Abstract:
A water skiing disk that is used by a water skier at slow speeds does not require bindings or other similar types of foot constraints and has a large exterior diameter dimension to hold up one or more skiers on the water at slow speeds while being light weight and easily transported by a single person.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention pertains to a water skiing disk that has a large exterior diameter dimension to hold up one or more skiers on the water at slow speeds. Because the water skiing disk is used at slow speeds, it does not require bindings or other similar types of foot constraints to secure the water skier&#39;s feet to the disk. Although the disk has a large diameter dimension, due to the novel construction of the disk, the weight of the disk is reduced and is easily transported by a single person. 
         [0003]    2. Description of the Related Art 
         [0004]    Conventional water skiing by a person involves the person wearing one or more skis on their feet with the person being towed by a boat at a substantial speed. The substantial towing speed is needed to keep the person afloat on the skis. Wider skis have been developed, for example wake boards, which enable the skier to be towed behind a boat at a reduced speed while remaining afloat. However, whether skiing on conventional skis or on a wake board, the speed required of the boat towing the skier is sufficient to require that the water skis or wake board be secured to the skier&#39;s feet. 
         [0005]    In conventional water skiing there is a significant force exerted on the skier by the tow rope of the boat pulling the skier. The force is due to the speed required to keep the skier afloat, and by the resistance exerted by the water on the ski or wake board moving through the water. The speed of the boat pulling the skier when water skiing or wake boarding is a primary factor in the difficulty experienced by a novice learning to water ski. In addition, the speed required of the boat towing the water skier is also a primary factor in the fatigue of the water skier, whether a novice skier or an experienced skier. 
       SUMMARY OF THE INVENTION 
       [0006]    The water skiing disk of the present invention overcomes disadvantages associated with conventional water skiing and water wake boarding by providing a disk of unique construction that can support a water skier on the water while being towed by a boat moving at a substantially decreased speed from that required when water skiing or wake boarding. The unique construction of the disk has a large diameter dimension that enables the water skier to stay afloat at reduced skiing speeds, and also enables more than one water skier to use the disk at a time. In addition, the unique construction of the disk which allows it to support a water skier at a significantly reduced speed also eliminates the need for foot bindings on the disk. This enables the water skier to move their feet to substantially any positions on the disk that are comfortable to the water skier when using the disk. Although the water skiing disk of the invention has an enlarged diameter dimension, the unique construction of the disk also reduces the weight of the disk and thereby enables it to be easily transported by a single person. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Further features of the water skiing disk of the invention are explained in the following detailed description of the disk and in the drawing figures. 
           [0008]      FIG. 1  is a plan view of the first, bottom surface of the water skiing disk of the invention. 
           [0009]      FIG. 2  is a side view of the water skiing disk of the invention. 
           [0010]      FIG. 3  is a side sectioned view of the water skiing disk. 
           [0011]      FIG. 4  is a plan view of the second, top surface of the water skiing disk showing the position of a vent hole that is used in constructing the disk. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0012]      FIG. 1  is a plan view of a bottom, first surface of the water skiing disk of the present invention  12 . In the preferred embodiment, the disk  12  has an exterior diameter dimension of 47 inches. It is contemplated that varying the exterior diameter dimension of the disk by plus or minus 2 inches from the preferred 47 inch exterior diameter of the disk would enable the disk to be used with substantially the same results in water skiing as the preferred 47 inch diameter disk. However, through experimentation it has been determined that the best results in water skiing with the disk  12  are achieved when the disk has a 47 inch diameter dimension combined with the other particular dimensions of the disk to be described. 
         [0013]    As seen in  FIG. 1 , the disk  12  has a circular outer peripheral edge  14 . There are no protrusions or obstructions on the circular outer edge  14  of the disk  12 .  FIG. 1  shows a first, bottom surface  18  of the disk  12 . It can be seen in  FIG. 1  that there are no holes or other obstructions through the disk within the disk outer edge  14 . 
         [0014]    Referring to  FIG. 2 , the outer peripheral edge  14  has a center axis  16  that defines mutually perpendicular axial and radial directions relative to the disk. The disk  12  has a second, top surface  22  that is opposite the first, bottom surface  18 . The disk  18  is specifically designed for water skiing on the first surface  18 . It can also be seen in  FIG. 2  that both the first surface  18  and second surface  22  of the disk are smooth, continuous disk surfaces with there being no obstructions or protrusions on the surfaces within the disk outer peripheral edge  14 . 
         [0015]    The particular cross-section configuration of the disk shown in  FIG. 2  results in the synergistic ability of the disk to support one or more water skiers when the skiers are towed on the disk  12  at a reduced speed over the water. The synergistic effect of the particular exterior cross-section configuration of the disk  12  enables a water skier to easily get up on the water using the disk when towed at a reduced speed, and to remain on the water using the disk when towed at a reduced speed. Because the particular configuration of the first, bottom surface  18  provides the stability of the disk as it is towed at slow speed over the water, the exterior configuration of the first surface  18  will be described in detail. It should be understood that the exterior configuration of the second surface  22  also contributes to the beneficial feature of the reduced weight of disk  12  which contributes to the ease and safety of using the disk  12 . 
         [0016]    Referring to  FIGS. 1 and 3 , the first, bottom disk surface  18  comprises a circular center section  24  that extends radially outwardly from the center axis  16  to a radius dimension of from 18 inches to 22 inches from the center axis  16 . Better performance is achieved when the radius of the center section  24  of the first disk surface  18  is in a range of from 19 inches to 19.5 inches. In the preferred embodiment of the invention, the radius of the circular center section is 19.47 inches, and the center section is flat and is positioned in a plane that is perpendicular to the center axis  16 . 
         [0017]    The axial distance between the first and second surfaces  18 ,  22  at the center axis  16  is preferably in a range of 1 to 2 inches. In a more preferred embodiment, the axial thickness between the first surface  18  and the second surface  22  at the center axis  16  is 1.5 inches. In the preferred embodiment of the invention, the axial thickness between the first surface  18  and the second surface  22  at the center axis  16  is 1.436 inches. 
         [0018]    Outside of the center section  24  of the first surface  18  of the disk, the disk bottom surface has a first annular intermediate section  26 . The first annular intermediate section  26  of the first surface  18  extends radially outwardly from the first center section  24  to a radius of from 2 inches to 6 inches from the center section. In the preferred embodiment of the invention, the first annular intermediate section  26  of the first surface  18  extends radially outwardly 4 inches from the preferred radial dimension of 19.47 inches of the first center section  24 . 
         [0019]    In addition to the above, the first annular intermediate section  26  of the first surface  18  has a radius of curvature in a range of from 225 inches to 235 inches. In the preferred embodiment of the invention, the radius of curvature of the first annular intermediate section  26  is 275.4 inches. 
         [0020]    The first  18  disk surface also has an annular outer section  28 . The annular outer section  28  extends radially outwardly from the annular intermediate section  26  to the outer peripheral edge  14  of the disk, or for a radial distance of substantially 1 inch. In the preferred embodiment of the invention, the first annular outer section  28  will have a radial dimension of 0.53 of an inch from the first annular intermediate section  26  of the preferred embodiment to the outer peripheral edge  14  of the disk. 
         [0021]    In addition, the first annular outer section  28  of the disk has a radius of curvature in a range of from 0.35 of an inch to 0.40 of an inch. In the preferred embodiment of the invention, the radius of curvature of the first annular outer section  28  is 0.375 of an inch. 
         [0022]    The second disk surface  22  of the disk  12  is designed as the top surface of the disk that will support the skier. The second surface  22  has a continuous, convex surface that extends from the center axis  16  of the disk out to the outer edge  14  of the disk. The second surface  22  extends from the center axis  16  to a radial dimension of 20 to 23 inches. In the preferred embodiment, the radial dimension of the continuous, convex top surface is substantially 23 inches. 
         [0023]    In addition to the radial dimension, the second, top surface  22  of the disk  12  has a radius of curvature in a range of from 500 inches to 600 inches. In the preferred embodiment of the invention, the radius of curvature of the top, second surface  22  is 552 inches. 
         [0024]    The second disk surface  22  also has an annular outer section  32  that is substantially a mirror image of the first surface annular outer section  28 . The annular outer section  32  of the second, top surface  22  extends around the outer peripheral edge  14  of the disk and has a radial width dimension of substantially one inch. In the preferred embodiment of the invention, the second annular outer section  32  of the top, second surface  22  has a radial dimension of 0.53 of an inch. 
         [0025]    The particular dimensions of the disk  12  discussed above result in the synergistic ability of the disk to raise one or more skiers upon the water and keep the skiers on the water with a reduced speed of a towing boat. The particular dimensions of the disk  12  discussed above enable even a novice user of the disk to easily get up on the water and stay on the water skiing at an operating speed as slow as 12-14 miles per hour. 
         [0026]    Referring to  FIG. 3 , the disk in its preferred form is constructed of a hollow plastic shell. The shell is comprised of a first saucer shaped piece  42  that defines the first, bottom surface  18  of the disk, and a second saucer shaped piece  44  that defines the second, top surface  22  of the disk. The two pieces  42 ,  44  are formed of plastic by rotational molding. Other means of forming plastic, for example blow molding, could also be used. However, the rotational molding process is preferred in performing the two pieces  42 ,  44  of the outer shell of the disk  12 . 
         [0027]    The top piece  22  is formed with a vent hole  46 . The vent hole in the preferred embodiment has a 1 inch diameter. The preferred position of the vent hole  46  is off center as shown in  FIG. 4 . The vent hole  46  is employed in injecting foam pellets into the interior of the disk between the two disk pieces  42 ,  44 . The foam pellets are also heated and rotary molded to form a rigid foam interior core  48  between the two pieces  42 ,  44  of the disk. 
         [0028]    In the preferred embodiment of the invention, the rotationally molded plastic that forms the two pieces  42 ,  44  on the opposite sides of the disk  12  is a polyethylene such as the Surpass® polyethylene MDPE RMs 539 produced by Nova Chemicals®. The foam employed in producing the rigid foam core  48  of the disk  12  is preferably rotational molded in the interior of the disk  12  from micro pellets at 10 pounds per cubic foot. 
         [0029]    The above construction results in a weight of less than 30 pounds for the 47 inch diameter disk  12 . In the preferred embodiment, the weight of the disk is 24 pounds. This light weight not only makes the disk easily transportable, but also contributes to the safety of the disk should a person be struck by the disk when skiing. 
         [0030]    Although the disk of the invention has been described above by reference to a particular embodiment of the disk, variations and modifications could be made to the disk described without departing from the intended scope of the following claims.