GB2060508A

GB2060508A - Inflatable Liferafts

Info

Publication number: GB2060508A
Application number: GB8033421A
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

Abstract

An inflatable liferaft comprising two superposed buoyancy tubes of equal capacity and two inflatable canopy support tubes of equal capacity for supporting a canopy, the interior of one of the support tubes being in communication with the interior of the upper buoyancy tube and the interior of the other canopy support tube being in communication with the interior of the lower buoyancy tube, whereby upon inflation of the two buoyancy tubes by separate pressurized air of gas supplies of equal capacity, one of the canopy support tubes is inflated by air or gas supplied to the upper buoyancy tube while the other of the canopy support tubes is inflated by air or gas supplied to the other buoyancy tube. <IMAGE>

Description

SPECIFICATION Inflatable Liferafts The present invention relates to inflatable liferafts and is particularly concerned with an inflatable liferaft having two superposed endless buoyancy tubes arranged to be inflated from separate pressurized air or gas supplies and inflatable canopy support means which upon inflation supports a canopy for the liferaft.

In one arrangement hitherto proposed, the canopy support means comprises a plurality of inflatable canopy support tubes extending upwardly and inwardly from the upper buoyancy tube to the centre of the liferaft, with the interior of each tube being in communication with the interior of the upper buoyancy tube so that air supplied to the upper buoyancy tube serves also to inflate the canopy support tubes.

It will be appreciated that where the two buoyancy tubes are of identical capacity, more air is needed for inflation of the upper buoyancy tube and canopy support tubes than is needed for inflation of the lower buoyancy tube. The pressurized air supplies are in the form of inflation cylinders containing pressurized air and it is considered desirable to utilize cylinders of identical capacity for inflation of the two buoyancy tubes.

To enable a liferaft as above described to be inflated using identical capacity inflation cylinders, it has been proposed to reduce the size of the upper buoyancy tube so that its capacity together with that of the canopy support tubes equals that of the lower buoyancy tube. While this solves the problem, it leads to increase manufacturing costs and other difficulties. In yet another arrangement, the two buoyancy tubes are of equal capacity and are fed with air from equal capacity inflation cylinders, excess air supplied to the lower buoyancy tube being vented off through a valve so that the two buoyancy tubes become fully inflated to equal pressures.

According to the present invention, there is provided an inflatable liferaft comprising two superposed buoyancy tubes of equal capacity and two inflatable canopy support tubes of equal capacity for supporting a canopy, the interior of one of the support tubes being in communication with the interior of the upper buoyancy tube and the interior ofthe other canopy support tube being in communication with the interior of the lower buoyancy tube, whereby upon inflation of the two buoyancy tubes by separate pressurized air or gas supplies of equal capacity, one of the canopy support tubes is inflated by air or gas supplied to the upper buoyancy tube while the other of the canopy support tubes is inflated by air or gas supplied to the other buoyancy tube.

Clearly, in the liferaft according to the invention, the two buoyancy tubes and their associated canopy support tubes will inflate to equal pressures from inflation cylinders of equal capacity.

In liferafts hitherto proposed, the canopy support tubes have taken the form of four radially extending portions extending upwardly and inwardly from the upper buoyancy tube to the centre of the liferaft where they are connected together by a connecting portion of cruciform configuration with the interior of each radial portion communicating with the interiors of the other radial portions through the cruciform portion. This particular form of arched construction presents difficulties in manufacture and in any event does not lend itself to use in a liferaft according to the invention in which the two canopy support tubes are required to be out of communication with each other.

In a particularly advantageous and novel arrangement of the canopy support tubes of the liferaft according to the invention, each canopy support tube comprises two leg portions extending from spaced positions along the buoyancy tubes 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 canopy support tube, the leg portions of which extend from spaced positions along the buoyancy tubes on the other side of the centre line of the liferaft.

To meet safety requirements the canopy is permanenetly secured to the upper buoyancy tube and to the canopy support tubes so that it cannot be torn away in adverse weather conditions. Where, however, such safety requirements are not imposed, the liferaft according to the invention may be provided for use with a detachable canopy.

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 side elevation, partly broken away, of an inflatable 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 Figs. 1 and 2, taken on the line lV-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. 2.

Referring first to Figs. 1 and 2, two inflatable buoyancy tubes 11 and 12 of equal capacity form a circular side wall of the liferaft shown and are arranged to be inflated by high pressure air or gas inflation cylinders 13 and 14 of equal capacity.

Two canopy support tubes 1 5 and 16 extend from the buoyancy tube 11 in arched form to support a canopy 17. The canopy support tube 15 comprises two leg portions 18 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 is similarly of arched form and 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 15.

Referring now to Fig. 4, the leg portion 18 of the support tube 15 is secured to the upper buoyancy tube 11 by sealing strip 24 in such a way that the end of the support tube is closed by the buoyancy tube 11. A bleed tube 25 extends from the support tube 18 to the lower buoyancy tube 12 to provide a communication between the interior of the support tube 18 and the interior of the buoyanncy tube 12. The leg portion 19 of the support tube 15 is similarly secured to the upper buoyancy tube 11 in the same manner as the leg portion 18 and, as shown in Fig. 2, a bleed tube 26 provides a communication between the interior of the leg portion 19 and the interior of the lower buoyancy tube 12 in the same manner as the bleed tube 25.

Referring now to Fig. 5, the leg portion 21 of the support tube 16 is connected to the upper buoyancy tube 11 by a sealing strip 27 at a part of the buoyancy tube 11 which is formed with an opening 28 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 support tube 16 is connected to the 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 an opening in the buoyancy tube corresponding to the opening 28.

Referring now to Fig. 3, it will be seen that the two bridge portions 20 and 23 of the support tubes 1 5 and 1 6 are juxtaposed in the inflated condition of the liferaft. The interiors of the bridge portions 20 and 23 are however not in communication with each other so that the inflation of the two support tubes 1 5 and 16 are entirely independent of each other Referring again to Figs. 1 and 2, the canopy 1 7 is secured along its periphery to the upper buoyancy tube 11 and is supported as shown by the two canopy support tubes 15 and 16 to which it is secured. Access to the liferaft may be obtained through an opening 29 formed in the canopy 17 in the quadrant defined by the leg portions 21 and 22 of the support tube 16. The opening 29 is closable by a flap 30.In the liferaft illustrated, three further openings (not shown) are provided in the canopy in the other three quadrants of the canopy defined by the leg portions of the support tubes 15 and 16.

The inflation cylinders 13 and 14, which are carried by a holder 31 are provided with operating cables (not shown), which, when pulled, open the cylinders to discharge air via air hoses 32 and 33 and aspirators 34 and 35 into the buoyancy tubes 11 and 12. By so arranging that the canopy support tube 16 is supplied with air from the buoyancy tube 11 while the canopy support tube 15 is supplied with air from the buoyancy tube 12, the two support tubes 15 and 16 and the two buoyancy tubes 11 and 12 are inflated to equal pressures from the equal capacity inflation cylinders 13 and 14.

The liferaft shown in the drawings may for example have a service capacity of 42 persons with an outside diameter of 5.28 m., an inside diameter of 4.46 m. and an overall height of 1.80 m. For a liferaft of this capacity each inflation cylinder may contain air or nitrogen at 3000 p.s.i.

(20.68 MPa).

In a preferred arrangement, two 42 person Liferafts attached to each other are contained in a single container, together with their inflation cylinders and are arranged to be inflated simultaneously so as to break out of the container and provide a total service capacity of 84 persons.

Provision is however made for separating the liferafts by a simple action of survivors or crew.

Claims

1. An inflatable liferaft comprising two superposed buoyancy tubes of equal capacity and two inflatable canopy support tubes of equal capacity for supporting a canopy, the interior of one of the support tubes being in communication with the interior of the upper buoyancy tube and the interior of the other canopy support tube being in communication with the interior of the lower buoyancy tube, whereby upon inflation of the two buoyancy tubes by separate pressurized air or gas supplies of equal capacity, one of the canopy support tubes is inflated by air or gas supplied to the upper buoyancy tube while the other of the canopy support tubes Is Inflated by air or gas supplied to the other buoyancy tube.

2. A liferaft according to claim 1, wherein each canopy support tube comprises two leg portions extending from spaced positions along the buoyancy tubes 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 canopy support tube, the leg portions of which extend from spaced positions along the buoyancy tubes on the other side of the centre line of the liferaft.

3. A liferaft according to claim 2, wherein the leg portions of each canopy support tube extend from the upper buoyancy tube, wherein the interior of each leg portion of one of the support tubes communicates with the interior of the upper buoyancy tube and wherein the interior of each leg portion of the other support tube is out of communication with the interior of the upper buoyancy tube, but communicates through a bleed tube with the interior of the lower buoyancy tube.

4. A liferaft according to claim 2 or 3, wherein the construction and mounting of the canopy support tubes is such that upon inflation of the liferaft the two support tubes inflate to bring the bridge portions to bear against each other at the centre line of the liferaft to form a self-supporting canopy support structure.

5. A liferaft according to claim 2, 3, or 4 of circular planform, wherein the leg portions of the canopy support tubes extend from equi-angularly or substantially equi-angularly spaced positions around the buoyancy tubes upwardly and inwardly toward the centre of the liferaft.

6. A liferaft according to any of claims 2 to 5, wherein each leg portion of each canopy support tube is so angled that the support tubes form an arched structure.

7. A liferaft according to any of the preceding claims, including first supply means for supplying a gaseous inflation medium to one of the buoyancy tubes and second supply means of the same capacity as the first supply means for supplying a gaseous inflation medium to the other of the buoyancy tubes.

8. A liferaft according to claim 7, wherein the first and second supply means comprise aspirators and high pressure cylinders of equal capacity containing air or other gas under equal pressures.

9. A liferaft according to claim 2 or any of claims 3 to 8 as appendent to claim 2, including a canopy attached to the canopy support tubes at least in the region of the bridge portions of the support tubes and along the periphery of the upper buoyancy tube.

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