GB2220388A - Lifejackets - Google Patents

Abstract

Improvements are made to lifejackets comprising inherent buoyancy layers which also form the skin of an inflatable compartment. The inherent buoyancy layers are joined to each other at their periphery forming an air tight compartment between the layers. The lifejacket has some inherent buoyancy when the inflatable compartment is deflated, and upon introducing air between the layers of inherent buoyancy material, sufficient buoyancy is added to make the lifejacket self righting.

Description

IMPROVEMENTS TO LIFEJACKETS This invention relates to improvements to lifejackets.

This specification describes a lifejacket of the type intended to rotate a person in the water from a face down to a face up position. Lifejackets with this performance are commonly used for example by yachtsmen, fishermen, workboat crews and the like. Standards are available which specify detailed performance requirements among them being British Standard 3595. Lifejackets built to these standards commonly have considerable buoyancy high up on the chest of the wearer and the position and amount of buoyancy tends to make the lifejacket cumbersome to wear especially when not in the water. For this reason standards, including BS 3595, permit some or all of the buoyancy to be provided by an inflatable compartment resulting in a less cumbersome lifejacket when the lifejacket is worn with the compartment in the deflated condition.In the case where partial buoyancy is provided by an inflatable compartment, the remainder of the required buoyancy is provided by inherent buoyancy such as foam plastics. The advantage of having some inherent buoyancy is that some flotation is available immediately the wearer enters the water, which gives at least some support until the inflatable portion is inflated.

It is customary for the inherent buoyancy portion of such a lifejacket to be contained inside the skin of the inflatable compartment, usually in suitably shaped blocks of foam plastics or similar material. Lifejackets of this type are provided with means of securing to the wearer and these are usually in the form of straps. The securing means are attached either directly to the skin of the inflatable portion or alternatively to a cover which surrounds the lifejacket. A cover, if provided, serves to prolong the life of the inflatable portion or to provide the additional role of a garment. For example the cover could also be a waterproof jacket providing protection for the wearer.

Experience has shown that lifejackets of the type described above are sometimes damaged by the skin of the inflatable portion becoming worn or punctured so that it would no longer hold air when inflated. This condition may not be known to the wearer until the lifejacket is required for use in a survival situation, thus causing a situation of potential danger. The presence of foam plastics blocks inside the skin of the inflatable portion can add to the problem of damage since the blocks create high spots which contribute to causing local chafe which destroys the air holding properties of the skin.

The object of the present invention is to reduce the possibility of damage to the air holding skin of the lifejacket and at the same time to reduce the complexity of manufacture .

According to the present invention there is provided a lifejacket having two or more layers of inherent buoyancy material, for example plastics foam of the type in which the cells are not interconnected commonly known as closed cell foam, each layer of plastics foam being joined to the other at its periphery by known means for example adhesive or by fusing by the application of local heat, thus forming a gas tight compartment between each layer of plastics foam, means for introducing gas between the layers thus separating the said layers except at the periphery, this separation increasing the total buoyancy of the lifejacket by approximately the amount of gas introduced.

The plastics foam sheets thus act in a dual role of providing inherent buoyancy and also acting as the skin of the inflatable portion. One advantage of this invention is that the resilience of plastics foam lends itself to absorbing impact or chafe and is much improved over the usual relatively thin materials used for the skin of known present designs of lifejacket. Furthermore the thickness of the plastics foam sheet inherent in the requirement to provide buoyancy before inflation also provides a considerably enhanced resistance to puncture. Thus the plastics foam, instead of contributing to chafe or puncture damage to a separate outer skin as used in current designs of lifejacket, now replaces the outer separate skin, considerably enhancing the reliability of the lifejacket.A further advantage of this invention is the elimination of a separate skin to provide an inflatable compartment with a consequent saving in manufacturing cost. A further advantage is that it is possible to obtain an improved disposition of the inherent buoyancy since it does not have to be sealed inside an inflatable skin.

In a further embodiment of the invention, gas is introduced between the sheets of plastics foam during the manufacture of the lifejacket as a means of creating inherent buoyancy. One advantage arising from this embodiment is a saving in cost of plastics foam since thinner sheets may be used. A further advantage is an increase in flexibility due to the use of free gas in place of closed cell plastics foam. In essence the result is the same in principle and it is only the size of the gas cells which changes. The invention lays in the method of achieving the variable size cells and the advantage resulting in having large cells in the core and small cells near the exterior faces.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings: Figure 1 is a plan view or front view of the lifejacket.

Figure 2 is a section through figure 1 at the position A A.

Figure 3 is a section through figure 1 at the position A A after the lifejacket has been inflated.

Figure 4 is a section through a lifejacket employing the alternative embodiment of the invention having some gas introduced during manufacture of the lifejacket as permanent iiiherent buoyancy.

Figure 5 shows the same cross section as in Figure four but with air introduced via a mouth tube by the wearer.

In Figure 1, two sheets of plastics foam 1 and 2, are formed in the shape of a typical lifejacket. The sheets 1 and 2, are of sufficient thickness to provide an adequate amount of inherent buoyancy, the thickness for example being in the region of 3 to 5 cm. The two sheets 1 and 2, are joined at the outer and inner periphery of each to the other with adhesive 3.

Figure 3, shows the two layers of plastic foam 1 and 2, separated by the introduction of air. Air is introduced into the lifejacket via a mouth tube 4, which is positioned so that the free end can be reached by the mouth of a person wearing the lifejacket. The mouth tube is fitted with a non return valve which prevents air escaping after it is introduced.

However the non return valve can be released manually in order to deflate the lifejacket after use, making it again less cumbersome to wear.

The mouth tube 4, comprises a simple piece of flexible plastics tubing without the customary flange moulded at its base, normally necessary when attaching a mouth tube to a lifejacket having a thin skin of air holding material. It is secured by inserting it at an angle into a previously formed hole in one of the plastics foam sheets 1 or 2, using adhesive to hold it in place and form an air tight seal.

Straps 5, are joined to the plastic foam 1, using adhesive, and are used to secure the lifejacket to the wearer. Alternatively the lifejacket my be contained in a cover to provide additional protection or to enhance its appearance or to make it part of a garment. When the lifejacket is contained in a cover for any of these purposes, the means of securing the lifejacket to the wearer will usually be built into the cover.

The term plastics is intended to include all natural or synthetic rubber like materials including natural rubber, Neoprene, polyethylene, Ethafoam and the like. For example the lifejacket described herein could be made from expanded Neoprene foam in suitable thickness and this would lend itself to incorporation into a wetsult. of the type worn by TjiVHFI surfboard sailors, dinghy sailors and others who participate in water activities and require thermal protection as well as buoyancy.

In the alternative embodiment of the invention shown in Figure 4, there are four layers of plastics foam, the two outermost layers on each face of the lifejacket, 6 and 7 on one face, and 8 and 9, on the other face being permanently inflated at the time of manufacture. This permanent inflation effectively provides inherent buoyancy in the same manner as sheets 1 and 2, depicted in Figures 1, 2 and 3. However the inherent buoyancy is achieved with the benefit of reduced cost of material and with improved flexibility resulting in a lifejacket which is less cumbersome to the wearer. The lifejacket is inflated by the the wearer via the mouth tube to its full shape when required in the same manner as the lifejacket shown in Figures 1, 2 and 3.

In addition to inflation via the mouth tube, either type of lifejacket according to this invention may be inflated by means of stored compressed gas by methods already well known.

Although this invention has been described with particular reference to lifejackets designed to turn a person in the water from a face down to a face up position, the invention is not limited to such lifejackets, but may also be applied to buoyancy aids and other flotation devices. Furthermore, the embodiment described is only typical of one of the many configurations possible.

Claims (8)

1. A lifejacket having two or more layers of inherent buoyancy material, each layer of inherent buoyancy material being joined to each other at its periphery in order to form a substantially airtight compartment between each layer, means for introducing gas or air into each said compartment in order to separate the layers except at the joined periphery, the separation increasing the total buoyancy of the lifejacket by approximately the amount of gas or air introduced.

2. A lifejacket as claimed in Claim 1 which provides some inherent buoyancy in the deflated condition, and when inflated provides adequate buoyancy to rotate a person in the water from a face down position to a face up position, which utilizes the inherent buoyancy material in the dual roles of providing buoyancy before inflation and also provides the skin of the inflatable buoyancy compartment or compartments.

3. A lifejacket as claimed in Claim 1 or Claim 2, in which the inherent buoyancy in each layer is in turn provided by further layers of inherent buoyancy, each of the further layers being permanently inflated thus creating inherent buoyancy with large cells at the core and smaller cells surrounding the core.

4. A lifejacket as claimed in Claim 1, Claim 2 or Claim 3, wherein the means of introducing gas or air into the compartments is a tube of flexible material inserted into a hole in the inherent buoyancy material and sealed in place in a gas tight manner, said tube being provided with means of preventing gas or air escaping.

5. A lifejacket as claimed in any preceding claim wherein inflation is acheived by the provision of a container of compressed gas, connected to the or each compartment.

6. A lifejacket as claimed in any preceding claim wherein straps are provided in order to secure the lifejacket to a person

7. A lifejacket as claimed in any preceding claim wherein a cover is provided in the form of a garment for securing the lifejacket to a person.

8. A lifejacket substantially as described herein with reference to Figures 1-5 of the accompanying drawings.