US3488782A - Swimming pool construction and adjunct - Google Patents

Description

Jan. 13, 1970 1 B|| |G ETAL SWIMMING PC-)OL CONSTRUCTION AND ADJUNCT 2 Sheets-Sheet l Filed July 3l, 1969 fw SGM o@ n. TM5 N. N 5 /R www fw mfw T.

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Jan. 13, 1970 J. BILLIG ET AL 3,488,782

SWIMMING POOL CONSTRUCTION AND ADJUNCT Filed July 3l, 1969 2 Sheets-Sheet 2 United States Patent O 3,488,782 SWIMMING POOL CONSTRUCTION AND ADJUNCT Jules Billig and Clemens Resseguier, New York, N.Y.,

assignors to Bilnor Corp., Brooklyn, N.Y., a corporation of New York F-iled July 31, 1969, Ser. No. 846,369 Int. Cl. E04h 3/16 U.S. Cl. 4-172 33 Claims ABSTRACT OF THE DISCLOSURE The invention contemplates a swimming pool of the variety in which a compliant plastic liner, such as of polyvinyl film or sheet material, defines the water-confining part of the pool cavity. The plastic liner comprises side and bottom panels, to one or both of which compliant plastic envelope is secured and effectively united. Valving means incorporated in the envelope enables the envelope to be amply filled with pool water, at the time the pool is itself filled. When the pool is filled the envelope is self-retaining with the desired contouring. Various contouring and valving arrangemnts are disclosed.

BACKGROUND OF THE INVENTION- GENERAL FIELD This invention relates to an improved swimming-pool construction, particularly pools in which a layer of pliable plastic, water tight sheet material lines the bottom and Igenerally the side-wall portions of the pool.

Pools of the character indicated are intended primarily for the sa-fe enjoyment of water enthusiasts. Because the water level is relatively shallow, as from one to four feet deep, the bottom is fiat, and the area for swimming is restricted, a challenge is presented, to provide enhanced enjoyment of the pool, through increased variety of uses thereof.

It is an object of the invention to provide a pool construction of the character indicated wherein increased utility and enjoyment are available from variously characterized bottom and/or side contouring formations of compliant material.

Another object is to provide contour formations of the character indicated as integral parts of the pool liner.

A specific object is to meet the above objects with formations integral with the pool liner and capable of simple erection during the filling of the pool. A further specific object is to provide formations integral with the pool liner, inherently self-filling or erecting during the filling of the pool.

Another specific object is to achieve the foregoing without requiring special earth excavation or erection of solid matter in order to retain desired contouring.

A general object is to achieve the foregoing objects with constructions of elemental simplicity, ruggedness, and low cost, lending themselves to fool-proof erection by the householder of the most modest mechanical talent.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention:

FIGULRE 1 is a perspective view of a swimming pool incorporating a central island formation in accordance with the invention;

FIGURE 2 is a simplified schematic cross-sectional view through the island part of FIGURE 1;

3,488,782 Patented Jan. 13, 1970 ICC FIGURE 3 is a simplified enlarged fragmentary sectional view to illustrate Valving of FIGURE 2;

FIGURE 3A is a view similar to FIGURE 3 to illustrate modified Valving;

FIGURE 4 is a view similar to FIGURE 2 to illustrate a modification;

FIGURE 4A is a fragmentary sectional view to show a modification of FIGURE 4;

FIGURES 5 and 6 are views similar to FIGURE 4 to illustrate other embodiments;

FIGURES 7, 8 and 9 are fragmentary sectional views through lstill further embodiments in which the contouring is achieved in conjunction with both bottom and sidewall portions of the pool liner;

FIGURE l0 is a fragmentary perspective view of another embodiment; and

FIGURES 1l and 11A are similar fragmentary sectional views to illustrate physical relationships for further valve embodiments.

Briefly stated the invention contemplates a swimming pool of the variety in which a compliant plastic liner, as of polyvinyl film or sheet material, defines the waterconfining part of the pool cavity. The plastic liner comprises side and bottom panels, to one or both of which an inflatable compliant plastic envelope is secured and effectively united. Valving means incorporated in the envelope enables the envelope to be amply filled, with pool water, at the time the pool is filled. And when the pool is filled, the envelope is self-retaining with the desired contouring. Various contouring and Valving arrangements are disclosed. Throughout the specification and claims the words filled, infiated, water-filled and water inflated lare used. These are intended to interchangeably define the desired condition within the envelope which may be all water, or water and air at various pressures.

Referring to FIGURE l, the invention is shown in application to a conventional swimming pool construction of generally circular or cylindrical shape. In accordance with practice, such a pool relies upon a rigid, easily erected frame, involving upper and lower frame rings 10-11, spaced vertically by plural struts 12. A stiffening shell 13, which may incude vertical corrugations, is contained by the frameworks 10-11-12, and a bag 15 of tough compliant plastic, such as l0 to 20 gauge polyvinyl (depending upon pool capacity) is suspended from ring 10 and serves as the deterrent to water seepage defining a water periphery which hugs the shell 13 and the ground at the bottom. When the pool is filled with water, as suggested in FIGURE l to the level 16, the water pressure on the sides and bottom causes the liner 15 to smoothly conform to the described backing structure and ground contour,

which is fiat and horizontal, in conventional installations.

In accordance with the invention, variously contoured bottom and side formations for conventional pools of the character indicated are provided by employing a compliant infiatable envelope as part of the bottom or side of the liner 15, such envelope being of a material such as polyvinyl readily securable, as by heat-sealing, to the material of liner 15. In the form illustrated by FIGURES l and 2, such an envelope defines an island or hassock 17 at the center of the pool.

The basic shape of the envelope of island 17 may be of generally prismatic formation, defined by an opstanding body wall portion 20 which may be cyindrical or polygonal; the body wall portion 20 extends between an upper end 21 which is closed and a lower end which is open, thereby defining an envelope cavity open at the lower end. The lower end of body 20 is outwardly flanged at 22 and there secured to a limited area of the bottom panel 15, as by a peripherally continuous heat seal or weld. To illustrate Valving principles, the envelope of FIGURE 2 is schematically shown with three valves 23-24425, the first two of which govern flow through the body 20, and the last of which functions at the top of the bowed end 21. Valve 23 is a check valve functioning t0 control one-way hydraulic flow in the direction to fill the envelope. Valve 24 is a throttle valve for selective discharge of the envelope, as when emptying the pool. And valve 25 is an air valve functioning to determine the quality of residual air trapped or introduced in the otherwise water-filled envelope. It will of course be understood that the indicated valves may be of elemental simplicity, preferably all-plastic and flush mounted to the envelope walls 20-21.

In a typical shipment of the liner 15, with envelope 17 sealed thereto, there is of course next to no air in the envelope, which is in collapsed and folded condition, in a manner best suited to compact packing requirements. At the pool site, liner 15 is frame-mounted in the customary manner, with the envelope 17 lying (collapsed) on the upper surface of liner 15. A small quantity of air is then introduced into the envelope, as by blowing or pumping action at valve 23. This small quantity need in no sense ll the envelope, and will be seen merely as a means of assuring buoyant lift of the top end 21 as the pool is filled. As the pool water-level rises, water will be admitted freely into the envelope via check valve 23, and when the pool level 16 is achieved, the water level in envelope 17 will be slightly lower, being determined by the compression pressure of trapped air at end 21. In FIGURE 1, this condition is seen to cause a small island 17 to be exposed above the water level.

As will be later described, while the use of air is quite helpful it is by no means necessary either for filling or in the ultimate structure and it is possible to fill the envelope using positive pressure at the valve.

In use, the island or hassock 17 is firmly positioned and is slightly locally yieldable below the water level. However, above water level it has a softer, more compliant texture, consistent with the gauge and nature of the envelope material and with the volume and pressure of trapped air. In either event, the safety inherent in such compliance will be apparent.

To drain the pool, conventional techniques are employed, except that throttle valve is opened to permit drainage and collapse of the envelope 17, as the pool level goes down. Preferably, the relief valve 25 includes provision for selective release yof all trapped air before the pool is drained, thus assuring that drainage of water will completely collapse the envelope 17.

FIGURES 3 and 3A illustrates alternative flushmounted valving structures. FIGURE 3 shows a check valve having a molded-plastic body 30 having a peripheral ange 31 sealed to the side or body wall 20 of the envelope, at an opening 32 therein. Valve body 30 has an inlet port or opening 33, and an outlet opening or openings 34, at opposite sides of the valve chamber 35. A valve member 36 is positioned by a flexible-tongue connection 37 in register with the inlet 33, which also serves as the checkvalve seat. Tongue connection 37 is anchored in the material of body 30 and is preferably self-biased for normal lightly resilient urging of the valve-closed position.

The described valve of FIGURE 3 will be seen to provide all the functions required of the schematically shown values 23-24 in FIGURE 2. During the pool-filling phase, the valve of FIGURE 3 freely admits water within the envelope lbody 20, and when emptying the pool one need only finger-depress or jam the valve member 36 in its unseated position, to allow full water drainage.

In the valving means of FIGURE 3A, the body 40 is essentially a fiush-mounted eye or grommet defining a restrictive orifice 41 which in one form allows water to bleed, i.e. to fiow at a restricted rate, from one to the other side of body wall 20. If the orifice 41 is of large proportions, the valving means of FIGURE 3A is shown to include an externally accessible plug element 42, pref- 4 erably flexibly hinged to the -body 40 by an integral strap connection 43. A concave groove or necked-down portion 44 between the axial limits of plug 42 will be understood to have detent-retaining coaction with orifice 41 when in valve-closed position.

FIGURE 4 illustrates a modified hassock or islandtype envelope wherein the trapped air relied upon to buoy the upper end 45 is provided by a foamed-plastic element 46. If the outer surface of element 46 is completely sealed against water absorption, then element 46 may be directly secured to the top or bottom surface of the end 45. However, in the form shown, a further panel 47 of pliable plastic such as polyvinyl, defines with end 45 a pocket for the retention of member 46, being heatsealed or otherwise bonded at flange 48 to the `upper end of the body wall 49. As will be appreciated `by those skilled in the art the use of certain closed cell foams will, in conjunction with conventional sealing techniques, permit the elimination of one or both polyvinyl elements 46 and 47. The single valve 50, which may be as described in FIGURE 3 will fully serve the inflation, orientation, and deflation of the envelope of FIGURE 4, it being noted that the structure of FIGURE 4 avoids any need to introduce air into the envelope. Preferably, however, two valves will be provided since the ability to clean- Water Hush is highly desirable; for simplicity, however, generally one-valve applications have been discussed.

In FIGURE 4A, we illustrate the employment of airmattress techniques to provide buoyant support of the upper end 45 of the envelope. As shown, a corrugated member 52 is so sealed to one of the surfaces of end 4S as to define a plurality of air pockets 52', distributed over the area of end 45.

FIGURE 5 illustrates that the trapped air beneath the upper end 53 of the envelope 54 need not be confined to the entire effective area of end 53. An annulus 55 of airfilled material, such as foamed plastic, is sized to support merely the peripheral edge portion of upper end 53, being retained in place by a conically shaped pliable member, as of polyvinyl sheet, having sealed flange connections to the upper and body parts of envelope 54, as will be understood. FIGURE 5 also illustrates that, when in inated position, the upper end 53 may be below pool water level 16, for the pleasurable use of the submerged pedestal 54 which is thereby established.

In the arrangement of FIGURE 6, the envelope 60 is specially contoured at its yupper end, by a central recess or pocket 61, so that the uppermost part of the end is on Vannulus 62. The annulus is self supporting as before depending upon the equalization of water pressure and the natural tendency of the body to assume its preoriented formed shape. If desired, air may `be introduced through valve 25 (not shown in this figure) or an annulus of foamed material 63 may be provided at the top for rigidity. The annulus 62 provides a convenient seating region, from which feet may be dangled, without support from the radially outer edge, or with the support of recess 61 if the feet are placed radially inwardly of seat 62. A hydraulic connection 64 connects the recess 61 to a submerged part of the envelope body, in order that a free-flooded wading pool may be available within recess 61. Infiation and defiation, using valve 50, is as previously described. Alternatively, the connection may be eliminated and water provided the interior recess by depressing any portion of the annulus.

FIGURE 7 illustrates a modification wherein the envelope 65 is so truncated that the peripheral edge of its cavity may be sealed to adjacent localized regions of both the side panel 66 and the bottom panel 67 of liner 15. Valve 50 again serves for automatic inflation as the pool is filled, and the provision of foamed material 68 at the outside corner of the envelope 65 assures both requisite buoyancy and a more yieldable or safety edge 69. The water shading suggests that a submerged seat, below Water level is afforded by the inflated structure of FIGURE 7.

IN FIGURE 8, the envelope 70 is a substantially flat sheet having sealed-fiange engagement to bottom and side panels 66-67 of the pool, along a sloping alignment, such that a collapsible ramp bottom is defined for the otherwise flat bottom of the pool. The phantom outline 71 suggests an air-filled slab, mattress, or foamed-plastic supporting element beneath ramp envelope 70. A che-ck valve 50 and a plugged orifice valve 40, as described for FIGURES 3 and 3A, respectively, are preferably carried at lower and upper parts of the ramp envelope, to facilitate Water-filling and drainage, las Will be understood.

FIGURES 9 and 10 illustrate embodiments of the invention wherein the envelope (73-74, respectively) is contoured as a set of stairs, which in FIGURE 9 ascend in the direction perpendicular to the adjacent part of the side wall 75 of the pool Wall, and which in FIGURE 10 ascend in the direction parallel to the adjacent part of the side wall 75. In either event, the envelope (73` or 74) may be generally prismatic, and open only at the bottom end, being sealed only to the bottom panel of liner in the manner already described for other embodiments. However, in FIGURES 9 and l0 the prismatic envelope shapes are truncated on both the bottom end and on one side, to illustrate that the side wall 75 of the liner 15 may serve at least in part to complete the sealed envelope. As previously indicated, flanged edges of the truncation are used to make the sealed connections, as at 76 to Wall 75 in FIGURE 9, and at 77 to wall 75 in FIGURE l0. Since sealing to side wall does increase the possibility of rupture during use the elimination of this may be desirable in some cases, whereupon an upstanding panel would of course be added. Phantom outlines 78-79 respectively indicate air-filled tread reinforcements for the stair treads, these treads being located by means previously described. Preferably, for stiffness, tread reinforcements 78-79 are of cut marine plywood, sealed by a continuous coat of plastic material, further coated with an air-foamed layer, and then further sealed `by a continuous coat of pliant material such as polyvinyl, readily bondable to the material of the envelope involved (73 or 74) the air-foamed layer will be understood to assure against injury to the envelope material or to others, by providing relatively soft yielding texture at the treads.

FIGURE ll is a simplified fragmentary diagram to illustrate the principle of self-inflation of envelope 80, using for illustration but a single valve orifice which may be of the type described at 40. Valve 40 is located near the top of envelope 80, and assuming that envelope 80 is in collapsed condition, it should lirst be grasped and lifted, with valve 40 to open, to permit a quantity of air to be induced therein. The pool is then filled and as the Water rises there will at the same time be some iloW through valve 40 to fill the envelope. As the pool becomes almost full, the air trapped above valve 40 will have assured buoyant erection of the envelope 80, and the time will come when pool level eclipses the valve opening; this event is schematically designated 81. The pool filling continues to the final level 16, thereby establishing a hydraulic head D1 above Water level 82 within envelope 80. The level 82 is above the level S1, to the extent that the hydraulic head D1 has achieved equilibrium with the conipressed air trapped above level 82. If the orifice 40 is left open, the envelope 80 remains self-restoring to the same elevated position, even if a bather has expelled envelope water at 46, due to sitting on the island; on the other hand, it may be desired to plug orifice 40 (as described in FIGURE 3A) to assure maintenance of the island shape, once self-inflated.

Stated differently it is possible once equilibrium has been achieved to permit passage of Water from within to without the envelope and visa versa to relieve pressure surges.

FIGURE llA is in all respects the same as FIGURE l1, except that the check valve 50 has been used in place of the orifice valve 40. Filling criteria and hydraulic-head considerations remains the same. The only difference is that the use of the check valve 50l obviates any need to plug the valve opening. Accordingly, similar reference notation is employed in FIGURE 11A.

Thus far, the invention has been described in the context of self-filling constructions, being predicated on the proposition that inherent buoyancy in an upper part of the envelope, whether in foamed plastic, air cells, or as merely an entrapped upper region of air, will always so raise the structure as to induce Water-filling through a check valve, as at 50. It will, of course, be apparent that for this result to be achieved, the water level inside the envelope must necessarily be below that of the pool, at 16.

On the other hand, it may be desired for one or more of the described envelopes to be water-filled to pool level or above, and in such instances the nature of inlet 33 to valve 50 (FIGURE 3), or that at 41 to valve 40 (FIG- URE 3A), will be seen to afford ready forced induction of water, as by merely holding a garden-hose to the valve inlet. In a typical operation of this kind, which, incidentally, represents the preferred utilization of the invention, as for example of the FIGURE 2 variety, a small quantity of air is first introduced into the envelope, the pool is then filled to just below its ultimate level, at which time the trapped air in the envelope will have raised or piloted the envelope to a partially extended but correct orientation. Water is then forced by hose pressure at the inlet check valve to fill the envelope, and if desired, the trapped air is vented at relief valve 25 to assure complete Waterfilling. The pool is then filled to capacity, i.e. to level 16, which may be somewhat lower than the Water-filled upper end of the envelope.

The described pressure-filling technique will be seen as applicable to all described envelope configurations, except that if the wading-pool embodiment of FIGURE 6 is to be used with the annular seat or rim 62 supported by a water column extending above the pool level 16, precautions must be taken to assure against blow-out of the wading-pool basin on recess 6l. FIGURE 6A illustrates that blow-out protection is achieved by a stiffening basin member 61' sealed to and therefore forming part of the envelope 60, as by a peripheral seal of member 61 to a suitably cut-out central part of the upper end of envelope 60. In the form shown, the stiffening basin member 61 is integrally formed with a flange 62 to define upper end of the envelope as a more stitiiy rigid body. The upstanding pliant side Wall 60 of the envelope is thus sealed to the outer edge of the basin member 61. The latter may be a single injection-molded piece of suitable plastic, such as polyvinyl, and the side Wall.60' may be of sheet polyvinyl stock, cut to length appropriate to the circumferential extent of Wall 60', and heat sealed on a vertically seamed connection (not shown) of the cut ends of the length of sheet material. Since liotation 63 is unnecessary to the water pressure-filled form of FIGURE 6A, it is not shown, although it may be provided for other reasons, such as more comfortable texture or velvety feel at the seating surface.

It has been observed that the self-infiating versions of the invention rely upon slight residual positive buoyancy, for erection and water-fillings, and that this is not neces- `sary for the water-pressurized employments, in which retaining force to the entire flange; the section of such a hoop of pipe is suggested by phantom outline 51 in FIG'- URE 4.

It will be seen that we have described novel pool constructions lending themselves to varied applications and uses, for the safe and more pleasurable employment of an otherwise conventional swimming pool. Whether self-infiated, or inflated by garden-hose application, our structures are readily erected by the homeowner himself. Moreover, it will be understood that while the envelope structures have been described as integrally united with the pool liner 15, they may be complete in and of themselves, as shown by the dashed line 49' in FIGURE 4. Thus the lower envelope panel may be virtual (as where it is defined by liner or it may be real. Then the same selfiniiating properties apply for the envelope 49-45 as long as the base fiange thereof is sufficiently well held down as the pool is filled; such holding may be accomplished by adhesive or snap-fastener action between the envelope flange and the liner bottom, but the pipe designation 51 suggests the further alternative of weighting the envelope flange. Of course, if such a unitary envelope 49-45 is hose-filled to a water level above the pool level 16, then movement of large envelopes is limited (or might even in some cases be desirable) in which case fastening the envelope in place could be eliminated.

Since all of the described shapes, as well as many others as will occur to the reader, may be self-contained (i.e. include a bottom envelope piece integral with the sides and top) it will be apparent that such envelope units may be interchangeable and sold separately to permit a greater choice with less inventory requirements on the dealer.

Regardless of the technique of envelope filling, however, it will be appreciated that the filled envelope does not Iand cannot achieve its intended function and result without the coaction from surrounding pool water, i.e. when the pool is filled.

While the invention has been described in detail for the preferred forms shown it will be understood that modifications may be made without departing from the scope of the invention as dened in the claims which follow. For example, the described version of FIGURE 11 wherein the orifice 40 is continuously open suggests a pleasurably useful device even though body weight may slowly collapse the inflated envelope; regardless of the degree of collapse, the stiffness of the basic envelope shape, or the piloting or positively buoyant effect of trapped air or floatation, will always Iassure shape restoration. Moreover, the abusive local incision of the filled envelope (below pool level) need not be disastrous, and may provide extended enjoyment, due to the resultive orifice action already described in connection with FIGURE 11.

Since arrangements have been described wherein there is a positive pressure inside the envelope vis-a-vis the pool it may be desirable to add circumferentially spaced or otherwise placed stress bands of polyvinyl or other material to insure shape retention. Where lthe envelope is to be heat sealed to the pool liner it is suggested that the envelope be slightly less in thickness than the liner insuring that in case of stress causing rupture the adjunct and not the pool is injured.

Although the specification discusses a number of constructions in all of which the sheet material lines both the bottom and sides, it is to be clearly understood that this invention applies with like import to pools wherein only the bottom liner is so formed, the side being for example metal with a water tight seal to the bottom sheet material.

What is claimed is:

1. A swimming pool including la compliant plastic liner at least at the bottom thereof and an upstanding side panel and a fillable compliant plastic envelope secured at least in part to a localized part of the upper surface of said bottom panel, the upper surface of the compliant plastic envelope defining with the liner surrounding said envelope the bottom contour of said pool said envelope including valve means accommodating the selective flow of liquid between the inner volume of said envelope and the adjacent volume of said pool.

2. A pool according to claim 1, wherein said envelope is generally concave with the concavity open on at least one side, thereby defining a peripheral edge of said envelope, said peripheral edge being secured at least in part to said bottom panel.

3. A pool according to claim 2, wherein said peripheral edge is also secured to a localized part of said upstanding side panel, said side panel also being of compliant plastic.

4. A pool according to claim 2, wherein said envelope is of generally prismatic formation defining an upstanding body wall between substantially parallel spaced ends one of which is open to define the open concavity.

5. A pool according to claim 1, wherein said envelope comprises a sheet with a peripheral edge substantially continuously secured to a localized area of said bottom panel, said localized area being less than the effective surface area of said sheet comprehended within the secured region of said sheet.

6. A pool according to cl-aim 4, wherein said prismatic formation is generally right-cylindrical on an upstanding axis.

7. A pool according to claim 6, wherein said pool is generally cylindrical and said prismatic formation is centrally secured to said bottom panel.

8. A pool yaccording to claim 4, wherein the upper end of said envelope is centrally recessed to an extent less than the space between said ends, and a hydraulic iiuid connection communicating between the recessed part of the body wall below normal water level in said pool.

9. A pool according to claim 1, in which said valve means includes an air valve which, in the filled condition of said envelope, at elevated part of said envelope.

10. A pool according to claim 9, in which said air valve is a pressure-relief valve.

11. A pool according to claim 1, in which said valve means is a check valve which, in the inflated condition of said envelope, is at an elevation below normal water level in said pool.

12. A pool according to claim 1, in which said valve means comprises two check valves one of which, in the filled condition of said envelope, is at an upper elevation of said envelope and the other of which, in the filled condition of said envelope, is at a lower elevation of said envelope.

13. A pool according to claim 12, wherein said check valves are oper-ative to check fiuid flow against egress from said envelope, said valve each including selectively operable means to permit opening the source for egress of fluid, whereby upon filling the pool and with an initial volume of air in said envelope, said lower check valve may be primarily responsible for automatic admission 0f pool water within said envelope, and upon operation of said selectively operable means of said upper valve, said upper valve may be caused to discharge to the desired eX- tent such air as is contained within said envelope; and fur-- ther whereby, upon draining the pool, the selectively operable means of at least the lower valve may be operative to drain fluid from said envelope.

14. A pool according to claim 1, wherein said valve means comprises a single check valve which, in the filled condition of said envelope, is near but short of the upper limit of said envelope, said check valve comprising a valve member admitting hydraulic fiow in the direction from said pool and into said envelope and responsive to hydraulic fiow in opposite direction to check the same, said valve member being further ineffective to check escaping air flow as water is admitted into said envelope, the normal pool-filled level being above the level of said check valve; whereby upon filling the pool, said envelope will fill with water to a level above said valve until the pressure of envelope-trapped air balances the hydraulic head represented by the extent to which the pool water level exceeds the water level within said envelope.

15. A pool according to claim 1, wherein said valve means includes a restrictive orifice which, in the filled condition of said envelope, is near but short of the upper limit of said envelope, said orifice providing locally restricted fluid communication between regions inside and outside said envelope, the normal pool-filled level being above the level of said orifice; whereby upon filling the pool said envelope may be filled with water to a level above the orifice until the pressure of envelope-trapped air balances the hydraulic head represented by the extent to which the pool water level exceeds the water level within said envelope may be self-draining.

16. A pool according to claim 1, in which the filled condition of said envelope, an air-entrapping member is positioned adjacent an upwardly facing region of said envelope.

17. A pool according to claim 16, in which said airentrapping member is of foamed material.

18. A pool according to claim 16, in which said airentrapping member is locally secured to said region of said envelope to define an air pocket between said member and said envelope region.

19. A pool according to claim 16, in which said airentrapping member is locally secured to said region of said envelope to define plural spaced air pockets of limited individual areas, between said member and said envelope region and distributed throughout said region.

20. A pool according to claim 1, wherein said envelope comprises a sheet which, in the filled condition of said envelope is substantially fiat and sloped from the horizontal, said sheet being substantially peripherally continuously secured in part to said bottom panel and in part to said side panel, thereby defining a ramp bottom for said pool.

21. A pool according to claim 4, wherein the opening of said concavity is also at a localized part of said up- -standing body wall, said envelope being substantially peripherally continuously secured in part to said bottom panel and in part to said side panel, said side panel being also of compliant plastic, thereby defining a prismatic formation contiguous to said bottom and side panels.

22. A pool according to claim 21, wherein said prismatic formation is generally rectangularly prismatic, truncated at the locus of securing to said panels.

23. A pool according to claim 21 wherein said prismatic formation is generally right cylindrically prismatic, truncated at the locus of securing to said panels.

24. A pool according to claim 21, wherein said prismatic formation included plural progressively stepped upwardly facing surfaces, and air-entrapping means carried at each of said upwardly facing surfaces.

25. A pool according to claim 24, wherein the direction of stepped progression is substantially parallel to the local side-panel region to which said prismatic formation is secured.

26. A pool according to claim 24 wherein the direction of stepped progression is substantially perpendicular to the local side-panel region to which said prismatic formation is secured.

27. A pool according to claim 1, wherein a portion of said liner is common to said envelope and liner, said portion together with said envelope defining a complete, llable enclosure within the pool.

28. In combination, a swimming pool filled to normal water level, and a prismatic bottom-contour characterizing element comprising an envelope of compliant plastic material having an externally characterized shape which in water-inflated condition has an external lowermost contour which conforms to the pool bottom and which invelope rest thereon within the filled pool defining with the pool bottom surrounding the element a new pool bottom contour, said envelope being water filled at least to substantially the normal water level of said pool, the trapped water mass within said envelope and the conforming nature of the pool bottom and lowermost element contour statically maintaining the element position in the pool.

29. The combination according to claim 28, in which said envelope is water filled to a level above normal pool water level, whereby the filled envelope as a whole is negatively buoyant and is therefore in loaded relation with the pool bottom.

30. The combination of claim 28, in which said envelope is slightly positively buoyant at an upper part thereof and is negatively buoyant at lower portions thereof.

31. In combination, a swimming pool filled to normal water level, and a prismatic bottom-contour characterizing element comprising an envelope of compliant plastic material having an externally characterized shape which in water-inflated condition has an external lowermost contour which conforms to the pool bottom and which envelope rest thereon which in the filled pool defining with the pool bottom lsurrounding the element a new pool bottom contour, said envelope being of vertical extent less than the pool depth and totally water-filled, and means locating said envelope with respect to a localized part of the bottom of the pool.

32. In combination, a swimming pool filled to normal water level, and a prismatic bottom-contour characterizing element comprising an envelope of compliant plastic material having an externally characterized shape which in water-inflated condition has an external lowermost contour which conforms to the pool bottom and which envelope rest thereon which in the filled pool defining with the pool bottom surrounding the element a new pool bottom contour, said envelope being of vertical extent less than the pool depth and totally water-filled, the overall envelope density exceeding unity, whereby the waterfilled envelope is negatively buoyant and therefore locates on the bottom of the pool.

33. The combination of claim 30, in which the overall density of the envelope, including positively buoyant parts thereof, exceeds unity, whereby the water-filled envelope is negatively buoyant but selforienting in located relation with the bottom of the pool.

References Cited UNITED STATES PATENTS 3,072,922 1/1963 Pyke 4 17215 3,355,745 12/1967 Jannuzzi 4-172.12 3,366,977 2/1968 Koehler 4-172.12

LAVERNE D. GEIGER, Primary Examiner H. K. ARTIS, Assistant Examiner

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