AN AUXILLARY FLOATATION DEVICE AND A FLOATATION DEVICE

Abstract

The present invention relates to a floatation device for encumbered people carrying equipment such as military personnel and offshore workers. Ideally, the floatation device includes an auxiliary floatation device for encumbered users that can be used with a primary lifejacket worn by a user. The auxiliary floatation device includes a buoyancy portion that, in 5 use, can be attached to the legs of the user, and the orientation of the torso of the user is controlled by the buoyancy force provided by the buoyancy portion and, in turn, effect the distance between the mouth of a user and waterline, which is referred to as the freeboard.

Claims

1-27. (canceled)

28. An auxiliary floatation device that can be used with a primary lifejacket worn by a user, the auxiliary floatation device includes a buoyancy portion that, in use, can be attached to the legs of the user, and the orientation of the torso of the user is controlled by the buoyancy force provided by the buoyancy portion and, in turn, effect the distance between the mouth of a user and waterline (the freeboard).

29. The auxiliary floatation device according to claim 28, wherein the buoyancy force of the auxiliary device is, when in use, the result of the device being fully submerged.

30. The auxiliary floatation device according to claim 29, wherein the buoyancy force of the auxiliary floatation device controls the orientation of the torso of the user to automatically orientate into a reclined position in the water, and in this position the user's back is directed downward and the face of the user is directed upward, and, when the user is in the reclined position in the water, the longitudinal axis of the torso of the user is in the range of 30 to 60 degrees to a horizontal waterline, measured in a forward direction of the user.

31. The auxiliary floatation device according to claim 28, wherein the buoyancy portion has a single buoyancy element only that extends across the buttock or pelvic region of the user and the device has a harness that includes leg straps that extend about each leg of the user for attaching the device to the user.

32. The auxiliary floatation device according to claim 28, wherein the buoyancy portion includes two buoyancy elements, and one of the buoyancy elements is attached to each thigh of the user, and suitably to each thigh of the user.

33. The auxiliary floatation device according to claim 32, wherein the auxiliary floatation device includes thigh straps that extend about the thighs of the user, and the thigh straps are removably connected to the buoyancy portion of the auxiliary floatation device using a quick attachment and release system.

34. The auxiliary floatation device according to claim 32, wherein the device includes a harness having a waist strap that, when in use, extends about the waist of the user and two legs straps extending from the waist strap, when in use, the leg straps extend about each leg of the user.

35. The auxiliary floatation device according to claim 28, wherein the buoyancy portion has a buoyancy force up to 100 N.

36. The auxiliary floatation device according to claim 28, wherein by increasing the buoyancy force the user can adjust their orientation into a more reclined position.

37. The auxiliary floatation device according to claim 28, wherein by reducing the buoyancy force the user can adjust their orientation into a more upright position.

38. The auxiliary floatation device according to claim 28, wherein the buoyancy portion includes at least one inflatable bladder, and the user can control the buoyancy force by increasing the degree of inflation of the bladder.

39. The auxiliary floatation device according to claim 38, wherein the auxiliary floatation device includes an oral inflation assembly that is arranged to allow a user wearing the auxiliary device to inflate at least one of the bladders by blowing from their mouth, and thereby the oral inflation assembly includes a hose and a one way valve that allows a person to blow into the hose to inflate the or each bladder, and the user can adjust the buoyancy force of the auxiliary floatation device by changing the degree to which the bladder(s) are inflated, and in turn, control the orientation of the torso of the user and improve the mouth freeboard.

40. The auxiliary floatation device according to claim 38, wherein the floatation device has a vent that the user can open and close to reduce the degree to which the bladder(s) is inflated.

41. The auxiliary floatation device according to claim 38, wherein the hose is a self-retracting the hose that is arranged in a coil formation, that can be pulled out to an extended form and auto-retract into a coiled retracted form.

42. The auxiliary floatation device according to claim 38, wherein the auxiliary floatation device includes a pressurised gas cylinder that is arranged to inflate the or each bladder, and the user can control the degree to which the or each bladder is inflated by controlling gas flow from the cylinder into the or each bladder and, in turn, enable the buoyancy force of the lower buoyancy to be adjusted to control the orientation of the torso of the user, and the device includes an ON/OFF valve for controlling the gas flow into the bladders, and a release bleed valve to control the flow of gas from the bladders.

43. The auxiliary floatation device according to claim 38, wherein the device includes at least one openable housing for containing at least one of the inflatable bladders in a compact configuration for storage while deflated.

44. The auxiliary floatation device according to claim 38, wherein the auxiliary device includes two openable housings, one of the housings from each bladder.

45. The auxiliary floatation device according to claim 38, wherein each housing is attached to the thigh straps.

46. The auxiliary floatation device according to claim 38, wherein the or each housing has a length in the range of 10 to 15 cm, a width in the range of 8 to 12 cm and height in the range of 5 to 10 cm, such that the or each bladder in a deflated condition can be stored in the housings and so that the auxiliary floatation device does not to interfere with normal military operations.

47. A floatation device for encumbered users including: a harness having a waist strap that extends about the waist of a user and at least one thigh strap that extends about a leg of a user below the buttock of the user; an upper abdominal buoyancy portion that is attached to the waist strap of the harness; and a lower buoyancy portion that is attachable to the thigh strap; wherein the orientation of the body of the user in the water is able to be controlled by the buoyancy force provided by the lower buoyancy portion and, in turn, effect the freeboard.

48. The floatation device according to claim 47, wherein the lower buoyancy portion is the auxiliary floatation device that can be used with a primary lifejacket worn by a user, the auxiliary floatation device includes a buoyancy portion that, in use, can be attached to the legs of the user, and the orientation of the torso of the user is controlled by the buoyancy force provided by the buoyancy portion and, in turn, effect the distance between the mouth of a user and waterline (the freeboard).

49. The flotation device according to claim 47, wherein the harness does not have a crotch strap.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] An embodiment of the present invention will now be described with reference to the accompanying representations, of which:

[0045] FIG. 1 is a schematic side view of an encumbered user wearing a floatation device including an upper abdominal lifejacket, an auxiliary floatation device attached to the legs of the user, and additional weight that may, for example, represent body armour, and a waist belt;

[0046] FIG. 2 is a schematic side view of a user with arrows representing the weight and buoyancy forces acting on the body of the user relative to a line extending through the mouth of the user that is perpendicular to a longitudinal axis of the user, in which the lever effect of the auxiliary floatation device to control the orientation of the torso of the user is represented by D.sub.1;

[0047] FIG. 3 is an enlarge view of the head region of the user shown in FIGS. 1 and 2, in which the torso of the user is located in a reclined or supine position by the auxiliary floatation device to increase the freeboard of the user;

[0048] FIG. 4 is a picture of an encumbered soldier wearing 30 kg of body armour, a primary life jacket and the auxiliary floatation device;

[0049] FIG. 5 is an enlarged view of the auxiliary floatation device illustrated in FIG. 4; and

[0050] FIG. 6 is graph illustrating the results of trials performed on seven different devices, in which trials 1 to 4 and trial 6 included the user wearing a primary lifejacket only, and trials 5 and 7 included the user wearing a primary life jacket and an auxiliary floatation device while the user is encumbered to varying degrees.

DETAILED DESCRIPTION

[0051] A preferred embodiment of a floatation device 20 will now be described with reference to the accompanying figures. Reference numerals have been included in the following description to help identify features of the preferred embodiment in the drawings. However, not all reference numerals have used in each Figure to maintain the clarity of the Figures.

[0052] The floatation device 20 includes a primary lifejacket 14 that is worn about the head or neck and the abdominal region of a user 13 and an auxiliary floatation device 11. The auxiliary floatation device 11 ideally includes two inflatable bladders 18, see FIGS. 4 and 5. Each of the bladders 18 may be attached to the thighs of a user 13 by means of a thigh harness including thigh straps 17 (see FIG. 4) that extend about each thigh of a user 13 below the user's buttock.

[0053] In addition to providing additional buoyancy to assist in maintaining an encumbered user 13 afloat, the auxiliary floatation device 11 enables the orientation of the torso of the user 13 to be controlled and held in a relatively stable position in water. For example, FIG. 1 illustrates the user 13 oriented in the supine position in which the frontal aspect of the user 13 forms an angle in the range of 30 to 60 degrees to the horizontal or the waterline 22. When the waterline 22 is calm with negligible waves, the orientation of the torso of the user 13 may be said to be held in equilibrium.

[0054] The physical phenomena that determines that static behaviour of a body immersed or partly immersed in a liquid is known as Archimedes principle. In summary, Archimedes principle states that a body immersed in a liquid is subjected by an upward force that is proportional to the amount of displaced liquid. In the case of lifejackets, a percentage of the lifejacket is underwater, which we refer to as the submerged volume that provides buoyancy, the remaining part of the lifejacket that is above the waterline 22 provides reserved buoyancy or additional buoyancy in the event that the user 13 is pulled beneath the water, a wave crashes over the user 13, and to cater for users 13 of different mass and different body types.

[0055] FIG. 2 illustrates the weight of the person W.sub.1, i.e., mass multiplied by gravity, the weight by which the person is encumbered W.sub.2, and the buoyancy forces of the primary life jacket including buoyancy forces of the neck and head rest BF.sub.3, buoyancy forces of the abdominal section BF.sub.2, and the auxiliary buoyancy BF.sub.3 of the auxiliary floatation device 11. The buoyancy force applied by the liquid on the user's body, BF.sub.4, is a function of the liquid displaced by the submerged parts of the user 13.

[0056] Controlling the angle of orientation of the torso of the user 13 in the water is a function of many parameters including the body type of the user, the location of the centre of mass of the user, the location of the centre of mass of the additional weight being carried by the user, the buoyancy forces of the lifejacket being worn by the user 13, and the lever effect of the buoyancy force BF.sub.1 of the auxiliary floatation device 11. The lever effect of buoyancy force BF.sub.1 can be expressed in terms of the normal portion of buoyancy force, namely BFN.sub.1, multiplied by the distance D.sub.1 to the frame of reference being the mouth of the user. As D.sub.1 is significantly greater than D.sub.4 and D.sub.5 from the mouth of the user, the buoyancy force BF.sub.1 of the auxiliary floatation device 11 has a major impact on the orientation of the longitudinal axis A-A of the torso of the user 13 in the water.

[0057] In summary, when the user 13 is in a stable orientation, or at equilibrium in the water, the sum of forces, namely the weight and the buoyancy should be equal. In addition, the sum of forces normal or the sum of the forces parallel to the longitudinal axis A-A of the torso of the user 13 should also be equal. Similarly, the static moments normal to the longitudinal axis of the torso of the user 13 can be expressed as follows:

D.sub.1.Math.BFN.sub.1+D.sub.4BFN.sub.2+D.sub.5.Math.BFN.sub.3+D.sub.3.Math.BFN.sub.4=D.sub.2.Math.WN.sub.2+D.sub.3WN.sub.1(equation 1)

wherein [0058] i) BF.sub.1 is the buoyancy force of the auxiliary floatation device 11 and BFN.sub.1 is the normal vector thereof, [0059] ii) BF.sub.2 is the buoyancy force of the chest portion of the lifejacket 14 and BFN.sub.2 is the normal vector thereof, [0060] iii) BF.sub.3 is the buoyancy force of the head and neck region of the lifejacket 14 and BFN.sub.3 is the normal vector thereof, [0061] iv) BF.sub.4 is the buoyancy force of the liquid acting the submerged portion of the body of the user 13 and BFN.sub.4 is the normal vector thereof, [0062] v) W.sub.1 is the weight of the user 13 at their centre of mass and WN.sub.1 is the normal vector thereof, and [0063] vi) W.sub.2 is the weight by which the user 13 encumbered and WN.sub.2 is the normal vector thereof.

[0064] By controlling the angle of orientation of the torso of the user 13, we have discovered that the freeboard (see FIG. 3) can also be significantly improved. For example, an encumbered user 13 may have a freeboard of less than 90 mm when oriented upright in the water. Whereas, when the same user 13 is positioned in supine orientation as a result of the auxiliary buoyancy, the freeboard can increase to above 90 mm and suitably in the range of 110 to 130 mm, and even more particularly approximately 120 mm.

[0065] As shown in FIG. 3, the maximum freeboard for a user 13 wearing a lifejacket 14 and the auxiliary floatation device 11 will occur when the user 13 is oriented at an angle so that the longitudinal axis A-A of the torso of the user 13 is in the range of 30 to 60 degrees to the horizontal. In our experience when the angle of orientation of the torso of an encumbered user 13 is greater than 60 degrees to the horizontal, the user 13 is oriented too upright in the water and the freeboard will not be maximised. Similarly, when the angle of orientation less than 30 degrees to the horizontal, the user can be oriented too horizontal which can also result in a reduction of the freeboard.

[0066] It will be appreciated that the auxiliary floatation device 11 does not increase the total buoyancy force applied to the user 13 (i.e. the sum of BF.sub.1, BF.sub.2, BF.sub.3 and BF.sub.4) if the overall elevation of the user's body in the water remains the same i.e., the portion of the user body submerged remains the same.

[0067] In any event, the auxiliary floatation device 11 is capable of orienting the user 13 into a stable orientation while increasing the freeboard compared to the situation in which the user 13 is oriented in an essentially upright position in the water.

[0068] The magnitude of the lever effect of the auxiliary floatation device 11 can be changed by changing either the distance at which buoyancy force acts on the user 13 from the nominated reference point, or by changing the magnitude of the buoyancy force BF.sub.1. While it may be possible to change the position of the auxiliary floatation device 11 on the user 13 prior to entering the water, once the user 13 is in the water it may be difficult to change the position of the auxiliary floatation device 11 on the user 13.

[0069] However, the degree to which the bladders 18 are inflated and hence the buoyancy force BF.sub.1 can ideally be adjusted when the user 13 is in the water. By way of example, the user 13 may allow more gas to enter into the bladders 18 or vent gas from the bladders 18 when in the water. In one example, the bladders 18 may be inflated using any suitable means including a pressurised gas cylinder (not shown in the Figures) that can be opened via a valve to allow the contents of the gas cylinder to inflate the bladders 18. The valve may have an ON/OFF or open/closed position. The bladders 18 may also have a vent valve for venting gas from the bladders 18. The gas cylinder may contain any suitable gas, including relatively inert gases such as nitrogen and/or carbon dioxide.

[0070] As can be seen in FIGS. 4 and 5, illustrate the bladders 18 in an inflated condition. Ideally the auxiliary floatation device 11 can be inflated by the user 13 blowing into an oral inflation assembly having a hose 15 connected to an opening into one of the bladders 18. The oral inflation assembly may include a valve, such as a one way valve that allows the user 13 to inflate the bladders 18 to the required amount and thereafter remove their mouth from the hose 15 without the risk of the bladders 18 going flat by air being discharging therefrom. The degree to which the user 13 can inflate the bladders 18 can be based on the user's perception of their orientation in the water.

[0071] As can be seen in FIGS. 4 and 5, the hose 15 is self-coiling into a spiral formation preventing the hose from dangling or being a tripping hazard prior to the user 13 entering the water. The bladders 18 are also ideally interconnected by a passageway 16 that allows gas in one bladder 18 to pass to the other bladder 18 to allow the bladders 18 to be inflated simultaneously. In another embodiment not illustrated in the figures, there may be no passageway interconnecting the bladders 18 so gas is unable to pass from one bladder 18 to the other.

[0072] Although not shown in the figures, the auxiliary floatation device 11 may include housings or similar valises about the size of the closed first for storing the bladders in a compact deflatted condition. The or each housing may be atach to the tigh straps. The or each housing may have a length in the range of 10 to 15 cm, a width in the range of 8 to 12 cm and height in the range of 5 to 10 cm and is sized so that the housings interfere with normal military operations.

[0073] The lifejacket 10 worn by the user 13 may be any suitable device including for example, the lifejackets mentioned in FIG. 6 namely the following lifejackets

TABLE-US-00001 TABLE 1 Lifejacket buoyancy 360 N Sample 1 275 N Sample 2 248 N Sample 3 275 N Sample 4 275 N and the auxiliary floatation device Sample 5 11 with a 100 N buoyancy force 290 N Sample 6 290 N and the auxiliary floatation device Sample 7 11 with a 75 N buoyancy

[0074] Ideally, the lifejacket 14 has a yoke or bib structure having an inflated head or neck rest portion, and an inflated chest portion. The chest portion of the yoke structure has two opposite lobes, and in the case of the bib structure, the chest portion is a single bladder. The lifejacket 10 may also include a first harness including a waist strap. The auxiliary floatation device 11 may also have a second harness including thigh straps 17 that extend about the legs of the user 13 below the user's buttock. Ideally, the lifejacket 10 is connected to the second harness of the auxiliary floatation device 11, for example, the thigh straps 17 and the waist strap may be interconnected.

[0075] Ideally, the buoyancy portions of the lifejacket 14 can be inflated, for example, may means of pressurised gas cylinders that are arranged to inflate the bladder(s) of the lifejacket 14. The lifejacket 14 may also have a mouth piece for oral inflation of the bladder(s).

[0076] With reference to FIG. 6, Samples 1 to 4 are lifejackets that can provide the following freeboards 120 mm, 120 mm, 140 mm and 160 mm respectively of whether the user 13 is unladen user. However, when the user 13 is encumbered with 30 kg of additional weight, the freeboard for Samples 1 to 4 each reduces to approximately 40 mm. In our view this freeboard is insufficient and significantly reduces the chances of survival of the user 13. In addition, the orientation of the torso of the user 13 was essentially uncontrolled and for Samples 1 to 4 was measured as being 52, 53.5, 65 and 71 degrees to the horizontal respectively when encumbered by 30 kg.

[0077] In contrast, Samples 5 and 6 comprise standard lifejackets 14 and the auxiliary floatation device 11 described herein. In the case of Sample 5, the freeboard for an unladen user 13 was approximately 160 mm which reduced to approximately 120 mm when encumbered by 15 kg and 20 kg respectively. The freeboard was measured as 80 mm when encumbered with 30 kg.

[0078] In the case of Sample 7, the free board ranged from 155 mm for an unladen user 13 to approximately 120 mm when the user 13 was encumbered by 30 kg. In addition, the angle of orientation of the torso of the user 13 was controlled by the auxiliary floatation device 11 to angles of 50 and 57 degrees respectively when encumbered by 30 kg.

[0079] We believe that the trials demonstrate a strong correlation between controlling the orientation of the torso of the user 13 using the auxiliary floatation device 11 to increase and indeed, maximise freeboard.

[0080] It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention.

[0081] For example, the auxiliary floatation device 11 may include an angle indicator that provides the user with a reading providing an approximately angle of orientation of the torso of the user 13 in the water. The user 13 can then adjust the degree inflation of the bladders 18 of the auxiliary device, i.e. increase or decrease, and thereby control the orientation of their torso in the water and, in turn, adjust the freeboard of the user 13.

[0082] In addition, the tigh straps, waist harness and so forth may have any suitable quick release mechanism for dooning and doffing the auxiliary flotation device and/or the primary lifejacket.