FIN FOR SURF CRAFT
A fin (410) with a discrete structural strand layer (420) that may include high tensile carbon fibre strands (422, 424) and high tensile strength and toughness Kevlar (426) strands. These structural strands may have a tensile strength substantially greater than the other materials typically used in a fin body. The structural strand layer (420) provides an economic and ready technique to vary and control a stiffness characteristic of the fin in a variety of directions or about a variety of axes of rotation; without varying the other common components that may be used in a fin body, for example core (412), layers of fibreglass fabric (414) and/or resin.
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1. Field of the Invention
The present invention relates to fins and methods for making them as may be applied to surf craft such as surfboards, windsurfers, paddleboards, wave and surf skis, kite-boards, wake boards and the like.
2. Description of the Art
Surf craft (including surfboards) often have one or more fins located on an underside of the surf craft that, for example, may be used for stability, controlling direction and facilitating turning of the surf craft. In addition surfboards may have multiple fins with different functions, for example an uppermost side fin with a curved or airfoil profile may function so as to provide to provide lift when the surfboard is travelling across the face of a wave and the uppermost side fin is located within the face of the wave. It also follows that extra acceleration and drive to the surfboard results.
Fin/s of turning surf craft may experience substantial side ways and other forces to the face of the fin/s. How the fin/s respond to these sideways and other forces in turns and other manoeuvres may strongly affect the performance of the surf craft for a particular set of surf conditions. The construction of a fin may in particular affect its response to sideways and other forces in use.
Current surfing trends, particularly in competitive surfing, involve multiple, high speed, sharp turns of a surfboard whilst a wave is being ridden. Such manoeuvring of a surfboard places very significant forces on the fins of the surfboard. Under such forces, the fins tend to experience bending (e.g. between the base and the tip of the fin) and twisting (e.g. between the leading and trailing edges of the fin). The fin's ability to return sharply to its normal state following the removal of the experienced force (e.g. via a turn) affects the performance of the fin and, consequently, the surfboard.
Commonly available fins for surfboards may be a composite structure of layers of bi-directional fibreglass fabric imbedded in a suitable resin and then moulded and/or shaped to the form of a fin. The word “bi-directional” in the following is taken to include the direction of the fibreglass strands within the closely woven fabric. The fibreglass strands being often made up of multiple fibres or filaments of fibreglass. Bi-directional fibreglass or other reinforcing fabric often has a basket weave pattern where the strands are closely interwoven orthogonally to form the fabric.
The reinforcing fibreglass fabric together with the impregnating resin or other suitable material typically determines the physical properties of the fin in terms of, by way of example, the stiffness characteristics, bending resistance, twisting resistance and/or flexibility of the fin to sideways and other forces in a turn or other manoeuvres. However for typical fins, varying the stiffness characteristics, flexibility or other such properties of the fin in an easily manufacturable and controllable fashion is difficult due to the many layers of reinforcing fabric with impregnating resin matrix contributing to the stiffness or flexibility across the fin. There is also the additional limitation of what is commercially available in reinforcing fabrics and the strand materials forming them.
None of these prior art fin devices and methods of construction for fins provides an entirely satisfactory solution to the provision of fins for surf craft where the desired stiffness characteristics and other physical properties may be varied in a controllable fashion, nor to the ease of providing a convenient and reliable way of manufacturing fins having different degrees of stiffness or other desirable physical properties.
SUMMARY OF THE INVENTIONThe present invention aims to provide an alternative method for constructing a fin in which the stiffness characteristics and other physical properties of the fin may be better controlled and/or varied as well as to the provision of fins with different, controlled stiffness characteristics which overcomes or ameliorates the disadvantages of the prior art, or at least provides a useful choice.
In one form, the invention provides a fin for surf craft comprising: a fin body and at least one layer of structural strands, located within the fin body; wherein the structural strands are in one or more non-woven arrangements; and the structural strands have a physical property greater than a corresponding physical property of other material forming the fin body; and wherein the physical property is selected from at least one of a toughness, a tensile strength, an elastic moduli and a Youngs modulus. Preferably at least a portion of the structural strands extend substantially from a base portion to a tip portion of the fin. Preferably at least a portion of the structural strands extend substantially from a base portion to a leading edge portion of the fin. Preferably at least a portion of the structural strands extend substantially from a leading edge portion to a trailing edge portion of the fin. Preferably at least one layer of structural strands in one or more arrangements is located within the fin body such that the at least one layer of structural strands is substantially parallel to opposing faces of the fin.
Preferably the structural strands of at least one layer are substantially parallel to each other. Preferably in a first arrangement, the parallel structural strands are generally parallel to a sweep angle of the fin. In an alternate first arrangement, the parallel structural strands are at a first angle to a sweep angle of the fin, the first angle being in the range of up to 20 degrees, more preferably the parallel structural strands are at a first angle of approximately 10 degrees to a sweep angle of the fin. Preferably a second arrangement the parallel structural strands are at a second angle to the vertical of the fin, the second angle being in the range of 20 to 40 degrees more preferably the parallel structural strands are at a second angle of approximately 30 degrees to the vertical of the fin. Preferably a third arrangement, the parallel structural strands are generally vertical.
Preferably in a primary arrangement, the parallel structural strands are generally perpendicular to a sweep angle of the fin. Preferably in a secondary arrangement, the parallel structural strands are at a first angle to a sweep angle of the fin, the first angle being in the range of 20 to 40 degrees, more preferably the parallel structural strands are at a first angle of approximately 30 degrees to a sweep angle of the fin. Preferably in a tertiary arrangement, the parallel structural strands are generally vertical.
Preferably at least one layer of structural strands comprises of a plurality of structural strands extending from at least one substantially common point in a substantially radial formation. Preferably at least one substantially common point is adjacent the base portion of the fin. Preferably at least substantially common point is adjacent at least one of a leading edge portion and a trailing edge portion of the fin.
Preferably at least one structural strand comprises of a plurality of filaments. Preferably at least one structural strand is made of at least one of carbon fibre, Kevlar, aramide, natural fibres and synthetic fibres. Preferably at least one structural strand has a tensile strength that is at least 1.5 times greater than the tensile strength of the other material forming the fin body. Preferably at least one structural strand has a Youngs modulus that is at least 1.5 times greater than a Youngs modulus of the other material forming the fin body. Preferably at least one structural strand has a toughness that is greater than a toughness of the other material forming the fin body. Preferably at least a portion of the structural strands comprises unidirectional filaments in a ribbon configuration. Preferably at least a portion of the structural strands have a width in the range of 0.5 to 3 mm. Preferably at least a portion of the structural strands has a width in the range of 1 to 2 mm. Preferably at least a portion of the structural strands comprises of at least about 3,000 filaments per structural strand.
Preferably a spacing between at least a portion of the structural strands is less towards the base portion compared with the tip portion of the fin. Preferably a spacing between at least a portion of the structural strands is in the range of 1 to 30 times a width of one structural strand, more preferably a spacing between at least a portion of the structural strands is in the range of 4 to 13 times a width of one structural strand. Preferably a spacing between at least a portion of the structural strands is in the range of 4 to 15 mm, more preferably a spacing between at least a portion of the structural strands is in the range of 9 to 13 mm.
In one form, the invention provides a fin for surf craft comprising: a fin body; and at least one layer of structural strands, located within the fin body; wherein the structural strands are in one or more woven arrangements that are at least one of an open weave and a scrim; wherein the structural strands have a physical property greater than a corresponding physical property of other material forming the fin body; and wherein the physical property is selected from at least one of a toughness, a tensile strength, an elastic moduli and a Youngs modulus. Preferably, further including a core structure located within the fin body. Preferably at least one layer of structural strands in one or more arrangements is embedded within a body of the fin such that the layer of structural strands is substantially parallel to a face of the core structure. Preferably at least one layer of structural strands are located intermediate the core structure and at least one of the opposing faces of the fin. Preferably the core is at least one of a foam core structure and a solid, non-foam core structure. Preferably at least a portion of the core structure is made of at least one of PVC foam, polyurethane foam, resin impregnated fibreglass, hardened resin, polyester mat, microspheres, plastic, bamboo and wood.
Preferably further including at least one layer of unidirectional carbon fibre fabric towards a base portion of the fin body, more preferably at least one layer of carbon fibre fabric is located about a periphery of the fin body.
Preferably a sweep angle of the fin is in the range of 20 to 60 degrees.
In yet another form, the invention provides a method of controlling a fin physical property for a surf craft, the method comprising: selecting one or more structural strands having a structural strand physical property greater than a corresponding physical property of other materials in a body of the fin; selecting a number of structural strands to provide the fin physical property; providing a layer of the structural strands in one or more arrangements; and embedding the layer of structural strands in the body of the fin; whereby varying at least one of the structural strands selection, the number of structural strands or the arrangement of the structural strands varies the fin physical property; and wherein the fin physical property is selected from at least one of: a stiffness characteristic, a bending resistance, a twisting resistance, a resistance to a deflection, a flexibility and a high elastic recoil; and wherein the structural strand physical property is selected from at least one of: a toughness, a tensile strength, an elastic moduli and a Youngs modulus. Preferably the step of providing a layer of structural strands includes the use of a template to locate one or more structural strands of one or more arrangements. Preferably the step of using a locating template further includes providing at least one of pins, adherents and securing systems to locate one or more structural strands. Preferably the step of using a locating template further includes the steps of: providing one or more reliefs machined into the template, and laying individual structural strands into respective reliefs to form a three dimensional structural strand layer. Preferably the step of providing a layer of structural strands includes the use of a numerically or a computer controlled machine to locate one or more structural strands of one or more arrangements.
Preferably the step of providing a layer of structural strands further includes a step of: configuring the arrangement of structural strands in a layer to vary the fin physical property. Preferably further including providing one or more structural strands largely parallel to a sweep angle of the fin such that the fin is provided with an increased resistance to a twisting of the fin. Preferably further including providing one or more structural strands at a first angle of up to 20 degrees to a sweep angle of the fin to provide the fin with an increased resistance to a twisting of the fin. Preferably further including providing one or more structural strands at a second angle in the range of 20 to 40 degrees to the vertical axis of the fin such that the fin is provided with an increased resistance to a deflection from the vertical axis.
A fin for surf craft produced according to the methods described above
In an alternate form, the invention provides a fin for surf craft substantially as described herein and a method of controlling a stiffness characteristic or other desired physical property of a fin for a surf craft substantially as described herein.
Further forms of the invention are as set out in the appended claims and as apparent from the description.
The description is made with reference to the accompanying drawings; of which:
The overall general axes of orientation to a surfboard 110 may be a vertical axis 128, a transverse or “sideways” axis 130 and a longitudinal or “stringer” axis 132.
The side fin/s 124 and/or centre fin/s 126 may also experience a variety of other hydrodynamic forces upon them during turns and complex manoeuvres which may cause them to deflect and/or twist from their at rest positions.
A description of the commonly available materials used to manufacture fins as illustrated in
The embodiment of the invention in
The term “stiffness characteristic” as a physical property in the following detailed description and claims is taken to include:
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- The resistance of the fin to deflection or twist forces in a variety of directions. Or in other words a twisting resistance and/or a bending resistance.
- The flexibility of the fin in a variety of directions or about a variety of axes.
- High elastic recoil or restoration of the fin after a force or a twist is applied to it is released. For example the snapping back of the fin after it has been deflected due to forces applied during a turn or complex manoeuvres. In other words energy or work put into the fin in a turn is returned, with little or no loss, to the surfer or rider of a surf craft at the completion of a turn.
- Stiffness, resilience and/or flexibility physical properties imparted to the fin by the combination of various materials of various tensile strengths, elastic moduli and other properties into the fin construction.
In addition toughness as a physical property in the following detailed description and claims is taken to include a comparatively moderate tensile strength material with improved ductility, for example Kevlar/aramide fibres may have a higher toughness compared with carbon fibres. Fibres with superior toughness have a high degree or resistance to repeated twisting and/or bending.
The carbon fibre strands 422 may be largely parallel to the sweep 220 of the fin 410 or offset from the sweep angle by up to 20 degrees, preferably approximately 10 degrees in the example shown in
A description of the structural strands used in the structural strand layer 420 is provided in the following by way of example only. “3 k” (3,000 filaments per strand) unidirectional carbon fibre strands in a largely ribbon form, “toe” form, may be used. “3 k” unidirectional Kevlar or Aramide equivalents strands in a substantially ribbon form may be used. Typically the ultimate tensile strengths of carbon and Kevlar/Aramide fibres may be at least 1.5 times or 2 times (2×) or more than commonly used fibreglasses such as E-glass and more than the other commonly used materials in a fin body. Similarly the elastic moduli such as Youngs modulus for carbon fibre and Kevlar/Aramide equivalents may be at least 1.5 times (1.5×), 2 times, 5 times or more than commonly used fibreglasses such as E-glass and more than the other commonly used materials in a fin body. The width of ribbon strands may be in the approximate range of 0.5 to 3 mm or more preferably in the range of 1 to 2 mm. The ribbon strands may have a thickness. The thickness of a ribbon strand may be greater than 0.1 mm. Natural fibres and synthetic fibres (in addition to those mentioned already) may also be suitable with appropriate resin, plastic and/or binder systems. It will be readily appreciated that these structural strand materials may be readily varied in terms of what may be selected for their use as would be exercised by a person skilled in the art of surf craft, surfboards in particular, design and manufacture. Furthermore the person skilled in the art would be guided in their choice of structural strands by their superior physical properties in comparison to the other materials used in the construction of the fin; for example carbon fibre over fibreglass and via a property such as tensile strength.
In one embodiment a layer of the structural strands may be fabricated by use of an aluminium template 610 as shown in
To aid in the laying up of the strands for each arrangement, pins or other locating, fixing, securing or otherwise aid devices (not shown) may be used at the periphery of the template 610 to locate and/or secure the strands in a desired arrangement. More complex arrangements or configurations may also be laid up and these are described below in detail with respect to
In the course of laying up the arrangements 710, 712, 714 of structural strands the individual strands may be impregnated with a suitable resin or binder in order that overlapping structural strands may be adhered together.
In the above example of forming a structural strand layer 420 the layer is not woven, that is the structural strands are not interlaced. In addition the layer is in the form of a scrim with clear apertures 814. From the above examples of ribbon strand widths and strand spacing the relative clear aperture may be from approximately 1 to 30 times (1×-30×) one ribbon strand width or more preferably from 4 to 13 times (4×-13×) one ribbon strand width. In further embodiments of the structural strand layer, described in detail below with respect to
The technique for forming the structural strand layer may also be adapted to a computer or numerically controlled apparatus to manufacture the structural strand layer. A numerically controlled (NC) machine (and/or computer controlled) may be particularly suited for the arrangements/configurations described below with respect to
The scrim structural strand layer may then be die or otherwise cut into the desired outline which for the example above is the full outline 612 of the fin. The structural strand layer may then be appropriately inserted into a mould of a fin with the other fin components, for example described above with respect to
Alternatively the scrim structural strand layer may be directly removed from the template board 610 without cutting to the fin outline 612. The scrim structural strand layer may then be appropriately incorporated into a traditional fin panel of fibreglass sheet and resin, formed by machine and/or hand. A desired fin may then be machine cut (for example NC machine) from the fin panel incorporating the structural strand layer. The machine cut fin may then be hand finished and polished.
Without wishing to be bound by theory, Finite Element Analysis (FEA) may be readily done for a typical homogeneous fin (not incorporating a structural strand layer).
It is apparent from
The technique described above for producing a structural strand layer allows for arrangements or configuration of the structural strands within the structural strand layer which may be very difficult or impossible to attain with commercially available stock reinforcing fabrics. In the following figures of
In a number of the
The stiffness characteristic of the fin 2910 in the region of the second arrangement 2914 may be higher than that of the region of the first arrangement 2912 due to the combined effect of the reduced spacing between adjacent structural strands together with the overlap between the second 2914 and first 2912 arrangements. Accordingly the fin 2910 may have stiffness characteristic of being very stiff towards the base and in particular for a portion to the mid section of the trailing edge 216 but with a particularly flexible or whip-like tip 218.
The spacings between the structural strands of the primary and secondary arrangements 4112, 4114 vary from the base 210 to the tip 218 so as to provide an increased stiffness characteristic towards the base 210 of the fin. A reduced spacing of the structural strands towards the base consequently increases the stiffness characteristic as well as providing a gradient of the stiffness characteristic across the depth of the fin.
The carbon fibre strands of the secondary arrangement 4114 may be largely perpendicular to the sweep angle of the fin as shown in
The primary and secondary arrangements 4112, 4114 of structural strands may be analogous to the embodiments of
In
Optionally, another arrangement of largely horizontal, parallel fibreglass strands 4116 may be further included in the fin construction. Alternatively the tertiary arrangement 4116 may use structural strands of Kevlar or aramide equivalents instead of fibreglass in order to improve the toughness performance of the fin as well as its stiffness characteristic. The fin embodiment 4110 may be constructed using RTM injection with vinyl ester as described above.
The embodiments of
It will be readily appreciated that elements from the described embodiments may be used to formulate other embodiments of the invention and still be within the scope of the invention.
In addition, between side fin/s 124 and centre fin/s 126 of surfboards the number and type of structural strand layers may differ. A greater stiffness characteristic for the centre fin 124 compared with the side fins 126 may be obtained by the use of a structural strand layer imparting a greater stiffness characteristic and/or multiple structural strand layers. For example: to the multiple structural strand layers for a centre fin, two structural strand layers may be used, one on each side of the core 412. In addition the choice of a core material and the dimensions of the core may also be varied in order to further change the stiffness characteristic or toughness of a fin. It will be readily appreciated that greater stiffness for a fin may be also achieved by changing the fin geometry/shape but this would also impact upon the hydrodynamic drag and other hydrodynamic properties.
The above described method and product of using a discrete structural strand layer allows the stiffness characteristics in terms of the amount of stiffness and distribution of the stiffness to be readily varied across the face of the fin and thru the fin body. For example to produce a component of twist about the horizontal/longitudinal axis of a fin. In addition the deflection and twist characteristics of stiffness may be varied from one face to the other face of a fin by either the layup of strands within an arrangement of a discrete structural strand layer and/or the position of the structural strand layer within construction of the fin. Fins with customised, multi-axis deflection and twist characteristics may be readily produced and tested. The technique disclosed here may be suitable for both small experimental and custom-built production runs common in surf craft fin research and development work and custom-built professional competition supply as well as readily adaptable to mass production of a fin product range with particular stiffness or flexibility characteristics.
For surfboards a fin product range incorporating a structural strand layer may be, for example, to:
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- A surf board rider's proficiency, strength and style of surfing. For example experienced surfers may prefer a stiffer fin range to improve surfboard performance. Professional surfers may require a custom-built fin with a stiffness characteristic tailored to their particular requirements.
- A surfboard rider's weight: heavier surfers may require stiffer fins to maintain hold through turns. The term “hold” is often used to describe the level of slippage movement of the tail of the surfboard during turns, particularly aggressive turns.
An example fin product range for surfboards may have the approximate dimensions and angles of:
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- “Large”, a depth/height 224 dimension of 119 mm, a base length 226 dimension of 118 mm and a sweep angle 220 of 34 degrees.
- “Medium”, a depth/height 224 dimension of 113 mm, a base length 226 dimension of 111 mm and a sweep angle 220 of 34 degrees.
- “Small”, a depth/height 224 dimension of 110 mm, a base length 226 dimension of 105 mm or 109 mm and a sweep angle 220 of 34 degrees.
- “Custom-Built/Competition”, a depth/height 224 dimension of 119 mm, a base length 226 dimension of 114 mm and a sweep angle 220 of 36 degrees.
- Sweep angles for surfboard fins according to the invention may be in the range of 20 to 60 degrees or more preferably in the range 26 to 56 degrees or in another preferred embodiment approximately 33 degrees.
A broad, simple example of a stiffness characteristic specification for a fin product range may be the amount of horizontal displacement of the fin tip 218 to an applied force as described above with respect to
Without wishing to be bound by theory we believe that the ability to readily vary the stiffness characteristic across a fin may enable further improvements in the performance of a surfboard in the areas of:
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- Stall characteristics
- The hold of the fin/s during a turn and complex manoeuvres.
- The sensation of “drive”/acceleration into and out of a turn. Stiffer fins tend produce a greater sensation of drive.
- The responsiveness of a surfboard may be affected by the stiffness of the fin/s. Stiffer fins may result in a more responsive surfboard. A more forgiving surfboard may result from more flexible fin/s.
- When transitioning from one turn to another a stiff fin with a high degree of elastic recoil may provide increased speed and acceleration from one turn to another as the surfboard transitions from one side fin to the opposing side fin.
- Flex: To make a fin that performs more efficiently the inventors had to ensure it could flex in multiple directions. This invention's technology is the latest development in fin flexion which draws on the material lay-up of the fin, the cambered foil, and the overall fin template. The result is a multi-directional flex pattern. This unique flex pattern allows the fin to ‘load-up’ and flex under pressure, and then de-coil once the pressure is released. Ultimately the fin stores energy during the transition between turns and then gives it back to the surfer in the form of superior speed and acceleration. The feeling can be compared to a slingshot, or whipping effect as the surfer enters and then exits through the turning arc.
- Foil: A highly efficient foil in combination with the invention can be the defining element that makes for exceptional fin performance. The highly cambered foil in the base of the fin provides drive and hold, the low cambered foil in the tip provides stability and allows the fin to release with control, even when the fin is pushed to the limits. This cambered foil also increases the fin's stall angle which helps to produce down-the-line speed and maintain projection through the entire turning arc.
- Template: The fin with the invention may feature an efficient, low aspect ratio elliptical template. The long base increases drive, moderate volume in the tip enhances the flex and coil characteristics, and the smooth transitional trailing edge reduces water separation, which is traditionally linked to cavitation. Translated, this means increased speed and drive through minimal water disturbance.
- Construction: Visually it's easy to see how technology and performance overlap. Structurally, the fin may draw on a combination of engineered Bi-axial Carbon (via two arrangements of uni-directional Carbon) and Uni-directional Kevlar to achieve the invention's flex pattern. The Uni-directional carbon fibre fabric (418) base further increases stiffness in the base of the fin, and helps to distribute pressure away from the plugs (of the surfboard) by reducing the twisting forces on the fin tabs securing the fin to the board. The Resin Transfer Moulding (RTM) process delivers consistency across manufacturing and guarantees the integrity of the flex and foils. Epoxy resin may be used to provide strength and material stability, while a lightweight moulded core further reduces the overall weight of the fin.
It will be readily appreciated that the above described method for readily altering the stiffness or flexibility properties of a fin of a surfboard may be readily applied to other surf craft such as windsurfers, paddleboards, wave and surf skis, kite-boarding, wake boards, and the like.
Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiments, it is recognized that departures can be made within the scope of the invention, which are not to be limited to the details described herein but are to be accorded the full scope of the appended claims so as to embrace any and all equivalent assemblies, devices and apparatus.
In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of”. A corresponding meaning is to be attributed to the corresponding words “comprise, comprised and comprises” where they appear.
It will further be understood that any reference herein to known prior art does not, unless the contrary indication appears, constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates.
Claims
1. A fin for surf craft comprising:
- a fin body; and
- at least one layer of structural strands, located within the fin body;
- wherein the structural strands are in one or more non-woven arrangements; and
- the structural strands have a physical property greater than a corresponding physical property of other material forming the fin body; and
- wherein the physical property is selected from at least one of a toughness, a tensile strength, an elastic moduli and a Youngs modulus.
2. A fin according to claim 1, wherein the fin comprises a base portion and a tip portion and at least a portion of the structural strands extends substantially from the base portion to the tip portion of the fin.
3. A fin according to claim 1, wherein the fin comprises a base portion and a leading edge portion and at least a portion of the structural strands extends substantially from the base portion to the leading edge portion of the fin.
4. A fin according to claim 1, wherein the fin comprises a leading edge portion and a trailing edge portion and at least a portion of the structural strands extends substantially from the leading edge portion to the trailing edge portion of the fin.
5. A fin according to claim 1, wherein the fin comprises opposing faces and at least one layer of structural strands in one or more arrangements is located within the fin body such that the at least one layer of structural strands is substantially parallel to the opposing faces of the fin.
6. A fin according to claim 1, wherein the structural strands of at least one layer are substantially parallel to each other.
7. A fin according to claim 6, wherein the fin comprises a sweep angle and, in a first arrangement, the substantially parallel structural strands are generally parallel to the sweep angle of the fin.
8. A fin according to claim 6, wherein the fin comprises a sweep angle and, in a first arrangement, the substantially parallel structural strands are at a first angle to the sweep angle of the fin, the first angle being in the range of up to 20 degrees.
9. A fin according to claim 8, the first angle is approximately 10 degrees.
10. A fin according to claim 6, wherein, in a second arrangement the substantially parallel structural strands are at a second angle to the vertical of the fin, the second angle being in the range of 20 to 40 degrees.
11. A fin according to claim 6, wherein the fin comprises a vertical component and, in a second arrangement, the substantially parallel structural strands are at an angle of approximately 30 degrees to the vertical of the fin.
12. A fin according to claim 6, wherein, in a third arrangement, the substantially parallel structural strands are generally vertical.
13. A fin according to claim 6, wherein the fin comprises a sweep angle and, in a primary arrangement, the substantially parallel structural strands are generally perpendicular to a sweep angle of the fin.
14. A fin according to claim 13, wherein, in a secondary arrangement, the substantially parallel structural strands are at a first angle to a sweep angle of the fin, the first angle being in the range of 20 to 40 degrees.
15. A fin according to claim 13, wherein, in a secondary arrangement, the substantially parallel structural strands are at a first angle of approximately 30 degrees to a sweep angle of the fin.
16. A fin according to claim 13, wherein, in a tertiary arrangement, the substantially parallel structural strands are generally vertical.
17. A fin according to claim 1, wherein at least one layer of structural strands comprises of a plurality of structural strands extending from at least one substantially common point in a substantially radial formation.
18. A fin according to claim 17, wherein the fin comprises a base portion and the at least one substantially common point is adjacent the base portion of the fin.
19. A fin according to claim 17, wherein the fin comprises a leading edge portion and a trailing edge portion and the at least substantially common point is adjacent at least one of a leading edge portion and a trailing edge portion of the fin.
20. A fin according to claim 1, wherein at least one structural strand comprises of a plurality of filaments.
21. A fin according to claim 1, wherein at least one structural strand is made of at least one of carbon fibre, Kevlar, aramide, natural fibres and synthetic fibres.
22. A fin according to claim 1, wherein at least one structural strand has a tensile strength that is at least 1.5 times greater than the tensile strength of the other material forming the fin body.
23. A fin according to claim 1, wherein at least one structural strand has a Youngs modulus that is at least 1.5 times greater than a Youngs modulus of the other material forming the fin body.
24. A fin according to claim 1, wherein at least one structural strand has a toughness that is greater than a toughness of the other material forming the fin body.
25. A fin according to claim 1, wherein at least a portion of the structural strands comprises unidirectional filaments in a ribbon configuration.
26. A fin according to claim 1, wherein at least a portion of the structural strands have a width in the range of 0.5 to 3 mm.
27. A fin according to claim 1, wherein at least a portion of the structural strands has a width in the range of 1 2 mm.
28. A fin according to claim 1, wherein at least a portion of the structural strands comprises of at least about 3,000 filaments per structural strand.
29. A fin according to claim 1, wherein the fin comprises a base portion and a tip portion and a spacing between at least a portion of the structural strands is less towards the base portion compared with the tip portion of the fin.
30. A fin according to claim 1, wherein a spacing between at least a portion of the structural strands is in the range of 1 to 30 times a width of one structural strand.
31. A fin according to claim 30, wherein a spacing between at lest a portion of the structural strands is in the range of 4 to 13 times a width of one structural strand.
32. A fin according to claim 1, wherein a spacing between at least a portion of the structural strands is in the range of 4 to 15 mm.
33. A fin according to claim 32, wherein a spacing between at least a portion of the structural strands is in the range of 9 to 13 mm.
34. A fin for surf craft comprising:
- a fin body; and
- at least one layer of structural strands, located within the fin body;
- wherein the structural strands are in one or more woven arrangements that are at least one of an open weave and a scrim;
- wherein the structural strands have a physical property greater than a corresponding physical property of other material forming the fin body; and
- wherein the physical property is selected from at least one of a toughness, a tensile strength, an elastic moduli and a Youngs modulus.
35. A fin according to claim 34, further including a core structure located within the fin body.
36. A fin according to claim 35, wherein at least one layer of structural strands in one or more arrangements is embedded within a body of the fin such that the layer of structural strands is substantially parallel to a face of the core structure.
37. A fin according to claim 35, wherein the fin comprises opposing faces and the at least one layer of structural strands are located intermediate the core structure and at least one of the opposing faces of the fin.
38. A fin according to claim 35, wherein the core is at least one of a foam core structure and a solid, non-foam core structure.
39. A fin according to claim 35, wherein at least a portion of the core structure is made of at least one of PVC foam, polyurethane foam, resin impregnated fibreglass, hardened resin, polyester mat, microspheres, plastic, bamboo and wood.
40. A fin according to claim 34, wherein the fin body comprises a base portion and further includes at least one layer of unidirectional carbon fibre fabric towards the base portion of the fin body.
41. A fin according to claim 40, wherein the at least one layer of carbon fibre fabric is located about a periphery of the fin body.
42. A fin according to claim 34, having a sweep angle of from 20 to 60 degrees.
43. A method of controlling a fin physical property for a surf craft, the method comprising:
- selecting one or more structural strands having a structural strand physical property greater than a corresponding physical property of other materials in a body of the fin;
- selecting a number of structural strands to provide the fin physical property;
- providing a layer of the structural strands in one or more arrangements; and
- embedding the layer of structural strands in the body of the fin;
- whereby varying at least one of the structural strands selection, the number of structural strands or the arrangement of the structural strands varies the fin physical property; and
- wherein the fin physical property is selected from at least one of: a stiffness characteristic, a bending resistance, a twisting resistance, a resistance to a deflection, a flexibility and a high elastic recoil; and
- wherein the structural strand physical property is selected from at least one of: a toughness, a tensile strength, an elastic moduli and a Youngs modulus.
44. A method according to claim 43, wherein the step of providing a layer of structural strands includes the use of a template to locate one or more structural strands of one or more arrangements.
45. A method according to claim 44, wherein the step of using a locating template further includes providing at least one of pins, adherents and securing systems to locate one or more structural strands.
46. A method according to claim 44, wherein the step of using a locating template further includes the steps of:
- providing one or more reliefs machined into the template, and
- laying individual structural strands into respective reliefs to form a three dimensional structural strand layer.
47. A method according to claim 44, wherein the step of providing a layer of structural strands includes the use of a numerically or a computer controlled machine to locate one or more structural strands of one or more arrangements.
48. A method according to claim 43, wherein the step of providing a layer of structural strands further includes a step of:
- configuring the arrangement of structural strands in a layer to vary the fin physical property.
49. A method according to claim 43, further including providing one or more structural strands largely parallel to a sweep angle of the fin such that the fin is provided with an increased resistance to a twisting of the fin.
50. A method according to claim 43, further including providing one or more structural strands at a first angle of up to 20 degrees to a sweep angle of the fin to provide the fin with an increased resistance to a twisting of the fin.
51. A method according to claim 43, further including providing one or more structural strands at a second angle in the range of 20 to 40 degrees to the vertical axis of the fin such that the fin is provided with an increased resistance to a deflection from the vertical axis
52. A fin for surf craft produced according to the method of claim 43.
53. (canceled)
54. (canceled)
Type: Application
Filed: May 17, 2011
Publication Date: Sep 19, 2013
Applicant: FIN CONTROL SYSTEMS PTY. LIMITED (New South Wales)
Inventors: Gregory John Scott (New South Wales), Michael James Durante (New South Wales)
Application Number: 13/696,590
International Classification: B63B 35/79 (20060101);