GB2254296A - Inflatable geodetic structure - Google Patents

Abstract

A device for use in assisting recovering of a man overboard at sea comprises a network of interconnected collapsible and inflatable tubes of flexible impermeable material and means such as a CO2 cylinder and associated actuating mechanism for rapidly inflating the network of tubes when desired. The device in its deflated and packed form is carried on the person of a yacht crew member, for example, so that if the latter should go overboard the device can be operated manually or automatically to provide a readily visible marker to which the crew member is tethered, making it easier to spot and recover the man overboard in heavy seas, for example. <IMAGE>

Description

DESCRIPTION OF INVENTION Title: "Inflatable Geodetic Structure" THIS INVENTION relates to rapidly erectable structures, more particularly to structures erectable by inflation, and it is an object of the invention to provide an improved structure which occupies little space in a stowed or collapsed condition and which can rapidly be deployed to afford a relatively large structure.

According to one aspect of the invention, there is provided a device comprising a network of collapsible and inflatable tubes of flexible impervious material, and means for inflating said tubes to form a three-dimensional geodetic structure.

An embodiment of the invention is described below by way of example, with reference to the accompanying drawings, wherein FIGURE 1 is a fragmentary perspective, highly diagrammatic view illustrating, in its deployed, inflated condition, a structure embodying the invention, in the form of a personnel or incid'ent marker buoy, FIGURE 2 illustrates diagrammatically an alternative form of cell or repeating unit for such a structure, FIGURE 3 shows, to an enlarged scale, a part of a structure such as is shown in Figure 1, FIGURE 4 is a perspective view showing part of a variant structure, and FIGURE 5 is a diagrammatic perspective view illustrating part of a yet further variant structure.

In a preferred embodiment, a structure embodying the invention is used as a marker buoy to mark the position of a crew member of a vessel, for example of a racing yacht, who has gone overboard.

Whilst crew on racing yachts will generally wear lifejackets whilst on duty, it will be appreciated that it is very easy to lose sight of a man or woman, even so equipped, who has gone overboard, from a moving vessel, particularly in heavy seas and from a vantage point relatively close to the water surface. Even if the manoverboard is not lost sight of, recovery from the water is generally difficult, particularly if he or she has lost consciousness or is otherwise unable to grasp a rope or net. Recovering a man-overboard is particularly problematic in very cold waters, for example in the southern oceans. In such conditions, a man-overboard will die from hypothermia if not recovered within a few minutes.

The preferred embodiment of the invention takes the form of a device which can serve as a readily visible marker for a man overboard and can assist in his or her recovery from the water.

The preferred embodiment of the present invention takes the form of an inflatable device which uses a minimum of materials and, in its deflated condition, can be made into a compact package which can be carried conveniently on the person and which can inflate almost instantly, when required, to form a large, buoyant temporary structure which is large enough to be visible in adverse conditions and can safely be man-handled in order to recover the manoverboard tethered to the structure. The structure does not need to be of great strength for this particular application but must be self-supporting and self-erecting.

Whilst self-inflating devices are already known, such as life-rafts and life jackets, these devices require large volumes of air or other gas for full inflation and thus either require a large gas cylinder to inflate a relatively large structure or are too small, when inflated, to act as a useful marker buoy.

The preferred form of marker device embodying the invention comprises a plurality of interlinked pneumatically inflatable tubes. When the device is inflated, it erects itself into a structure of interconnected struts each formed by a respective inflated said tube. In one embodiment each tube is of a soft, thin, flexible, impermeable material and is of approximately two inches in length. The tubes are so interlinked that, in the inflated device, they form a three dimensional geodetic structure such as is illustrated diagrammatically at 10 in Figure 1.

Figure 3 shows to an enlarged scale as compared with Figure 1 a basic element 12 of a structure which could be replicated indefinitely, as indicated by broken lines, to produce a cubic three dimensional structure such as that shown in Figure 1. It will be appreciated that the basic element 12 illustrated in Figure 3 should not necessarily be regarded as a manufactured integer which is connected with similar integers to form the structure.Thus, for example, the basic element illustrated in Figure 3 may actually be assembled by, for example, connecting corner pieces each affording six tubular stubs extending along mutually perpendicular axes from a junction region, with or without the interposition of simple straight tube lengths, or may be assembled by connecting together units affording two or even three corner joints, according to the form of manufactured unit which is most economical to manufacture.

The basic element of the structure may take different forms from that illustrated in Figure 3, for example, as illustrated at 14 in Figure 4, by having the locations at which the horizontal members 16 branch from the vertical members 18 staggered with respect to each other. Such a modified structure may, for example, be assembled from prefabricated units of T-shape.

In all the preferred embodiments the emphasis is on the provision of a very large ratio of the volume of the envelope of the inflated structure to the volume of the deflated structure. It is also desirable to secure a very large ratio of the volume of said envelope of the inflated structure to the total internal volume of the inflated tubes, i.e. to the volume of gas required to inflate the structure.

The device may be incorporated in a lightweight package to be carried on the person and which may comprise the network of inflatable tubes, in a deflated condition, folded or rolled into a compact body within a container and connected by a strong line or lanyard with a part of the device secured to the person, a supply of gas, for example a small CO2 cylinder, and a mechanism operable to release the folded or rolled up network of tubes from the container and to release gas from the container to inflate the structure. Said mechanism may be operable manually by the person to whom the device is secured, for example by the latter pulling a rip-cord of the like, or may be operated automatically upon immersion in water of an immersion sensor forming part of the device.

Figure 1 illustrates the device fully deployed, connected by the aforementioned lanyard with a man in the water. As illustrated, the geodetic structure, when fully inflated, presents a visual marker substantially higher above the water surface, and wider from any aspect, than the visible portion of the man in the water. The parts of the structure are, of course, marked and coloured so as to have maximum visibility, for example being fluorescent orange. The structure may have additional markings, for example in the form of areas of flexible reflective sheet material secured to the structure, or of streamers attached to the structure or in the form of small active lights or other emitters.Non-return valves are placed either at strategic points in the structure or at every junction between tubes, in order to ensure that the structure will remain inflated even if punctured in one or several places.

The structure preferably has multiple gas paths extending from the inflating means (e.g. CO2 cylinder) to ensure both rapid and reliable inflation. In order to ensure reliable pneumatic self-erection of the structure, the risk of kinking of the tubes (which would impede the flow of air or other inflating gas) must be minimised. This may be achieved by having redundant members in the framework which reduce the kinks in adjacent members in the framework until the inflating gas flows, or alternatively by packing the structure so that kinks occur in controlled places but air is enabled to flow through these places through lengths of small-section, perforated, stiff inner tube provided at these places. Subject to the strengths of the materials and joints used, the structure may have considerable compressive strength, may be made extremely light and may be made to be very reliable in self-erection.

Whilst the structure illustrated in Figure 1 is based on a cubic repeating cell, other arrangements are possible. For example, the structure may be based on a tetrahedral repeating cell as illustrated in Figure 2, affording greater strength than the cubic repeating cell of the arrangement of Figures 1 and 3.

The inflatable structure may take other threedimensional forms. For example, as illustrated in Figure 5, the structure may be formed from a continuous tube 24 formed into loops which cross one another and are secured together at the crossing points, for example by clips indicated schematically at 30. The loops in this case may be substantially random or may follow some regular pattern.

Likewise, the structure may comprise a plurality of such continuous tubes interleaved with one another and clipped to one another and to themselves where appropriate. The use of a single continuous tube, or of a small number of continuous tubes, in the manner noted above, avoids the need for complex gas-tight joints or branches between tubes. In such arrangements the or each continuous tube may have only one respective valve. The use of a number of such tubes affords a certain redundancy in case of puncture of one or other of the tubes.

As regards the numbers and sizes of tubes in the structure, the variations are infinite depending on the materials, applications, and particularly the feasibility of machine-forming of the structure on a continuous basis.

While it is possible to hand-fabricate such a structure, an automated manufacturing technique is, of course, to be preferred. By way of example, a structure embodying the invention may have the overall form of a 2m cube with 15cm struts of 10mum diameter.

Multiple air paths are inherently part of the structures described. Non return valves may be of the joker, flap or aortic forms.

Although the structures outlined above were devised to meet a particular need in the marine disaster area, such inflatable geodetic structures may have applications in many other fields, for example as: (a) markers in desert or jungle situations, (b) decoy dummy vehicles used by the military (at present fully inflated balloon-type decoys are used), (c) self-erecting screens or frames to support posters or other sheet material for display, in theatrical or exhibition work, (d) barriers for blocking hazardous areas; for example by making corridors temporarily inaccessible, (e) means for cushioning the fall of persons or objects, in a manner similar to a safety net.

An inflatable geodetic structure embodying the invention could be made in spherical or cylindrical form to provide a device which could cover large distances downwind across water or smooth terrain (in the manner of a saltbush).

An inflatable geodetic structure embodying the invention might, if rendered appropriately reflective, for example by the use of reflective mesh known per se, serve as a radar target-or warning reflector. As illustrated in Figure 2, such a structure when inflated might be arranged to form a cube-corner reflector, i.e. a structure affording at least one recess defined by three mutually perpendicular reflective surfaces meeting in an internal corner to afford reflection of a beam striking the reflector substantially along its path of incidence. Such an inflatable reflector would assist in small craft rescue for without an effective radar reflector, a small craft such as a dinghy is difficult to detect on either downward looking aircraft radar or on shipping radar.

Claims (4)

1. A device comprising a network of interconnected collapsible and inflatable tubes of flexible impervious material, and means for inflating said tubes to form a three-dimensional geodetic structure.

2. A device according to claim 1 for use in assisting recovery of a man overboard at sea, wherein the device in a collapsed and deflated form is adapted to be carried on the person and wherein the device includes self-inflating means incorporating a supply of compressed gas, whereby said network of tubes can be rapidly deployed and inflated, when required, on operation of a manual actuator or automatically on immersion in water.

3. A device according to claim 1 or claim 2 incorporating a plurality of non-return valves at respective positions in the structure to provide a high probability that, once the structure is inflated, at least some part of the structure will remain inflated even if some other part thereof is punctured or improperly sealed.

4. A device according to claim 1 and substantially as hereinbefore described 1with reference to, and as shown in the accompanying drawings.