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This application is a continuation-in-part of U.S. patent application Ser. No. 09/272,824, filed on Mar. 19, 1999, having the title “Support System for Vessels Such as Swimming Pools,” which was a continuation of U.S. patent application Ser. No. 08/858,637, now issued as U.S. Pat. No. 5,884,347, filed May 19, 1997, having the same title, the entire contents of each of which are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to vessels such as swimming pools and more particularly to strapless support systems for above-ground swimming pools and to buttresses for walls of the above-ground swimming pools. 
     BACKGROUND OF THE INVENTION 
     The popularity of swimming pools, particularly in residential areas, continues to increase. This increased popularity is based at least in part on the availability of aesthetically appealing above-ground pools, whose durability permits cost-effective purchasing by consumers. Above-ground pools additionally are particularly useful in areas where substantial excavation is either impermissible or undesirable. In densely-populated regions, for example, residential lawns may not be sufficiently large to accommodate the space required for in-ground pools. Moreover, in some cases they may be inadequate to accommodate the equipment necessary to excavate in-ground pools, even if space for such pools exists. Alternatively, above-ground pools may be preferable because of the decreased time typically needed for installation (and, if necessary, removal) or the lesser maintenance requirements and costs often associated with them. 
     Many substantially-permanent above-ground pools are generally either circular or oval in shape, with each type comprising multiple vertical walls and a frame. Because of their strength, galvanized steel or other compositions are usually chosen as materials from which the walls are made. Nonetheless, water pressure present at and near the bottoms of filled pools often requires the walls of above-ground pools to be braced for reliable performance. This bracing requirement is particularly pertinent in connection with oval pools, whose elongated side walls are especially vulnerable to collapse from the outward pressure exerted by the water contained therein. 
     As a consequence of this vulnerability, existing oval above-ground pools are constructed with braces supporting the lower sections of their side walls. Each brace includes three pieces, denominated an “upright” portion, an “angled” portion, and a “connecting” portion. FIG. 1 illustrates such braces  10  of above-ground pool  14 , whose generally oval shape requires use of multiple vertical side walls  18 . As shown in FIG. 1, upright portion  22  extends upward from bottom  26  of side wall  18 , with connecting portion  28  being either at ground level or buried underground. An end of each of upright portion  22  and angled portion  30  connects to a respective end of connecting portion  28 , while the other end  34  of angled portion  30  attaches to upright portion  22 . The resulting structure resembles the outline of a right triangle, with angled portion  30  constituting the hypotenuse. 
     FIG. 1 details the protruding nature of braces  10 . Such braces  10  frequently extend outward several feet from side walls  18  on both sides of pool  14 , increasing the surface area of the lawn required for installing the pool. This increased surface area can cause difficulties in installing pools in areas subject to covenants or zoning regulations, as insufficient land may remain post-installation to meet setback and other legal or contractual requirements. Braces  10  may also inhibit lawn maintenance adjacent pool  14  and, to some, may detract from the aesthetic appeal of the pool itself. The three-piece structure of each brace  10  additionally increases its associated manufacturing and installing cost, while supporting less than the entire vertical height of a side wall  18 . 
     Furthermore, the nature of above-ground pools requires support straps that extend a substantial horizontal distance beneath the pool. Such straps render it difficult to construct a pool having a “deep” end because the straps run the substantial horizontal length of the pool and prevent the liner forming the bottom of the pool from filling a hole that has a depth extending below the straps. Removing the straps changes pressure allocations. It is thus desirable to provide a pool that alleviates the need for straps extending a substantial distance below the pool and that alleviates the protruding braces shown in FIG. 1, while providing support for a deep pool or a pool having a deep end. It is also desirable to provide such a pool that keeps the pool removable, i.e., that does not require a concrete fill and that is easy to assemble. 
     SUMMARY OF THE INVENTION 
     The present invention, by contrast, provides a support system intended to resolve these issues. Particularly suited for vessels such as elongated above-ground pools, the support system includes a set of, typically, one-piece buttresses adapted to support the entire vertical height of one or each of a series of side walls. The flared design of the buttress, furthermore, matches the support it provides the side wall to the outward water pressure present along its height for enhanced reliability, permitting use of fewer buttresses than the number of existing braces that would otherwise be necessary. The one-piece design of the buttress further eliminates some of the manufacturing and installation costs associated with existing braces, while its sleek appearance is more likely to please discerning observers. 
     The diminished footprint of the innovative buttress additionally reduces the surface area required for its corresponding pool. Setback and similar requirements thus pose fewer problems than with existing pools, permitting pools incorporating the present invention to be located in smaller (especially narrower) lawns. Consequently, more residential customers in densely-populated areas are able to situate these pools in the lawn space available to them, increasing the market for the pools beyond that existing today. Abolishing the open areas between the angled portions of current braces and the ground additionally avoids many of the difficulties associated with providing lawn care in those areas. Additionally, residential and other customers are able to enjoy pools having deep ends because of a feature that makes it possible to provide an area of the pool that is deeper than a standard installation provides. 
     In some embodiments of the invention, each buttress is a unitary structure whose height approximates that of the side wall or walls of its associated pool. At least one surface of the buttress contacts the side wall along substantially its entire height, supporting the height of the wall continuously against the outward pressure exerted when the pool is filled with water. Because the buttress defined by these embodiments flares along its height it assumes, in side elevational view, the general form of a truncated, solid triangle. Embodiments of the buttress further comprise notched sections to retain the bottom rim of the pool—and therefore help retain the side walls—in place. 
     Additionally included in some support systems of the present invention may be elongated cross-members spanning the width of the pool. Often called “omegas” because of their cross-sectional appearance, the cross-members, when present, are buried so that only their upper surfaces are above the ground. Buttresses on each side of the pool may be bolted or otherwise attached to the upper surfaces to retain them in position relative to the ground. Protruding from the upper surface of a cross-member adjacent its ends are one or more tabs, which in use fit into slots in the bottom rim of the pool to maintain its position. The buttresses, side walls, bottom rim, and cross-members thus can interact to preserve the position and structure of the pool relative to the ground. Alternatively, the buttresses may extend below ground level and be bolted, interlocked, or otherwise connected or fitted to the cross-members. 
     A further option that may be included in some embodiments of the invention is a support system that alleviates the straps that extend below the pool. This feature may accompany the pool system or may be sold as a separate kit. It permits above-ground pool owners to have a deeper pool than is conventionally available. 
     It is therefore an object of the present invention to provide a system for supporting a vessel designed to be filled with water or similar fluid. 
     It is also an object of the present invention to provide a system including one or more buttresses for supporting the side wall or walls of an above-ground swimming pool. 
     It is a further object of the present invention to provide a system in which a buttress supports a wall of a pool substantially continuously along the height of the wall. 
     It is another object of the present invention to provide a system for supporting pool walls in which the supporting structures extend only minimally beyond the exteriors of the walls. 
     It is an additional object of the present invention to provide a system, including one or more buttresses, for supporting a vessel such as an above-ground pool, in which the buttresses comprise notched sections to retain the bottom rim of the pool in position. 
     It is yet another object of the present invention to provide a system for supporting an above-ground swimming pool in which buttresses, side walls, the bottom rim, and cross-members interact to maintain the position and structure of the pool relative to the ground. 
     It is also an object of this invention to provide a system for supporting an above-ground swimming pool that enables a deep pool or a pool having a deep end, while still maintaining the position and structure of the pool relative to the ground. 
     It is still a further object of this invention to provide a substantially strapless support system that uses plates and beams that support the pool relative to the ground, while incorporating buttresses that extend only minimally beyond the exterior of the walls. 
     Other objects, features, and advantages of the present invention will be apparent with reference to the drawings and remainder of the text of this application. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an oval pool having an existing set of braces. 
     FIG. 2 is a perspective view of an oval pool utilizing a support system of the present invention. 
     FIG. 3 is a side elevational view of a portion of the pool and of a buttress of the support system of FIG.  2 . 
     FIG. 4 is a top plan view of the buttress of FIG.  3 . 
     FIG. 5 is a side elevational view of the buttress of FIG. 3 together with a surface of a cross-member of the support system of the present invention. 
     FIG. 6 is a perspective view of a portion of the cross-member of FIG.  5 . 
     FIG. 7 is a (nominally) front elevational view of the buttress of FIG. 3 together with portions of the cross-member of FIG.  5  and the bottom rim of the pool of FIG.  2 . 
     FIG. 8 is a perspective view of an alternative buttress of the present invention. 
     FIGS. 9A-C are (nominally) front elevational views of yet alternative buttresses and cross-members for use as support systems of the present invention. 
     FIG. 10 is a perspective view of a portion of a strapless support system of the present invention. 
     FIG. 11 is an exploded perspective view of the strapless support system of FIG.  10 . 
     FIGS. 12A-B are top plan views of oval pools having a strapless support system of FIG. 10 installed at or near opposing sides of the pools. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 2-5 and  7  illustrate buttresses  38  of the present invention. As shown in FIG. 2, buttresses  38  may be used in connection with pool  14 ′ instead of braces  10 . Doing so can diminish significantly the surface area required for installation of pool  14 ′, permitting pool  14 ′ to be positioned in areas inadequate for placement of pool  14 . As noted earlier, setback and similar requirements additionally pose fewer problems for pool  14 ′ because of its smaller overall size. 
     FIGS. 2 and 3 detail typical locations of buttresses  38  in connection with pool  14 ′. Illustrated in FIG. 2 is a set of buttresses  38  spaced along side  42  of (generally) oval pool  14 ′. Although not shown in FIG. 2, a similar set of buttresses  38  may be spaced along opposite side  46  of pool  14 ′. Because pool  14 ′ is oval, sides  42  and  46  are elongated relative to ends  50  and  54  and subject to greater stresses caused by the pressure of water W within the pool  14 ′. 
     This pressure within pool  14 ′ additionally is greatest at bottom  26  of side wall  18  (adjacent ground G) and decreases toward the corresponding top  58  of the wall  18 . To support the entirety of height H of side wall  18 , the above-ground height of buttresses  38  may be substantially similar or identical to height H and, as shown in FIG. 3, most or all of their surfaces  62 A and  62 B (see FIGS. 4 and 7) may contact the side wall  18 . To match more closely the support provided side wall  18  to the pressure of water W as a function of height H, buttresses  38  additionally may be flared in depth as illustrated in FIGS. 2 and 3. Such flaring results in buttress  38  having its minimum depth D 1  at its top  66  and its maximum depth D 2  at its bottom  70  (also adjacent ground G), with the depth increasing substantially continuously between top  66  and bottom  70 . Buttress  38  thus resembles, in the side elevational view shown in FIG. 3, a right triangle. 
     Unlike brace  10 , however, buttress  38  of FIG. 3 has solid sides  74 A and  74 B, a solid face  78 , and is truncated at top  66 . Surfaces  62 A and  62 B, moreover, function as flanges of buttress  38 . The result is a unitary structure for buttress  38  that both provides greater and more uniform and continuous support for side wall  18  and has a sleeker profile than braces  10 . Furthermore, for some embodiments of buttress  38 , maximum depth D 2  does not exceed ten inches, an amount significantly less than the distance (typically thirty-six inches) from pool  14  that braces  10  protrude. Other dimensions of an exemplary buttress  38  include height between approximately forty-two and sixty inches, width of approximately four inches, and a minimum depth D 1  of approximately two to four inches. Buttress  38  is usually made of metal such as galvanized steel but may be manufactured of other materials when necessary or appropriate. The face  78 , sides  74 A and  74 B, and surfaces  62 A and  62 B of buttress  38  additionally need not be integrally formed, although so forming them may avoid reducing the strength of the overall structure. Surfaces  62 A and  62 B also need not necessarily be formed at substantially right angles to respective sides  74 A and  74 B as shown in FIG.  4 . 
     FIG. 5 illustrates notched section  82  of buttress  38 . In use, buttress  38  may be connected (by bolts or other suitable means) to a cross-member  86  spanning the width of pool  14 ′. Such a cross-member  86  is shown in FIG.  6  and is buried in ground G so that only upper surface  90  is visible, and it is to this surface  90  that buttress  38  connects. Attaching buttress  38  to cross-member  86  in this manner thus retains the buttress  38  in position relative to ground G. Once buttress  38  is positioned, rim  94  (see FIG. 7) may be fitted into section  82  to assist in fixing its placement relative to the ground G. Slots of rim  94  additionally may receive tabs  98  protruding from upper surface  90  of cross-member  86  to complete its positioning. Side wall  18  may then be fitted into rim  94  in conventional fashion to retain it in place. Those skilled in the art will thus recognize that buttresses  38 , side wall  18 , rim  94 , and cross-members  86  of the present invention may be designed if desired to interact appropriately to preserve the position and structure of pool  14 ′ relative to the ground G. 
     Shown in FIG. 8 is an alternative buttress  38 ′. Unlike corresponding components of buttress  38 , face  78 ′ of buttress  38 ′ is curved, and surfaces  62 A′ and  62 B′ are formed at acute angles to respective sides  74 A′ and  74 B′. Buttress  38 ′ additionally extends beyond notched section  82 ′ to terminate at lower edge  102 , which in use is buried underground. 
     FIGS. 9A-C detail alternate cross-members  106 A-C. Like upper surface  90  of cross-member  86 , upper surfaces  110  of cross-members  106 A-C are at or near the level of ground G. Similar to buttress  38 ′, furthermore, buttresses  114 A-C extend so that lower edges  118 A-C are buried underground. In the buttress  114 A of FIG. 9A, lower edges  118 A are bent to form flanges  122 , which include apertures in which bolts  126  or other fasteners may be placed. Horizontal sections  130  additionally include apertures for receiving bolts  126 , thereby permitting buttress  114 A to be fastened to cross-member  106 A. By connecting buttress  114 A to horizontal sections  130  rather than vertical sections  134  of cross-member  106 A, bolts  126  are subjected to reduced shear stresses. Optionally excavating ground G to pour a concrete or other base C beneath horizontal section  130  may enhance the ability of buttress  114 A to support a pool. 
     Cross-members  106 B and  106 C instead may include slots  138  or recessed segments  142  for receiving pins or tabs  146  of buttresses  114 B or  114 C. Such slots  138  or recesses formed by segments  142  effectively retain buttresses  114 B or  114 C in position relative to respective cross-members  106 B or  106 C by engaging, or interlocking with, tabs  146  below ground G. Although lower edge  118 B is flanged and lower edge  118 C is not, such edges  118 B-C may be interchanged as necessary or desired. In any case, the result is a relatively secure positioning of a buttress  38 ′,  114 A,  114 B, or  114 C vis{grave over (-a)}-vis a cross-member  106 A,  106 B, or  106 C by connecting them underground. 
     FIGS. 10-12 illustrate strapless support system  210  of the present invention. This system alleviates the use of at least one pair of straps that extend a substantial length underneath the water-containing portion of traditional above-ground pools. The system allows a deeper excavation area, but still provides support for the walls using a system of buttresses, cross-members, vertical beams, and a plates that support the walls against the pressure of the water in the pool. 
     If the system is sold as an expandable kit, intended to expand the size of an already-installed pool, it is possible to provide different sized kits for different sized pools. Such kits permit the pool to be deeper on just one side, i.e., a “deep end,” or they may provide for a deeper pool in general. 
     As shown in FIG. 10, buttress  38  may be used in connection with alternate cross-members  212 , plates  220 ,  224 , and  226 , and vertical beam  222 . Similar to cross-member  86 , alternate cross-member  212  is adapted to cooperate with buttress  38  and pool rim  94 . More particularly, it may cooperate in any of the ways previously described. For example, alternate cross-member may cooperate with buttress  38  as illustrated and described in reference to FIGS. 9A-C or it may have a tab protruding from its horizontal upper surface  218  that may be received by slots of rim  94  in order to serve as a guide for the placement of rim  94 , as discussed above. 
     Alternate cross-member  212 , however, is also adapted to cooperate with vertical beam  222  and with plates  220 ,  224 , and  226 . In a preferred embodiment, each of two alternate cross-members  212 , two associated vertical beams  222 , and two buttresses  38 , are supported by three plates  220 ,  224 , and  226 . However, it may be possible to achieve similar support effects using only two of the plates, i.e., using plate  220  and only one of plates  224  and  226  located anywhere along cross-member  212 . The assembly is supported in the ground G by block  240 , which is typically a concrete block, but may be made from any suitable material. Block  240  acts as a support to keep system  210  level in the ground G and to provide a means for suitable weight distribution. Any suitable support means may serve this purpose. 
     FIG. 11 details the location of alternate cross-member  212  in connection with the additional support system elements including buttress  38 , vertical beam  222  and plates  220 ,  224 , and  226 . Cross member  212  may be any length that provides appropriate support for the system. A particularly suitable length for an alternate cross-member is about four feet. Buttress  38  (or  38 ′ as shown in FIG. 8) is connected at or near the first end  214  of alternate cross-member  212  by means similar to those described above and has the features described above. 
     Vertical beam  222  has a channel  246 , resembling a U-shaped channel, which in use cooperates with channel  244  of alternate cross-member  212 . Vertical beam  222  is of a length and depth appropriate to provide support for the system, and preferably has a length of about twelve inches so that it appropriately stabilizes the system in the ground. Vertical beam  222  is usually made of metal such as galvanized steel but may be manufactured of other materials when necessary or appropriate. It is connected at or near the second end  216  of alternate cross-member  212  (by bolts, screws, or nuts, or other suitable means, non-limiting examples including truss head machine screws and hex nuts) and is substantially perpendicular to the longitudinal axis of alternate cross-member  212 . 
     Plates  220 ,  224 , and  226  function to support and secure system  210  in place. They provide correct structural support for the system, i.e., ensure that the buttresses  38  are placed at correct distances from one another. Plates  220 , 224 , and  226  also provide lateral support. They are usually made of metal such as galvanized steel, but may be manufactured from any suitable material. Plates  220 ,  224 , and  226  may have various dimensions, exemplary dimensions including a range from about forty three inches to about forty seven inches. Plates  220 ,  224 , and  226  may each have a flange  252  to facilitate connecting the plate to the system. Flange  252  may also act as a further support by “grabbing” ground G and alleviating any slippage that may occur when system  210  is in place. Plates  220 ,  224 , and  226  may also have grooves  254  which prevent buckling that may occur if a flat plate is used, providing further structural support. 
     Front plate  220  also secures system  210  in ground G, as shown in FIG.  10 . It also acts to “grab” into ground G, which is one of the aspects of system  210  that allows the removal of the traditional straps. Front plate  220  is connected to vertical beam  222  using suitable connecting means, such as those described above. Front plate  220  will be at an angle that is substantially perpendicular to cross-member  212 . Plates  224  and  226  are connected to the horizontal upper surface  218  of alternate cross-member  212  at or near first and second ends  214  and  216 , respectively, using suitable connecting means. As noted, although the three plates  220 ,  224 , and  226  provide the preferred support, the invention may be practiced using less than the three plates  220 ,  224 , and  226 . For example it may be possible to retain only front plate  220  for support. The system  210  is shown as additionally supported by block  240  and angle brace  242 . 
     FIG. 11 also illustrates optional inserts  250  and  248 , which may be made of Styrofoam or other relatively pliable or pressure absorbing material, which may optionally be inserted into channel  244  of alternate cross-member  212  and channel  246  of vertical beam  222 . Inserts  250  and  248  help prevent system  210  from sinking into ground G by providing a surface for ground G to abut. They essentially act as space-fillers to keep the dirt from entering channels  244  and  246 . An optional angle brace  242  may be attached to alternate cross-member  212  to stabilize alternate cross-member on block  240 . Angle brace  242  holds alternate cross-member  212  (and thus strapless support system  210 ) in place. Although angle brace  242  is particularly useful, any type of support or stabilization technique may be used to secure cross-member  212  on block  240 . 
     FIGS. 12A-B illustrate top plan views of the strapless support system  210  of this invention assembled and in place in the bottom of two types of pools. FIG. 12A shows the invention in connection with a relatively small pool, for example a fifteen by twenty-four foot pool. In this embodiment, system  210  completely replaces the conventional straps  402  (that are shown in FIG.  12 B), with plates  220  (not shown),  224 , and  226  and alternate cross-members  212 . An expandable liner (not shown) is used with system  210  to line the pool and to provide a deep or deeper pool than would conventionally be available. FIG. 12B shows the system  210  located at or near opposing sides of the pool, replacing one set of straps in order to create a deep pool or a pool having a deep end. It may also be possible to completely replace straps  402  using one or more system  210  on a larger sized pool. 
     In order to deepen a pool or to provide a deep end, a preferred embodiment of the strapless support system  210  is assembled according to FIG.  10 . Block  240  is placed in a trench in the ground G. The trench should correspond to the appropriate dimensions of the system components. 
     As detailed in FIG. 11, vertical beam  222  is attached to the second end  216  of alternate cross-member  212  and the buttress  38  is attached to the first end  214  of cross member  212 . Front plate  220  is attached to vertical beam  222 . Second and third plates  224  and  226  are attached to the top surface  218  of the alternate cross-member  212  at or near the first and second ends  214  and  216 , respectively. Inserts  250  and  248  are then inserted into the channels  244  and  246  of the alternate cross-member  212  and vertical beam  222 . An angle brace  242  or other form of support is installed on either the alternate cross member  212  at or near the first end  214  or on the block  240  to provide stability. The completed assembly may then be placed in the trench on block  240  and at least partially buried underground. The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention.

Summary:
Support systems for vessels such as above-ground swimming pools are disclosed. Each system may include one or more buttresses adapted to support substantially the entire vertical height of the side wall or each of a series of side walls of the pool. A strapless support system to provide a pool having a deep end is also disclosed. The buttresses, which flare along their lengths, closely match the support they provide each side wall to the outward water pressure present along its height for enhanced reliability. The diminished space required for installation of the disclosed buttresses reduces the surface area required for their associated pool.