US20080032575A1

US20080032575A1 - Impact resistant surfboard

Info

Publication number: US20080032575A1
Application number: US11/462,753
Authority: US
Inventors: Michael D. Wyrsta; David S. Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-08-07
Filing date: 2006-08-07
Publication date: 2008-02-07

Abstract

Waterboards such as surfboards are described that are formed of a combination of a resilient foam core with an outer shell of polycarbonate or polyurethane. Such waterboards may further include fibrous material bonded to or embedded in the outer shell for additional strength.

Description

RELATED APPLICATIONS

NOT APPLICABLE.

FIELD OF THE INVENTION

The present invention relates to watersports equipment, especially waterboards such as surfboards, body boards, sailboards, and other buoyant waterboards, and to materials and methods for constructing such equipment.

BACKGROUND OF THE INVENTION

The following discussion is provided solely to assist the understanding of the reader, and does not constitute an admission that any of the information discussed or references cited constitute prior art to the present invention.
Board surfing and a variety of other water sports which utilize buoyant boards have become highly popular. Modern boards for these purposes, i.e., waterboards, are typically formed of a fiberglass-reinforced polyester or epoxy resin shell enclosing a low density core, usually a polystyrene or polyurethane foam. These foam materials have properties which have contributed to their common use in surfboard construction. They can readily be shaped, can be provided in a suitable density range, and are relatively inexpensive.
In addition to the requirement for buoyancy, surfboards (and most other waterboards) should also provide a substantial degree of structural strength to accommodate the loads to which the board is subjected during use. Such structural strength (i.e., mechanical strength) is normally provided by a combination of construction elements. Because the polystyrene or polyurethane foam core of typical boards is weak, many boards incorporate a wood reinforcing member in the core in the form of a “stringer”, thereby providing additional strength, as well as providing a reference line to assist a shaper in maintaining symmetry in the board during the shaping process.
The stringer is normally placed by cutting the foam core member into two halves by means of a cut at right angles to the dorsal surface extending from the nose to the tail. A wooden stringer (i.e., a beam member) is placed between the two halves and fastened to each of them (e.g., using an adhesive). The wooden beam member is typically further secured to the dorsal and ventral surfaces of the core by adhering fiberglass fabric strips along its length. In effect, the wooden beam member, together with the adhered fiberglass strips, forms an “I-beam” which stiffens the entire board. Further major reinforcement is provided by a layer of fiberglass fabric reinforcement embedded in a polyester or epoxy resin coat covering the entire core member, i.e., a shell.
A few variations of the basic surfboard construction indicated above have been described.
For example, Shanelec, U.S. Pat. No. 4,961, describes surfboards which are formed by fusing expanded polypropylene beads in a mold under steam pressure.
Esposito, U.S. Pat. No. 6,779,478 describes a “surfboard made of a high density ethyl vinyl acetate contained within a polyethylene shell.” The surfboard is generally formed by shaping the ethyl vinyl acetate into the form of a surfboard, wrapping the shaped ethyl vinyl acetate with a protective polyethylene shell, and heating the polyethylene-wrapped shape to fuse the polyethylene with the ethyl vinyl acetate.
Hamilton, U.S. Pat. No. 5,816,876 describes a surfboard which includes rails encapsulated with a tight woven band of fabric.
Mollin, U.S. Pat. No. 6,652,340 describes a surfboard formed by joining two shell sections to create a hollow surfboard.

SUMMARY OF THE INVENTION

The present invention is concerned with providing surfboards and other waterboards which are both stronger and more durable than conventional boards. These improvements are accomplished by utilizing different materials and/or material combinations in the construction of the boards. Desirably the low density core material is a resilient foam and the outer shell is formed using a polyurethane or polycarbonate, though polyester resins, epoxy resins and polyvinyl ester resins can also be used in forming the shell. Advantageously, these materials allow custom board construction using conventional forming techniques, but result in a board which is both stronger and more resistant to impact damage than conventional boards. In particular, use of such a resilient foam core makes the board much more resistant to local crush damage which occurs with conventional boards when a relatively small area is compressed, causing permanent local deformation (crushing) of the polystyrene or polyurethane foam core.
Thus, in a first aspect the invention concerns a buoyant waterboard which includes an expanded, elastomeric plastic core and a polycarbonate or polyurethane shell which coats and is adhered to the core, or alternatively a polyester resin, epoxy resin, or polyvinyl ester resin shell can be used.
In particular embodiments, the core comprises beads fused under steam pressure; the core comprises expanded polypropylene, porous expanded polypropylene, expanded polyethylene, porous expanded polyethylene, block polymers of polystyrene butadiene styrene (SBS), e.g., expanded SBS; the core has a density of 1-5 pounds per cubic foot (pcf), e.g., 3-4 pcf, 2-4 pcf, 2-3 pcf, or 2.2-2.6 pcf; the core includes surface visible reference marks and/or at least one reference line; the core includes a central longitudinal reference line or series of reference marks arranged along a central longitudinal line the core includes at least one reference line or mark and does not include a stringer.
For additional strength, reinforcement can be added to the basic board. Thus, in certain embodiments, the waterboard includes a fibrous material bonded on the exterior of the core; the core includes a fibrous material in the interior of the core; the core includes longitudinally-oriented reinforcing material, where that reinforcing materials does not extend through the thickness of the core; the shell coating includes a fibrous material; fibrous material used in the core and/or in the shell is or includes glass fiber, KEVLAR®, polyimide fiber, polyurethane fiber, and/or carbon fiber; the board includes a stringer, which may, in certain embodiments, be a perforated stringer, a wood stringer, a polyurethane stringer, a polypropylene stringer, a composite material stringer, or a plurality of such stringers.
Shell coatings as specified above may be applied in a number of different ways, including but not limited to dipping, layer coating (e.g., hand layering), by adhesion of a solid sheet (e.g., using an adhesive or other bonding agent or using heat and pressure.
In particular embodiments, the waterboard is a surfboard, a sailboard, a body board, a skimboard, or a skiboard.
A related aspect of the invention concerns a method for making a buoyant waterboard, by forming a core in the desired shape of the waterboard from an expanded elastomeric plastic, and applying and adhering to that core a coating which is substantially a polycarbonate, polyurethane, polyester, epoxy, or polyvinyl ester resin, which may be free of fiber reinforcement, or may include fiber reinforcement.
In particular embodiments, the board, the materials, and/or the construction is as specified for the preceding aspect or otherwise described herein.
A related aspect of the invention concerns a waterboard blank dimensioned for shaping of a waterboard core (e.g., a surfboard core), or a rough finished waterboard core formed in the shape of a waterboard (e.g., a surfboard or other waterboard indicated above), made of a resilient plastic foam. Such resilient foam can be a foam as specified for an aspect above. Such blank may be contoured on lateral surfaces to approximate the outline of a waterboard (e.g., surfboard) while still requiring additional shaping to form a finished core. A rough finished waterboard core will at least approximate a particular waterboard shape, but may, in some case, require additional final shaping to create the desired core contours. Also, a rough finished waterboard core (or a blank) may include one or more stringers already in place (e.g., stringers made of materials as indicated above).
Another related aspect concerns a kit for making a custom waterboard, e.g., a surfboard. The kit includes at least one packaged elastomeric foam core (e.g., packaged in a cardboard box), and can also include instructions for further forming the core and/or for applying a shell and/or materials for forming a shell (e.g., resin and/or fiber-reinforcing material).
As used herein, the terms “polyurethane”, “polycarbonate”, “polyethylene”, “polypropylene”, “polystyrene butadiene styrene”, “polyester”, “epoxy”, and “polyvinyl ester” have their usual meaning as understood by those in the resin and plastics field, and are understood to refer to classes of materials. A person familiar with use of such materials can readily select materials within such classes having the strength, resiliency, and formability characteristic suitable for the present application.
In the context of the boundary between the exterior of the core of a waterboard and the shell, the term “adhered” means a physically strong joining. Depending on compatibility with the materials in the core and the shell respectively, this may be accomplished in a number of different ways, e.g., through use of a separate adhesive or other joining materials, by direct adhesion of a shell resin to the core during curing of the shell resin, or by a direct joining of the shell and core, e.g., using heat and pressure.
Additional embodiments will be apparent from the Detailed Description and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of an exemplary surfboard.

FIG. 2 shows a side view of the exemplary surfboard of FIG. 1.

FIG. 3 shows a cross-section through the surfboard of FIG. 1 showing the placement of core, stringer, and shell with fibrous reinforcing material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to the construction of surfboards and other waterboards using materials which provide greater strength and resiliency than conventionally constructed waterboards. As is generally understood, surfboards must have the mechanical strength and structural integrity to withstand not only the power of the sea, but also of the stresses produced by the weight and actions of the surfer as he or she rides and controls the board. Such stresses may be divided into horizontal stresses, which are stresses perpendicular to the horizontal plane of the surfboard as it floats, and lateral stresses in the horizontal plane of the board, especially those generally perpendicular to the long axis of the board. By way of nomenclature, the various parts of a surfboard are commonly identified using a number of conventional terms. The leading edge of the board is the “nose”, the trailing edge the “tail”, and the edges connecting the nose and the tail are “rails”. The upper surface of the board, when floating in the water, is called the “dorsal” surface, and the surface in contact with the water is called the “ventral” surface.
For illustrative purposes, an exemplary surfboard is shown in plan view in FIG. 1. The nose 12, tail 14, rail 16, dorsal surface (or deck) 18 and ventral surface 20 are pointed out. The same exemplary surfboard is shown in side view in FIG. 2, where the curvature of the surfboard is shown by the deviation from straight reference line 10.
The surfboard of FIG. 1 is shown in cross-section in FIG. 3. As illustrated, the core (i.e., the interior of the board) 22 is a resilient foam with a single I-beam-shaped stringer 24 located in the middle. As described below, such a stringer is optional, but may be incorporated if desired. The shell 26 includes fiber reinforcement 28 and resin or sheet material 29 (which generally impregnates and/or is sandwiched with the fiber reinforcement). Once again, such fiber reinforcement is optional, but may be incorporated if desired, e.g., to provide additional strength and/or stiffness.
The lateral and horizontal stresses to which a surfboard or other waterboard is subjected during use may be simulated under static and/or dynamic test conditions. A simple testing method is brick testing.
In brick testing, a surfboard is laid on two supports, or stands such that the dorsal surface is up, and one support is under the nose of the board with the other support under the tail. One or more bricks (or other weights) are placed in the middle of the dorsal surface of the board. Bricks are progressively added (e.g., one-by-one) until the breaking strength of the board is reached, and the board breaks. The weight of the bricks added before the board breaks provides a measure of the strength of the board, and thus of its ability to withstand surfing activity, e.g., under extreme conditions.
Many current conventional surfboards have less than desirable strength and typically undergo complete breakage when their breaking strength is reached. Furthermore, the boards are susceptible to excessive impact damage in which the interior foam core is permanently deformed (e.g., crushed), creating a weak point and potentially creating a water infiltration point if the shell is cracked.
The present invention addresses these limitations in two ways. First, the present boards are constructed using a high strength resilient foam core, either with or without a stringer or other such longitudinal reinforcing member. Combined with the resilient foam core, is a high strength shell of polyurethane or polycarbonate.

Core Materials and Construction

The incorporation of the resilient foam core addresses the problem of permanent core deformation, because the resilient foam will accommodate moderate deformation but will spring back to its original shape without permanent damage to the core. Such deformations may occur, for example, during handling or transport of the board when it impacts any hard surface, especially if the impact area is small. Similarly, hard surface impacts may occur during use when the board contacts a rock or another surfboard or the like.
Exemplary resilient foam materials include, without limitation, EPP (expanded polypropylene), PEPP (porous EPP), EPE (expanded polyethylene), PEPE (porous EPP), block polymers of SBS (poly styrene butadiene styrene), and/or ESBS (expanded SBS).
For particular applications and materials, a range of densities of the foam core can be suitable. In particular cases, the foam has a density of 1-5 pounds/cubic foot (pcf), 2-4 pcf, 3-4 pcf, 2-3 pcf, or 2.2-2.6 pcf.
Persons familiar with plastic foams are familiar with techniques for forming such materials. In many cases, the present materials are formed as expanded beads (or other small particulate shapes), which are then fused, typically under conditions of pressure and heat to form a desired shape. Such shape may be a finished core shape, e.g., ready for coating, or may be a blank or rough shape. The blank can be shaped into a desired core shape using conventional techniques such as wire cutting, planning, shaving, and sanding, or using CNC shaping machines.
Selections of the present materials are sufficiently strong that it is not necessary to utilize a stringer or other reinforcement in the core. However, if desired, one or more stringers can be installed, either during or after the core or core blank is initially made. For placement of the stringer during the initial process of making the blank or core, the stringer should be constructed of a material to which the core material will adhere, or be at least partially coated with such material, which is itself well-adhered to the stringer. The stringer is positioned in the form or forming chamber, and the core material is formed around and/or against the stringer.
Alternatively, the stringer can be incorporated in the core after the initial forming process by cutting the core blank longitudinally, and adhering the core blank pieces against the stringer or stringers. The materials and methods used for adhering the core blank pieces to the stringer will be selected as appropriate for the core blank and stringer materials.
Stringers can be constructed of a variety of materials, such as wood, polypropylene, polyurethane, and composite materials, e.g., fiber-reinforced composites. Conventionally, wood stringers are used which are rectangular in cross-section. However, stringers can have other cross-sectional shapes and/or can be perforated. Such changes in shape and/or perforation can, for example, enhance strength to weight ratio, allowing greater contribution to board strength and stiffness while minimizing the added weight, and/or increase the resistance to separation (e.g., by increasing surface area and/or by providing shapes which resist such separation) between the stringer and the foam core material. Especially for stringers made of plastic or of composites having plastic binders, the shape of the stringer may be essentially any desired shape. Examples of such shapes can include relatively flat sections generally in the plane of the dorsal and/or ventral surfaces of the core, connected by a web section which can be relatively thin. Those flat sections can be at the surface of the core, or can be partially or fully embedded in the foam. Examples of such shapes include I-beam and C-member shapes.
Another core reinforcement method involves the use of fibers distributed within and/or on the surface of the core. Such fibers may run the length or a substantial fraction of the length of the core, or may be shorter. For example, relatively short fibers, e.g., 2-5, 4-10, 8-20 mm in length can be mixed in the expanded beads prior to fusion. Fusing the beads will then incorporate the fibers throughout the core blank, which can provide additional stiffness. Alternatively, or in addition, long fibers can be adhered on all or a part of the surface of the core, e.g., on both dorsal and ventral surfaces and/or around the rails.
Prior to application of the shell, graphic or other aesthetic elements can be added to the core, e.g., around the shaped surface of the core. For example, the shaped core may be at least partially coated with a pigmented layer (e.g., paint or pigmented resin) and/or graphic overlays or other graphic elements can be added which will be visible through the shell when applied.
In addition to their function as reinforcing or strengthening members, stringers can also serve as a reference line for a board shaper, e.g., assisting the board forming to maintain symmetry as the board is shaped. Such reference function can alternatively or additionally be provided by reference lines or marks, typically surface visible lines of marks. For example, a reference line or series of marks may be provided on the dorsal and/or ventral surface of a rough finished core and/or the reference line or marks may extend a significant depth into the core such tat they remain visible during shaping.

Shell Materials and Construction

In the present waterboards, the foam core is enclosed with a generally water-impermeable coating, e.g., of polycarbonate or polyurethane. These materials provide high strength and good resistance to environmental factors such as salt water and ultraviolet light. Alternatively, polyester, epoxy or polyvinyl ester resins may also be used. The coating should be well-adhered to the foam core, and desirably is well adhered to any exposed surface of a stringer, if present. Once again, achieving such adhesion will be performed using techniques selected as appropriate for the materials being used. Typically the adhesion will involve the shell resin, separate adhesive or other separate bonding material, or melt bonding (e.g., using heat and/or solvent to create the melt), which may use pressure to assist in creating a good bond.
In many cases, a polyurethane shell will be incorporated as a resin coating (e.g., by molding or layering around the core), and a polycarbonate shell will be incorporated by bonding a sheet or sheets around the core (e.g. using heat and pressure) and/or as a pourable resin (e.g., by molding and/or layering around the core).
Application of pourable resins can be performed in a number of different ways. For example, the resin can placed around the core by spreading, dipping, and/or molding (e.g., injection molding), with or with the presence of reinforcing fiber.
As indicated, if desired, the shell can be reinforced with fibrous materials. Persons familiar with the use of reinforcing fiber for plastic resins can select suitable fiber materials based on the usual considerations. Examples of fibers which can be useful in the present invention include polyimide, polyurethane, carbon, glass, and KEVLAR® fibers, and mixtures of such fibers.
After incorporation of the shell, additional coatings can be applied if desired. Examples include, without limitation, coatings for traction and/or graphics, and the like.
All patents and other references cited in the specification are indicative of the level of skill of those skilled in the art to which the invention pertains, and are incorporated by reference in their entireties, including any tables and figures, to the same extent as if each reference had been incorporated by reference in its entirety individually.
One skilled in the art would readily appreciate that the present invention is well adapted to obtain the ends and advantages mentioned, as well as those inherent therein. The methods, variances, and compositions described herein as presently representative of preferred embodiments are exemplary and are not intended as limitations on the scope of the invention. Changes therein and other uses will occur to those skilled in the art, which are encompassed within the spirit of the invention, are defined by the scope of the claims.
It will be readily apparent to one skilled in the art that varying substitutions and modifications may be made to the invention disclosed herein without departing from the scope and spirit of the invention. For example, variations can be made to the board shape and to the combinations of materials incorporate in the boards. Thus, such additional embodiments are within the scope of the present invention and the following claims.
The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein. Thus, for example, in each instance herein any of the terms “comprising”, “consisting essentially of” and “consisting of” may be replaced with either of the other two terms. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.
In addition, where features or aspects of the invention are described in terms of Markush groups or other grouping of alternatives, those skilled in the art will recognize that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group or other group.
Also, unless indicated to the contrary, where various numerical values or value range endpoints are provided for embodiments, additional embodiments are described by taking any 2 different values as the endpoints of a range or by taking two different range endpoints from specified ranges as the endpoints of an additional range. Such ranges are also within the scope of the described invention.
Thus, additional embodiments are within the scope of the invention and within the following claims.

Claims

1. A buoyant waterboard, comprising

an expanded, elastomeric plastic core;

and a plastic resin shell coating and adhered to said core.

2. (canceled)

3. The waterboard of claim 1, wherein said core comprises expanded polypropylene.

4. (canceled)

5. The waterboard of claim 1, wherein said core comprises expanded polyethylene.

6. (canceled)

7. The waterboard of claim 1, where said core comprises block polymers of polystyrene butadiene styrene (SBS).

8. The waterboard of claim 1, wherein said core comprises expanded SBS.

9. (canceled)

10. (canceled)

11. (canceled)

12. (canceled)

13. (canceled)

14. (canceled)

15. The waterboard of claim 1, wherein said core further comprises a fibrous material in the interior of said core.

16. (canceled)

17. The waterboard of claim 1, where in said shell coating further comprises a fibrous material.

18. The waterboard of claim 13, wherein said fibrous material comprises glass fiber.

19. The waterboard of claim 13, wherein said fibrous material comprises KEVLAR®.

20. The waterboard of claim 13, wherein said fibrous material comprises polymide fiber.

21. The waterboard of claim 13, wherein said fibrous material comprises polyurethane fiber.

22. The waterboard of claim 13, wherein said fibrous material comprises carbon fiber.

23. The waterboard of claim 1, further comprises a stringer.

24. The waterboard of claim 19, wherein said stringer is perforated.

25. (canceled)

26. (canceled)

27. (canceled)

28. The waterboard of claim 19, wherein said stringer is a composite material stringer.

29. (canceled)

30. The waterboard of claim 1, wherein said shell coating is a polycarbonate.

31. The waterboard of claim 1, wherein said shell coating is a polyurethane.

32. The waterboard of claim 1, wherein said shell coating is a polyester.

33. (canceled)

34. The waterboard of claim 1, wherein said shell coating is a polyvinyl ester.

35. (canceled)

36. (canceled)

37. (canceled)

38. The waterboard of claim 1, wherein said waterboard is a surfboard.

39. The waterboard of claim 1, wherein said waterboard is a sailboard.

40. The waterboard of claim 1, wherein said waterboard is a body board.

41. (canceled)

42. (canceled)

43. The method for making a buoyant waterboard, comprising

forming a core in the desired shape of said waterboard from an expanded elastomeric plastic; and

applying and adhering to said core a coating substantially comprising a polycarbonate or polyurethane resin.

44. The waterboard of claim 1, wherein

said expanded elastomeric plastic core comprises expanded polypropylene, expanded polyethylene, or expanded SBS, and

said plastic resin shell comprises polyurethane and polycarbonate.