GB2060509A

GB2060509A - Inflatable Liferafts

Info

Publication number: GB2060509A
Application number: GB8033422A
Authority: GB
Original assignee: RFD Inflatables Ltd
Current assignee: RFD Inflatables Ltd
Priority date: 1979-10-18
Filing date: 1980-10-16
Publication date: 1981-05-07
Also published as: GB2060509B

Abstract

An inflatable liferaft comprising an inflatable side wall buoyancy tube, a canopy secured at its periphery to the buoyancy tube, one or more inflatable canopy support tubes for supporting the canopy and to which the canopy is secured and which subdivides or subdivide the canopy into two or more zones bounded by the buoyancy tube and the support tube or tubes, and one or more culverts 30, 31, 32 interposed between the canopy and the or each canopy support tube, whereby with the canopy flooded with water in an overturned disposition of the liferaft, water can flow from one zone to the other or another through the culvert or culverts to facilitate draining of water from the canopy when the liferaft is being righted. <IMAGE>

Description

SPECIFICATION Inflatable Liferafts The present invention relates to inflatable liferafts and is particularly concerned with inflatable liferafts provided with a flexible canopy supported by one or more inflatable canopy support tubes.

An inflatable liferaft which has been proposed comprises two superposed inflatable buoyancy tubes forming a side wall structure, a floor secured at its periphery to the base of the lower buoyancy tube, and a canopy secured at its periphery to the upper buoyancy tube and supported in a raised position by inflatable canopy support tubes extending from the buoyancy tubes upwardly and inwardly toward the centre of the liferaft.

It is a safety requirement that the canopy shall be secured not only to the upper buoyancy tube but also to the canopy support tubes so as to avoid the risk of the canopy being torn from the liferaft under adverse weather conditions. It has however been found unsatisfactory to provide a liferaft meeting these requirements as in the event that the liferaft is overturned, water which collects in the canopy cannot readily be drained away to one point of the canopy because of the obstruction created by the canopy support tubes.

It is an object of the present invention to provide an inflatable liferaft in which the aforesaid disadvantage is overcome.

According to the present invention, there is provided an inflatable liferaft comprising an inflatable side wall buoyancy tube, a canopy secured at its periphery to the buoyancy tube, one or more inflatable canopy support tubes for supporting the canopy and to which the canopy is secured and which subdivides or subdivide the canopy into two or more zones bounded by the buoyancy tube and the support tube or tubes, and one or more culverts interposed between the canopy and the or each canopy support tube, whereby with the canopy flooded with water in an overturned disposition of the liferaft, water can flow from one zone to the other or another through the culvert or culverts to facilitate draining of water from the canopy when the liferaft is being righted.

The or each culvert preferably comprises a tubular insert arranged between the canopy and the or each canopy support tube, the canopy and the or each support tube being joined together along the length or a part of the length of the support tube except at the location of the insert where the inner surface of the canopy and the outer surface of the canopy support tube are joined to the outer surfaces of the insert.

In a particularly advantageous arrangement, two canopy support tubes are provided, each of which comprises two leg portions extending from spaced positions along the buoyancy tube on one side of a centre line through the liferaft upwardly and inwardly toward the centre line of the liferaft where they are joined together by a bridge portion which is juxtaposed to the bridge portion of the other support tube, the leg portions of which extend from spaced positions along the buoyancy tube on the other side of the centre line of the liferaft. The canopy is thus subdivided into four zones each of which is bounded by the buoyancy tube and two adjacent leg portions of the support tubes.A plurality of tubular inserts is then interposed between the canopy and each leg portion, so that when the canopy is flooded in an overturned disposition of the liferaft, water drains through the inserts from any one of the zones of the canopy into another during the righting of the liferaft.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 is a schematic side elevation of a liferaft according to the invention, Fig. 2 is a plan view of the liferaft shown in Fig.

1, Fig. 3 is a scrap section of the liferaft shown in Figs. 1 and 2, taken on the line Ill-Ill in Fig. 2, Fig. 4 is a scrap section of the liferaft shown in Fig. 2, taken on the line IV--IV in Fig. 2, and Fig. 5 is a scrap section of the liferaft shown in Figs. 1 and 2, taken on the line V-V in Fig. 3.

Referring first to Figs. 1 and 2, two inflatable buoyancy tubes 11 and 1 2 of equal capacity form a circular side wall of the liferaft shown and are arranged to be inflated by two high pressure air or nitrogen inflation cylinders 13 and 14 of equal capacity. Two canopy support tubes 15 and 16 extend from the buoyancy tube 11 to form an arched support structure for a canopy 1 7. The canopy support tube 15 comprises two leg portions 1 8 and 19 which extend from the buoyancy tube 11 upwardly and inwardly toward a centre line of the liferaft where they are joined by a bridge portion 20.The other canopy support tube 16 similarly comprises two leg portions 21 and 22 which extend from the buoyancy tube 11 upwardly and inwardly toward the centre line of the liferaft, where they are joined by a bridge portion 23 which bears against the bridge portion 20 of the support tube 1 5.

The leg portion 1 8 of the support tube 1 5 is secured, as shown in Fig. 3, to the upper buoyancy tube 11 in such a way that the end of the leg portion is closed by the buoyancy tube 11.

A bleed tube 24 extends from the support tube 18 to the lower buoyancy tube 12 to provide a communication between the interior of the leg portion 1 8 and the interior of the buoyancy tube 12. The leg portion 19 of the support tube 1 5 is similarly secured to the upper buoyancy tube 11 in the same manner as the leg portion 1 8 and a bleed tube 25 similarly provides a communication between the interior of the leg portion 19 and the interior of the lower buoyancy tube 12. The leg portion 21 of the support tube 16 is connected to the upper buoyancy tube 11 where the latter is formed with an opening which provides a communication between the interior of the leg portion 21 and the interior of the upper buoyancy tube 11.In like manner, the leg portion 22 of the buoyancy tube 16 is connected to upper buoyancy tube 11 and communication between the interior of the leg portion 22 and the interior of the upper buoyancy tube 11 is provided by a further opening in the buoyancy tube 11. The bridge portions 20 and 23 of the two support tubes 1 5 and 1 6 bear, as shown in Fig. 4, against each other in the inflated condition of the liferaft and form with the leg portions a self-supporting canopy support structure for supporting the canopy 17.

The canopy 17 is constructed from four juxtaposed sheets 171, 172, 173 and 174, abutting edges of which are joined together where the canopy is joined to the leg portions 18, 19,21 and 22 of the support tubes 15 and 16, with the abutting edges of adjacent sheets being covered by tapes, 26, 27, 28 and 29.

Referring more particularly to Fig. 3 the canopy sheet 171 and its adjacent abutting sheet 1 74 are secured to the leg portion 18 by V-shaped strips 33 and 34 (shown only in Fig. 5). One outer surface of each strip is adhered to the leg portion 18 while the other outer surface of the strip is adhered to the canopy sheet. Three tubular inserts 30, 31, and 32, only two of which are shown in Fig. 3, are provided at spaced positions along the leg portion 18 and at these positions the abutting sheets 171 and 174 are as shown in Fig. 5 adhered to the upper outer surface of each insert while the upper outer surfaces of the V-shaped strips 33 and 34 are adhered to the lower surface of the insert. Tubular inserts are, as shown in Fig.

2, provided between the canopy sheets 171 and 172 and the leg portion 19 of the support tube 15, as well as between the canopy sheets and the leg portions 21 and 22 of the support tube 16 and are identical to the inserts 30,31 and 32 and secured in the same manner. The canopy sheets 171 to 174 are in addition secured to the buoyancy tube 11 along the length thereof by a V-shaped strip 35.

With reference to Fig. 2, the canopy sheets 171 to 174 are reinforced in the region of the crown of the canopy by a crown patch 36. In addition, the canopy sheets 1 71 to 1 74 are provided with openings 37 for access to the liferaft, the openings being closable by cover sheets (not shown). The inflation containers 1 3 and 14 are conveniently housed in a fabric holder 38 and pressurised air or nitrogen supplied to the two buoyancy tubes 11 and 12 via high pressure hoses 39 and 40 and aspirators 41 and 42, the high pressure hoses 39 and 40 passing through a support tube 43 secured at one end to the buoyancy tube 12 and at the other end to the holder 38.

In operation, the liferaft is inflated by pressurised air or nitrogen from the inflation cylinders 13 and 14, which provide for independent inflation of the two superposed buoyancy tubes 11 and 12, the canopy support tube 15 being inflated from the lower buoyancy tube 12 and the canopy support tube 16 being inflated from the upper buoyancy tube 11.

In the event that the liferaft overturns in the water, the righting of it is facilitated by the provision of the tubular inserts (30,31 and 32) which open up and allow water which has collected in any of the zones bounded by the upper buoyancy tube 11 and the leg portions of the support tubes 1 5 and 16 to drain into any other of the zones taking a lowermost disposition during the righting operation.

It will be appreciated that the canopy is permanently adhered to the upper buoyancy tube 11 and the two support tubes 15 and 1 6 even at those places where the tubular inserts 30 to 32 are interposed and meets the requirements imposed upon the manufacturer by safety regulations.

To improve thermal insulation of the liferaft, the canopy 1 7 is formed as a double skin in which the canopy sheets 171 to 174 form the outer skin and an inner skin is formed, as shown in Fig. 5, by inner sheets such as sheets 44 and 45 secured to the outer sheets in the region of the leg portions of the support tubes.

Claims

1. An inflatable liferaft comprising an inflatable side wall buoyancy tube, a canopy secured at its periphery to the buoyancy tube, one or more inflatable canopy support tubes for supporting the canopy and to which the canopy is secured and which subdivides or subdivide the canopy into two or more zones bounded by the buoyancy tube and the support tube or tubes, and one or more culverts interposed between the canopy and the or each canopy support tube, whereby with the canopy flooded with water in an overturned disposition of the liferaft, water can flow from one zone to the other or another through the culvert or culverts to facilitate draining of water from the canopy when the liferaft is being righted.

2. A liferaft according to claim 1, wherein the or each culvert comprises a tubular insert arranged between the canopy and the or each canopy support tube and wherein the canopy and the or each support tube are joined together along the length or part of the length of the support tube except at the location of the insert where the inner surface of the canopy and the outer surface of the canopy support tube are joined to the outer surfaces of the insert.

3. A liferaft according to claim 2, wherein the one or more inflatable canopy support tubes comprise two or more leg portions extending from spaced positions along the buoyancy tube, upwardly and inwardly toward the centre of the liferaft where they are joined together and wherein at least one of the culverts is interposed between the canopy and each leg portion.

4. A liferaft according to claim 3, wherein two canopy support tubes are provided, each of which comprises two leg portions extending from spaced positions along the buoyancy tube on one side of a centre line through the liferaft upwardly and inwardly toward the centre line of the liferaft where they are joined together by a bridge portion which is juxtaposed to the bridge portion of the other support tube, the leg portions of which extend from spaced positions along the buoyancy tube on the other side of the centre line of the liferaft, whereby the canopy is subdivided into four zones each of which is bounded by the buoyancy tube and two adjacent leg portions of the support tubes.

5. A liferaft according to claim 4, wherein the canopy is constructed from four juxtaposed sheets, abutting edges of which are joined to the leg portions of the support tubes.

6. A liferaft according to claim 5, wherein the abutting edge of each canopy sheet is joined to the leg portion of the support tube by a V-shaped strip, one outer surface of which is adhered to the leg portion of the support tube while the other outer surface of the strip is adhered to the canopy sheet, except in the region of each of the inserts where the outer surfaces of the insert are adhered to the outer surface of the strip and the inner surface of the canopy sheet.

7. A liferaft according to any of claims 3 to 6, wherein a plurality of culverts is interposed between the canopy and each leg portion.

8. A liferaft according to any of the preceding claims, wherein the buoyancy tube is the upper of two superposed inflatable buoyancy tubes forming the side wall and wherein a floor is secured at its periphery to the base of the lower buoyancy tube.

9. An inflatable liferaft substantially as hereinbefore described with reference to the accompanying drawings.