GB2052398A

GB2052398A - Inflatable liferaft

Info

Publication number: GB2052398A
Application number: GB8021813A
Authority: GB
Original assignee: RFD Inflatables Ltd
Current assignee: RFD Inflatables Ltd
Priority date: 1979-07-04
Filing date: 1980-07-03
Publication date: 1981-01-28
Also published as: GB2052398B

Abstract

In an inflatable liferaft having a support panel (12 or 13) which serves as a floor and an inflatable buoyancy tube (11) extending round the support panel, the inner and outer walls of the buoyancy tube are joined together along their upper and lower edges and further joined together along join lines (21) between the upper and lower edges to divide the interior of the buoyancy tube into compartments (24-27). The join lines between the upper and lower edges extend in directions transverse to the upper and lower edges and are spaced apart along the length of the buoyancy tube, thereby to restrain separation of the inner and outer walls in such a manner that a vertical cross-section of the buoyancy tube, when inflated, is vertically elongate. The liferaft may be reversible and a boarding arrangement (14, 15) for such an embodiment is described which includes two opposed entrances. <IMAGE>

Description

SPECIFICATION Inflatable liferaft The present invention relates to inflatable liferafts having a floor and a buoyancy tube extending around the floor.

In inflatable Iiferafts hitherto proposed the buoyancy tube extending round the floor is provided by one or more annular compartments of circular vertical cross-section. To provide sufficient freeboard it may become necessary to use either a single compartment of a very large diameterortwo or more such compartments arranged one on top of the other. A disadvantage of such arrangements is that for a particular interior capacity of the liferaft and a particular freeboard the compartment or compartments provide too much buoyancy and are thus wasteful of material and inflating gas. Since the inflating gas is usually provided, at least in part, by a cylinder of such gas, a high inflation requirement requires an increased cylinder size and increased weight.The weight of a liferaft can be an important factor, especially when the liferaft is for use in an aircraft because the load of an aircraft is generally required to be minimized.

In addition, where a single compartment is provided, an air leak can render the liferaft unusable. For this reason, two such compartments are often used and although an air leak in one will still leave suffi cientbuoyancyto allowthe liferaftto be used, the freeboard provided by a single compartment may make use of the liferaft difficult or dangerous.

According to the present invention there is provided an inflatable liferaft having a support panel to serve as a floor and an inflatable buoyancy tube extending round the support panel, the buoyancy tube having inner and outer walls joined together along their upper and lower edges and further joined together along join lines between the upper and lower edges to divide the interior of the buoyancy tube into compartments, the join lines extending in directions transverse to the upper and lower edges and being spaced apart along the length of the buoyancy tube, thereby to restrain separation of the inner and outer walls in such a mannerthat a vertical cross-section of the buoyancy tube, when inflated, is vertically elongate.

Preferably, the join lines divide the interior of the buoyancy tube into two compartments or groups of compartments which are independently inflatable and the inflation capacity of one or the other or each of the compartments or groups of compartments is such as to provide the liferaft with a buoyancy and freeboard sufficient to support the maximum permitted load without inflation of the other compartment or group of compartments.

In a preferred embodiment of the invention, the join lines divide the buoyancy tube into a first com partment having a first portion which extends along the lower edge of the buoyancy tube and second portions which at spaced intervals along the first portion extend upwardly therefrom toward the upper edge of the buoyancy tube and a second compartment having a first portion which extends along the upper edge of the buoyancy tube and second portions which extend downwardly therefrom towards the lower edge of the buoyancy tube and between the second portions of the first compartment.

The liferaft according to the invention may include a further support panel secured along the upper edge of the buoyancy tube to serve as a protective canopy for occupants of the liferaft and the liferaft may be made reversible so that whichever of the support panels is lowermost serves as the floor and whichever of the support panels is uppermost serves as the protective canopy. With this arrangement, a drainage tube may be provided which extends between the two support panels and through the interiorofthe liferaftto provide a communication between openings in the two panels, whereby water collecting on the support panel which is uppermost drains away through the drainage tube.

The buoyancy tube may be interrupted by an entrance opening for the boarding of survivors and the entrance opening may be provided with a boarding platform comprising a floor panel extending outwardly from the buoyancy tube at a lower edge of the entrance opening and being supported by an inflatable support tube connected at its ends to the buoyancy tube and extending along the edges of the floor panel. The boarding platform may furthermore be provided with side walls extending upwardly from the sides of the floor panel and supported by a further support tube connected at its ends to the buoyancy tube and extending along the edges of the sidewalls and bridging the outermost ends thereof.

The opening bounded by the further support tube may then be closed by a cover panel which may be made removable.

The entrance opening in the buoyancy tube may be provided on one side of the liferaft and a further entrance opening provided on the other side of the liferaft with a further boarding platform of the same construction as the first mentioned boarding platform and where the liferaft is reversible the floor panel of one of the boarding platforms is arranged at the lower edge of its opening in one of the two reversible dispositions of the liferaft and the floor panel of the other of the boarding platforms is arranged at the lower edge of its entrance opening in the other of the two reversible dispositions of the liferaft.

The cover panel or each of the cover panels may be made removable so that the boarding platform with the floor panel lowermost can be used as a look-out position by a survivor who can use the further support tube as a handrail.

In an alternative embodiment of the invention the join lines may divide the buoyancy tube into a first compartment having a first portion which extends along the lower edge of the buoyancy tube and second portions which, at spaced intervals along the first portion, extend upwardly therefrom towards the upper edge of the buoyancy tube and a second com partment or a second group of compartments extending between adjacent second portions of the first compartment.

The first compartment in the alternative embodi ment of the invention may include a third portion which extends along the upper edge of the buoyancy tube. The second portions of the first compartment in this embodiment of the invention may either lead into the third portion so that the second group of compartments is formed between adjacent second portions and the first and third portions of the first compartment or may terminate before reaching the third portion so that a single second compartment is formed which has its upper edge bounded by a lower edge of the third portion of the first compartment, extends between adjacent second portions of the first compartment and is bounded at its lower edges by the first portion of the first compartment.

Where the liferaft is designed to support a load such as a single human whose weight varies over the floor, the second portion of the first compartment may be more closely spaced along the buoyancy tube in the region of the liferaft designed to support the greater load than along the remainder of the buoyancy tube thereby to provide additional buoyancy where it is needed.

Where the liferaft is for use by one person only the floor and the buoyancy tube are preferably elongated to allowthe person to adopt a semi-reclining position in the liferaft, a cover panel being provided over the liferaft which gives access to the interior of the liferaft and which covers the person in the liferaft.

The cover and/or floor panels may be double skinned and may, in use, be inflated to provide an insulating layer of air around an occupant.

Where the interior of the buoyancy tube is divided into two compartments which are independently inflatable one of the compartments may be connected to a pressurised gas supply for inflation while the other of the compartments may be provided with an inlet for oral inflation.

The liferaft may be made from a flexible material waterproofed on one surface only or on both surfaces.

Two embodiments of the invention will now be described by way of example with reference to the accompanying schematic drawings in which: Fig. 1 is a side elevation of an inflatable liferaft according to a first embodiment of the invention, Fig. 2 is a plan view of the liferaft shown in Fig. 1, Fig. 3 is an end elevation of the liferaft shown in Fig. 1, Fig. 4 is a section of part of the liferaft shown in Fig. 2 taken on the line IV-IV in Fig. 2, Fig. 5 is a section of part of the liferaft shown in Fig. 2 taken on the line V-V in Fig. 2, Fig. 6 is a plan view of the part of the liferaft shown in Fig. 5, and Fig. 7 is a side elevation partly in section of a one-man liferaft according to a second embodiment of the invention.

Referring first to Figs. 1 to 3, a multi-seat liferaft comprises a buoyancy tube 11 to the lower edge of which is secured an inflatable panel 12 which serves as a floor and to the upper edge of which is secured an inflatable panel 13 which serves as a canopy.

Boarding platforms 14 and 15 are provided on opposite sides of the buoyancy tube 11 to facilitate boarding of survivors, who enter the liferaftthrough one or other of entrance openings 16 provided on opposite sides of the liferaft.

Referring now to Fig. 4, the buoyancy tube 11 comprises inner and outer walls 17 and 18 which are joined together at their upper and lower edges 19 and 20 and furtherjoined together along a join line 21 between the upper and lower edges 19 and 20. As best seen in Fig. 1,thejoin line line 21 extends in a ser- pentine path around the buoyancy tube 11 and is arranged symmetrically about a central horizontal plane to divide the buoyancy tube 11 into equal upper and lower compartments 22 and 23. The lower compartment 23 comprises a first portion 24which extends along the lower edge of the buoyancy tube and second portions 25 which at spaced intervals along the first portion 24 extend upwardly therefrom toward the upper edge of the buoyancy tube 11.The upper compartment 22 comprises a first portion 26 which extends along the upper edge of the buoyancy tube 11 and second portions 27 which extend downwardly from the portion 26 toward the lower edge of the buoyancy tube 11 and between the second portion 25 of the lower compartment 23.

The upwardly and downwardly extending parts of the join line 21 so restrain the separation of the inner and outerwalls 17 and 18 of the buoyancytubethat a vertical cross-section of the buoyancy tube 11, when inflated, is vertically elongate as shown in Fig. - 4.

The compartments 22 and 23 are independently inflatable and the inflation capacity of each is arranged to be such as to provide the liferaft with a buoyancy and freeboard sufficient to support the maximum permitted load without inflation of the other compartment. Inflation of the compartments 22 and 23 is provided by separate cylinders (not shown) of pressurised gas, which are provided with valves which are opened either automatically on the liferaft entering the water or by manual operation.

Tubes (not shown) may be provided to allow for oral topping-up of the two compartments.

Referring again to Fig. 4, the floor panel 12 and the canopy panel 13 are of identical construction, each being formed bytwo fabric sheets 28 and 29 which are joined together at spaced locations by ring welds 30. The panels 12 and 13 which are formed with central openings, are secured at their outer edges to the buoyancy tube 11 and at their inner edges to a tube 31 which extends between the two panels 12 and 13 and through the interior of the liferaft. The panels 12 and 13 are arranged to be in communication with the buoyancy tube 11 and inflatable therewith.

It will be seen that the liferaft is symmetrical about the central horizontal plane and is therefore reversible in the water so that whichever of the panels 12 and 13 is lowermost serves as the floor and whichever of them is uppermost serves as the protective canopy. The tube 31 serves as a water drain age tube with water which collects on the panel which is uppermost draining away through the tube 31. The tube 31 may additionally be used to catch rain water falling on the panel serving as the canopy by providing a collection rim (not shown) around the interior of the tube 31 and a pipe (not shown) leading through the tube 31 into the interior of the liferaft.

Referring now to Figs. 5 and 6, the boarding platform 15 includes a floor panel 32 of trapezoidal shape extending outwardly from the buoyancy tube 11 at a lower edge of the associated entrance opening 16. The floor panel 32 is supported by a support tube 33 connected at its ends to the buoyancy tube 11 and extending along the edges of the floor panel 32. Side walls 34 and 35 extend upwardly from the side edges of the floor panel 32 and are supported by a further support tube 36 connected at its ends to the buoyancy tube 11 and extending along the upper edges of the sidewalls 34 and 35 and bridging the outermost ends of the sidewalls. The opening bounded by the further support tube 36 is closed by a cover panel 37 which is removably secured to the tube 36.

The boarding platform 14 is of the same construction as the boarding platform 15 but is inverted in relation to the boarding platform 15 so that the floor panel 32 and the supporttube 33 of the boarding platform 14 are uppermost in the disposition of the liferaft shown in Fig. 1 and the support tube 36 with its cover panel 37 lowermost. With this arrangement, the liferaft is reversible on the water, the floor panel 32 of one of the boarding platforms 14 and 15 being located at the lower edge of its associated opening 16 in one of the two reversible dispositions and the floor panel 32 of the other of the boarding platforms 14 and 15 being arranged at the lower edge of its entrance opening 16 in the other of the two reversible dispositions of the liferaft.

The liferaft illustrated in Figs. 1 to 6 is stowed in a deflated condition in a container (not shown) and discharged into the water in its container. Upon the container entering the water, gas under pressure is automatically released from the supply cylinders causing the liferaft to inflate and expand out of its container. The two compartments 22 and 23 of the buoyancy tube 11 inflate independently and communications are provided for the inflation of the support panels 12 and 13 serving as the floor and the canopy as well as the pairs of support tubes 33 and 36 of the boarding platforms 14 and 15.

Survivors in the water make their way to the appropriate one of the boarding platforms 14 and 15, climb on to the floor panel 32 with the aid of handholds (not shown) and enter the liferaft through the associated entrance opening 16. Provision is made for closing the opening 16 when all survivors are aboard. The liferaft is furthermore fitted out to provide conventional facilities for the occupants. The panels 12 and 13 may be made from an opaque material with translucent portions to provide adequate daylight within the liferaft.

It has been found desirable to provide a look-out facility on liferafts whilst maintaining adequate protective cover for the occupants. In the liferaft shown in Figs. 1 to 6, use can be made of one ofthe boarding platforms by removing its cover panel 37, thereby enabling a look-out to stand on the platform and use the upper supporttube 36 as a handrail.

The liferaft illustrated in Figs. 1 to 6 may be made from a lightweight material waterproofed on one side only to minimise weight. The vertically elongate shape of the buoyancy tube 11 provides a high freeboard for optimum buoyancy and a minimum quantity of material. By providing compartments 22 and 23 shaped as illustrated the liferaft gives sufficient buoyancy and freeboard even if one of the compartments is only partially inflated or is uninflated.

The buoyancy tube 31 in the embodiments of the invention illustrated in Figs. 1 to 6 is shown as a rigid tube extending between the cover and floor panels 12 and 13. In an alternative arrangement the tube 31 may be replaced by an inflatable tube in communication with the buoyancy tube 11 and inflatable therewith.

Referring now to Fig. 7, a single seat liferaft is shown which comprises a floor 38 of oval plane rum and narrower at one end than the other. An inflatable buoyancy tube 39 is secured to and extends along the periphery of the floor 38 and has inner and outer walls 40 and 41 connected together at their upper and lower edges 42 and 43. In addition, the walls 40 and 41 are also connected together between the upper and lower edges along a join line 44 which divides the buoyancy tube into two compartments 45 and 46. The join line 44 extends in a stretch 44a parallel to but spaced from the upper edge of the buoyancy tube 39 and then extends in a downward stretch 44b to a point adjacent to but spaced from the lower edge of the buoyancy tube 39.The join line then executes a series of loops in a serpentine path, each loop comprising a stretch 44e parallel to but spaced from the lower edge of the buoyancy tube, an upward stretch 44d to a point adjacent to but spaced from the upper stretch 44a, a stretch 44e parallel to the upper stretch 44a, and a downward stretch 44f which extends to the level of the lower stretch 44c. The frequency of the loops is greater at the broader end of the floo r 38 than at the narrower end. The lower stretch 44e at the last loop leads to an upward stretch (not shown) which leads to the start of the upper stretch 44a. This upward stretch and the downward stretch 44b form an air passage 47 connecting the top and bottom edges of the buoyancy tube. The buoyancy tube 39 is thus formed into the two compartments 45 and 46, the compartment 46 having a first portion 48 extending around the lower edge of the liferaft, a plurality of second portions 49 formed by the loops of the join line 44 and extending upwardly from the first portion 48 at spaced intervals there-along and a third portion 50 extending along the upper edge of the liferaft. The first and third portions 48 and 50 are connected by the air passage 47.

The second portions 49 have an increased frequency at the broader end of the floor 38. The second compartment 45 is surrounded by the first, second and third portions of the first compartment.

The upwardly and downwardly extending stretches 44d and 44f of each loop of the join line 44 so restrain the separation of the inner and outer walls 40 and 41 that a vertical cross-section of the buoyancy tube 39, when inflated, is vertically elon gate. This can be seen in the vertical cross-section of the liferaft shown atthe right-hand end of Fig. 7.

A cylinder 51 of pressurised gas is slung from beneath the buoyancy tube 39 and is connected through a valve (not shown) to the compartment 46 of the buoyancy tube 39. The valve may be opened to inflate the first compartment 46 either automatically on the liferaft entering the water or by manual operation. A tube 52 leads to the compartment 46 to allow oral inflation of that compartment.

The compartment46 is so dimensioned and arranged that on inflation it will provide the liferaft with sufficient buoyancy and freeboard to carry a single person safely without inflation of the compartment 45. The increased frequency of the second portions 49 at the broader end of the floor 38 supplies the increased buoyancy needed that end to support the greater weight of the occupant at that end. It may be that the occupant will not be able to inflate the compartment 45 to provide additional buoyancy and will need to rely on the buoyancy obtained from the inflation of the compartment 46 only. On the other hand, inflation ofthe compartment 45 provides additional buoyancy where the first compartment is under-inflated.

The liferaft illustrated in Fig. 7 is completed with conventional fittings such as a water pocket 53 to stabilise the liferaft and a cover 54 which is provided with a waterproof zip (not shown) to allow access to the interior of the liferaft and a hood 55 with an aperture forthe face of an occupant, who adopts a semireclining position in the liferaft. The floor 38 and the cover 54 may be double skinned and be inflated in use to provide an insulating layer around an occupant.

The buoyancy tube 39 by virtue of its vertically elongate shape provides a high freeboard with optimum buoyancy and with the least amount of material, thereby enabling the weight of the liferaft to be minimised. A lightweight material waterproofed on one surface only may be used to obtain a further reduction in weight.

In the embodiment of the invention illustrated in Figs. 1 to 6 each of the panels 12 and 13 is constructed from sheets 28 and 29 which are spotwelded at locations 30. In an alternative form of construction, the two sheets 28 and 29 are welded together along spaced radial lines which divide the panel into a plurality of sectors each of which is inflatable. To provide a communication between adjacent sectors for inflation gas each join line may be interrupted by a transverse tube, one end of which opens into one ofthe sectors while the other end opens into the other of the sectors. In this arrangement for the panels 12 and 13 alternate sectors may be made from a coloured opaque material while the remaining sectors made from a translucent material to provide daylight within the liferaft.

Claims

1. An inflatable liferaft having a support panel to serve as a floor and an inflatable buoyancy tube extending round the support panel, the buoyancy tube having inner and outer walls joined together along their upper and lower edges and further joined together along join lines between the upper and lower edges to divide the interior of the buoyancy tube into compartments, the join lines extending in directions transverse to the upper and lower edges and being spaced apart along the length ofthe buoyancy tube, thereby to restrain separation of the inner and outer walls in such a manner that a vertical cross-section of the buoyancy tube, when inflated is vertically elongate.

2. A liferaft according to claim 1 wherein the join lines divide the interior of the buoyancy tube into two compartments or groups of compartments which are independently inflatable.

3. A liferaft according to claim 2 wherein the inflation capacity of one or the other or each of the compartments or groups of compartments is such as to provide the liferaft with a buoyancy and freeboard sufficient to support the maximum permitted load without inflation ofthe other compartment or groups of compartments.

4. A liferaft according to claim 1, 2 or 3, wherein the join lines divide the buoyancy tube into a first compartment having a first portion which extends along the lower edge of the buoyancy tube and second portions which at spaced intervals along the first portion extend upwardly therefrom toward the upper edge of the buoyancy tube and a second compartment having a first portion which extends along the upper edge of the buoyancy tube and second portions which extend downwardly therefrom towards the lower edge of the buoyancy tube and between the second portions of the compartment.

5. A liferaft according to any of claims 1 to 4 comprising a further support panel secured along the upper edge of the buoyancy tube to serve as a protective canopy for occupants of the liferaft.

6. A liferaft according to claim 5, wherein the liferaft is reversible so that whichever of the support panels is lowermost serves as the floor and whichever of the support panels is uppermost serves as the protective canopy.

7. A liferaft according to claim 5 to 6, comprising a drainage tube extending between the two support panels and through the interior of the liferaft to provide a communication between openings in the two panels, whereby water collecting on the support panel which is uppermost drains away through the drainage tube.

8. A liferaft according to claim 7, wherein means are provided for catchment of rain water drained into the drainage tube.

9. A liferaft according to any of the preceding claims, wherein the buoyancy tube is interrupted by an entrance opening for the boarding of survivors.

10. A liferaft according to claim 9, wherein the entrance is provided with a boarding platform comprising a floor panel extending outwardly from the buoyancy tube at a lower edge of the entrance and being supported by an inflatable support tube connected at its ends to the buoyancy tube and extending along the edges of the floor panel.

11. A liferaft according to claim 10, wherein the boarding platform is provided with side walls extending upwardly from the sides of the floor panel and supported by a further support tube connected at its ends to the buoyancy tube and extending along the upper edges of the sidewalls and bridging the outermost ends thereof.

12. A liferaft according to claim 11, wherein the opening bounded by the further support tube is closed by a cover panel.

13. A liferaft according to claim 11 or 12, as appendantto claim 6 wherein the entrance opening is provided on one side of the liferaft, wherein a further entrance opening is provided on the other side of the liferaft with a further boarding platform of the same construction as the first-mentioned boarding platform and wherein the floor panel of one of the boarding platforms isatthe lower edge of the entrance opening in one of the two reversible dispositions of the liferaft and the floor panel of the other of the boarding platforms is atthe lower edge of its entrance opening in the other of the two reversible dispositions of the liferaft.

14. A liferaft according to claim 12 or claim 13 as appendant to claim 12, wherein the or each cover panel is removable so that the boarding platform with the floor panel lowermost can be used as a look-out position by a survivor who can use the furthersupporttube as a handrail.

15. A liferaft according to claim 1,20r3,wherein the join lines divide the buoyancy tube into a first compartment having a first portion which extends along the lower edge of the buoyancy tube and second portions which, at spaced intervals along the first portion, extend upwardly therefrom towards the upper edge of the buoyancy tube and a second compartment or a second group of compartments extending between adjacent second portion of the first compartment.

16. A liferaft according to claim 15, wherein the first compartment includes a third portion which extends along the upper edge of the buoyancy tube.

17. A liferaft according to claim 16, wherein all the second portions of the first compartment lead into the third portion so that the second group of compartments is formed between adjacent second portions and the first and third portions of the first compartment.

18. A liferaft according to claim 16, wherein the second portions of the first compartment terminate before reaching the third portion so that a single second compartment is formed which has its upper edge bounded by a lower edge of the third portion of the first compartment, extends between adjacent second portions of the first compartment and is bounded at its lower edges by the first portion of the first compartment.

19. A liferaft according to any of claims 15 to 18, wherein the second portions of the first compartment are more closely spaced along the buoyancy tube in the region of the liferaft designed to support the greater load than along the remainder of the buoyancy tube, thereby to provide additional buoyancy where it is needed.

20. A liferaft according to any of claims 2 to 19 comprising first inlet means connected to a pressurised gas supply for inflation of one of the two compartments or groups of compartments and second inlet means for oral inflation of the other compartmentor group of compartments.

21. A liferaft substantially as hereinbefore described with reference to Figs. 1 to 6 or 7. of the accompanying drawings.