GB2605361A

GB2605361A - Blank for a buoyant sports board

Info

Publication number: GB2605361A
Application number: GB2103782.5A
Authority: GB
Inventors: Morley Stewart; Skinner Benjamin
Original assignee: Exofuse Ltd
Current assignee: Exofuse Ltd
Priority date: 2021-03-18
Filing date: 2021-03-18
Publication date: 2022-10-05
Also published as: GB202103782D0

Abstract

A blank 100 for a buoyant sports board, such as a surfboard, comprises a body structure 102 formed of a first material; and a core structure 104 formed of a second different material; wherein the core structure is embedded within the body structure and is a reticulate structure comprising a plurality of interconnected elongate members 106. The core structure preferably comprises multiple regions having different stiffness to provide varying torsional stiffness along the length of the board. The first material may comprise a foam material; the second material may comprise fibre-reinforced polymers. A method of producing a blank comprises inserting the core structure in a mould, introducing the first material into the mould and curing the first material to form a body structure in which the core is embedded. The core structure may be vacuum formed against a mould surface or may be additively manufactured. A method of producing a board may comprise cutting the blank into a desired shape and coating the cut blank. A core structure for a buoyant sports board blank and a buoyant sports board are further claimed.

Description

BLANK FOR A BUOYANT SPORTS BOARD

FIELD OF THE INVENTION

The present invention relates to blanks from which buoyant sports boards, such as surfboards and the like, may be formed, and methods for producing said blanks. The present invention relates to buoyant sports boards, such as surfboards and the like, and methods for producing said buoyant sports boards. The present invention relates to core structures for inclusion, such as embedding, within buoyant sports boards and blanks for buoyant sports boards, and method for producing such core structures.

BACKGROUND

Typically, surfboards and other buoyant sports boards are produced from pre-formed polyurethane or polystyrene foam blanks. Said blanks are then shaped by professionals, called "shapers", into a desired shape using various tools. The shaped blank is then coated or "glazed" with sheets of, typically, fibreglass (i.e., glass-reinforced polymer). Finally, the unit may be sanded and polished.

The foams used for the blanks and surfboards tend to be fragile and deformable materials. Accordingly, "stringers" are embedded in the foam material to increase strength and rigidity. A stringer is a stiff, thin slat, usually made of wood or a fibre-reinforced polymer. The stringer is arranged along a surfboard's central plane of reflection, down the middle of its deck and its keel.

Stringers and use thereof increase the complexity of the surfboard manufacturing process.

SUMMARY OF THE INVENTION

The present inventors have realised that eliminating the use of stringers tends to reduce manufacturing complexity of surfboards and the like, and tends -2 -to facilitate the production line manufacturing of surfboards and the use of automated production processes.

In a first aspect, there is provided a blank for a buoyant sports board, the blank comprising a body structure formed of a first material, and a core structure formed of a second material different to the first material. The core structure is embedded (e.g. wholly) within the body structure. The core structure is a reticulate structure comprising a plurality of interconnected elongate members (i.e. the core structure is arranged or configured as a net or network, for example, a network, mesh, or lattice of interconnected elongate elements).

The core structure may comprise one or more through holes through which the first material of the body structure extends. The core structure may comprise multiple different regions along a length of the core structure, the multiple different regions having different respective stiffnesses, thereby to provide varying torsional stiffness along the length of the core structure. One or more characteristics of one of the multiple different regions may be different to the one or more characteristics of another of the multiple different regions. The one or more characteristics may be selected from the group of characteristics consisting of: density of the interconnected elongate members, connectedness of the interconnected elongate members, density of the second material, and thickness of the second material. The core structure may comprise a region of lower stiffness disposed along the length of the core structure between two regions of higher stiffness.

The first material may comprise one or more materials selected from the group of materials consisting of: a closed cell foam material; an open cell foam material; a ballistic foam material; a lineal foam material; polyurethane; polyurethane foam; polystyrene; expanded polystyrene; extruded polystyrene; prolapse polystyrene; polystyrene foam; extruded polystyrene foam; expanded polypropylene; ethylene propylene diene monomer; polyurethane resin; epoxy resin; and a combination of expanded polystyrene and extruded polystyrene The second material may comprise one or more materials selected from the group of materials consisting of: polypropylene; polycarbonates; acrylonitrile -3 -butadiene styrene; nylon; polyvinyl chloride; aluminium; titanium; fibre-reinforced polymers; glass fibre-reinforced polymers; carbon fibre-reinforced polymers; aramid fibre-reinforced polymers; and para-aramid fibre-reinforced polymers.

A plan view of the core structure may define an approximately oval, teardrop, or surfboard-shape. The core structure may have one or more dimensions selected from the group of dimensions consisting of: a length of between 100cm and 1 000cm; a width of between 30cm and 100cm; and a thickness of between 3cm and 30cm. The elongate members of the core to structure may extend within the body structure in three mutually orthogonal directions.

The buoyant sports board may comprise a first surface and a second surface opposite to the first surface. A plurality of the elongate members of the core structure may extend within the body structure in a direction between the first and second surfaces.

In a further aspect, there is provided a buoyant sports board comprising a body structure formed of a first material, and a core structure formed of a second material different to the first material. The core structure is embedded (e.g. wholly) within the body structure. The core structure is a reticulate structure comprising a plurality of interconnected elongate members (i.e. the core structure is arranged or configured as a net or network, for example, a network, mesh, or lattice of interconnected elongate elements).

The core structure may comprise a central spine disposed along a longitudinal axis of the buoyant sports board.

The buoyant sports board may comprise a first surface and a second surface opposite to the first surface. The first surface may define a first and a second region, the first and second regions being spaced apart along a length of the buoyant sports board, the first and second regions being regions in which a user of the buoyant sports board typically place their feet during use of the buoyant sports board. The core structure may comprise a region of reduced -4 -stiffness which, when viewed normal to the first surface, is disposed along the length of the buoyant sports board between the first and second regions.

The buoyant sports board may comprise a first surface and a second surface opposite to the first surface. The first surface may define a first and a second region, the first and second regions being spaced apart along a length of the buoyant sports board, the first and second regions being regions in which a user of the buoyant sports board typically place their feet during use of the buoyant sports board. When viewed normal to the first surface, one or more of the elongate members of the core structure may extend from or to the first and second regions.

The buoyant sports board may comprise a first surface and a second surface opposite to the first surface. The buoyant sports board may comprise one or more fins disposed on the second surface. When viewed normal to the second surface, one or more of the elongate members of the core structure may extend from or to the one or more fins.

The buoyant sports board may comprise a first surface and a second surface opposite to the first surface, and edges or rails disposed between the first surface and the second surface. When viewed normal to the first surface, one or more of the elongate members of the core structure may extend from or to the edges or rails.

In a further aspect, there is provided a method of producing a blank for a buoyant sports board. The method comprises: providing a core structure, the core structure being a reticulate structure comprising a plurality of interconnected elongate members; inserting the core structure in a mould; introducing a first material into the mould in which the core structure is located; and curing the first material, wherein the cured first material forms a body structure in which the core structure is embedded; wherein the core structure is formed of a second material different to the first material.

The step of providing the core structure may comprise vacuum forming a sheet of the second material against a mould surface. -5 -

The step of providing the core structure may comprise additively manufacturing the core structure.

In a further aspect, there is provided a method of producing a buoyant sports board, the method comprising: providing a blank, the blank being in accordance with any preceding aspect; cutting the blank substantially into a desired shape for the buoyant sports board; and coating the cut blank in a coating material.

The step of providing the blank may comprises performing a method according to any preceding aspect.

The buoyant sports board may be in accordance with any preceding aspect.

In a further aspect, there is provided a core structure for a buoyant sports board blank, the core structure being a reticulate structure comprising a plurality of interconnected elongate members.

The core structure may comprise one or more through holes. The core structure may comprise multiple different regions along a length of the core structure, the multiple different regions having different respective stiffnesses, thereby to provide varying torsional stiffness along the length of the core structure. The core structure may comprise one or more materials selected from the group of materials consisting of: fibre-reinforced polymers; glass fibre-reinforced polymers; carbon fibre-reinforced polymers; aram id fibre-reinforced polymers; and para-aramid fibre-reinforced polymers. A plan view of the core structure defines an approximately oval, teardrop, or surfboard-shape.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1A is a schematic illustration (not to scale) of top view cross section of a blank for a buoyant sports board; Figure 1B is a schematic illustration (not to scale) of side view cross section of the blank; -6 -Figure 2 is a process flow chart showing certain steps of a process of producing a surfboard from the blank; Figure 3A is a schematic illustration (not to scale) of top view cross section of a surfboard produced from the blank; Figure 33 is a schematic illustration (not to scale) of side view cross section of the surfboard; Figure 4 is a schematic illustration (not to scale) of top view cross section of the surfboard; Figure 5 is a schematic illustration (not to scale) of top view cross section of another surfboard with a differently shaped core structure; Figure 6 is a process flow chart showing certain steps of a process of producing the blank; Figures 7A -7E are schematic illustrations (not to scale) showing various stages of the process of Figure 6; and Figure 8 is a schematic illustration showing a vacuum forming process for use in producing a blank.

DETAILED DESCRIPTION

Figure 1A is a schematic illustration (not to scale) of top view cross section of a blank 100 for a buoyant sports board.

Figure 1B is a schematic illustration (not to scale) of side view cross section of a blank 100 for a buoyant sports board In this embodiment, the blank 100 is for a surfboard.

The blank 100 comprises a body structure 102 and a core structure 104.

The body structure 102 is formed of a first material. In this embodiment, the first material is polyurethane. -7 -

The core structure 104 is formed of a second material different to the first material. In this embodiment, the second material is a carbon fibre-reinforced polymer.

The core structure 104 is embedded within the body structure 102. In particular, in this embodiment, the core structure 104 is wholly embedded within the body structure 102 such that the core structure is spaced apart from external surfaces of the body structure 102.

The core structure 104 is a reticulate structure. The core structure 104 comprises a plurality of interconnected elongate members 106. The elongate to members 106 are arranged to form a net or network of interconnected members. The elongate members 106 may form a multifurcating structure, or branch-like structure.

In this embodiment, the core structure 104 comprises a plurality of through holes 108. In other words, the elongate members 106 of the core structure 104 define a plurality of loops. The first material of the body structure 102 is disposed though the through holes 108 of the core structure 104. In other words, the body structure 102 is connected through the through holes 108 of the core structure 104 from a first (or upper) side of the core structure to a second (or lower) side of the core structure 104 opposite to the first side 104.

Advantageously, this tends to improve the overall strength of the blank 100 and tends to reduce or eliminate a likelihood of delamination occurring, e.g. during production of a surfboard from the blank 100, or during use of a surfboard produced from the blank 100.

In this embodiment, the body structure 102 is approximately surfboard-shaped, e.g. the body structure 102 may be approximately oval, elliptical, or tear-drop shaped when viewed from above as in Figure 1A. The body structure 102 is so shaped as to correspond to a crude or rough outline of the desired shape for the surfboard to-be-formed (as illustrated in Figures 2 and 3). This tends to reduce the volume of a waste portion of the body structure 102 which is removed from the blank 100 to produce the surfboard. A length of the body structure 102 may be between 100cm and 1000cm. A width of the body -8 -structure 102 may be between 30cm and 100cm A height of the body structure 102 may be between 3cm and 30cm In this embodiment, a plan view of the core structure 104 defines an approximately oval, teardrop, or surfboard-shape. In other words, when viewed 5 from above as in Figure 1A, the core structure 104 defines an approximately oval, teardrop, or surfboard-shape. In this embodiment, the core structure 104 may be considered to be a substantially planar structure, i.e. when view from the side, as shown in Figure 1B, the core structure 104 has a substantially curvilinear shape. A length of the core structure 104 may be between 1cm and 10 1000cm. A width of the core structure 104 may be between 1cm and 100cm. A thickness of the core structure 104 may be between 0.01cm and 10cm.

Figure 2 is a process flow chart 200 showing certain steps of a process of producing a surfboard from the blank 100.

At step s202, the blank 100 is provided.

At step s204, the blank 100 is sculpted or shaped into the desired shape for the surfboard. This shaping of the blank 100 may be performed by a human (e.g. a surfboard shaper) using various tools, or by an automatic cutting machine (e.g. a computer numerical control (CNC) machine), or a combination thereof.

At step s206, the shaped blank is coated in a skin or coating material.

Any appropriate coating material may be used, for example, fibreglass and resin combination. This coating provides a hard outer shell that is resistant to damage.

Thus, a surfboard is produced Figure 3A is a schematic illustration (not to scale) of top view cross section of a surfboard 300 produced from the blank 100.

Figure 3B is a schematic illustration (not to scale) of side view cross section of the surfboard 300.

The surfboard 300 comprises the shaped body structure 102 and the core structure 104 embedded therein. -g -

In this embodiment, a longitudinal axis 302 of the surfboard 300 runs along the length of the surfboard 300 from a front end (or nose) 304 of the surfboard 300 to a rear end (or tail) 306 of the surfboard 300. Preferably, in plan view (as in Figure 3A), the surfboard 300 is substantially symmetrical about its longitudinal axis 302.

The surfboard 300 comprises an upper surface (or deck) 308, and a lower surface (or keel) 310 opposite to the upper surface 308. The surfboard further comprises edges or rails 312 along its sides between the upper and lower surfaces 308, 310.

to In this embodiment, the core structure 104 comprises an elongate central spine 314 along its length. Other elongate members 106 of the core structure 104 extend outwards from the central spine 314, towards the rails 312 of the surfboard 300. In plan view (as in Figure 3A), the central spine 314 of the core structure 104 is aligned along the longitudinal axis 302 of the surfboard 300.

Preferably, in plan view (as in Figure 3A), the core structure 104 is substantially symmetrical about the central spine 314. Preferably, in plan view (as in Figure 3A), the central spine 314 is substantially straight. In some embodiments, the central spine 314 may be thicker and/or have increased width compared to other elongate members of the core structure 104.

Advantageously, the relatively rigid and strong core structure 104, including the central spine 314, embedded within the body structure 102 tends to provide improved strength and rigidity to the surfboard 300, without use of a conventional stringer. Thus, conventional stringers may be omitted.

In this embodiment, the core structure 104 is wholly embedded within the shaped body structure 102. Thus, the core structure 104 is spaced apart from a surface of the body structure 102 at the front end 304, the rear end 306, the upper surface 308, the lower surface 310, and the rails 312.

By omitting the use of a conventional stringer (which conventionally is exposed at an external surface of a conventional surfboard blank during shaping), and having the core structure 104 wholly embedded within the shaped body structure 102, the surfaces of the body structure 102 being shaped during -10 -the production of the surfboard 300 tend to be substantially homogeneous. In other words, there tends to be no deviancy in material of the surfaces that are shaped. This advantageously tends to facilitate shaping of the surfboard 300 from the blank 100, e.g. allowing for faster and more efficient shaping.

Moreover, the use of production line manufacturing methods and/or the use of automated production processes and apparatus tend to be facilitated.

The relatively rigid and strong core structure 104 embedded within the body structure 102 tends to provide improved strength and rigidity throughout the surfboard 300, as opposed to primarily along a longitudinal axis of the surfboard as tends to be the case with conventional stringers. This advantageously tends to allow for use of a lighter weight coating material (which may be less strong than those typically used) for coating the shaped blank 100. Furthermore, the coating may be simply applied and a need for complex coating processes tends to be obviated. Moreover, the improved strength and rigidity throughout the blank 100 during its shaping, as provided for by the core structure 104, tends to facilitate the use of production line manufacturing methods and/or the use of automated production processes and apparatus.

Advantageously, the surfboard 300 tends to provide for improved user experience, as will now be described with reference to Figures 4 and 5.

Figure 4 is a schematic illustration (not to scale) of top view cross section of the surfboard 300.

Figure 5 is a schematic illustration (not to scale) of top view cross section of another embodiment of the surfboard 300 in which a different shape core structure 104.

In this embodiment, the core structure 104 comprises multiple different regions having different respective stiffnesses. The different regions may have different respective positions along a length of the core structure 104. As such, the multiple different regions may provide varying torsional stiffness to the surfboard 300 along the length of the core structure. The varying stiffness in the different regions may be provided by varying one or more characteristics of the core structure 104 in those regions. Examples of characteristics that may be varied to vary the stiffness of the core structure 104 include, but are not limited to, the density of the interconnected elongate members, the interconnectedness of the interconnected elongate members, the density of core structure material (i.e. the second material), and the thickness of the core structure material.

More specifically, in this embodiment, the core structure 104 defines a first region 401, a second region 402, and a third region 403.

The first region 401 is a region where it is expected that, in use, a user adopting a preferred or standard stance would place their leading foot. The first region 401 is a so-called "high stiffness region" having a relatively high stiffness.

The second region 402 is a region where it is expected that, in use, a user adopting a preferred or standard stance would place their trailing foot. The second region 402 is a so-called "high stiffness region" having a relatively high stiffness. The stiffness of the core structure 104 in the second region 402 may be substantially the same as that in the first region 401.

The third region 403 is disposed along the length of the core structure 104 between the first region 401 and the second region 402. The third region 403 is a so-called "low stiffness region" having a relatively low stiffness. In this embodiment, the relatively low stiffness of the third region is provided by their being a lower number and density of elongate members 106 and/or lower interconnectedness of the elongate members 106 within the third region 403 compared to the first and second regions 401, 402.

The third region 403 defines a region of relatively low torsional strength between the first and second regions 401, 402. This allows for relative rotation between the first and second regions 401, 402. Accordingly, during use and when the user adopts a standard or preferred stance, the regions at which the feet of the user are positioned may rotate to some extent. This tends to provide an improved user experience and tends to allow for improved performance. For example, it may be possible for a user to create thrust by pressing or releasing from the surfboard 300 with their feet.

Furthermore, in this embodiment, respective pluralities of the elongate members 106 extend between the various surfboard structures and the regions -12 -at which the user's feet are typically located while surfing. For example, elongate members 106 extend between regions of the surfboard 300 proximate to the rails 312 and each of the first and second regions 401, 402. Also, elongate members 106 extend between regions of the surfboard 300 proximate to the fins and each of the first and second regions 401, 402. (The positions of the fins of the surfboard 300 are shown in Figure 5 and indicated by the reference numeral 500.) During use of the surfboard, the elongate members 106 that connect together the various surfboard structures and the regions 401, 402 at which the user's feet are typically located tend to transfer vibrations from to those various surfboard structures to the user's feet. Thus, for example, forces exerted on the fins or rails 312 by the waves/water while surfing may be felt by the user through their feet. The nature of the core structure 104 and its tunability tends to provide for variations of flex and tensile purposes across the full surface area of the surfboard 300. This tends to enhance the user experience (i.e. the "feel of the board") and performance.

Thus, an improved user experience may be provided What will now be described is a process of producing the blank 100.

Figure 6 is a process flow chart showing certain steps of a process 600 of producing the blank 100.

At step s602, the core structure 104 is provided. In this embodiment, the core structure 104 is provided by cutting, e.g. using a laser cutting or other high-precision cutting tool, the shape of the core structure from a sheet of the second material, i.e. a sheet of carbon fibre-reinforced polymer.

At step s604, the core structure 104 is secured to a mould surface of a first mould tool.

Figure 7A is a schematic illustration (not to scale) showing the core structure 104 secured to a mould surface 700 of a first mould tool 702. In this embodiment, the core structure 104 is secured to the mould surface 700 by a vacuum between the core structure 104 and the mould surface 700 established by vacuum lines 704 passing through the first mould tool 702.

-13 -At step s606, a second mould tool is positioned against the first mould tool 702 over the core structure 104.

Figure 7B is a schematic illustration (not to scale) showing the second mould tool 706 positioned against the first mould tool 702 over the core structure 104. Thus, a first mould cavity 708 is established. The first mould cavity 708 is defined between the first mould tool 702 and the second mould tool 706. The core structure 104 is located within the first mould cavity 708.

At step s608, the first mould cavity 708 is filled with the first material in liquid form, i.e. liquid polyurethane. In particular, in this embodiment, the liquid polyurethane is injected into the first mould cavity 708 via a first injection line 710 passing through the second mould tool 706.

At step s610, the polyurethane in the first mould cavity 708 is cured, for example by waiting a certain time period and/or by applying heat.

At step s612, the vacuum holding the core structure 104 against the first 15 mould tool 702 is removed, and the first mould tool 702 is moved away from the second mould tool 706.

Figure 7C is a schematic illustration (not to scale) showing the first mould tool 702 being moved away from the second mould tool 706. This movement is indicated in Figure 7C by a double-headed arrow and the reference numeral 712. The cured polyurethane 713 (in the first mould cavity 708) and the core structure 104 bonded thereto are retained in the second mould tool 706.

Ay step s614, a third mould tool is positioned against the second mould tool 706 over the core structure 104.

Figure 7D is a schematic illustration (not to scale) showing the third mould tool 714 being positioned against the second mould tool 706 over the core structure 104. This movement of the third mould tool 714 is indicated in Figure 7D by an arrow and the reference numeral 716.

Figure 7E is a schematic illustration (not to scale) showing the third mould tool 714 positioned against the second mould tool 706 over the core structure 104. Thus, a second mould cavity 718 is established. The second -14 -mould cavity 718 is defined between the second mould tool 706 and the third mould tool 714. The cured polyurethane and the core structure 104 bonded thereto are located within the second mould cavity 718.

At step s616, the second mould cavity 718 is filled with the first material in liquid form, i.e. liquid polyurethane. In particular, in this embodiment, the liquid polyurethane is injected into the second mould cavity 718 via a second injection line 720 passing through the third mould tool 714.

Advantageously, the injected liquid polyurethane tends to flow through the through holes 108 of the core structure 104 to contact (and, in the next step s618, bond with) the cured polyurethane 713.

At step s618, the polyurethane in the second mould cavity 718 is cured, for example by waiting a certain time period and/or by applying heat.

At step s620, the second and third mould parts 706, 714 are moved away from the article formed therebetween.

Figure 7F is a schematic illustration (not to scale) showing the second and third mould parts 706, 714 being moved away from the article (i.e. the blank 100) formed therebetween. This movement of the second and third mould parts 706, 714 is indicated in Figure 7F by arrows and the reference numeral 722.

Thus, a process 600 of producing the blank 100 is provided.

The above-described manufacturing methods and apparatuses tend to be scalable.

The above-described surfboard tends to have a reduced weight compared to conventional surfboards.

The above-described methods tend to provide for faster surfboard 25 production.

It should be noted that certain of the process steps depicted in the flowcharts of Figures 2 and 6 and described above may be omitted or such process steps may be performed in differing order to that presented above and shown in Figures 2 ad 6. Furthermore, although all the process steps have, for convenience and ease of understanding, been depicted as discrete temporally- -15 -sequential steps, nevertheless some of the process steps may in fact be performed simultaneously or at least overlapping to some extent temporally.

In particular, in the above embodiments of a method of producing a blank, a first cured polyurethane portion is formed in the first cavity. A second polyurethane portion is subsequently fused with the first cured polyurethane portion. The resulting blank 100 has a body 102 formed of the cured first and second polyurethane portions, i.e. may be considered a stepwise-formed cured polyurethane body 102.

In other embodiments, however, the body 102 of the blank 100 is formed of a single volume of polyurethane, i.e. is formed in a single step. The body 102 may be formed as a single monolithic item. In such embodiments, the core structure 104 may be suspended between two mould tools. For example, in some embodiments, the core structure 104 is suspended between the second mould tool 706 and the third mould tool 714. This suspension may be accomplished, for example, by supporting pins extending from one of the second mould tool 706 or the third mould tool 714, or, for example, by pinching contact between each of the mould tools 706, 714 at one or both ends of the core structure 104. A cavity is thus formed between the second mould tool 706 and the third mould tool 714, and the core structure 104 is located within this cavity. Liquid polyurethane (or other material) may then be injected into the cavity, for example via the first injection line 710 passing through the second mould tool 706 and/or the second injection line 720 passing through the third mould tool 714. The liquid polyurethane may flow through the through holes in the core structure 104. The liquid polyurethane is then cured, for example by waiting a certain time period and/or by applying heat, thereby to produce an integrally formed cured polyurethane body 102 of the blank 100.

The second mould tool 706 and the third mould tool 714 may then each be moved away from the body 102 of the blank 100. If applicable, the supporting pins are moved out of and away from the body 102 by movement of the associated mould tool. Alternatively, if applicable, a portion or portions of the core structure 104 protruding from, i.e. extending beyond an outer surface of, the cured polyurethane body 102 is then cut away or otherwise removed.

-16 -Advantageously, this method tends to result in an improved homogeneity of the material of the body 102. In particular, homogeneity of the integrally formed cured polyurethane body 102 tends to be improved compared to, for example, that of a stepwise-formed polyurethane body 102. This tends to provide improved flex characteristics and structural integrity to the blank 100.

Also, a stronger bind between the core structure 104 and the cured polyurethane body 102 tends to be afforded to the integrally formed cured polyurethane body 102. A stronger bind of the cured polyurethane body 102 itself also tends to be provided. Thus, a likelihood of delamination or other to breakage of the blank 100, for example when in use within a surfboard, tends to be reduced.

Advantageously, the integrally formed body 102 does not have a fracture line or fracture layer associated with formation of the stepwise-formed cured polyurethane body 102. More advantageously still, regions of the integrally formed cured polyurethane body 102 which extend through the through holes of the core structure tend not to have fractures or weakness associated with formation of the stepwise-formed polyurethane body 102.

In the above embodiments, the low stiffness region is disposed along the length of the core structure between the first region and the second region.

Specifically, the low stiffness region is disposed along the length of the core structure between the regions at which the feet of the user are typically positioned. This tends to provide improved responsiveness to user input, i.e. relative rotation of the first and second regions on application of force by the user, and improved thrust generation. However, in other embodiments, one or more low stiffness regions are disposed elsewhere along the length of the core structure relative to the regions at which the feet of the user are typically positioned. The number and relative positions of the low stiffness regions may be selected to provide customised flexibility and tensile strength characteristics to regions of the surfboard. This may provide customised responsiveness to user input to various regions of the surfboard.

In the above embodiments, the buoyant sports board is a surfboard. However, in other embodiments, the buoyant sports board is a different type of -17 -buoyant sports board, for example, a windsurfing board, a wake board, a paddle board, a body board, or a hydrofoil sailing board.

In the above embodiments, the body structure of the blank is made of polyurethane. However, in other embodiments, the body structure of the blank is made of one or more different materials instead of or in addition to polyurethane. The body structure may be made of one or more materials selected from the group of materials consisting of: a closed cell foam material; an open cell foam material; a ballistic foam material; a lineal foam material; polyurethane; polyurethane foam; polystyrene; expanded polystyrene; extruded polystyrene; prolapse polystyrene; polystyrene foam; extruded polystyrene foam; expanded polypropylene; ethylene propylene diene monomer; polyurethane resin; epoxy resin; and a combination of expanded polystyrene and extruded polystyrene.

In the above embodiments, the core structure of the blank is made of carbon fibre-reinforced polymer. However, in other embodiments, the core structure of the blank is made of one or more different materials instead of or in addition to carbon fibre-reinforced polymer. The core structure may be made of one or more materials selected from the group of materials consisting of: polypropylene; polycarbonates; acrylonitrile butadiene styrene; nylon; polyvinyl chloride; aluminium; titanium; fibre-reinforced polymers; glass fibre-reinforced polymers; carbon fibre-reinforced polymers; aram id fibre-reinforced polymers; and para-aramid fibre-reinforced polymers, such as Kevlar 0.

In the above embodiments, the body structure is substantially surfboard-shaped. However, in other embodiments, the body structure is a different 25 shape, e.g. whereby a plan view of the body structure may define an approximately cuboid, oval or teardrop shape, or any other shape.

In the above embodiments, the body structure has the above-provided dimensions. However, in other embodiments, one or more dimensions of the body structure is different to those provided above.

In the above embodiments, a plan view of the core structure 104 defines an approximately oval, teardrop, or surfboard-shape. Also, when viewed from -18 -the side, the core structure 104 a substantially curvilinear shape. However, in other embodiments, the core structure is a different shape.

In the above embodiments, the core structure has the above-provided dimensions. However, in other embodiments, one or more dimensions of the core structure is different to those provided above.

In the above embodiments, the core structure 104 may be considered to be a substantially planar structure. That is to say, when viewed from the side, the core structure 104 has a substantially curvilinear shape. Also, in the above embodiments, the core structure 104 is provided by cutting its shape from a to sheet of material. However, in other embodiments, the core structure has a different structure. For example, elongate members 106 of the core structure 104 may extend (e.g. within the body structure 12) in three mutually orthogonal directions. One or more of the elongate members 106 of the core structure 104 may extend within the body structure 102 in a direction between the upper and lower surfaces 308, 310. For example, one or more elongate members 106 of the core structure 104 may extend within the body structure 102 to or from a location at or proximate the upper surface 308 with the first and/or second region 401, 402, thereby to improve transmission of vibration to a user's feet in use. This may provide further improved responsiveness to user input of various regions to the buoyant sports board, and/or further improved thrust generation.

In some embodiments, providing the core structure 104 may comprise one or more processes instead of or in addition to cutting the shape of the core structure from a sheet of material. Providing the core structure 104 may comprise one or more processes selected from the group of processes consisting of: a vacuum forming process; an additive manufacturing process; a thermocompression moulding process; an injection moulding process; a stamping process; and a computer numerical control machining process.

By way of example, in some embodiments, the first mould part 702 may be used to vacuum form the core structure. The mould surface 700 of the first mould part 702 may be shaped so as to mould the core structure 104 such that it extends out of the plane of its original sheet of material. Figure 8 is a schematic illustration (not to scale) showing the core structure 104 secured to -19 -the mould surface 700 of the first mould tool 702 of such an embodiment. In this embodiment, indentations and/or protrusions on the mould surface 700 force that core structure 104 to extend in the z-direction when the core structure 104 is vacuum formed against the mould surface 700. The vacuum forming of the core structure 104 comprises establishing a vacuum between the core structure 104 and the mould surface 700 by vacuum lines 704 passing through the first mould tool 702. The vacuum forming process depicted in Figure 8 may replace that performed at s604 and depicted in Figure 7A and described above. The method of forming the blank may continue with step s606, at which the second mould tool 706 is positioned against the first mould tool 702 on which the core structure 104 has been vacuum formed.

Claims

-20 -CLAIMS1. A blank for a buoyant sports board, the blank comprising: a body structure formed of a first material; and a core structure formed of a second material different to the first material; 5 wherein the core structure is embedded within the body structure; and the core structure is a reticulate structure comprising a plurality of interconnected elongate members.
2. The blank of claim 1, wherein the core structure comprises one or more through holes through which the first material of the body structure extends.
3. The blank of claim 1 or 2, wherein the core structure comprises multiple different regions along a length of the core structure, the multiple different regions having different respective stiffnesses, thereby to provide varying torsional stiffness along the length of the core structure.
4. The blank of claim 3, wherein one or more characteristics of one of the multiple different regions is different to the one or more characteristics of another of the multiple different regions, the one or more characteristics being selected from the group of characteristics consisting of: density of the interconnected elongate members, connectedness of the interconnected elongate members, density of the second material, and thickness of the second material.
5. The blank of claim 3 or 4, wherein the core structure comprises a region of lower stiffness disposed along the length of the core structure between two regions of higher stiffness.
6. The blank of any of claims 1 to 5, wherein the first material comprises one or more materials selected from the group of materials consisting of: a closed cell foam material; an open cell foam material; a ballistic foam material; a lineal foam material; polyurethane; polyurethane foam; polystyrene; expanded polystyrene; extruded polystyrene; prolapse polystyrene; polystyrene foam; extruded polystyrene foam; expanded polypropylene; ethylene propylene diene monomer; polyurethane resin; epoxy resin; and a combination of expanded polystyrene and extruded polystyrene.
7. The blank of any of claims 1 to 6, wherein the second material comprises one or more materials selected from the group of materials consisting of: polypropylene; polycarbonates; acrylonitrile butadiene styrene; nylon; polyvinyl chloride; aluminium; titanium; fibre-reinforced polymers; glass fibre-reinforced polymers; carbon fibre-reinforced polymers; aram id fibre-reinforced polymers; and para-aram id fibre-reinforced polymers.
B. The blank of any of claims 1 to 7, wherein a plan view of the core structure defines an approximately oval, teardrop, or surfboard-shape.
9. The blank of any of claims 1 to 8, wherein the core structure has one or more dimensions selected from the group of dimensions consisting of: a length of between 100cm and 1000cm; a width of between 30cm and 100cm; and a thickness of between 3cm and 30cm.
10. The blank of any of claims 1 to 9, wherein the elongate members of the core structure extend within the body structure in three mutually orthogonal directions.
11. The blank of any of claims 1 to 10, wherein the buoyant sports board comprises a first surface and a second surface opposite to the first surface; and a plurality of the elongate members of the core structure extend within the body structure in a direction between the first and second surfaces.
12. A buoyant sports board comprising: a body structure formed of a first material; and a core structure formed of a second material different to the first material; 10 wherein the core structure is embedded within the body structure; and the core structure is a reticulate structure comprising a plurality of interconnected elongate members.
13. The buoyant sports board of claim 12, wherein the core structure comprises a central spine disposed along a longitudinal axis of the buoyant sports board.
14. The buoyant sports board of claim 12 or 13, wherein: the buoyant sports board comprises a first surface and a second surface opposite to the first surface; the first surface defines a first and a second region, the first and second regions being spaced apart along a length of the buoyant sports board, the first and second regions being regions in which a user of the buoyant sports board typically place their feet during use of the buoyant sports board; and the core structure comprises a region of reduced stiffness which, when viewed normal to the first surface, is disposed along the length of the buoyant sports board between the first and second regions.
15. The buoyant sports board of any of claims 12 to 14, wherein: the buoyant sports board comprises a first surface and a second surface opposite to the first surface; the first surface defines a first and a second region, the first and second regions being spaced apart along a length of the buoyant sports board, the first and second regions being regions in which a user of the buoyant sports board typically place their feet during use of the buoyant sports board; and when viewed normal to the first surface, one or more of the elongate members of the core structure extend from or to the first and second regions.
16. The buoyant sports board of any of claims 12 to 15, wherein: the buoyant sports board comprises a first surface and a second surface opposite to the first surface; the buoyant sports board comprises one or more fins disposed on the second surface; and when viewed normal to the second surface, one or more of the elongate members of the core structure extend from or to the one or more fins.
17. The buoyant sports board of any of claims 12 to 16, wherein: the buoyant sports board comprises a first surface and a second surface opposite to the first surface, and rails disposed between the first surface and the second surface; when viewed normal to the first surface, one or more of the elongate members of the core structure extend from or to the rails.
18. A method of producing a blank for a buoyant sports board, the method comprising: -24 -providing a core structure, the core structure being a reticulate structure comprising a plurality of interconnected elongate members; inserting the core structure in a mould; introducing a first material into the mould in which the core structure is located; and curing the first material, wherein the cured first material forms a body structure in which the core structure is embedded; wherein the core structure is formed of a second material different to the first material.
19. The method of claim 18, wherein the step of providing the core structure comprises vacuum forming a sheet of the second material against a mould surface.to
20. The method of claim 18, wherein the step of providing the core structure comprises additively manufacturing the core structure.
21. A method of producing a buoyant sports board, the method comprising: providing a blank, the blank being in accordance with any of claims 1 to 11; cutting the blank substantially into a desired shape for the buoyant sports board; and coating the cut blank in a coating material.
22. The method of claim 21, wherein the step of providing the blank comprises performing a method according to any of claims 18 to 20.
23. The method of claim 21 or 22, wherein the buoyant sports board is in accordance with any of claims 12 to 17.
24. A core structure for a buoyant sports board blank, the core structure being a reticulate structure comprising: a plurality of interconnected elongate members.
25. The core structure of claim 24, wherein: the core structure comprises one or more through holes; to the core structure comprises multiple different regions along a length of the core structure, the multiple different regions having different respective stiffnesses, thereby to provide varying torsional stiffness along the length of the core structure; the core structure comprises one or more materials selected from the group of materials consisting of: fibre-reinforced polymers; glass fibre-reinforced polymers; carbon fibre-reinforced polymers; aram id fibre-reinforced polymers; and para-aramid fibre-reinforced polymers; and a plan view of the core structure defines an approximately oval, teardrop, or surfboard-shape.