6. A system as claimed in claim 5 when dependent on claim 2, wherein a plurality of hoops (15) are provided at spaced apart locations along the passageway between the inlet and the outlet, said hoops (15) forming said support.

7. A system according to claim 1, wherein each at least one elongate resilient member (24) comprises a plurality of elongate resilient members (24), each resilient member (24) extending generally parallel to the length of the channel (11) and being spaced around the channel (11).

8. A system according to claim 1, characterised in that the channel (11) is formed by a tube of foldable material.

9. A system according to claim 5, characterised in that the passage is a spiral-shaped chute (13) extending from the inlet to the outlet.

10. A system according to claim 9, wherein the chute is a closed spiral tube (13).

11. A system according to claim 9 when dependent on claim 5, wherein the spiral chute (13) is connected to the hoop (15) so as to locate the spiral chute relative to the hoop.

12. A system according to claim 11, characterised in that the centre line of the spiral chute (13) is eccentrically located relative to the axis of the hoop (15) as the chute extends past the at least one hoop (15), the connection between the spiral chute (13) and the hoop (15) allowing the centre line (13) of the spiral chute (13) to move between a maximum spacing and a minimum spacing relative to the axis of the hoop (15) to compensate for elongation and contraction of the spiral chute (13).

13. A system as claimed in claim 12, wherein a plurality of angularly spaced flexible links (19, 20) extend between the hoop (15) and the spiral trough (13) on said at least one hoop (15), wherein the longer links (19) are inextensible to limit the maximum separation of the centreline and the axis, and the shorter links (20) are resiliently extendable to allow movement of the centreline towards the axis.

14. A system as claimed in claim 9, wherein the passageway (11) comprises a series of alternately oppositely facing flats (40) spaced along the length of the tube (30), each of the flats (40) being inclined relative to the length of the tube.

15. A system according to claim 14, wherein at least some of the planar surfaces (40) are made of an elastically extensible material to compensate for elongation and contraction of the tube.

16. The system of claim 1, wherein the outlet is on an inflatable structure.

17. A system according to claim 16, wherein the inflatable structure is a lifeboat (12) and the tube outlet is located in the lifeboat.

18. An escape chute comprising an elongated generally vertically extending tube (30, 31, 32) and a series of partitions (34) within the tube, each partition (34) being formed by a ramp (40) extending across the tube, the ramp (40) having an upper edge (41) connected to the tube (30, 31, 32) and a lower edge (44) spaced from the tube (30, 31, 32), characterised in that a funnel outlet (49) depends vertically from each opening (48) to provide a vertical portion of said path (34), the ramp (40) and funnel outlet (49) together with the tube forming a path for a person to slide through the tube (30, 31.32).

19. An escape chute according to claim 18, wherein the ramp (40) and the funnel outlet (49) are arranged in sequence along the tube (30, 31, 32) such that a person sliding through the tube (30, 31, 32) will come into contact with a series of ramps (40) and funnel outlets (49).

20. An escape chute according to claim 18, wherein each ramp (40) is caused to rotate about the tube axis relative to the ramps (40) of the preceding and succeeding members (34).

21. An escape chute according to claim 20, wherein successive inclined surfaces (40) are rotated 90 ° relative to each other in the same direction, so that the sliding path is a spiral path.

22. An escape chute according to claim 18, wherein each ramp (40) has first and second spaced apart side edges (42, 34), the first side edge (42) being connected at least in part to the tubes (30, 31, 32) and the second side edge (43) being connected to a deflector surface (45) which is connected to the tubes (30, 31, 32), the deflector surface lying in a plane which is at an obtuse angle to the plane of the associated transverse ramp (40), the deflector surface (45) being arranged to impart a twisting force to the evacuee in the same sense as the relative rotation between successive ramps (40).

23. An escape chute according to claim 18, wherein a peripheral surface (46) extends around the lower portion of each transverse ramp (40) to form a pocket with the ramp (40) and terminates at its lower end in an opening (48) leading to the next ramp.

24. An escape chute according to claim 23 wherein each peripheral surface (40) has an upper edge (50) connected to the tubes (30, 31, 32) and an edge having a lower edge defining said opening.

25. An escape chute according to claim 24, wherein each transverse ramp (40) is connected to the tubes (30, 31, 32) only along the portion of the edge (41) of the transverse ramp (40) which is above the line at which the upper edge (50) of the associated peripheral surface (46) is connected to the tubes (30, 31, 32) so that the portion of the tubes (30, 31, 32) below the upper edge (50) of the peripheral surface can be crushed upwardly without crushing the associated path component (34).

26. An escape chute according to any of claims 18 to 25 wherein at least one of said transverse inclined surfaces (40) is perforated.

27. An escape chute according to any one of claims 18 to 25 wherein each funnel outlet (49) is sized to closely fit the circumference of a person passing therethrough such that the rate of descent of the person during passage is delayed.

28. An escape chute according to any one of claims 18 to 25 wherein the pipe is formed from a plurality of annular walls (30, 31, 32) of flexible material, each wall surrounding a respective element, the walls being connected end to form said pipe.

29. An escape chute according to claim 28, wherein a collar (53) extends around the connection between successive walls (30, 31, 32).

30. An escape chute according to claim 29, wherein each wall (30, 31, 32) has an upper edge (35, 56) and a lower edge (37, 58), each of said edges comprising a plurality of circumferentially spaced sleeves (36; 57), the sleeve (36, 57) of each of said edges (35; 56; 37; 58) forming a channel for receiving said collar (53) with the sleeve (36, 57) of the adjacent edge (35; 56; 37; 58) of the adjacent wall (30, 31, 32).

31. An escape chute according to claim 29 or 30, wherein at least some of the walls (30, 31, 32) extend with a further hoop (53) around the location spaced between said connecting portions.

32. An escape chute according to claim 31, wherein said further collar (53) is located at the same level as the junction of the peripheral surface (46) and the wall (30, 31, 32) according to claim 23.

33. A system according to claim 1, wherein the passageway is formed by an escape slot according to 18.