Abstract:
A method of preventing crown hydration of a golf green by providing a polyethylene tube, stretching the tube to form a stretched tube, cutting the tube in a spiral fashion to form a first sheet with force striations at an acute angle to an edge of the sheet, forming a second sheet in a similar manner as the first sheet with a force striations at an acute angle, securing a surface of the first sheet to a surface of the second sheet with the force striations of the first sheet at a relative angle to the force striation of the second sheet to form a layered sheets, providing a plurality of layered sheets, securing the edges of the layered sheets to form a golf green cover, and applying a holding means through a reinforced section to hold the cover in place.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is a divisional application of U.S. patent application Ser. No. 10/032,652 filed Nov. 13, 2001 now U.S. Pat. No. 6,739,088. 

   This invention relates to a cover for turf, and more particularly, to a temporary protective winter turf cover for use on golf course greens, tee areas of a golf course and similar areas. 
   BACKGROUND OF THE INVENTION 
   The increased popularity of golf throughout the world has led to a substantial increase in the need for more golf courses. Additionally, every day, on which a golf course stays open if it would normally be closed, increases the effectiveness and profitability of the course. In the Northern climates, competitiveness to stay open as late in the fall and open as early as possible in the spring is the challenge faced by today&#39;s golf course superintendents. 
   Besides the need to be open early in the spring, the golfers also demand an excellent putting surface right away and throughout the year. As a result of this competition for golfers, courses need to be the best and open at all costs to make the money. In the Southern climates, this is not very difficult, except for rainy days. 
   The picture changes in the Northern climates, however. Almost all golf courses in the Northern climates close down for the winter. The golf courses then reopen once the courses, and especially the greens, are in condition for the golfers to use without causing injury to themselves or damage to greens. 
   Traditionally, a golf course uses a composition, generically referred to a top dressing, to cover the putting surface or golf green in an attempt to protect the green during the winter season. Top dressing is usually a mixture of sand with soil or peat, which is placed over the top of the green in order to protect the grass during the winter months. From the years of experience, it becomes clear, that this top dressing composition and method of application do not always protect the turf from winter injury. 
   For a golf course putting surface or green, grass is visible. Directly below the surface grass is the crown, which is invisible from the green&#39;s surface. Directly below the crown are the roots of the grass or putting surface, which roots are also invisible from the green&#39;s surface. 
   A major problem for a golf course putting surface or green is crown hydration. Crown hydration is the number one killer of turf on putting greens during any given winter season. Crown hydration results from the freeze and thaw cycles of winter weather. Almost any cover on a golf green permits water to penetrate through this surface of the golf course green. 
   As this water penetrates to the green, it comes into contact with the crown. It is common for the water, which has penetrated through the cover and into the green, to re freeze and cause great damage to the crown, and, hence, the root system of the green. Such damage is called crown hydration of the green and causes major problems in getting the green ready to play. 
   Presently, other protection methods are being used, including; expanded particle products, straw, and lace coated or woven polyethylene. These methods or devices provide somewhat effective methods of protecting greens during the winter. 
   However, there is a very fine line between protecting and overprotecting a green, especially during midwinter or early spring growth. The present method of the expanded particle blanket often insulates the turf too much on sunny winter days, especially those days where snow cover is lacking, and over stimulates the turf into a falsified sense of spring and the grass starts to grow. Such growth at this time is not acceptable for providing an acceptable green. 
   Life expectancy for the expanded products is about three years. If used more than the three years, it can easily lead to crown hydration. The expanded products, with their two inches of thickness, create many problems. Such insulating foamed, characteristics make them bulky, hard to store, handle and dispose of when their usefulness is gone. 
   The lace-coated cover is an effective cover only as long as water does not penetrate therethrough. However, it is lace coated, that is to say that are apertures in the coating, thereby allowing water to penetrate the cover and get to the turf or crown underneath. As previously explained, there are certain problems with allowing the protective cover to breathe during the course of the winter. If the temperature alone warms the snow, it will allow moisture to pass through cover and possibly causing crown hydration to the turf underneath. 
   Another drawback of early or midwinter growth, is that before the covers are placed over the turf, chemicals are applied to protect against particular turf diseases associated with winter dormancy and spring growth. If early growth occurs, these chemicals are then absorbed into the root too early. This early absorption requires that the covers be removed and the chemicals reapplied. This is a waste of time, chemicals and money. 
   Also, the protective covers must be easily removed to save labor and time, while still allowing for removal, in order for the golf course to be used during midwinter warm spells. Private courses can charge anywhere from $60.00 to $200.00 and up per round per golfer. Assuming four golfers per round at 30 rounds per day, the income can range from $7,200.00 per day to $24,000.00 and up for every extra day of play in gained revenue by having the turf open for play on warm winter days, instead of closed as is the standard procedure. 
   Another problem with existing covers is that neither rapid cooling nor rapid warming can be prevented. Yet without this ability, the most undesired crown hydration occurs, usually in a very rapid fashion. 
   A protective turf cover must have at least five desirable qualities. Firstly, it must protect the turf from excessive moisture gain in the crown area. Secondly, it must protect the turf without over stimulating the turf to make it come out of the dormancy too early in the spring. 
   Thirdly, a cover must be easily removable if weather warms sufficiently in order to allow play to resume, at a time when the course is not otherwise playable. Large amounts of revenue can be lost in some climates if greens are covered, the weather warms enough to allow play, but too much time and money is needed to remove the green covers to allow play to be resumed. 
   Fourthly, any cover must last as long as possible. A life expectancy of at least three to more than seven years is a must to cut costs on reorders and old cover disposal. Fifth, the covers must be fabricated from a material, which can be folded and stored into as small as space as possible. 
   SUMMARY OF THE INVENTION 
   Among the many objectives of this invention is the provision of a golf green cover, which permits a golf green to be used in efficient fashion. 
   A further objective of this invention is the provision of a golf green cover, which prevents crown hydration. 
   Yet a further objective of this invention is the provision of a golf green cover, which greatly reduces crown hydration. 
   A still further objective of this invention is the provision of a golf green cover, which is easily installed. 
   Another objective of this invention is the provision of a golf green cover, which is easily stored. 
   Yet another objective of this invention is the provision of a golf green cover, which is easily folded. 
   Still, another objective of this invention is the provision of a golf green cover, which is easily unfolded. 
   Also, an objective of this invention is the provision of a protective winter turf cover, which may be easily disposed of at the end of its useful life. 
   A further objective of this invention is the provision of a protective winter turf cover, which has repeated uses. 
   A still further objective would be to provide a cover, which will delay rapid cooling. 
   Yet a further objective would be to provide a cover, which will delay rapid warming. 
   These and other objectives of the invention (which other objectives become clear by consideration of the specification, claims and drawings as a whole) are met by providing a protective winter turf cover from a layered polyethylene laminated sheet with each layer having force striations running at an angle to the edge of the sheet and with the force striations of one layer at an angle to the force striations of the adjacent layer, thereby forming a turf cover, which is lightweight, compactly foldable, and substantially impermeable to water. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  depicts a perspective view of a standard a golf green  110 . 
       FIG. 2  depicts a perspective view of the winter turf cover  100  of this invention being installed on a golf green  110 . 
       FIG. 3  depicts a perspective view of a ground holding device  120  for the winter turf cover  100  of this invention being installed on a golf green  110 . 
       FIG. 4  depicts a perspective view of the panel edge joining device  140  for panels  142  of cover  100  of this invention. 
       FIG. 5  depicts a perspective view of a plain polyethylene tube  150  used to form the winter turf cover  100  of this invention. 
       FIG. 6  depicts a perspective view of an oriented, stretched, polyethylene tube  160 , based on plain tube  150 , used to form the winter turf cover  100  of this invention. 
       FIG. 7  depicts a perspective view of a spiral cut  170  of the oriented, stretched tube  160 , used to form the winter turf cover  100  of this invention. 
       FIG. 8  depicts a perspective view of an oriented sheet  180  based on spiral cut  170  of the stretched polyethylene tube  160 , used to form the winter turf cover  100  of this invention. 
       FIG. 9  depicts a perspective view of a three sheet cross lamination  190  based on oriented sheet  180 , used to form the winter turf cover  100  of this invention. 
       FIG. 10  depicts a perspective view of a panel  142  with foam  148  thereon. 
       FIG. 11  depicts a perspective view of a panel  142  with foam  148  therein. 
   

   Throughout the figures of the drawings, where the same part appears in more than one figure of the drawings, the same number is applied thereto. 
   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In accordance with the present invention, a temporary protective winter turf cover, as a protective cover, is provided for a grass surface, especially a golf green. Any polymer capable of being formed into a light weight, flexible sheet is suitable for forming winter turf cover. In a preferred form, the protective winter turf cover is formed from at least one polyethylene sheet. The preferred polyethylene will be discussed below 
   Each polyethylene sheet has at least two layers of laminated polyethylene as its base. Preferably, each layer in the polyethylene sheet is in an orientated cross laminated fashion to provide strength and integrity to the cover. The covers are preferably factory seamed to the largest piece manageable, in order to provide both a one-piece for a green and a water tight barrier between the weather elements and the underlying turf. For a particular golf course, each turf cover can be labeled for its respective green in a standard fashion. 
   The protective winter turf cover is formed with a layered polyethylene laminated sheet with each layer having force striations running at an angle to the edge of the sheet and with the force striations of one layer at an angle to the force striations of the adjacent layer, the resulting turf cover being lightweight, compactly foldable, and substantially impermeable to water. 
   In a preferred form, each layer is preferably rectangular and has force striations running at an acute angle to an edge. Preferably the acute angle is about 20 to about 70 degrees relative to the edge of the layer. In a more preferred form, the force striations are running at an angle of about thirty degrees to about sixty degrees relative to the edge of the layer. In the most preferred form, the force striations are running at an angle of about forty degrees to about fifty degrees relative to the edge of the layer. 
   With two layers being laminated adjacent to each other, the relative angle between the striations of each layer ranges from about sixty degrees to about 120 degrees. In a more preferred form, the relative angle between the striations of each layer ranges from about 70 degrees to about 110 degrees. In most preferred form, the relative angle between the striations of each layer ranges from about 80 degrees to about 100 degrees. 
   Due to the particular structure of the cover, rapid cooling or rapid warming of the covered golf green is avoided. While it is not desired to bound by any particular theory, the following postulate is offered for this success. The impermeability of the cover combined with the ultra white color provides a cover which will substantially delay either rapid cooling or rapid warming. The ultra white reflects sunlight and delays heating. The impermeability prevents undesired water contact. 
   The turf cover of the present invention provides a protective turf cover that has many advantages. There are at least five outstanding advantages of this turf cover. First, the turf cover protects the turf from excessive moisture gain in the crown area. Second, the turf cover protects the turf without over stimulating the turf to make it come out of the dormancy too early in the spring. Third, a cover must be able to be easily removed if weather, typically winter weather, warms and allows play to resume. Fourth, a cover must be able to be easily replaced, when, again typically winter weather, if the weather cools and requires play to cease. 
   Large amounts of revenue can be lost in some climates if greens are covered, the weather warms enough to allow play, but too much time and money is needed to remove the green covers to allow play to be resumed. 
   Fifth, covers must last as long as possible. A life expectancy of three to seven years is a must to amortize costs on reorders and old cover disposal. Fifth, the covers must be fabricated from a material, which can be folded and stored into as small as space as possible. 
   In one illustrative embodiment, the sheets used to cover the turf are generally flat rectangles, having a flap on one end to accommodate field seaming of the pieces for larger areas. The flap provides for the joining of one sheet to another in an efficient manner in the field, and reduces the bulk of the sheet carried to the field. 
   In a most preferred embodiment, the sheets used to cover the turf are generally flat rectangles joined together by an adhesive at the edge thereof. Enough sheets are used to form a winter turf cover for a golf green. Because of the foldability and flexibility of the individual sheets, the winter turf cover for each golf green retains the flexibility and storability as well as the required ease of installation and removal. 
   In another preferred embodiment, the protective covers have attached thereto, various thicknesses of a foam layer to act as the aforementioned cold weather insulator. The foam layer may also be sandwiched therebetween. 
   The foam layer is thin enough and flexible enough to maintain the ease of handling required. The thinness of the foam is believed to be operable because of the sheet orientation in the layers of turf cover. 
   The thickness of the foam layer can be empirically determined by the insulation factor or by the location of a golf course, especially in relationship to the geographical location and general layout and its relationship to the surrounding foliage and elevation of the proposed area. Having a variable foam thickness or none at all will provide the user with variable choices in turf covers that are currently unavailable. 
   Due to the structure of the sheets, the foam layer can be much thinner than other foam-containing sheets of the prior art. In this manner, even with the thin foam layer, such sheets can be easily stored and carry out the other desired functions. 
   Referring now to  FIG. 1  and  FIG. 2 , a winter turf cover  100  is placed over a golf green  110 . The laminated structure of the winter turf cover  100  provides for a lightweight, substantially durable and water-impermeable material. By keeping water or snow from contacting or penetrating golf green  110 , crown hydration during winter months of colder climates is avoided. 
   Adding  FIG. 3  and  FIG. 4  depicts a perspective view of a ground holding device  120  for the winter turf cover  100 . One part of ground holding device  120  includes at various positions in the fabric  122  of the winter turf cover  100  are reinforced tabs  124 . Each reinforced tab  124  serves to receive a nail  132  or have nail  132  removed therefrom a plurality of times for panels  142  to form the winter turf cover  100  of this invention. 
   Through each reinforced tab  124  may have a nail  132  with a slide washer  126  between the nail head  134  and the reinforced tab  124  in order to hold turf cover  100  in place. Such reinforced tabs  124  are on one, two, three or four sides of a preferably rectangular fabric  122 . Thus, each reinforced tab  124  and each nail  132  provide part of ground holding device  120 . 
   In a preferred form, reinforced tab  124  is formed by applying heavy tape  136  on one or both sides of panel  142 . The panel  142 , at a section thereof, is between two pieces of tape  136 . Tape  136  seals panel  142  as slide washer  126  forced by nail  132  in general and nail head  134  in particular to the golf green  110 . 
   For the most part, tape  136  is placed at the edge of panel  142 . However, when an undulating version of green  110  is covered, nails  132  through panel  142  away from the edge  146  of panel  142  into golf green  110 , may be sealed by tape  136 . 
   Also as a part of ground holding device  120  is a panel edge joining device  140 , for those situations when the turf cover  100  is not one piece. Panel edge joining device  140  permits one panel  142  to be joined to at least one other panel  142  in order to form winter turf cover  100 , and maintain the required impermeability. Panel edge joining device  140  may be situated on one, two, three, or four sides of the preferably rectangular fabric  122 . With panel edge joining device  140 , sheets of rectangular fabric  122  may be joined to form winter turf cover  100 . 
   Panel edge joining device  140  may have any desired structure. In a preferred form, panel  142  has an adhesive edge  144  to form an aggressive joining system. This adhesive edge  144  or joining material is then applied to a second, third or more of panel  142 , while overlapped to create permanent, impermeable sheet of the winter turf cover  100  as required to cover a golf green  110 , as required for each application. 
   In a preferred form, each cover  100  is preformed. Thus adhesive edge  144  is formed on panel  142  and adhered to a second panel  142 ′. Adhering is accomplished in any suitable fashion, obviously to avoid compromising the impermeability of the cover. The seaming is done in any suitable fashion. 
   The preferred adhesive seaming is accomplished by either high speed extrusion or by hot-air, rotational sealing. Thus, preferably, prior to shipping, covers are manufactured to specifications and therefore received in a full size configuration. No field seaming, is required. Because of the structure, of the cover, it may be easily folded, even as full sized. The cover may even be marked to simplify placement of the cover on the green. 
   It is also possible for winter turf cover  100  to be circular or any other desired shape in order to cover the green. What is critical for the winter turf cover  100  is that the cover  100  be impermeable to water. 
   Adding  FIG. 5 ,  FIG. 6 ,  FIG. 7 , and  FIG. 8  combine to depict the formation of fabric  122  or winter turf cover  100 . A plain tube  150 , preferably of polyethylene, is stretched to form a grained or stretched tube  160 , based on plain tube  150 . Stretched tube  160  undergoes a spiral cut  170  of the stretched tube  160 , used to form the winter turf cover  100 . Spiral cut  170  of stretched tube  160  permits a grained sheet  180  to be formed. Grained sheet  180  has force striations  182 , which run at 45 degree angles to the edge of the grained sheet  180 . 
   Adding  FIG. 9  to the consideration, a cross lamination with force striations  182  of the sheets and angles is depicted. Such structure preferably provides protection from the water and permit formation of panels  142  and thence winter turf cover  100  of this invention. Thus, this use of cross grains and lamination provide the contact turf cover  100  with water-impermeability and high puncture resistance. 
     FIG. 10  and  FIG. 11  combine to show the use of a foam layer  148 . In  FIG. 10 , foam layer  148  is exposed on sheet  180 . In  FIG. 11 , foam layer  148  is sandwiched between two of sheet  180 . The foam layer  148  is provided in any suitable fashion with minimized reduction in the storability and other desired features winter turf cover  100 . 
   This application—taken as a whole with the abstract, specification, claims, and drawings being combined—provides sufficient information for a person having ordinary skill in the art to practice the invention as disclosed and claimed herein. Any measures necessary to practice this invention are well within the skill of a person having ordinary skill in this art after that person has made a careful study of this disclosure. 
   Because of this disclosure and solely because of this disclosure, modification of this method and device can become clear to a person having ordinary skill in this particular art. Such modifications are clearly covered by this disclosure.