AU2005220278B1

AU2005220278B1 - Surfboard fin assembly

Info

Publication number: AU2005220278B1
Application number: AU2005220278A
Authority: AU
Inventors: Michael George Cremin
Original assignee: Cremin Michael Gordon
Current assignee: Cremin Michael Gordon
Priority date: 2005-10-11
Filing date: 2005-10-11
Publication date: 2006-09-14
Anticipated expiration: 2025-10-11

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Michael Gordon Cremin Actual Inventor: Michael Gordon Cremin Address for Service: I.P. Monopoly Services P.O.Box 321 MOOREBANK NSW 2170 Invention Title: SURFBOARD FIN ASSEMBLY Details of Associated Application Nil The following statement is a full description of this invention including the best method of performing the invention known to the inventor:- (N 2 t-q- 0 The present invention relates to an improved surfboard fin assembly, and to a surfboard that includes same.

c Although the invention will be hereinafter described with particular reference to its application for surfboards, it will be understood by persons skilled in the art that the invention has broader application and may also be

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used for wakeboards, sailboards, kiteboards, water skis, and the like.

There have been many attempts to provide improved fin assemblies for various water planing boards, such as surfboards and wakeboards, for the purpose of increased maoeuvrability and stability.

US Patent No. 4,940,438 discloses a surfboard fin assembly having an axial rear fin and two axially opposed side fins located forwardly of the rear fin.

The side fins are canted at an angle to the longitudinal axis of the surfboard and are tilted outwardly relative to the surface thereof.

US Patent No. 6,254,446 discloses a wakeboard fin assembly having two fins extending from a base portion at an acute angle to each other. An axial ridge on the base portion extends between the two fins to divert water flow into the fins.

US Patent No. 3,201,807 discloses a water ski stabilizer assembly having dual fins which are in substantially inverted V-shaped relation to each other o S3 and extend from an axial mounting plate at approximately 75 degrees angular relation to the mounting plate.

oo c US Patent No. 6,149,479 discloses a wakeboard fmin assembly having axial front and rear fins and a pair of axially opposed side fins located inwardly of 0each front and rear fin. The members of each pair of side fins have an

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'1 interior side surface canted outwardly at an angle from the perpendicular axis of the wakeboard.

US Design Patent No. 291,715 shows a surfboard fin assembly having an axial rear fin which is substantially +-shaped (or cruciform shaped) when viewed from the front, each of the vertical and opposed horizontal cross fins having a conventional tuna fin contour.

US Patent Application No. 2004/0092180 discloses a surfboard fin assembly having an axial rear fin which is substantially +-shaped when viewed from the front and two axially opposed vertical side fins located fbrwardly of the +-shaped fin.

The aforementioned fin assemblies each affect the manoeuvrability and stability of their respective water planing board to some extent, but are not ideally suited to optimally utilizing a wave's energy to negotiate a sharp turn in the same way that a dolphin, shark or the like drop their pectoral fins down at an angle to create a sharp directional change.

c 4 Early surfboards used single axial rear fins but these experienced slow transition rail to rail due to the pivot point provided by the vertical fin being 00 along the longitudinal axis of the board.

t\, c-i Twin fin surfboards were developed to quicken rail to rail transitions by 0 having each fin located at opposite sides of the board's axis and canted or aligned in a direction to the board's nose. The board can thus pivot off either side fin.

Characteristics of both single and twin fin surfboards are provided by having thruster fins assembled as a spaced apart three fin array consisting of an axial rear fin and a pair of axially opposed side fins which are aligned in a direction to the board's nose. Thruster fin assemblies are now commonplace in surfboard design.

However, surfboards fitted with thruster fins, whilst providing an acceptable level of manoeuvrability and stability for most surfers, have a limited optimum capacity to grip the water when required for sharp turns. This limitation in the grip capacity is determined by the spacing apart of the fins and their substantially perpendicular orientation to the board's surface.

It is an object of the present invention to provide a surfboard fin assembly that confers improved grip of the water in a wave for enabling shlarper turns than is possible with single fin, twin fin or thruster fin surfboards of the prior art.

It s aothr "~"tof hepresent invention to overcome or substantially chNM. thsotoigs n isdvantages of theC prior art, or to at icast OC) pro'dc a useful aftcrnat'vc..

According to the iHve~lU~cm dter i's ProvideeQl a surfboard comprising: C91J a board 1 avg ifla L Cl a tin assembly located at thei rear end, the tfin assem-rbly including: (i)1 a main fin aligned along the longitudinal axis and extending perpenldicularly from11 a surface- of Lhe, boavd, and a vair of wing fins exten-vding Fromw- respecutive' opo sidso' til main- fin,1 1 eac w n. ujl~eing an angle oif between abou~t "0 degr'es and 60) degees to) t-he Iain fint vliurcin thue ulain fin arid eakuh of the wing fins ha1ive a rearll Cut away portion adapted to provide. the release of any turbulence or cavitation of water created during iiiiu of the surfboard. 2-ad wbereini the miafi fin extends.

F14t-ter to .b A,rice pe rpenrdie ularly vFrom the bo-a thart each offl1 the i wi Preferably, each wing fin defines ani angle of between 42 diegrees and 48 degrees to the main fn, find most preferably 145 degrees.

It is ptvefertced that each witig fit is cotnneeted to the mnaini fjt, at a location abOlutt two. thirdso h distantce filom the tip of'the mnain 1un to wvhere the ma0n1i is connected to the board.

Alternatively, each wing fin may be connec 1 to th L anfn to1a1cn locaiion whe-re the main fin is co-mnccted to the- boa-rd.

00 Tn a preferred torm, the main. fin. is tuna fin. Shaped.

wjngn fin~ shaped.

1_w' n of thc fvng-ins are preferably tuna nS in one form of the invention, the fin assembly is permanently secured to the board, In anOthle fo-rtm of the Ipnitin th flit asebly is tabricaked in one piece by irchton. mPou'ldg 1n yet another form of the invention, the board inrcludes a fin box, and the,. fin assemblyV 1S reli10v ably atached to the fI bDox.

pr Merab,h eacrh of the aInn wing, tins are rigid, but mpay alternatively be Partly fle~xible.

in order that the invention may be readily uujiderstoodi and put into practical j V CA 1.9 U %Jlipcfl. 1 IllII drc3 ,Illt -Ae~Tct, ref-krence_ 1now b;e m ade to the accmpaivng, d---is .i .hch: Fig. 1 is an elevated side view ofua preferr-ed suirfboaid according to thu Prtesent invention, with th i sebl shw on the topi 0 7 2 Fig. 2 is an end view of the surfboard of Fig. Iwith the fin assembly shown on the bottom, 00 1c Fig. 3 is a top view of the surfboard of Fig. 1, 0 Fig. 4 is a top view of the fmin assembly of the surfboard of Fig. 1, Fig. 5 is a side view of the fin assembly of the surfboard of Fig. 1, Fig. 6 is a perspective view of another preferred fin assembly according to the present invention, the fin assembly further including means for removable attachment to a fin box adapted to be secured to a board, Fig. 7 is an end view of the fm assembly of Fig. 6 in readiness for attachment to a fin box located in a board, Fig. 8 is a view from the rear end of the surfboard of Fig. 1 showing what happens when a surfboard rider is applying downward pressure so as to negotiate a left turn, and Fig. 9 is a similar view to that of Fig. 8 showing what happens when a surfboard rider is applying downward pressure so as to negotiate a right turn.

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The surfboard 10 shown in Figs. 1 to 3 has a board 12 with a longitudinal axis 14, a front end or nose 16, a rear end or tail 18, and a fin assembly 00oo located at the rear end 18.

F, The fin assembly 20 (also shown in isolation in Figs. 4 and 5) includes a main fin 22 which is aligned along the longitudinal axis 14 and extends cl perpendicularly from a surface of the board 12 which is adapted to be lowermost when the surfboard is in use. The fmn assembly 20 also includes first and second wing fins 24,26 extending from respective opposite sides of the main fin 22. In the embodiment shown, each wing fin 24,26 defines an angle of 45 degrees to the main fin 22, but this angle may vary to between about 30 degrees and 60 degrees to the main fin. Variation of the angle within the aforementioned range may be determined by the characteristics of the surf to be experienced by a rider of the surfboard.

The first and second wing fins 24,26 are, in this embodiment, connected to the main fin 22 at a location two thirds of the distance from the tip 28 of the main fin 22 to where the main fin 22 is connected to the board 12. This location where the fins interconnect may also be varied along the length of the main fin depending on the surf characteristics and possibly by the skill level of the rider.

Each of the main and wing fins 22,24,26 are tuna fin shaped and have a rear cut away portion 30,32,34, respectively. The cut away portions promote the o 9 0release of any turbulence or cavitation of water created during turning of the surfboard o00 rc The fin assembly 20 of the surfboard 10 is, in the embodiment shown in Figs. 1 to 5, permanently secured to the board 12 by conventional means.

The fin assembly 20 itself is fabricated in one piece by injection moulding of, say, a polycarbonate material, but may alternatively be fabricated as three separately injection moulded fins which are then screwed together using stainless steel threaded inserts and screws. Other ways of fabricating the fin assembly of the invention involve manual shaping processes with the use of materials such as fibreglass, where the three fins are glassed together with rovings and matting, or (ii) marine ply and fibreglass, where the three fins are individually shaped from marine ply, then stuck together and glassed over with fibreglass matting. Other materials may be used in the fabrication of the fin assembly 20, such as aluminium, which may be cast in one piece in the shape of the fin assembly, or cast in three pieces in the various shapes of the main and wing fins and are then welded or screwed together and coated with an appropriate material.

The fin assembly 40 shown in Figs. 6 and 7 includes attachment means 42 for a fin box 44 which is adapted to be secured to a board 46. The attaclhment means 42 comprises a beam 48 connected to the main fin 50 and a adjustable catch mechaniism 52 which can be operated to remove the fin assembly 40 from its attachment to the fin box 44 when required. The fin o 4=) 0 assembly 40 also includes first and second wing fins 54,56 extending upwardly (with reference to Figs. 6 and 7) at an angle of 48 degrees from 00 respective opposite sides of the main fin 50. The fin box 44 is sunk into the c surface of the board 46 which is, in use, lowermost in the water.

tIn 0An example of the use of the surfboard of the present invention will now be described with reference to Figs. 8 and 9 and with language that is familiar to surfers. When the surfboard 10 is paddled onto a wave that is about to break in an attempt to surf the wave, the wing fins 24,26 help to push the board 12 into a take off position due to their angle which presents a face to the oncoming wave. The motion or energy of the wave pushes the underside of the wing fins and enables the surfer to get up on his or her feet more quickly than can be achieved with conventional surfboards. As the surfer drops down the face of the wave, the fin assembly self adjusts to a stable position, assisted by its symmetrical arrangement.

The fin assembly launches extremely quickly out of bottom turns in either a left or right direction when the board is laid over at speed. This is because the angle of the wing fins relative to the main fin maintains optimal grip due to at least one of the wing fins being perpendicular or close to perpendicular to the water surface. The main fin stabilizes and guides the turn.

As the surfer applies downward pressure on the board so as to negotiate a left turn, as shown in Fig. 8, there is downward water resistance pressure on the main and wing fins as shown by the arrows, with none of these fins o o 11

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0coming out of the water. The left side wing fin 24 (or the inside wing fin as the surfboard negotiates a left turn) grabs water and optimizes grip and oo stability as it approaches and becomes vertical, thus serving as a pivot point t'c for the turn. At the same time this is happening, there is downward pressure on the rear end or tail of the board which allows the right side wing fin 26 to

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ride up, lifting the board's weight off the water surface. An inverted Vshaped jet of water is constantly rushing between the wing fins and the main fin and being released rearwardly of the fin assembly, further assisting in providing grip and stability and increasing the turning speed. As the surfer applies downward pressure on the board so as to negotiate a right turn, as shown in Fig. 9, there is downward water resistance pressure on the main and wing fins as shown by the arrows, the effects of which are similar to those described above for when the board negotiates a left turn. The rear cut away portions of each of the main and wing fins further assist in optimizing grip and stability during turns.

The inverted V-shaped jet of water produced by the fin assembly of the present invention also helps the board glide over any slow or dull sections of a wave.

When performing aerial manoeuvres, the downward pressure applied to the tail of the board just before take off tends to angle the wing fins upwardly, thereby piromoting lift and causinlg the wave's energy to propel the board (with rider) upwardly for "big air".

o 12 0 When stalling is needed to prolong time in a barrel, the wing fins may also assist to slow the board's speed.

00 c When the fin assembly of the present invention is mounted on a longboard, nose rides can be prolonged. In conventional longboards, the weight of the surfer on the nose of the board urges the tail of the board to lift. The effect of ,l the wing fins, however, is to push the tail of the board downwardly despite the surfer's weight being on the board's nose. The effect is analogous to that of a rear spoiler of a racing car which constantly forces the rear of the car downwardly so as to prevent unwanted lift of the rear wheels from the track.

In addition, the fin assembly of the present invention improves the manoeuvrabiiity and turning of a iongboard.

It will be apparent to persons skilled in the art that various modifications may be made in details of design and construction of the surfboard fin assembly described above without departing from the scope or ambit of the present invention.

Claims

2. The surth~ocard ntclaim 1 wherein each wing fin def-ics. 'n angle of bctw;ccn _42 degrees and 48 degrees to the main fin.
3.The sarfbioard of claim 2whrnteageis4 lre.
4. T1he surfboard of ainy one of clalms I to 3 whereim eacht wing fin is coninected to the main fir] at it iocatiOii albout two thirds of thv, distancue from t-he tip of the main fin to where the manfin is conniected to the boord. Thc surfbDoard of any one of claims I to 3 wilercin each winig ftin is connected to the main fin at or adjace-nt a ilcation where thei main fin is 00 con nected to die board.
6.The surfboard of any one of claiMs I to .5 wherein the main fin is tuna fin
7. Tle sufboard of any onc of claims I to 6 wherein each of thc wing fir's arc tunla finl Shaped. UM. ThOUrfbardJU of. any one of claims 1, to 7 whereith'le f1:in assembly Is permnanently secured to the board
9. Thue surfboard of any onc of claims 1I tO 8 whurcin. thc finor assembly is fabricated im one piece by injection moulding. 1Q The cuirtboardl ofany one of claims I to(9 where-in the hoard includies a fin box, and the fin assembly is removably attached to the fin box. Dtd24 July 2c*006 MACIAJ3L uoIK M )N :R I:MN Patient Attorney fi-r the Applicant Gcorge- Griziotis.