US 3428978 A
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Description (OCR text may contain errors)
Feb. 25, 1969 c. s. JOHNSON SHARK SCREEN Filed Aug. 29, 1967 FIG. 2.
l.\'\- EX /0R. C. SCOTT JOHNSON V. C. MULLER ROY MILLER ATTORNEYS.
United States Patent 3,428,978 SHARK SCREEN Clarence Scott Johnson, Oxnard, Calif. (574A Canal Road, Sarasota, Fla. 33581) Filed Aug. 29, 1967, Ser. No. 664,218 US. Cl. 9--11 Int. Cl. 1363c 9/16 3 Claims ABSTRACT OF THE DISCLOSURE The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
It has recently been proposed, as exemplified by the patent to Fest, 3,222,701, to protect persons referred to by the provision of a screen in the form of a cylindrical bag for containing the person.
It is known, as a result of tests of this invention, that if a bag of the type referred to is to be of optimum practicability it should embody certain features, among which are:
(a) Completely isolate the person from ambient water to thereby prevent diffusion of blood, perspiration, odors, and body wastes into ambient water which attract marine life, such as sharks,
(b) The bag must be of a material which does not emit odors or resemble food which would attract or excite marine life,
(c) The material must be opaque and preferably of low reflectivity such as dark green, dark blue, or black,
(d) Outside protuberances which might move by water action and thereby arouse the curiosity of marine life must be avoided,
(e) Sharp transition edges which are susceptible to being bitten by marine life should preferably be avoided,
(f) The bag material must have a density greater than water so that it will sink and retain a predetermined shape when filled with water,
(g) A plurality of stacked buoyant flotation collars should be provided at the top as a safety factor against puncture and as an upstanding shroud above the water line to obscure the occupants head from vision,
(h) Prior to inflation, it should be foldable into a flat package having a volume approaching the volume of its material and be stowable in the users survival vest, and
(i) It should be simple in construction and subject to economical manufacture.
The subject of the invention which fulfills the requirements aforesaid is depicted in the drawing, in which:
FIG. 1 is a broken away side elevation showing use in the sea;
FIG. 2 is a top elevation of FIG. 1; and
FIG. 3 is a section taken on line 3--3, FIG. 2.
The invention in its most simplified form may be constructed of two sheets 10, 12 of thermoplastic material, such as polyvinyl chloride, sheet being rectangular and of a length equal to the circumference of the screen and of a height equal to the height of the entire screen plus approximately the height of collars 14, sheet 12 being of a diameter slightly in excess of the diameter of the screen.
3,428,978 Patented Feb. 25, 1969 Sheet 10 is folded upon itself and its vertical edges heat sealed together forming a tube. Its upper edge is then folded down a distance approximately equal to the height of the collars and heat sealed peripherally along lines 16, forming three separate compartments 18. The edge of the circular bottom 12 is then heat sealed to the periphery of the lower edge of tube 10. Valves 20 for inflating the compartments may be affixed to the respective compartments at the most convenient stage of construction. It lap seams are employed, they should be at the edge of the material so that no loose flaps are present on the outside surface of the screen.
FIG. 3 illustrates a mode of construction in which loose flaps 22 are disposed within the screen, the exterior vertical joint 24 and the bottom joint 26 appearing only as lines. In this construction, sheet 10 is folded and seamed as previously described and then turned inside out, disposing flaps 22 on the inside. It is then cross seamed as previously described forming the three compartments. The bottom 12 is then heat .sealed to tube 10 along circular line 26, thus placing the bottom flaps 22 inside the screen.
As so far described, tube 10 and compartments 18 are formed from a single sheet of material, preferably of a dark color with low reflectivity. This is to be normally preferred for wartime use since the dark collars also aid in obscuring the device and its occupant from enemy attack. For peacetime use, however, it would usually be more desirable to construct the collars of a bright color, such as orange, so that the occupant can be more readily located. In such construction, one additional seam would be required slightly below the lowermost compartment 18. At this point the bright material forming the compartments would be heat sealed to the lower dark material by a seam extending peripherally around the device. A lap seam may be employed provided loose flaps on its outside are avoided or a seam having flaps 22 may be employed which disposes the flaps on the inside. In the event it is desired to reduce the size of the lower end of the screen where less space is required for the legs of the occupant, tube 10 may be tapered, such as in the form of a frustum of a cone. Also, if it is desired to render the circular edge joining tube 10 and bottom 12 less susceptible to being bitten, bottom 12 may be preformed to a curved shape, such as hemispherical, to thereby reduce or eliminate such edge, thus forming a smooth edgeless transition between the tube and the bottom wall.
The thermoplastic material which has been employed with satisfactory results is of .008 to .010 thickness. If desired, this may be reinforced with nylon. The overall height of the bag should be about the height of the tallest person who might occupy it, 76 having been selected as an ideal height with diameters of about 24" and 36." When folded into flat rectangular packages, these occupy a volume of approximately 70 and cubic inches, respectively. The valves referred to may be of the type employed with air mattresses, floats, and the like, which may be closed after inflation with breathing air. A miniature gas bottle, such as CO may also be attached to the valves, if desired.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings.
What is claimed is:
1. Apparatus for deterring attacks by marine life, such as sharks, upon a person floating in an erect position in the sea, comprising:
(a) a tubular bag having a bottom and adapted to contain sea water, the bag being imperforate to confine marine life attracting body emanations therewithin;
(b) a plurality of stacked inflatable toroidal collars disposed at the top of the bag and extending above the surface of the Water a suificient distance to obscure vision of the head of the person from a lateral direction;
(0) the bag being constructed of sheet thermoplastic material having a density greater than water, whereby it sinks to maintain it in a predetermined shape;
(d) said bag having a vertical welded seam, a circumferential Welded seam adjacent its bottom, the collars being formed by a plurality of spaced parallel circumferential welded seams separating the collars into non-communicating compartments adapted to contain gas, the lowermost compartment having sulficient buoyancy to float the bag with the other com parts disposed above water level; and
(e) a valve for each compartment through which inflating gas may be applied.
2. Apparatus in accordance with claim 1 wherein the bag is of smaller cross section at its bottom than at its top.
3. Apparatus in accordance with claim 1 wherein the bottom is shaped to eliminate a discrete transitional circumferential edge susceptible of being bitten by marine life.
References Cited UNITED STATES PATENTS TRYGVE M. BLIX, Primary Examiner.
US. Cl. X.R.