The invention relates to survival garments,

A survival garment is worn to protect a person from getting wet when the person is immersed in water. Such garments can be worn for water-based sports but are often used by service personnel such as helicopter and fixed wing pilots for use in sea evacuation as well as naval personnel (both surface and submarine) and merchant mariners. They are also used by people on offshore oil and gas rigs. Examples are immersion suits and submarine escape suits.

A survival garment commonly comprises a body portion for surrounding a torso of a wearer and arm and leg portions for receiving the arms and legs of a wearer. The garment fits tightly around the ankles and wrists of a wearer and may include a hood for covering the head of a wearer. The wrists, neck and ankles may be provided with seals so that the garment is water-tight. The garment is made from a waterproof material such as a rubber or plastics coated fabric.

When the wearer is immersed in water, the wearer usually floats on his/her back. The body portion of the garment includes a back portion for covering a back of a wearer, and, on immersion, this portion is forced against the back of the wearer by the hydrostatic pressure of the water. This places the material of the garment in direct or very close contact with the person's body and can result in a heat path that leads to rapid cooling of the body, which is undesirable for survival. This area of the body is rich in blood vessels and thus the potential heat loss is significant.

It is known in garments for outdoor use, such as shown in WO2013/070086, to provide a garment with an insulating layer forming predetermined holes each capable of holding a volume of air. Such garments are not, however, designed for wear while immersed in water and the insulating layer takes no account of the effects of hydrostatic pressure on the insulating layer, which would reduce or remove the insulating effect. According to the invention, there is provided an survival garment for use in water comprising a body portion for surrounding a torso of a wearer and arm and leg portions for receiving the arms legs of a wearer, the body portion including a back portion for covering a back of a wearer, an inner layer of material being provided between the back portion and the body of a wearer, the inner layer of material spacing the body from the back portion by a layer of air, the inner layer having sufficient resistance to deformation to maintain said air layer under hydrostatic pressure when the wearer is floating on the wearer's back in water .

By including the material that maintains an air layer even under the pressure of the surrounding water, an insulating layer is formed and maintained between the outer layer and the skin of a wearer when immersed in water so reducing the transfer of heat from the wearer's body to the water. This improves the survival prospects of a wearer.

The following is a more detailed description of an embodiment of the invention, by way of example, reference being made to the accompanying drawings, in which:-

Figure 1 is a schematic plan view of a survival garment in the form of an immersion suit,

Figure 2 is a view of the suit of Figure 1 from the back showing the extent of an insulating air layer of the suit,

Figure 3 is a schematic side view of a person wearing the suit of Figures 1 and 2 a floating in water, Figure 4 is a section on the line X - X of Figure 3,

Figure 5 is a detail of the suit at Y in Figure 4 with the person floating in water, Figure 6 is a similar view to Figure 5 but with a thermal liner of the suit omitted, and Figure 7 is a similar view to Figure 5 but with the suit in air. Referring first to Figure 1, the immersion suit 10 comprises arm portions 11, leg portions 12, a body portion 13 and a hood 14 including a face opening 15. The arm portions 11 end in cuffs 16 that form a water-tight seal around the wrists of a wearer. The leg portions 12 end in respective foot portions 17. A front closure 18 can be opened to allow the suit 10 to be donned, after which the closure 18 is closed. The face opening 15 seals around the face of a wearer, so making the suit water-tight.

The arm portions 11, leg portions 12, body portion 13 and hood 14 of the immersion suit 10 may be formed from panels of a woven fabric coated with a synthetic rubber or polymer such as a polyvinylchloride or polyurethane. The coating may be a moisture vapour permeable material such as that sold under the trade mark GO ETEX. The panels may be sealed together by stitching and taping, by gluing or by welding.

The body portion 13 covers the front and the back of the torso of a wearer 23. Referring to Figure 2, the part of the body portion covering the back of the torso of a wearer 23 includes two side-by-side layers 19a, 19b of insulating material. The layers 19a, 19b are located on respective opposite sides of the spine of the wearer 23 and each layer 19a, 19b extends from the upper leg of the suit to a shoulder and from the spine to a respective side of the suit. The layers 19a, 19b are located on the inside of the suit between the suit and the body of the wearer 23.

Referring next to Figures 3, 4 and 5, each insulating layer 19a, 19b is formed by a drop thread material comprising spaced layers of woven material 20a, 20b interconnected by drop threads 21 that extend at 90° to the layers 20a, 20b and having a stiffness to resist compression of the layers 20a, 20b, at least to an extent to be described below. This stiffness may be achieved by coating the threads 21 with resin. The woven layers 20a, 20b are preferably permeable. The drop threads 21 may be interwoven with the outer layers 20a, 20b. The insulating layers 19a, 19b may have a thickness of from 3mm to 20mm but are preferably between 3mm and 5mm. Materials of this kind are made by the company Baltex. The insulating layers 19a, 19b thus form an open layer of insulating air across the back of the wearer, Referring to Figure 5, a thermal liner 22 may be provided between the insulating layers 19a, 119b and the wearer's body. The thermal liner 22 is may be a quilted material and is preferably moisture vapour permeable. The liner 22 may be attached to the insulating layers 19a, 19b. Alternatively, the liner 22 may be omitted, as seen in Figure 6.

In use, the suit is donned by the wearer 23 who enters the water: floating on the wearer's back, as seen in Figures 4 and 5. The hydrostatic pressure of the water tends to compress the back of the suit but the strength of the drop threads 21 is such that this compression is resisted, so maintaining an insulating layer of air between the water and the wearer 23. This reduces heat loss from the back of the wearer 23, an area of human body rich in blood vessels and so liable to high heat loss. At the same time, the permeable nature of the insulating layers 19a, 19b allows water vapour to transpire through the insulating layers 19a, 19b to and through the suit so increasing the comfort of the wearer 23. The thermal liner 22, where provided, further reduces heat loss from the wearer 23 but does not inhibit transpiration.

The presence of the insulating layers 19a, 19b adds buoyancy to the suit. The buoyancy added by the suit to the wearer's natural buoyancy is important since, if the suit is worn in emergency situations where the wearer 23 sinks into water in an enclosed space, such as a helicopter or an aircraft, excessive buoyancy from the suit can prevent or inhibit escape since this buoyancy will force the wearer upwards within the space. It has been found that, if a suit adds more than 175N of buoyancy, escape in such situations may be prevented or inhibited. Accordingly, it is preferred that the suit described above with reference to the drawings add no more than 175N of buoyancy to a wearer.

The insulating layers 19a, 19b need not be formed by a drop thread fabric as described above with reference to the drawings. It could be formed by any material that provides and insulating layer between the water and the wearer 23 that is maintained under the hydrostatic pressure of water immersion. As described above, the insulating layers 19a, 19b extend across the back of a wearer 23. It will be appreciated that it may also extend across other areas of the suit 10 that are immersed in water in use, such as areas of the legs and/or arms.

The suit described above is an immersion suit but the same structure may be applied to other garments such as survival suits and protection garments, for example submarine escape suits, pilot immersion protection garments and suits for people working on offshore oil and gas platforms. In all these cases, a suit of the kind described above with reference to the accompanying drawings provides good thermal insulation when the wearer is immersed in water and does not have undesirably excessive buoyancy. When worn out of water, the suit is comfortable, particularly in hot surroundings, since, as seen in Figure 7, perspiration can transpire across the thermal liner 22, the insulating layers 19a, 19b and the panels.