INFLATABLE LIFERAFT

Abstract: A liferaft has a floor (21) and a roof (22) separated by an inflatable structure (13a-13f). When inflated, the floor (21) and the roof (22) are generally parallel to provide a liferaft that is reversible. Drainage passages (28) are provided extending between the floor (21) and the roof (22) prior to inflation so that, during inflation, water from the roof (22) can drain through the floor (21). Boarding ramps (19) are provided which include an inflatable tube (33) connecting with the inflatable structure (13a-13f) of the liferaft. The boarding ramps (19) are normally held deflated and packed against the inflatable structure (13a-13f) but, once they are released, air from the inflatable structure (13a-13f) inflates the tube (33) of the boarding ramp (19) to deploy the boarding ramp (19).

Description: INFLATABLE LIFERAFT The invention relates to liferafts. A known form of liferaft comprises two members connected by an inflatable structure which, when inflated, separates the members to form an enclosure, with one member forming a generally planar floor and the other member forming a generally planar roof to the enclosure. An example of a liferaft of this type is shown in US-A-3037218. One problem with a liferaft of this type occurs on inflation, particularly inflation under water. As the inflatable structure inflates, the floor and roof members are initially deployed in their planar configurations. The member that forms the roof can be covered with significant quantities of water and the weight of this water can be such as to prevent the inflatable structure inflating properly and deploying the liferaft . According to a first aspect of the invention, there is provided a liferaft comprising two members connected by an inflatable structure, which, when inflated, separates the members to form an enclosure, with one planar member forming a generally planar floor and the other planar member forming a generally planar roof to the enclosure, a passage being provided between the first and second members, the passage being open as the inflatable structure inflates to allow water to drain from the surface of the planar member. It is also a problem both with liferafts of the type shown in US-A-3037218 and with other liferafts, that evacuees need assistance in boarding the liferaft. It has previously been proposed to provide boarding ramps which project from the liferaft and up which evacuees can crawl to gain access to the liferaft. The projection of such boarding ramps from a liferaft can be a problem because they can interfere with the deployment of adjacent liferafts and, in addition, many of them may not be needed because, where there is more than one entrance, not all entrances may be used. According to a second aspect of the invention, there is provided a liferaft comprising an inflatable structure and an entrance ramp including at least one inflatable member, the inflatable member being in communication with the inflatable structure, the boarding ramp being held in a collapsed disposition and being releasable from said collapsed disposition, the release permitting the inflatable member to inflate with gas from the inflatable structure to deploy the boarding ramp . The following is a more detailed description of some embodiments of the invention, by way of example, reference being made to the accompanying drawings in which: - Figure 1 is a plan view from above of a deployed liferaft showing drainage passages and projecting boarding ramps, Figure 2 is a side elevation of the liferaft of Figure 1, viewed in the direction of the arrow X in Figure 1, Figure 3 is a side elevation of the liferaft of Figure 1 viewed in the direction of the arrow Y in Figure 1, Figure 4 is a cross-section on the lines A-A of Figure 2, Figure 5 is a plan view of one of the drainage passages shown in Figure 1, Figure 6 is a side elevation of the drainage channel of Figure 5, Figure 7 is a partial cross-section through a tube of the liferaft of Figures 1 to 4 showing one of the boarding ramps in a collapsed disposition and held against the tube by two sheets of material, Figure 8 is a similar view to Figure 7 but showing the boarding ramp in a deployed disposition, and Figure 9 is a partial side elevation of the liferaft in the direction shown in Figure 2 and showing the deployed boarding ramp to a larger scale. Referring first to Figures 1 to 4 , the liferaft is generally octagonal in plan view with two opposed side walls 10, two opposed end walls 11 and four corner walls 12 interconnecting the end walls and the side walls. As seen in Figures 2 and 3, the walls are formed by an inflatable structure including six stacked inflatable tubes 13a-13f. The two uppermost tubes 13a, 13b and the two lowermost tubes 13e,13f are continuous around the liferaft. Each of these tubes, 13a, 13b, 13e, 13f thus has eight corners 14. The corners of all the tubes 13a, 13b, 13c, 13d, 13e, 13f are thus vertically aligned. The two remaining tubes 13c, 13d are discontinuous at the side walls 10 and the end walls 11 to form opposed side entrances 15 and opposed end entrances 16, respectively. The tubes 13a-13f are formed from a rubberized fabric material in known fashion. Accordingly, their construction will not be described in detail. Each entrance includes a doorway formed by a sheet 17 of rubberized fabric provided with a securable cover 18 that can be rolled back, as seen in Figures 2 and 3. Each side entrance 15 is associated with a respective pair of boarding ramps 19. The construction and operation of these boarding ramps 19 will be described in more detail below. The uppermost tube 13a and the lower most tube 13f are each provided with a respective succession of water pockets 20 extending around the associated tube 13a, 13f. As shown, there are 32 water pockets 20 on each tube 13a, 13f. These water pockets 20 are of conventional design. The liferaft is also provided with a floor 21 and a roof 22. The floor 21 and the roof 22 are both made from rubberized fabric material of suitable strength. In this regard, it will be appreciated from the description of the drawings above and from the drawings themselves that the liferaft is reversible. The floor 21 could act as a roof and the roof 22 could act as a floor. The periphery of the roof 22 is sandwiched between the uppermost tube 13a and the next adjacent tube 13b. The periphery of the floor 22 is sandwiched between the lowermost tube 16f and the next adjacent tube 16e. As seen in Figure 4, the roof 22 and the floor 21 are separated within the liferaft by an inflatable internal structure comprising two pairs of cross beams 23, with the beams 23 of each pair separated by three spaced vertical columns 24. The beams 23 and the columns 24 are formed by inflatable tubes of known design. As seen in Figure 4, one cross beam 23 of each pair extends across the floor 21 between the side walls 10 and the other cross beam 23 of each pair extends across the roof 22 between the side walls 10. The two pairs of cross beams 23 are spaced apart along the length of the liferaft. The roof 22 and the floor 21 are provided with respective circular entrances 25 in register with one another. These entrances 25 are interconnected by a tube including a slanting diverter (not shown) . The tube can be open to allow access into the interior of the liferaft. The entrance 25 on the roof 22 is designed to be connected to an escape chute of the kind shown in our PCT Application Publication No. WO 97/22514. Accordingly, this will not be described in any further detail . The roof also includes three attachment points 26 by which gas cylinders may be mounted on the roof for supplying gas to the inflatable structure via an inflation system (not shown) of conventional type. There are also four tubes 27 extending between the roof 22 and the floor 21. These are to allow the drainage of rain water from the roof 22 and these tubes 27 may be provided with valves and outlets to allow such rain water to be collected and used as drinking water. The roof 22 and the floor 21 are also provided with three drainage passages 28. One such passage 28 is shown in Figures 5 and 6. With reference to those Figures, each passage 28 comprises a tubular sleeve 29 of flexible foldable material extending inwardly from an aperture 30 in the floor/roof 21/22. The aperture 30 is covered by a circular mesh 31. The end of the sleeve 29 remote from the mesh 31 is provided with a draw string 32. The drainage passages 28 in the roof are in register with drainage passages 28 in the floor 21. Before the inflatable structure is inflated, the sleeves 29 of all the drainage passages 28 are rolled back so that they leave the associated apertures unobstructed. Each drainage passage 28 in the roof 22 is then connected to the registering drainage passage 28 in the floor 21 by breakable threads 40 to form a continuous passage between the roof 22 and the floor 21. The purpose of this will be described below with the description of the deployment of the liferaft on inflation. As seen in Figure 1, two drainage passages 28 are located on a lateral axis 38 of the roof 22, each adjacent a respective side entrance 15. The third drainage passage is located on a longitudinal axis 39 of the roof 22 adjacent the intersection of this axis 39 with the lateral axis 38. The boarding ramps 19 are located adjacent the side entrances 15. Referring to Figures 1, 2, 3 and 8, each boarding ramp 19 comprises a U-shaped inflatable tube 33 connected at the base of the U to either the uppermost tube 13a or the lowermost tube 13 f. This base of the U-shaped tube is in gas communication with the associated tube 13a/13f. The space between the limbs of the U is filled with a mesh material 34. As also seen in Figures 2 and 8, two straps 35, forming hand grips or foot rests, are arranged between each boarding ramp 19 and the adjacent side entrance 15. As best seen in Figures 1 and 2, there are two boarding ramps 19 associated with each side entrance 15. One boarding ramp 19 extends radially from the upper tube 13a and the other boarding ramp extends radially from the lower tube 13 f. The boarding ramps 19 are on respective opposite sides of a vertical plane passing through the centre of the side entrances 15. Thus, there is provided a boarding ramp 19 usable whichever way the liferaft falls. As seen in Figure 5, when deflated, the U-shaped tube 33 and the mesh material 34 are rolled up against the associated tube 13a, 13f. They are held in this position by a retaining device formed by two sheets of material 36,37 attached at spaced points to the adjacent tube 13a, 13f. The first sheet 36 wraps around the folded boarding ramp 19 and then connects to the second sheet 37. This connection may be by any releasable device such as the engaging hooks and eyes sold under the trade mark VE CRO. Thus, when the sheets are separated, by being ripped apart by an evacuee, the pressure of air from the associated tube 13a, 13f inflates the U-shaped tube 33 and deploys the boarding ramp 19. The volume of the U-shaped tube 33 is so small in comparison with the volume of the associated tube 13a, 13f as to make little difference to the rigidity of the associated tube 13a, 13f. In use, the liferaft is deflated and packed and stored on an appropriate vessel. As mentioned above, it may be associated with an escape chute of the kind described in WO-A-97/22514. When required, the liferaft is thrown from the side of the vessel and, as it hits the water, the inflation system is actuated automatically. Thus, gas from the cylinders mounted on the attachment portions 26 of the roof 22 is supplied to the inflatable structure. This happens very quickly and the first effect is to form the upper and lower tubes 13a, 13f into their octagonal shape so spreading the floor 21 and the roof 22 into their octagonal shapes. This may occur when the liferaft is wholly or partially under water or when the liferaft is being covered by high seas. As the roof 22 is spread, water will collect on the roof 22. The weight of this water may be sufficient to withstand the forces of the expanding inflatable structure. This problem is overcome by the drainage passages 28. They are of sufficient size, number and location that water passes through these passages from the roof 22 to the floor 21 and so prevents such water inhibiting the inflation of the inflatable structure. In this regard, it will be appreciated that there is less inflatable structure at the side entrances 15 than elsewhere in the liferaft. The liferaft will thus have a tendency to fold around the lateral axis 38 extending between these side entrances 15. Thus, the drainage passages 28 located adjacent the side entrances 15 convey water from these areas. In addition, the interconnection between the passages 28 tends to trough the roof 22 in the centre of the liferaft so collecting the water in the region of the passages 28. As the pressure within the inflatable structure increases, the threads extending between the registering drainage passages 28 are broken and the inflatable structure continues inflating until it is fully deployed. This separates the sleeves 29 to break the passage between the roof 22 and the floor 21. By this time, all significant water will have been drained from the roof 22 and the drainage passages 28 are no longer needed. The use of a polygonal shape with registering corners to the tubes 13a- 13f provides a rigid structure since the corners are stiffer than the remainder of the tubes 13a-13f. Evacuees then board the liferaft preferably through the escape chute entrance 25. If, however, there are evacuees in the water, they can release the boarding ramps 19 as described above and clamber aboard using the straps 35 and the side entrances 15. They can also use the end entrances 16. Once within the enclosure formed by the liferaft, the evacuees can close the drainage passages 28 by use of the drawstrings 32. Those passages 28 in the floor can be used as balers. The tubes 27 can be used to collect water. It will be appreciated that there are a number of variations that can be made to the liferaft described above with reference to the drawings. The liferaft could have any convenient shape. This need not be a polygonal shape, it could be a circular shape. There may be more or less entrances. The boarding ramps 19 are optional. There may be more or less drainage passages 28. The drainage passages 28 could be constantly continuous between the roof 23 an the floor 21 even when the liferaft is fully deployed. The drainage passages 28 may be located other than as shown. The boarding ramps need not be used on a liferaft of the kind described above with reference to the drawings; they could be used on any suitable liferaft. The boarding ramps could have 10 any required configuration, they need not be formed by a U- shaped tube and a mesh. Any form of inflatable tube or tubes could be used with the structure receiving gas from an adjacent inflatable structure.

Claims: 11 CLAIMS 1. A liferaft comprising two members (21,22) connected by an inflatable structure (13a-13f) , which, when inflated, separates the members (21,22) to form an enclosure, with one member forming a generally planar floor (21) and the other member forming a generally planar roof (22) to the enclosure, a passage (28) being provided between the first and second members (21,22), the passage (28) being open as the inflatable structure (13a-13f inflates to allow water to drain from the surface of the member (21,22) forming the roof. 2. A liferaft according to claim 1 wherein the inflatable structure (13a-13f) is connected between respective peripheries of the members (21,22), the passage (28) being located inwardly of said peripheries. 3. A liferaft according to claim 2 wherein, prior to deployment, the members (21,22) are interconnected (40) in the region of said passage so that, as the inflatable structure (13a-13f) inflates, the member forming the roof (22) provides a depression around the passage (28) , for the collection of water. 4. A liferaft according to claim 3 wherein the interconnection (40) breaks after a predetermined inflation of the inflatable structure (13a-13f) . 5. A liferaft according to claim 4 wherein the interconnection comprises at least one thread-like member (40) that is broken as the inflatable structure (13a-13f) inflates to separate the members (21,22). 12 6. A liferaft according to any one of claims 1 to 5 wherein, after a predetermined inflation of the inflatable structure (13a-13f) , the passage is rendered discontinuous. 7. A liferaft according to claim 6 wherein the passage includes two openings (30) each on a respective member (21,22), and a tube (29) interconnecting the openings, the tube (29) separating at said predetermined inflation. 8. A liferaft according to claim 7 wherein said tube is formed by two tube portions (29) each extending from a respective opening (30) , each tube portion (29) having an end remote from the associated opening, said ends being separately connected. 9. A liferaft according to claim 8 wherein the tube portions (29) are formed from a foldable material, the tube portions (29) being so arranged as to maintain said passage (28) open prior to inflation of the inflatable structure (13a- 13f) . 10. A liferaft according to claim 8 or claim 9 wherein the end of each tube portion (29) is closable (32) after the tube portions (29) have separated. 11. A liferaft according to any one of claims 1 to 10 wherein the member forming the roof (22) is, when the inflatable structure (13a-13f) is inflated, symmetrical about two mutually orthogonal axes in the plane of the member (22) , the passage (28) being provided at or adjacent the intersection of said axes. 13 12. A liferaft according to any one of claims 1 to 11 wherein said passage is one of two or more such passages (28) . 13. A liferaft according to claim 13 when dependent on claim 11 wherein at least one passage (28) is arranged along one of said axes . 14. A liferaft according to any one of claims 1 to 13 wherein each member (21,22) has first and second sides, the inflatable structure including a plurality of inflatable tubes (13b-13d) which, when inflated, lie in respective parallel but spaced planes, said planes being generally parallel to the planes of the roof and floor members (21,22), the tubes (13a- 13f) extending side-by-side between the first sides of the members (21,22) at the peripheries of the roof and members (21,22) . 15. A liferaft according to claim 14 wherein two additional tubes (13a, 13e) are provided, each additional tube (13a, 13e) extending around the periphery of a respective member (21,22) on the second side thereof . 16. A liferaft according to claim 14 or claim 15 wherein at least one entrance (15,16) is provided in said tubes (13b- 13d) . 17. A liferaft according to any one of claims 14 to 16 wherein the liferaft has the shape of a polygon in plan view, each tube (13a-13f) including at least one corner forming a corner of the polygonal shape, the corners of the tubes (13a- 13d) being in vertical register at the corners of the polygonal shape when the inflatable structure is inflated. 14 18. A liferaft comprising an inflatable structure (13a- 13f) and an entrance ramp (19) including at least one inflatable member (33) , the inflatable member (33) being in communication with the inflatable structure (13a-13f), the boarding ramp (19) being held in a collapsed disposition and being releasable from said collapsed disposition, the release permitting the inflatable member (33) to inflate with gas from the inflatable structure (13a-13f) to deploy the boarding ramp (19) . 19. A liferaft according to claim 18 wherein the boarding ramp (19) is mounted on the inflatable structure (33) . 20. A liferaft according to claim 19 wherein the boarding ramp (19) is held in said collapsed disposition against the inflatable structure (13a-13f) . 21. A liferaft according to claim 20 wherein the inflatable structure includes an inflatable tube (13a, 13f), the boarding ramp (19) in said collapsed disposition being held against a side surface of the inflatable tube (13a, 13f), the boarding ramp (19) when deployed projecting radially outwardly of said tube (13a, 13f) . 22. A liferaft according to any one of claims 18 to 21 wherein a releasable holding device (36,37) is provided on the inflatable structure (13a, 13f) for holding the boarding ramp (19) in the collapsed disposition. 23. A liferaft according to claim 22 wherein the holding device comprises a sheet of foldable material (36) connected to the inflatable structure (13a, 13f) and wrapping around the boarding ramp (19) to hold the boarding ramp (19) in the 15 collapsed disposition. 24. A liferaft according to claim 23 wherein a second sheet of foldable material (37) is connected to the inflatable structure (13a, 13f) at a position spaced from the connection between the first-mentioned sheet of foldable material (36) and the inflatable structure (13a, 13f), the two sheets of foldable material (36,37) connecting together to hold the boarding ramp (19) in the collapsed disposition, the connection being separable to deploy the boarding ramp (19) . 25. A liferaft according to claim 25 wherein the connection is made using a plurality of hooks on one sheet (36) that engage a plurality of loops on the other sheet (37) , the connection being separable by pulling the sheets apart (36,37) . 26. A liferaft according to any one of claims 18 to 25 wherein the inflatable member (33) is generally U-shaped when inflated with a sheet of material (34) extending between the limbs of the member.

Inventors: BELL RICHARD EDWARD, MAGEE MARK, SCOTT THOMAS GEORGE, BELL, RICHARD, EDWARD, MAGEE, MARK, SCOTT, THOMAS, GEORGE
Applicants: BELL RICHARD EDWARD, MAGEE MARK, SCOTT THOMAS GEORGE, WARDLE STOREYS LTD, BELL, RICHARD, EDWARD, MAGEE, MARK, SCOTT, THOMAS, GEORGE, WARDLE STOREYS (SAFETY & SURVIVAL EQUIPMENT) LIMITED
Application year: 1999
Main classification: B63C9
IPC codes: B63B7, B63B27, B63C9