U.S. patent application number 10/458592 was filed with the patent office on 2004-12-09 for self-adjusting board fin.
This patent application is currently assigned to Rosebank Holdings Pty. Ltd.. Invention is credited to Larkin, Scott Andrew.
Application Number | 20040248482 10/458592 |
Document ID | / |
Family ID | 33490451 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040248482 |
Kind Code |
A1 |
Larkin, Scott Andrew |
December 9, 2004 |
SELF-ADJUSTING BOARD FIN
Abstract
An adjusting fin for a watercraft consisting of a fin removably
attached to a spindle that is held within a fin box. The spindle is
rotatable within the fin box such that the fin can pivot with
action of water against the fin as the watercraft moves through the
water. Adjustable stops act against cams on the spindle to limit
the range of rotation available, thus allowing the adjusting fin to
be set up to suit the prevailing conditions and the expertise of
the user. An optional biasing means biases the fin towards a
neutral position which is perpendicular to an underside of the
watercraft.
Inventors: |
Larkin, Scott Andrew;
(Queensland, AU) |
Correspondence
Address: |
BUCKINGHAM, DOOLITTLE & BURROUGHS, LLP
50 S. MAIN STREET
AKRON
OH
44308
US
|
Assignee: |
Rosebank Holdings Pty. Ltd.
New South Wales
AU
|
Family ID: |
33490451 |
Appl. No.: |
10/458592 |
Filed: |
June 9, 2003 |
Current U.S.
Class: |
441/79 ;
114/39.15 |
Current CPC
Class: |
B63B 32/64 20200201;
B63B 32/66 20200201 |
Class at
Publication: |
441/079 ;
114/039.15 |
International
Class: |
B63H 009/00; B63B
035/79; B63B 001/00; B63B 035/00 |
Claims
1. An adjusting fin comprising: (a) a fin box fixable to a
watercraft; (b) a spindle seated in the fin box for rotation about
a longitudinal axis of the spindle; (c) a fin associated with the
spindle so as to pivot relative to the watercraft with rotation of
the spindle; (d) at least one cam associated with said spindle; (e)
at least one cam engaging stop adjustable to restrict the extent of
rotation of the spindle, and thus limit the degree of pivot of the
fin; and (f) a biasing means that biases the fin towards a neutral
position.
2. (canceled)
3. The adjusting fin of claim 2 wherein the biasing means acts upon
the spindle.
4. The adjusting fin of claim 2 wherein the biasing means acts upon
the cam of the spindle.
5. The adjusting fin of claim 2 wherein the biasing means is a
spring.
6. The adjusting fin of claim 1 wherein the fin box comprises a
base and a detachable cover and wherein the spindle is retained
between the base and cover.
7. The adjusting fin of claim 1 wherein the fin is removably
attached to the spindle.
8. The adjusting fin of claim 1 wherein the position of the fin
relative to the spindle is adjustable for fine trimming of the
watercraft.
9. The adjusting fin of claim 1 wherein the cam engaging stop is a
grub screw.
10. A watercraft including an adjusting fin, said adjusting fin
comprising: (a) a fin box fixed to the watercraft; (b) a spindle
seated in the fin box for rotation about a longitudinal axis of the
spindle; (c) a fin removably attached to the spindle so as to pivot
relative to the watercraft with rotation of the spindle; (d) at
least one cam associated with said spindle; (e) at least one cam
engaging stop adjustable to restrict the extent of rotation of the
spindle, and thus limit the degree of pivot of the fin; and (f) a
biasing means that biases the fin towards a neutral position.
11. (canceled)
12. A fin box assembly comprising: (a) a base for fixing in a
surfboard; (b) a spindle seated in the base for rotation about a
longitudinal axis of the spindle; (c) at least one cam associated
with said spindle; (d) at least one cam engaging stop adjustable to
restrict the extent of rotation of the spindle; (e) a removable
cover retaining the spindle in the base; and (f) a biasing means
that biases the spindle towards a neutral position.
13. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from the international
patent application number PCT/AU01/01596 filed Dec. 11, 2001,
Australian Patent Application Serial No. PR2894 filed Feb. 6, 2001,
and Australian Patent Application Serial No. PR1979 filed Dec. 11,
2000.
BACKGROUND OF INVENTION
[0002] This invention relates to surf craft, such as surfboards and
surf skis, and particularly to a pivoting fin for surf craft.
[0003] It has long been recognized that fins are essential for
stability of watercraft and particularly surf craft. Surfboards
commonly employ a single fin on the underside of the board at the
rear. The fin is centrally placed between the sides of the board,
which are known as the rails.
[0004] As surfboard riders became more skilled they shortened the
boards to increase maneuverability. These shorter boards were able
to make much tighter turns on a wave then the earlier long boards.
However, the shorter boards had less stability and were therefore
much harder to ride. This problem was addressed by employing
multiple fins on the underside of the boards. Numerous
configurations are known but the most popular are double fin and
triple fin configurations. The double fin configuration has two
identical side fins position equidistant from a longitudinal center
axis of the board. The triple fin configuration (known as a
thruster) is similar to the double fin configuration but with the
addition of a slightly larger center fin.
[0005] The maneuverability of a surfboard is achieved by the
combination of the effect of the rails and the fins acting against
the water. However, the effective area of the fin in the water is
greatly reduced in many riding maneuvers, particularly sharp turns
and fast runs across the face such as riding a tube. In fact, for a
double or triple fin surfboard the side fin away from the wave face
may be completely out of the water and the fins in the water will
be at a less than optimum angle.
[0006] A number of inventions have been proposed for adjustable
fins that trim the craft, be it a surfboard, surf ski or other surf
craft, for optimum performance.
[0007] Reference may be had to U.S. Pat. No. 4,733,496, in the name
of Michael Wallner, of Australia. The Wallner fin includes a
pivoting rudder-like section that swings out relative to a fixed
section when a turn is commenced. The fixed section incorporates a
flange with a groove of varying depth that is deepest in the
middle. An adjustable spring-loaded pin in the rudder-like section
seats in the groove to bias the sections towards alignment. The
flange extends laterally and therefore produces drag that reduces
the effectiveness of the Wallner innovation.
[0008] U.S. Pat. No. 5,567,190, in the name of Oates, describes a
fin box assembly that is adjustable to allow the angle of attack of
the fin to be varied with respect to the longitudinal axis of the
surfboard. The fins on the board can be trimmed to suit the
prevailing conditions and the experience of the rider. The static
adjustment proposed by Oates is useful for long boards but of
limited advantage for shorter, more maneuverable boards.
[0009] Benham, U.S. Pat. No. 5,813,890, recognized that the fin
angle of watercraft, particularly windsurfer boards, needs to be
continuously changing depending upon the action of the board. When
the windsurfer board is traveling in a straight line the fin is
most suitably in a neutral position that is perpendicular to the
underside of the board. If the board is turning, or keeling over
under the force of the wind, the fin should be at an angle to the
board so as to maintain maximum effective length in the water.
Benham devised a pivoting fin that is biased towards the neutral
position by an elastomeric spring. The fin is free to pivot in a
ninety degree range under the influence of the water pressure as
the watercraft turns or keels over. Benham also provides a
mechanism for locking the fin in a fixed angular position relative
to the board, but does not provide any mechanism for limiting the
range of pivot of the fin.
SUMMARY OF INVENTION
[0010] In one form, although it need not be the only or indeed the
broadest form, the invention resides in an adjusting fin
comprising: a fin box fixable to a watercraft; a spindle seated in
the fin box for rotation about a longitudinal axis of the spindle;
a fin associated with the spindle so as to pivot relative to the
watercraft with rotation of the spindle; at least one cam
associated with said spindle; and at least one cam engaging stop
adjustable to restrict the extent of rotation of the spindle, and
thus limit the degree of pivot of the fin.
[0011] Suitably the adjusting fin further comprises biasing means
that biases the fin towards a neutral position. The biasing means
suitable acts upon the spindle, and most suitably upon the cam of
the spindle.
[0012] Suitably the fin box comprises a base and a detachable cover
with the spindle retained between the base and cover.
[0013] It is an object of the invention to provide an improved fin
for surf craft.
[0014] It is a further objective to provide a self-adjusting fin
with a selectable range of pivot.
[0015] These and other objects of this invention will be evident
when viewed in light of the drawings, detailed description, and
appended claims.
BRIEF DESCRIPTION OF DRAWINGS
[0016] The invention may take physical form in certain parts and
arrangements of parts, a preferred embodiment of which will be
described in detail in the specification and illustrated in the
accompanying drawings which form a part hereof, and wherein:
[0017] FIG. 1 is a sketch of an assembled adjusting fin;
[0018] FIG. 2 is an end view of the adjusting fin of FIG. 1 showing
a range of movement;
[0019] FIG. 3 is a bottom view of the adjusting fin of FIG. 1;
[0020] FIG. 4 is a sketch of a spindle;
[0021] FIG. 5 is a sketch of the underside of the spindle of FIG.
4, showing spring locating stubs;
[0022] FIG. 6 is a sketch of the fin box base;
[0023] FIG. 7 is a sketch of the fin box cover;
[0024] FIG. 8 is a sketch of the rear part of the underside of a
triple fin surfboard employing two adjusting fins; and
[0025] FIG. 9 is a rear view of the surfboard of FIG. 8.
DETAILED DESCRIPTION
[0026] Referring to FIG. 1, there is shown a fin assembly 1
consisting of a fin box 2 and fin 3. The fin box 2 has a sculptured
outer surface for glassing into the underside of a surfboard in
conventional manner. The fin 3 is held in a spindle 4 by screws 5
in a manner described in greater detail below. For simplicity the
adjusting fin will be described by reference to a surfboard. It
will be appreciated that the adjusting fin is not limited to this
application but may equally as well be employed on a surf ski,
windsurfer, or other watercraft.
[0027] The fin box 2 is formed in two parts as a base 6 and a cover
7. The spindle 4 is captured in the fin box 2 between the cover 7
and the base 6. The cover is attached to the base by screws 8. The
fin 3 pivots with rotation of the spindle 4, which is limited in
range of rotation by adjustable stops 9. The possible range of
rotation is shown in FIG. 2 with the fin shown in the neutral
position (perpendicular to underside of board) and the extent of
pivot shown in dotted outline.
[0028] Also in FIG. 2 is shown the depth of glassing of the fin box
into a board. When correctly glassed in the surface of the board
should be at about the dotted line 10. The locating stubs 11 are
sanded off after installation.
[0029] The elements of the adjusting fin are seen more clearly in
the bottom view of FIG. 3, and the sketches of each element in
FIGS. 4-7. The screws 8 attach the cover 7 to the base 6, so
capturing the spindle 4. As seen in FIG. 4, the spindle has cams 12
at each end. The range of rotation of the spindle is limited when
the cams contact the adjustable stops 9. Adjusting the depth of
stops changes the range of rotation and therefore limits the range
of pivot of the fin. The usual arrangement for a triple or double
fin board is for the range to be set in the manner shown in FIG. 2,
that is that the fin only pivots away from the neutral position on
one side. This is depicted more clearly in FIGS. 8 and 9.
[0030] Also seen most clearly in FIG. 4 is the cavity 13 that
receives the base of the fin 3. The fin is removably positioned in
the cavity and retained by screws 5. Although it has been found
that there may be benefit to have the fin detachable from the
spindle, it will be appreciated that the fin and spindle could
equally as well be formed as a single unit. Furthermore, if the fin
and spindle are formed separately, means other than screws could be
used to retain the fin 3 in the cavity 13. Such means includes
pins, bolts, clips or glue.
[0031] The screws 5 allow for a certain amount of fine trimming of
the position of the fin 3. The fin can be moved forward or back,
tilted about its own center or twisted relative to the longitudinal
axis of the fin box. For an expert rider these fine adjustments can
add perceptibly to the performance of the board. The fin 3 may be
biased towards a neutral position where the fin is maintained
generally perpendicular to the underside of the board. It has been
found that biasing is not essential as the fin 3 tends towards an
optimum position as the board moves through the water. However, as
mentioned above, there can be situations in which a fin is
completely out of the water. In this case it is convenient for the
fin to return to the neutral position. This is achieved by locating
a biasing means, such as a spring, under the cam 12 on tabs 14. As
will be clear by reference to FIG. 6, the spring locates between
the base 6 and the tabs 14 to bias the rotation of the spindle 4.
Adjustable stop 9 acts against the opposite side of the cam 12 to
stop the spindle 4 at the neutral position. The spring will be on
the right or left side as required for the position of the fin.
[0032] Turning now to FIG. 6, it can be seen that the base has as a
simple structure with a pair of seats 15 at each end to support the
spindle. It is conveniently made as a single moulded plastics
element. The cams 12 travel in the recess formed by seat pairs 15.
A spring boss 16 is formed in the base of the recess to seat the
spring. Thus the spring operates between the boss 16 in the base
and the tab 14 on the cam to bias the spindle towards the neutral
position.
[0033] The cover 7 is shown in more detail in FIG. 7. It is
suitable formed as a moulded plastics element, like the base 6. A
hole 17 is formed in the cover to allow passage of the fin. Flanges
18, at each end of the hole 17, act to restrain the spindle between
the cover 7 and the base 6.
[0034] The adjusting fin has a number of advantages over the prior
art fins. Firstly, the fin is self-adjusting by the pressure of
water acting on the fin as the craft passes through the water.
Secondly, the adjustable stops allow the rider to easily limit the
range of pivot and therefore trim the craft for prevailing
conditions and individual skill. Thirdly, the fin can be actively
biased towards the neutral position.
[0035] The invention is particularly advantageous for a
professional surfer who currently requires a number of boards to
suit different conditions. It is possible with the invention to
have a single board that can be reconfigured in moments. The surfer
is not only able to adjust the fins, but is able to change the fin
as desired. This can lead to a significant reduction in the number
of boards required by a professional surfer.
[0036] The invention also offers significant advantage in surfboard
manufacture. At present, a precision jig is required to manufacture
a double or triple fin board with the side fins having a set pitch.
With the invention the fin box can be positioned accurately with
the adjustment of the fins occurring later. There is no need for a
precision jig to set the angle of the fins during glassing of the
board.
[0037] The invention has been described with reference to preferred
and alternate embodiments. Obviously, modifications and alterations
will occur to others upon the reading and understanding of the
specification. It is intended to include all such modifications and
alterations insofar as they come within the scope of the appended
claims or the equivalents thereof.
* * * * *