U.S. patent application number 15/921535 was filed with the patent office on 2018-09-20 for fins with improved fluid dynamic properties.
This patent application is currently assigned to Flying Fin Systems PTY LTD. The applicant listed for this patent is Flying Fin Systems PTY LTD. Invention is credited to Glenndin George MILLER.
Application Number | 20180265174 15/921535 |
Document ID | / |
Family ID | 63520957 |
Filed Date | 2018-09-20 |
United States Patent
Application |
20180265174 |
Kind Code |
A1 |
MILLER; Glenndin George |
September 20, 2018 |
FINS WITH IMPROVED FLUID DYNAMIC PROPERTIES
Abstract
A fin for use on a surfboard, the fin comprising: a leading
edge, a trailing edge, and a base, the base comprising at least one
mount for mounting the fin onto a surfboard; a first and a second
outer fin surface which meet along the leading edge and the
trailing edge and abut the base; and a first ridge protruding
laterally from the first outer fin surface, and/or a second ridge
protruding laterally from the second outer fin surface; wherein the
shape and configuration of the fin creates an area of lower water
pressure around and in front of the fin, as well as disrupting
and/or reducing the size of trailing vortices, resulting in
additional forward thrust for the board on which the fin is
mounted.
Inventors: |
MILLER; Glenndin George;
(Margaret River, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Flying Fin Systems PTY LTD |
Margaret River |
|
AU |
|
|
Assignee: |
Flying Fin Systems PTY LTD
Margaret River
AU
|
Family ID: |
63520957 |
Appl. No.: |
15/921535 |
Filed: |
March 14, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62471299 |
Mar 14, 2017 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B63B 32/60 20200201;
B63B 32/66 20200201 |
International
Class: |
B63B 35/79 20060101
B63B035/79 |
Claims
1. A fin for use on a surfboard, the fin comprising: a leading
edge, a trailing edge, and a base, the base comprising at least one
mount for mounting the fin onto a surfboard; a first and a second
outer fin surface which meet along the leading edge and the
trailing edge and abut the base; and a first ridge protruding
laterally from the first outer fin surface, and/or a second ridge
protruding laterally from the second outer fin surface.
2. A fin according to claim 1, wherein the first ridge protrudes
laterally from the first outer fin surface, and/or the second ridge
protrudes laterally from the second outer fin surface, to a maximum
distance from the centreplane of between 1.5 to 6 times greater
than the maximum distance of the centreplane to a non-ridged
portion of the first outer fin surface, wherein the centreplane
passes through the leading edge and trailing edge of the fin.
3. A fin according to claim 1, wherein the first ridge protrudes
laterally from the first outer fin surface, and/or the second ridge
protrudes laterally from the second outer fin surface, to a maximum
distance from the centreplane of between 3 to 3.5 times greater
than the maximum distance of the centreplane to a non-ridged
portion of the first outer fin surface, wherein the centreplane
passes through the leading edge and trailing edge of the fin.
4. A fin according to claim 1, wherein the first ridge and/or the
second ridge are located adjacent the base.
5. A fin according to claim 1, wherein the first ridge and the
second ridge are located equidistant from the base.
6. A fin according to claim 1, wherein the first ridge comprises a
first ridgeline, and/or the second ridge comprises a second
ridgeline, and the first and second ridgelines are on a plane
substantially parallel to the base and/or the adjacent bottom
surface of the surfboard to which the fin is mounted.
7. A fin according to any claim 6, wherein the distance of the
first ridgeline and/or the second ridgeline to the base is
preferably between approximately 1% and 30% of the distance of the
base to the tip of the fin.
8. A fin according to claim 6, wherein the distance of the first
ridgeline and/or the second ridgeline to the base is preferably
between approximately 4% and 8% of the distance of the base to the
tip of the fin.
9. A fin according to claim 1, wherein the first ridge comprises
first ridge sides, and/or the second ridge comprises second ridge
sides, and at least a portion of the first ridge sides and/or
second ridge sides comprise concave, convex, and/or flat
portions.
10. A fin according to claim 6, wherein the first ridgeline and/or
second ridgeline end at the leading and/or trailing edge.
11. A fin according to claim 1, wherein the fin comprises a third
ridge protruding laterally from the first outer fin surface, and/or
a fourth ridge protruding laterally from the second outer fin
surface.
12. A fin according to claim 11, wherein the third ridge and/or the
fourth ridge are smaller and located further from the base than the
first ridge and/or the second ridge.
13. A fin according to claim 11, wherein the third and/or fourth
ridges are on a plane that is substantially parallel to the base,
and/or a plane that is substantially parallel to the adjacent
bottom surface of the surfboard.
14. A fin according to claim 11, wherein the third ridge protrudes
laterally from the first outer fin surface, and/or the fourth ridge
protrudes laterally from the second outer fin surface, to a maximum
distance from the centreplane of between 1.5 to 6 times greater
than the maximum distance of the centreplane to a non-ridged
portion of the first outer fin surface, wherein the centreplane
passes through the leading edge and trailing edge of the fin.
15. A fin according to claim 11, wherein the third ridge protrudes
laterally from the first outer fin surface, and/or the fourth ridge
protrudes laterally from the second outer fin surface, to a maximum
distance from the centreplane of between 3 to 4 times greater than
the maximum distance of the centreplane to a non-ridged portion of
the first outer fin surface, wherein the centreplane passes through
the leading edge and trailing edge of the fin.
16. A fin according to claim 11, wherein the third ridge comprises
third ridge sides, and the fourth ridge comprises fourth ridge
sides, and at least a portion of the third ridge sides and/or
fourth ridge sides comprise concave, convex, and/or flat
portions.
17. A fin according to claim 1, wherein the fin is an adjustable
fin comprising: a base comprising: a mount for attaching the fin to
a surfboard; and an insert member extending in a direction contrary
to the mount; a fin section comprising: two outer fin surfaces
which meet at a leading edge and a trailing edge comprising the
first and the second outer fin surfaces; an underside surface
comprising an opening to an internal cavity within the fin section,
the internal cavity within the fin section configured to house the
insert member of the base and enable slidable movement of the
insert member in a direction towards the leading edge or the
trailing edge; and a lock that is manipulable, wherein the lock can
releasably couple to the insert member at one of two or more
locking positions thereby preventing slidable movement of the
insert member; wherein the fin section is configured to adjust
relative to the base by manipulating the lock to uncouple the lock
from the insert member at a first locking position, slidably moving
the insert member through the internal cavity, and releasably
coupling the lock to the insert member at a second locking
position.
18. A fin according to claim 1, wherein the fin is a detachable fin
comprising: a base comprising: a mount for attaching the fin to a
surfboard; and an insert member extending in a direction contrary
to the mount; a fin section comprising: two outer fin surfaces
which meet at a leading edge and a trailing edge comprising the
first and the second outer fin surfaces; an underside surface
comprising an opening to an internal cavity within the fin section,
the internal cavity within the fin section configured to house the
insert member of the base; and a lock that is manipulable, wherein
the lock can releasably couple to the insert member thereby
preventing movement of the fin section relative to the base;
wherein the fin section is uncoupled and detached from the base by
manipulating the lock to uncouple the lock from the insert
member.
19. A fin according to claim 1, wherein the mount comprises one or
more mounting blocks capable of attaching to commercially available
fin plug and fin box systems, or a base attachment plate comprising
a substantially flat base attachment surface which contacts the
external bottom surface of a surfboard on to which it is
mounted.
20. A fin according to claim 1, for mounting to any one of the
boards in the group comprising: surfboard, shortboard, kneeboard,
longboard, minimal, soft board, kiteboard, wind surfer, stand up
paddleboard, wakeboard, rescue board, bodyboard, or another board
used in surface water sports or activities.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 62/471,299, filed Mar. 14, 2017. The contents of
the above patent application is incorporated by reference herein in
its entirety.
TECHNICAL FIELD
[0002] The present invention relates to the shape and configuration
of a fin, keel, propeller, rudder, or plane on a vessel travelling
on or under the water which can create an area of lower pressure
around, and in front of it, as well as disrupt and/or reduce the
size of trailing vortices resulting in additional forward
thrust.
BACKGROUND ART
[0003] The following discussion of the background art is intended
to facilitate an understanding of the present invention only. The
discussion is not an acknowledgement or admission that any of the
material referred to is or was part of the common general knowledge
as at the priority date of the application.
[0004] A surfboard, stand-up paddleboard (SUP), or similar type of
board for use in water sports and other activities can be viewed in
one sense as a summation of hydrodynamic surfaces. The surface of
the bottom of the board in contact with water generates lift and
affects speed. More importantly though, it is the fins working in
collaboration with rail and bottom contour that most influence the
feel of the board when changing direction. Since the form shape of
surfboards including the rails and bottom surface has undergone
finer and finer adjustments over the past few decades, the largest
gains that can still be made to a board's performance is in fin
modification.
[0005] Predominant factors that influence the effect of the fins
include (i) foil shape, and the curve from leading to trailing edge
as it changes from base to tip; (ii) template shape, which is the
combination of depth, width, and rake that make up the profile of
the fin; (iii) stability and flex, which can depend on the
materials from which a fin is made; and (iv) fin placement, which
comprises tow and camber of the fins, the distance between the
fins, and the distance of the fins from the rear of the board.
[0006] Foils comprise surfaces which affect lift and drag. Where
one surface of a foil is curved and the other, predominantly flat
(a `flat foil`), it takes less effort (drag) for liquid to flow
past the flat surface as the path of least resistance than the
curved surface. As a result, more water will flow past the flat
surface of the foil creating an area of high pressure. Conversely,
an area of low pressure is created adjacent to the curved surface
of the foil. This difference in pressure creates lift towards the
curved side of the foil. The more curve a foil has, the more drag
it induces over the curved surface which means that a foil with
greater curvature will have more lift at lower speeds. The problem
is at higher speeds that additional drag will develop turbulence
and stall the flow across the foil. Side fins on a surfboard are
usually flat foils which are oriented with the flat face of the
foil facing towards the centre or stringer of the board. The
resulting pressure differential assists to pull the board fins and
rail of the surfboard down into the water. Therefore, thicker, more
curved foils are preferred by surfers for slow waves, and flatter,
finer foils for faster waves.
[0007] Template shape affects stability and control. As an example,
fins that are deeper, with a wider base and more rake provide
greater stability and control as a result of a relatively large
surface area. However, more surface area causes greater drag and
slows a board down. As a generalisation known amongst surfers, fins
with a greater surface area are more preferred for steep and heavy
waves, choppy and irregular conditions, for heavier surfers, and/or
surfers with a flowing style. Alternatively, fins with less surface
area are more preferred for sloped, clean and glassy waves, for
lighter surfers, and/or surfers that exercise extreme and radical
manoeuvres.
[0008] The flex of a surfboard fin can affect stability in turns.
For example, a flexible tip on a fin can dampen or smooth out some
of the bite when a surfer changes direction on a surf board. But a
stable fin base is crucial to prevent or minimise turbulence which
can generate drag and disturb the lift causing loss of fin control,
making the board slow and out of control. Less flex can make turns
more off a pivot.
[0009] `Toe` can be considered in terms of the angle the base of
the side fins are pointed in towards the centre of the board
relative to the leading edge and trailing edge at the base. `Cant`
can be considered in terms of the angle the body of a fin is set at
relative to the bottom surface of the board in a plane
perpendicular to the direction of the stringer. Both toe and cant
affect the `angle of attack` of fin foils in their movement through
the water. A greater angle forces more water flow around the
outside curved surface of the foil at lower speeds making it easier
to initiate turns on slower waves. However, too much angle at
higher speeds increases turbulence and drag slowing down the
board.
[0010] Thus, there is a compromise between pursuing the balance and
stability such fins, keels, rudders, planes (on a submarine or
other vessel), or similar extensions are required to provide,
whilst benefiting from any potential forward thrust if possible,
but at the same time minimising drag forces as the trade-off for
having such an extension travelling through the water off the
vessel.
SUMMARY OF THE INVENTION
[0011] In a first aspect, the invention provides a fin for use on a
surfboard, the fin comprising:
[0012] a leading edge, a trailing edge, and a base, the base
comprising at least one mount for mounting the fin onto a
surfboard;
[0013] a first outer fin surface and a second outer fin surface
which meet along the leading edge and the trailing edge and abut
the base;
[0014] a first ridge protruding laterally from the first outer fin
surface, and a second ridge protruding laterally from the second
outer fin surface.
[0015] In a preferred embodiment, the first ridge and/or second
ridge protrude from the first outer fin surface and second outer
fin surface, respectively, on a plane that is substantially
parallel to the base. When the fin is mounted onto a surfboard, the
first ridge and/or second ridge protrude from the first outer fin
surface and second outer fin surface, respectively, on a plane that
is preferably substantially parallel to the adjacent bottom surface
of the surfboard.
[0016] In a preferred embodiment, first ridge sides form out of the
first outer fin surface either side of the first ridge, and second
ridge sides form out of the second outer fin surface either side of
the second ridge.
[0017] The first ridge is preferably on a plane substantially at
right-angles to the centreplane of the fin, wherein the centreplane
of the fin comprises a plane that passes through the leading edge
and trailing edge of the fin.
[0018] The second ridge is preferably on a plane substantially at
right-angles to the centreplane of the fin, wherein the centreplane
of the fin comprises a plane that passes through the leading edge
and trailing edge of the fin.
[0019] At the crest of the first ridge is preferably a first
ridgeline, and at the crest of the second ridge is preferably a
second ridgeline.
[0020] The first ridgeline is preferably on a plane substantially
at right-angles to the centreplane of the fin, wherein the
centreplane of the fin comprises a plane that passes through the
leading edge and trailing edge of the fin.
[0021] The second ridgeline is preferably on a plane substantially
at right-angles to the centreplane of the fin, wherein the
centreplane of the fin comprises a plane that passes through the
leading edge and trailing edge of the fin.
[0022] The first ridgeline and second ridgeline are preferably on a
plane substantially parallel to the base and/or the adjacent bottom
surface of the surfboard to which the fin is mounted. The first
ridgeline and/or the second ridgeline preferably comprises a curve,
at least adjacent the leading edge and trailing edge.
[0023] The first ridge preferably protrudes laterally from the
first outer fin surface to a maximum distance from the centreplane
of between 4 mm and 50 mm, wherein the centreplane of the fin
comprises a plane that passes through the leading edge and trailing
edge of the fin. More preferably, the first ridge preferably
protrudes laterally from the first outer fin surface to a maximum
distance from the centreplane of between 6 mm and 20 mm, even more
preferably, between 8 mm and 12 mm. The second ridge preferably
protrudes laterally from the second outer fin surface to a maximum
distance from the centreplane of between 4 mm and 50 mm, wherein
the centreplane of the fin comprises a plane that passes through
the leading edge and trailing edge of the fin. More preferably, the
second ridge preferably protrudes laterally from the second outer
fin surface to a maximum distance from the centreplane of between 6
mm and 20 mm, even more preferably, between 8 mm and 12 mm.
[0024] The first ridge side and/or second ridge side, or at least a
portion of the first ridge side and/or second ridge side, are
substantially flat in one embodiment. In another embodiment, the
first ridge side and/or second ridge side, or at least a portion of
the first ridge side and/or second ridge side, comprise a curve.
Where they comprise a curve, preferably, the first ridge side
and/or second ridge side, or at least a portion of the first ridge
side and/or second ridge side, are concave. Alternatively or in
addition, where they comprise a curve, preferably, the first ridge
side and/or second ridge side, or at least a portion of the first
ridge side and/or second ridge side, are convex. A ridge side on
one side of the first ridgeline or second ridgeline may comprise a
different shape to the ridge side on the other side of the
ridgeline. For example, amongst others, a ridge side on one side of
a ridgeline on the fin of the invention may comprise a concave
portion, while the ridge side on the other side of the ridgeline
may comprise a flat or convex portion, amongst the multitude of
possible combinations.
[0025] In a preferred embodiment, the first ridge and/or the second
ridge are located adjacent or close to the base. Therefore, when
the fin according to the invention is mounted to the bottom surface
of a surfboard, the first ridge and/or the second ridge, and
adjacent ridge sides will be located close to the surface of the
surfboard. Preferably, the first ridge and/or the second ridge are
located within 40 mm of the base. More preferably, the first ridge
and/or the second ridge are located within 25 mm of the base. In a
further embodiment, the first ridge and/or the second ridge are
located within 10 mm of the base, wherein measurement from the base
is from where the mount meets the outer fin surfaces.
[0026] The first ridgeline and/or the second ridgeline are
preferably located within 30 mm of the base. More preferably, the
first ridgeline and/or the second ridgeline are located within 20
mm of the base. Even more preferably, the first ridgeline and/or
the second ridgeline are located within 10 mm of the base, wherein
measurement from the base is from where the mount meets the outer
fin surfaces.
[0027] The first ridge and second ridge are preferably located
approximately the same distance (equidistant) from the base, or
located approximately the same distance (equidistant) from the tip
of the fin, wherein the tip is at the top of the fin at the
opposite end to the base where the leading and trailing edges
meet.
[0028] The length of the first ridge and the second ridge is
preferably most or all of the length between the leading edge and
the trailing edge of the fin. Alternatively, the length of the
first ridge and the second ridge is preferably less than the length
between the leading edge and the trailing edge of the fin. That is,
each ridge preferably comprises a front end adjacent to the leading
edge of the fin, and a rear end adjacent to the trailing edge.
[0029] The first ridgeline and/or the second ridgeline may comprise
a sharp edge, or may comprise a rounded edge, a squared edge or
another shape, or a combination of both a sharp and rounded ridge
edge or another shape, along the length of the ridgelines.
[0030] In a preferred embodiment of the fin of the invention, the
fin comprises a third ridge protruding laterally from the first
outer fin surface, and a fourth ridge protruding laterally from the
second outer fin surface. The third ridge and fourth ridge are
preferably smaller than the first ridge and second ridge. The third
ridge and fourth ridge are preferably located approximately the
same distance (equidistant) from the base, and the third ridge and
fourth ridge are preferably the same size, shape and
configuration.
[0031] At the crest of the third ridge is preferably a third
ridgeline, and at the crest of the fourth ridge is preferably a
fourth ridgeline. The third and fourth ridgelines are preferably
substantially parallel to the base and/or the adjacent bottom
surface of the surfboard to which the fin is mounted. The third
ridgeline and/or the fourth ridgeline preferably comprises a curve,
at least at one or both ends of the ridgeline.
[0032] The third ridge and fourth ridge are preferably
substantially parallel to the base and/or the adjacent bottom
surface of the surfboard to which the fin is mounted, or the third
ridge and fourth ridge may have a slight acute angle of attack
towards the base. That is, the end of the third ridge and fourth
ridge that is closest to the leading edge may be closer in distance
to the base than the end of the third ridge and fourth ridge that
is closest to the trailing edge. The `angle of attack` of the third
and/or fourth ridge of the fin (or keel, or plane or other
extension from a vessel) towards the base is preferably between
1.degree. and 5.degree., more preferably between 2.degree. and
3.degree..
[0033] Third ridge sides preferably form out of the first outer fin
surface either side of the third ridge, and fourth ridge sides form
out of the second outer fin surface either side of the fourth
ridge.
[0034] The third ridge preferably protrudes laterally from the
first outer fin surface by between 2 mm and 40 mm, more preferably,
by between 5 mm and 20 mm, even more preferably by between
approximately 8 to 12 mm, from the centreplane. The second ridge
preferably protrudes laterally from the second outer fin surface by
between 2 mm and 40 mm, more preferably, by between 5 mm and 20 mm,
even more preferably by between approximately 8 to 12 mm, from the
centreplane.
[0035] The third ridge sides and/or fourth ridge sides or at least
a portion of the third ridge sides and/or fourth ridge sides are
flat in one embodiment. In another embodiment, the third ridge
sides and/or fourth ridge sides or at least a portion of the third
ridge sides and/or fourth ridge sides comprise a curve. Where they
comprise a curve, preferably, the ridge sides or a portion of the
ridge sides are concave. Alternatively, or in addition, where they
comprise a curve, preferably, the ridge sides or a portion of the
ridge sides are convex. A ridge side on one side of a ridgeline on
the fin of the invention may comprise a different shape to the
ridge side on the other side of the ridgeline. For example, amongst
others, a ridge side on one side of the third or fourth ridgeline
on the fin of the invention may comprise a concave portion, while
the ridge side on the other side of the ridgeline may comprise a
flat or convex portion, amongst the multitude of possible
combinations.
[0036] The third ridge is preferably smaller and located further
from the base than the first ridge on the first outer fin surface.
The fourth ridge is preferably smaller and located further from the
base than the second ridge on the second outer fin surface.
[0037] The maximum thickness (from a front view) of the fin (or
keel, or plane or other extension from a vessel) from the first
ridge to the second ridge, and/or from the first ridgeline to the
second ridgeline, is preferably between approximately 1.5 to 6
times, more preferably between approximately 2 to 4.5 times, even
more preferably, approximately 3 to 3.5 times, thicker than the
maximum thickness of the non-ridged portion of the fin (or keel, or
plane or other extension from a vessel).
[0038] In a preferred embodiment of the fin (or keel, or plane or
other extension from a vessel) according to the invention, the
first ridge protrudes laterally from the first outer fin surface,
and/or the second ridge protrudes laterally from the second outer
fin surface, to a maximum distance from the centreplane of between
1.5 to 6 times, more preferably between approximately 2 to 4.5
times, even more preferably, approximately 3 to 3.5 times, greater
than the maximum distance of the centreplane to a non-ridged
portion of the first outer fin surface, wherein the centreplane
passes through the leading edge and trailing edge of the fin. A
non-ridged portion of the first outer fin surface is a portion of
the fin that does not comprise any lateral or other protrusion from
the outer fin surface.
[0039] The distance of the first ridgeline to the base, and/or
second ridgeline to the base, is preferably between approximately
1% and 30%, more preferably between approximately 2% and 15%, even
more preferably between approximately 4% to 8%, of the distance of
the base to the tip of the fin (or keel, or plane or other
extension from a vessel).
[0040] The maximum thickness (from a front view) of the fin (or
keel, or plane or other extension from a vessel) from the third
ridge to the fourth ridge, and/or from the third ridgeline to the
fourth ridgeline, is preferably between approximately 1 to 6 times,
more preferably between approximately 2 to 5 times, even more
preferably between approximately 3 to 4 times, thicker than the
maximum thickness of the non-ridged portion of the fin (or keel, or
plane or other extension from a vessel).
[0041] In a preferred embodiment of the fin (or keel, or plane or
other extension from a vessel) according to the invention, the
third ridge protrudes laterally from the first outer fin surface,
and/or the fourth ridge protrudes laterally from the second outer
fin surface, to a maximum distance from the centreplane of between
1.5 to 6 times, more preferably between 2 to 5 times, even more
preferably, between 3 to 4 times, greater than the maximum distance
of the centreplane to a non-ridged portion of the first outer fin
surface, wherein the centreplane passes through the leading edge
and trailing edge of the fin.
[0042] The distance between the third ridge and/or fourth ridge to
the base (where the fin meets the mount) is preferably between
approximately 2% to 30%, more preferably between approximately 5%
to 25%, even more preferably between approximately 12% to 18%, of
the distance of the base to the tip of the fin.
[0043] The third and/or fourth ridge preferably starts
approximately one third of the distance of the total fin behind the
front of the fin (or keel, or plane or other extension from a
vessel). The third and/or fourth ridge preferably ends
approximately one third of the distance of the total fin from the
end of the fin (or keel, or plane or other extension from a
vessel).
[0044] The shape of the third and/or fourth ridge of the fin (or
keel, or plane or other extension from a vessel) is preferably a
substantially a flat foil with a flat upper surface facing away
from the base. The maximum height of the third and/or fourth ridge
is preferably approximately 1 mm to 20 mm, more preferably 3 mm to
10 mm, even more preferably, between approximately 4 mm to 6
mm.
[0045] The portion of the height of the outer fin surfaces of the
fin (or keel, or plane or other extension from a vessel) comprising
ridges is preferably approximately 10% to 40%, more preferably 20%
to 30%, even more preferably 23% to 28% of the total height of the
fin from base to tip.
[0046] The fin according to the invention may comprise one or more
additional ridges protruding from the first and/or the second outer
fin surfaces, similar in shape, size, and configuration to those
ridges described herein, or different in size, shape, and
configuration.
[0047] The first and a second outer fin surfaces which meet along
the leading edge and the trailing edge and abut the base comprise
the ridges described herein preferably protruding from an otherwise
predominantly smooth curved surface common to known surfboard fins.
Alternatively, the first and/or second outer fin surfaces may not
be predominantly smooth curved surfaces but may contain other
features, shapes and edges. In some non-limiting examples, the
first and/or second outer fin surfaces may comprise flat surfaces
at different planes abutting each other along various straight
and/or curved edges located between the leading edge and trailing
edge; or the first and/or second outer fin surfaces may comprise
deformities, organised in a pattern or irregular such as dimples or
bumps.
[0048] Side Fins
[0049] The fin according to the invention as described above is
preferably symmetrical along its centreplane, the centreplane
comprising a plane that passes through the leading edge and
trailing edge, and the fin can be used as a centre fin on a
surfboard or other watercraft in line with the centre stringer or
centreline of the surfboard. That is, the one or more ridges are
the same or substantially identical in shape, size and
configuration on the first outer in surface to the one or more
ridges on the second outer fin surface.
[0050] The fin according to the invention for use as a side fin in,
for example, a dual fin, thruster, or quad fin arrangement, amongst
other arrangements, may comprise: [0051] (i) the same symmetrical
fin as described above; [0052] (ii) an unsymmetrical embodiment of
the fin described above on the same or on a different cant; or
[0053] (iii) a flat foil embodiment of the fin described above on
the same or on a different cant.
[0054] In an unsymmetrical embodiment of the fin described above, a
side fin according to the invention for use in a dual, thruster,
quad or other fin arrangement on a surfboard, is preferably
asymmetrical along its centreplane, the centreplane comprising a
flat plane that passes through the leading edge and trailing edge.
Preferably, the position, size and configuration of the first ridge
and second ridge is different and not symmetrical along the
centreplane of the fin. Preferably, the position, size and
configuration of the third and fourth ridges is different and not
symmetrical along the centreplane of the fin.
[0055] In a flat foil embodiment of the fin according to the
invention comprises only a first ridge and/or a third ridge, as
described above, protruding laterally from the first outer fin
surface. This is to suit, for example, the side fins in a three-fin
`thruster` arrangement which comprise flat foils having one
substantially flat outer fin surface facing the centre stringer or
centreline of the surfboard.
[0056] For the purposes of describing the invention, the first
outer fin surface is the right or starboard side of a fin
positioned on the right or starboard side of a surfboard, meaning
the other port side, comprising a flat outer fin surface, will face
towards the centre stringer or centreline of the surfboard.
Alternatively, the first outer fin surface is the left or port side
of a fin positioned on the left or port side of a surfboard,
meaning the other starboard side, comprising a flat outer fin
surface, will face towards the centre stringer or centreline of the
surfboard.
[0057] The benefit of side fins comprising a flat foil
configuration are well known in the art and the two flat foils
either side of a symmetrical fin are commonly referred to as a
`thruster` arrangement. That is because standard side flat foil
fins provide `lift` or thrust' in a direction perpendicular to the
non-flat (curved) side of the fin according to Bernoulli's law.
Thus, these side fins are usually positioned with a `toe` of a few
degrees inwards towards the centre of the board so that the
resulting lift will be directed slightly forward (if the toe is too
high, the lift is cancelled out by greater drag of the angled fin
facing the direction of the water) adding a small amount of forward
thrust to the surfboard as it is ridden on the surface of a
wave.
Detachable and Adjustable Fin
[0058] The fin according to the invention may be a non-adjustable
(fixed') fin or may comprise a detachable and/or adjustable fin.
The detachable and/or adjustable fin comprises at least a base
portion and a fin section, wherein the base portion comprises the
mount. The fin section can be removed or uncoupled from the base
portion, or reattached or coupled to the base portion. The
adjustable fin enables adjustment of the position of the fin
section relative to the base portion in a direction towards the
leading edge or trailing edge, or in another manner.
[0059] In an embodiment of the invention, the fin is an adjustable
fin comprising:
a base portion comprising: [0060] a mount for attaching the fin to
a surfboard; and [0061] an insert member extending in a direction
contrary to the mount; a fin section comprising: [0062] two outer
fin surfaces which meet at a leading edge and a trailing edge
comprising the first and the second outer fin surfaces; [0063] a
first ridge protruding laterally from the first outer fin surface,
and/or a second ridge protruding laterally from the second outer
fin surface; [0064] an underside surface comprising an opening to
an internal cavity within the fin section, the internal cavity
within the fin section configured to house the insert member of the
base portion and enable slidable movement of the insert member in a
direction towards the leading edge or the trailing edge; and [0065]
a lock that is manipulable, wherein the lock can releasably couple
to the insert member at one of two or more locking positions
thereby preventing slidable movement of the insert member; wherein
the fin section is configured to adjust relative to the base
portion by manipulating the lock to uncouple the lock from the
insert member at a first locking position, slidably moving the
insert member through the internal cavity, and releasably coupling
the lock to the insert member at a second locking position.
[0066] In an embodiment of the invention, the fin is a detachable
fin comprising:
[0067] a base portion comprising: [0068] a mount for attaching the
fin to a surfboard; and [0069] an insert member extending in a
direction contrary to the mount;
[0070] a fin section comprising: [0071] two outer fin surfaces
which meet at a leading edge and a trailing edge comprising the
first and the second outer fin surfaces; [0072] a first ridge
protruding laterally from the first outer fin surface, and/or a
second ridge protruding laterally from the second outer fin
surface; [0073] an underside surface comprising an opening to an
internal cavity within the fin section, the internal cavity within
the fin section configured to house the insert member of the base
portion; and [0074] a lock that is manipulable, wherein the lock
can releasably couple to the insert member thereby preventing
movement of the fin section relative to the base portion; wherein
the fin section is uncoupled from the base portion by manipulating
the lock to uncouple the lock from the insert member, and the fin
section is coupled to the base portion by manipulating the lock to
couple the lock to the insert member.
[0075] Preferably the lock projects into the internal cavity. More
preferably, the lock is manipulated from an outer fin surface. The
lock can preferably be manipulated from the first and/or second
outer fin surface. More preferably, the third and/or fourth ridge
incorporates the lock. The lock preferably comprises at least one
knob accessible for a user at the first and/or second outer fin
surface for manipulating the lock, and turning the knob uncouples
or recouples the lock from the insert member. The knob can
preferably be finger turned by a user, for example, while in the
water and without the requirement of any tools. More preferably,
the knob is located within the third and/or fourth ridge, and the
knob has an exterior surface, and a portion of the exterior surface
of the knob lies flush with the third and/or fourth ridge and ridge
sides of the third and/or fourth ridge when the lock is coupled to
the insert member.
[0076] The insert member is preferably substantially planar. The
insert member preferably comprises two or more teeth, and a valley
between two teeth forms a locking position. The two or more teeth
are preferably located at an end of the insert member. The two or
more teeth preferably point in a direction substantially contrary
to the mount.
[0077] The lock preferably comprises a locking portion which is
received at a locking position in a valley thereby coupling the
lock to the insert member, and turning the knob moves the locking
portion out of the valley and the locking position, thereby
uncoupling the lock from the insert member and enabling slidable
movement of the insert member through the internal cavity.
Following slidable movement of the insert member through the
internal cavity, re-turning the knob can preferably move the
locking portion into the same or a different valley and a locking
position, thereby recoupling the lock to the insert member.
[0078] A portion of the internal cavity and the insert member are
preferably configured to form a sliding joint which also couples
the fin section to the base portion. More preferably, the sliding
joint is a sliding dovetail joint.
Dual Fin
[0079] In a further embodiment of the fin according to the
invention, a second fin section is preferably attached to the fin
(or fin section of an adjustable and/or detachable fin) according
to the invention as described above by one or more attachment
means. Attachment means may, in some non-limiting examples,
comprise rods, plates, pins, bars, and/or be formed from a portion
of either the fin or the second fin section. More preferably, the
one or more attachment means comprise one or more ribs. The one or
more attachment means preferably preserve a minimum distance
between the fin and the second fin section of between approximately
0.25 mm and 5 mm. The one or more attachment means more preferably
preserve a minimum distance between the fin and the second fin
section of approximately 1 mm. The attachment means preferably
reduce or remove any fluttering effect on either the fin or second
fin section caused by water passing around and between the fin and
the second fin section.
[0080] The second fin section is preferably positioned
substantially parallel to the fin and offset such that the leading
edge of the second fin section is not aligned with the leading edge
of the fin. The second fin section preferably comprises a flat foil
having a substantially flat outer fin surface, and a curved outer
fin surface. In a preferred embodiment, the leading edge of the fin
is in a position forward of the leading edge of the second fin
section. Preferably, the leading edge of the fin is forward of the
leading edge of the second fin section by approximately 5 mm to 15
mm, and more preferably by approximately 10 mm.
[0081] The second fin section preferably comprises at least one
passage through which water can pass. The passage comprises an
opening on each outer fin surface of the second fin section through
which water can enter and exit. The passage preferably comprises an
opening on the substantially flat outer fin surface, and an opening
on the curved outer fin surface, and the opening on the curved
outer fin surface is located between the trailing edge of the
second fin section and the minimum distance between the fin and the
second fin section. Preferably, the opening of the passage on the
substantially flat outer fin surface of the second fin section is
located closer to the leading edge of the second fin section than
the opening of the passage on the curved outer fin surface of the
second fin section, wherein water can enter the opening on the
substantially flat outer fin surface, pass through the passage, and
exit through the opening on the curved outer fin surface. A passage
through the second fin section and/or an opening is preferably not
round or another shape that would cause water passing through the
passage to form a vortex. The openings and passages may be created
from drilling or cutting holes or perforations through the second
fin section or from the shape of a mould used to make the fin.
[0082] A dual fin according to the invention is preferably mounted
in the position of a side fin on a surfboard wherein: [0083] the
second fin section comprises a flat foil having a substantially
flat outer fin surface facing the centre or stringer of the
surfboard, and a curved outer fin surface facing the adjacent rail
of the surfboard; [0084] the fin is in a position closer to the
adjacent rail of the surfboard than the second fin section; and
[0085] the leading edge of the fin is positioned closer to the
front of the board than the leading edge of the second fin
section.
[0086] In a preferred embodiment, the second fin section comprises
at least one passage comprising an opening on the substantially
flat outer fin surface, and an opening on the curved outer fin
surface of the second fin section through which water can pass.
When the dual fin of the invention is mounted to a surfboard which
is moving in a substantially forward direction through water during
normal use, the at least one passage in the second fin section is
preferably configured to: [0087] enable water to enter an opening
on the substantially flat outer fin surface of the second fin
section, pass through the passage, and exit through an opening on
the curved outer fin surface in a location between the trailing
edge of the second fin section and the position of the minimum
distance between the fin and the second fin section; and [0088]
substantially prevent water passing in the reverse direction
through the passage.
[0089] The openings preferably comprise holes or perforations on
the surface of the substantially flat and curved outer fin surfaces
of the second fin section through which water can enter and exit,
respectively. Preferably, the opening on the substantially flat
outer fin surface of the second fin section is positioned closer to
the leading edge than the opening on the curved outer fin
surface.
[0090] The second fin section may be the same size, shape, and
configuration, or a different size, shape and configuration, to the
fin. The second fin section may have a different fin template to
the fin. Preferably, the size and template of the second fin
section is smaller than the fin and is positioned above the one or
more lateral ridges on the fin.
[0091] Two or more dual fins according to the invention may be
mounted to a surfboard.
[0092] Alternatively, a third fin section may be attached to a fin
according to the invention on the other outer fin surface not
attached to the second fin section. This fin comprising the second
and third fin sections may be symmetrical and be used as a centre
fin on a surfboard.
[0093] In another embodiment, two or more fins according to the
invention may be joined together.
Mount
[0094] The mount or `mounting means` for a fin of the invention as
herein described, may comprise a variety of means known for
mounting or attaching a fin to a surfboard or another board.
[0095] In a preferred embodiment of an adjustable fin of the
invention, the mount comprises one or more mounting blocks for
attaching to one or more surfboard fin plugs and/or fin boxes. The
one or more mounting blocks are preferably compatible with, and
capable of attaching to commercially available fin plug and/or fin
box systems. Preferably, the one or more mounting blocks can be
mounted to commercially available FCS.RTM. fin plugs and/or
Futures.RTM. fin boxes.
[0096] In another preferred embodiment, the mount comprises a base
attachment surface which is directly and fixedly secured to the
external bottom surface of the surfboard with adhesive and/or screw
type fasteners as described herein. The adhesive is preferably
Araldite.RTM., marine silicon, or another epoxy or non-latex
construction silicone adhesive that can maintain an adhesive
connection between a fin of the invention and a surfboard or
another board, particularly when exposed to water. The marine
silicon may provide up to, or greater than 600% elongation ability
thereby providing a bond between the fin of the invention and a
surfboard on to which it is mounted, which will unlikely break even
under the forces of a heavy surfer turning sharply and quickly on a
heavy wave. The base attachment surface preferably provides
recesses or cavities of a size sufficient to accommodate the
adhesive to provide such a bond between the surfboard and the
fin.
[0097] Preferably, one or more screws or screw type fasteners
secure a base attachment plate comprising at the base attachment
surface to the surfboard and preferably in combination with
adhesive. The one or more screws may be secured to the surfboard at
a variety of different positions through the base attachment plate.
Preferably, the screws are placed at least in front of the leading
edge of the fin, behind the trailing edge, and adjacent to each
outer fin surface. The screws may be secured to the surfboard
through holes in the base attachment plate through which adhesive
is injected. The screws can preferably be turned with a hex or
Allen key and screw plugs, for example, plastic screw plugs, may be
pre-set in the surfboard into which the screws can be driven and
embedded to secure the base of the fin to the surfboard.
[0098] In another embodiment, the base attachment surface may be
`fiberglassed` onto the surfboard using traditional `glassing`
methods known in the art. For example, comprising placing `rovings`
around the outer edge or border of the base attachment surface.
Gap
[0099] A gap may be created between the base of the fin (or
underside surface of the base) and the surfboard onto which the fin
is mounted. In this respect, the fin according to the invention can
comprise one or more gaps between the base of the fin and the
surfboard onto which it is mounted. These gaps may vary in shape,
size, and height between surfboard and base, according to the
desired vortices to be created around the fin as water passes the
fin according to the invention.
[0100] The height of the gap between the base of the fin and the
external outer surface of the surfboard is preferably between
approximately 0.5 mm and 25 mm. The height of the gap is more
preferably between approximately 5 mm and 20 mm. The height of the
gap is more preferably approximately 15 mm. The height of the gap
for a surfboard fin or other type of fin, for example, a keel, is
preferably between 1% and 20%, more preferably between 2% and 10%,
even more preferably between 2.5% and 7.5%, of the total height of
the fin/keel, etc. from base to tip.
Safety
[0101] For the purpose of maintaining the safety of users of one or
more fins of the invention on a surfboard, the fin preferably
comprises a weak portion adjacent the base and mount or on the base
portion for the adjustable and/or detachable fin. The weak portion
comprises a portion of the fin that can more easily be broken than
the remaining portion of the fin. Under strong forces acting on a
fin of the invention, for example, heavy contact of: a reef, the
surfer, another surfer, another board, or rocks, amongst others,
the fin can break at the weak portion. The purpose of the breakage
is to reduce the potential damage to the person the fin comes into
contact with, or reduce or minimise damage to the board to which
the fin is mounted which can occur if a fin gets torn out of the
board due to catching on a reef or rock, as some non-limiting
examples.
[0102] A further safety feature is the overmolding of flexible
polymer over titanium alloy fin portions, when used, to prevent
sharp leading and tailing edges from being a danger to the surfer
or other nearby persons in the water.
Board Type
[0103] The fin of the invention as herein described, may be mounted
to any one of the boards in the group comprising: surfboard,
shortboard, kneeboard, longboard, minimal, soft board, kiteboard or
a board used for kite surfing, wind surfer, stand up paddleboard,
wakeboard, rescue board, bodyboard, or another board used in
surface water sports or activities. Reference herein to a
`surfboard` can also include reference to any one of these other
boards.
Fin Arrangement
[0104] More than one fin of the invention may be mounted to a
surfboard. For example, a thruster fin setup on a surfboard may
comprise up to three fins of the invention as described herein.
Alternatively, a single fin or a quad fin setup comprising fins of
the invention may be mounted on to a surfboard. In some
non-limiting examples, a fin arrangement may comprise: [0105] Three
fins according to the invention in a three-fin `thruster`
arrangement; [0106] Two non-adjustable (fixed) side fins according
to the invention, and an adjustable version of a centre fin
according to the invention, in a three-fin `thruster` arrangement;
[0107] Two adjustable or non-adjustable (fixed) side fins according
to the invention and a standard centre fin in a three-fin
`thruster` arrangement; [0108] Two standard side fins and an
adjustable version of a centre fin according to the invention in a
three-fin `thruster` arrangement; or [0109] An adjustable or
non-adjustable (fixed) centre fin according to the invention with
no side fins in a `single fin` arrangement; [0110] amongst many
other such possible fin arrangements.
[0111] Various combinations are therefore possible for using fins
of the invention as described herein, exclusively, or in
combination with existing standard fins or other types of fins on a
surfboard.
[0112] The overall side template profile of a fin according to the
invention will preferably resemble a standard surfboard fin shape
as known in the art.
Process for Mounting a Fin of the Invention
[0113] The present invention further provides a process of mounting
a fin of the invention as herein described, to any one of the
boards in the group comprising: surfboard, shortboard, kneeboard,
longboard, minimal, soft board, kiteboard, wind surfer, stand up
paddleboard, wakeboard, rescue board, bodyboard, or another board
used in surface water sports or activities. The present invention
also provides a process of mounting a fin of the invention to a
surfboard by mounting the fin using a mount as described
herein.
Process for Manufacturing a Fin of the Invention
[0114] The present invention also provides a process of
manufacturing a fin according to the invention as described herein.
The fin of the invention is preferably constructed from common
materials known to be used to make surfboard fins including:
plastics, recycled plastics, carbon fibre, fiberglass, texalium,
glass epoxy laminate, Kevlar.TM. carbon, resin composite material,
polycarbonates, and/or from other materials described herein.
[0115] In one embodiment of the invention, a portion of, or the
entire fin is constructed from, or comprises, a metal or a metal
alloy. The metal is preferably strong, light weight, and incapable
of rusting or significant corrosion.
[0116] In a preferred embodiment, the metal is titanium.
Preferably, the metal is a titanium alloy. More preferably, the
titanium alloy comprises between approximately 3.5% to 4.5%
vanadium, and between approximately 5.5% to 6.75% aluminium. Evan
more preferably, the titanium alloy comprises approximately 4%
vanadium and approximately 6% aluminium. This titanium alloy can
provide beneficial flex characteristics for a surfboard fin
constructed wholly or almost wholly from this material. The
titanium alloy in the fin section preferably comprises holes or cut
outs of the same or various sizes which can further reduce the
weight of the fin and increase the flex characteristics of the fin.
The titanium or titanium alloy is preferably encased within a
flexible polymer overmold by the process of overmolding. The
overmolding may be molded to cover the shape of the titanium alloy
fin, or may form a larger portion of a fin which contains within it
a titanium alloy fin portion.
[0117] Use of the titanium alloy in the fin of the invention
enables a thinner fin to be constructed. Where a commercially
available shortboard fin may be 7 mm to 8 mm thick at its thickest
point on the fin section, the titanium alloy fin is preferably
between approximately 1.5 mm and 3 mm thick, and more preferably
between 2 mm and 2.5 mm thick, at its widest point (base and mount
excluded). With the overmolding over the titanium alloy, the fin is
preferably between approximately 2.5 mm and 4 mm thick, and more
preferably between 3 mm and 3.5 mm thick at its widest point.
[0118] In another embodiment, the whole fin, or a portion of the
fin comprises dust or flakes of: titanium, or titanium alloy
comprising approximately 4% vanadium and approximately 6%
aluminium.
[0119] Alternatively, the metal is aluminium. The fin may be formed
in one part or from two halves joined together or from more
components.
[0120] Similarly to the large number of different fins currently
available for mounting to a surfboard or another type of board
described herein, the upper portion of the fin according to the
invention above the ridges can comprise a variety of different:
shapes or templates or even cants; outer fin surface shapes or
features; sizes; types of foils; colours; materials from which the
fin section is constructed; rakes; depths; widths; cants; cut-outs;
and other designs and extensions including channels, `tunnels` and
`wings`, amongst others. In this regard, a user can select and
mount a fin of the invention to a board with attributes that is
desired by the user or suitable for the user's requirements and
appropriate for the board the fin or fins are mounted on.
Other Applications
[0121] The shape and configuration of the fin according to the
invention has benefits in disrupting vortices and increasing
forward thrust for surface watercraft including surfboard fins as
herein described. These benefits can also be advantageous for other
vessels that travel through water. Thus, this shape and
configuration is applicable for such extensions on these other
types of vessels including for the examples provided as
follows.
Keels
[0122] In a second aspect, keels on yachts, catamarans, and other
boats; hydrofoils on vessels including boats and surfboards, and
fins on kayaks and canoes, may comprise the shape and configuration
of one or more of the ridges described for the fin of the
invention. Similar to the surfboard fin, the configuration would
provide benefit from: creating a vortex due to the surfaces of (i)
the hull of the boat, (ii) the lower main ridge surface (adjacent
the hull), and (iii) the minor third and fourth ridges, working in
concert; therein creating a region of lower water pressure around
the keel and in front of the keel; and disruption and/or reduction
of the size of the trailing vortices behind the keel (and an area
of higher pressure to `push` against'); which lead to thrust
towards the area of lower pressure in front of the keel. The
result, is an overall increase in forward velocity for the boat or
other vessel when compared to a keel without the ridges described
herein. On a hydrofoil including a hydrofoil surfboard, the ridges
of the invention may be positioned, for example, amongst others, at
or adjacent the base of the hydrofoil to reduce drag in the region
where the hydrofoil meets the underwater wing at the opposite end
to the end of the hydrofoil connecting the surfboard.
Planes, Rudders, Ducts
[0123] Submarines, submersibles, (underwater) diver propulsion
vehicles, and similar underwater vessels comprise fins, planes,
rudders and ducts at various positions on the hull and/or conning
tower (where applicable) to assist stability as these vessels move
through water. These fins, planes, rudders, and ducts often have a
cross-section similar to a plane wing or comprise an elliptical or
flat (planar) cross-section. In this respect, these planes and
other extensions may comprise the shape and configuration of one or
more of the ridges described for the fin of the invention to:
provide the benefits from creating an area of lower pressure in
front of and at the planes and other extensions, while disrupting
trailing vortices immediately behind them, resulting in additional
thrust in a forward direction than when compared to the absence of
the ridges.
Propellers and Impellers
[0124] In a third aspect of the invention, propellers and impellers
may also comprise the shape and configuration of the ridges
described for the first or second aspects of the invention to
provide the benefits from creating an area of lower pressure in
front of and at the propellers and impellers, while disrupting
trailing vortices immediately behind them, resulting in additional
thrust in a forward direction than when compared to the absence of
the ridges.
BRIEF DESCRIPTION OF DRAWINGS
[0125] The present invention will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0126] FIG. 1. matching rendered and black and white illustrations
showing (A) a port (left) side view, (B) a starboard (right) side
view, (C) a front view, and (D) a rear view, of a preferred
embodiment of a fixed (non-adjustable) centre fin according to the
invention; the fins comprising mounting blocks which can be secured
within FCS.RTM. fin plugs.
[0127] FIG. 2. matching rendered and black and white illustrations
showing (A) bottom perspective view, (B) top perspective view, (C)
bottom view, and (D) top view, of the preferred embodiment of the
non-adjustable centre fin shown in FIG. 1.
[0128] FIG. 3. rendered illustrations showing (A) a perspective
view, and (B) a front view, of a preferred embodiment of a
three-fin thruster arrangement of non-adjustable fins according to
the invention; and matching rendered and black and white
illustrations showing (C) a starboard side view, and (D) a port
side view of the starboard side fin of the thruster arrangement of
(A) and (B), the fins comprising mounting blocks which can be
secured within FCS.RTM. fin plugs.
[0129] FIG. 4. illustrations of (A) a side view, (B) a front view,
and (C) a side view, of preferred embodiments of a non-adjustable
centre fin according to the invention with a mounting block which
can be secured within a Futures.RTM. fin box.
[0130] FIG. 5. matching rendered and black and white illustrations
showing (A) front view, (B) top perspective view, (C) port side
view, (D) top view, and (E) bottom view, of a preferred embodiment
of a non-adjustable centre fin according to the invention with a
base attachment surface for mounting the fin to the bottom surface
of a surfboard.
[0131] FIG. 6. illustrations showing a (A) front view, (B) a rear
view, (C) top view, (D) bottom view, (E) starboard side view, and
(F) port side view, of a non-adjustable port side fin (left side
fin) according of the invention for use in a dual, thruster or quad
arrangement, with mounting blocks that can be secured within
FCS.RTM. fin plugs.
[0132] FIG. 7. illustrations showing a (A) front view, (B) a rear
view, (C) top view, (D) bottom view, (E) right or starboard side
view, and (F) left or port side view, of a non-adjustable port side
fin according to the invention for use in a dual, thruster or quad
arrangement, with a mounting block that can be secured within a
Futures.RTM. fin box.
[0133] FIG. 8. illustrations showing a (A) front view, (B) a rear
view, (C) top view, (D) bottom view, (E) right or starboard side
view, and (F) left or port side view, of a non-adjustable port side
fin according to the invention for use in a dual, thruster or quad
arrangement, with mounting blocks that can be secured with a base
attachment surface for mounting the fin to the bottom surface of a
surfboard.
[0134] FIG. 9. (A) Graphical representation of a sectional
component of a conventional modem surfboard coupled with either the
Inventive fins (fins according to the invention) or Standard fins,
and showing the two geometries modelled; illustrations of: (B) the
simulation domains at the Waterline 1 for the fins modelled, and
(C) a front view of the geometry with inlet flow moving into the
paper (as denoted by crosses).
[0135] FIG. 10. Graphical representation of a mesh distribution on
the rear Inventive fin (15.7 million faces, such as those appeared
on the fin, are used in the simulation at Waterlevel 1). The
overall mesh cell thickness on the board is 0.4 mm and on the fin
is 0.06 mm, leading to y-H in the range of 30.about.100-300 to
allow wall function to be used.
[0136] FIG. 11. Secondary velocity vectors (Ux, Uz) comparison
between right (a) Inventive fins and (b) Standard fins (at 10 m/s).
(c) shows the position of the cutting plane through the lateral
fins.
[0137] FIG. 12. Secondary velocity vectors (Ux, Uz) comparison
between right (a) Inventive fins and (h) Standard fins (at 10 m/s).
(c) shows the position of the cutting plane aft of the lateral
fins.
[0138] FIG. 13. Secondary velocity vectors (Ux, Uz) comparison
between central Inventive fins and Standard fins (at 10 m/s). (c)
shows the position of the cutting plane through the aft central
fin.
[0139] FIG. 14. Flow field comparison showing lateral velocity Ux
[m/s] on a cut-plane located at the gap height under the lateral
Inventive fin immediately adjacent to the board surface.
[0140] FIG. 15. Streamlines generated besides the Inventive fins
and Standard fins (at 10 m/s) showing the formation of a
longitudinal wake vortex behind the lower ridge'.
[0141] FIG. 16. The comparison on the geometry of Inventive fin
(inner side fins) and the Standard fin (outer side fins), with
inlet flow moving out the paper (as denoted by dots), where `right`
fin is the starboard fin and `left` fin is the port fin in the
thruster arrangement.
[0142] FIG. 17. illustrations showing (A) a port side view, (B)
exploded port side view, (C) exploded front view, and (D) exploded
top perspective view, of an adjustable version of a preferred
embodiment of a fin according to the invention with a base
attachment surface for mounting the fin to the bottom surface of a
surfboard.
[0143] FIG. 18. is an illustration showing (A) a side view, (B) a
front view, (C) a perspective view, and (D) a bottom view, of a
further adjustable version of a preferred embodiment of a fin
according to the invention. Mount comprises mounting blocks which
attach to FCS.RTM. fin plugs.
[0144] FIG. 19. is an illustration showing (A) an exploded front
view, and (B) an exploded perspective view, of the embodiment shown
in FIG. 18.
[0145] FIG. 20. is an illustration showing (A) a side view, (B) a
front view, (C) a cross sectional front view, and (D) a bottom
view, of a further adjustable version of a preferred embodiment of
a fin according to the invention.
[0146] FIG. 21. is an illustration showing (A) an exploded front
view, (B) an exploded perspective view, and (C) an underside
perspective view (of the base) of the fin shown in FIG. 20.
[0147] FIG. 22. is an illustration showing (A) an exploded front
view, (B) a front view, (C) a cross sectional front view, (D) a
perspective view, and (E) an exploded perspective view, of a
further adjustable version of a preferred embodiment of a fin
according to the invention.
[0148] FIG. 23. is an illustration showing (A) a perspective view
(B) an exploded perspective view, and (C) a front view, of a
further adjustable version of a preferred embodiment of a fin
according to the invention; and (D) a front view, of a further
adjustable version of a preferred embodiment of a fin according to
the invention.
[0149] FIG. 24. is an illustration showing (A) an exploded side
perspective view, and (B) an exploded side perspective view, of the
bottom portion of the fin section of the embodiment shown in FIGS.
18 to 23.
[0150] FIG. 25. is an illustration showing (A) a front perspective
view, (B) a side view, and (C) a rear perspective view from above,
of a preferred embodiment of a propeller according to the
invention.
[0151] FIG. 26. is an illustration showing (A) a cross-sectional
front view, (B) a cross-sectional side view, and (C) a rear
perspective view from below, of a preferred embodiment of a
propeller according to the invention.
[0152] FIG. 27. is an illustration showing a portion of a front
view cross-section, of a preferred embodiment of a propeller
according to the invention.
[0153] FIG. 28. is an illustration showing a partial front view of
a boat comprising a keel according to a preferred embodiment of the
invention.
[0154] FIG. 29. is an illustration showing (A) a partial rear
perspective view of a boat comprising a keel according to a
preferred embodiment of the invention, and (B) a partial rear
perspective view of the keel.
[0155] FIG. 30. is an illustration showing (A) a partial front
view, and (B) a partial side view, of a boat comprising a keel
according to a preferred embodiment of the invention.
[0156] FIG. 31. is an illustration showing (A) a rear view, and (B)
a partial side perspective view, of a catamaran comprising keels
according to a preferred embodiment of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0157] Those skilled in the art will appreciate that the invention
described herein is susceptible to variations and modifications
other than those specifically described. It is to be understood
that the invention includes all such variations and modifications.
The invention also includes all of the steps, features,
compositions and compounds referred to or indicated in the
specification, individually or collectively and any and all
combinations or any two or more of the steps or features.
[0158] The present invention is not to be limited in scope by the
specific embodiments described herein, which are intended for the
purpose of exemplification only. Functionally equivalent products,
compositions and methods are clearly within the scope of the
invention as described herein.
[0159] Throughout this specification, unless the context requires
otherwise, the word "comprise", or variations such as "comprises"
or "comprising", will be understood to imply the inclusion of a
stated integer or group of integers but not the exclusion of any
other integer or group of integers.
[0160] Other definitions for selected terms used herein may be
found within the detailed description of the invention and apply
throughout. Unless otherwise defined, all other scientific and
technical terms used herein have the same meaning as commonly
understood to one of ordinary skill in the art to which the
invention belongs.
[0161] Features of the invention will now be discussed with
reference to the following preferred embodiments.
Surfboard Fins
[0162] A preferred embodiment of a fin according to the invention
is shown in a variety of views in FIG. 1 and FIG. 2. The fin can be
used as the centre fin of a three-fin thruster arrangement. This
embodiment is a fixed, and non-adjustable form of the fin of the
invention. The fin comprises a leading edge 602, a trailing edge
604, and a base 606, the base 606 comprising mounting blocks 608
which can be secured into FCS.RTM. plugs in a surfboard to mount
the fin onto a surfboard. The mounting blocks 608 comprises the
`mount` 609 (or `mounting means`).
[0163] The fin further comprises a first outer fin surface on the
`port` or `left` side of the fin (the port side outer fin surface
610), and a second outer fin surface on the `starboard` or `right`
side of the fin (the starboard side outer fin surface 612), when
considered from the rear or trailing edge 604 of the fin looking
towards the front or leading edge 602. The port side outer fin
surface 610 meets the starboard side outer fin surface 612 along
the leading edge 602 and the trailing edge 604. Both the port side
outer fin surface 610 and the starboard side outer fin surface 612
abut the base 606 by meeting along separate edges of the base 606
as shown in FIG. 2C.
[0164] Protruding laterally from the port side outer fin surface
610 adjacent the base 606 is a port side main ridge 614 (i.e. a
"first ridge") from leading edge 602 to trailing edge 604. This may
also be considered a port side main protrusion. Protruding
laterally from the starboard side outer fin surface 612 adjacent
the base 606 is a starboard side main ridge 616 (i.e. a "second
ridge") from leading edge 602 to trailing edge 604. This may also
be considered a starboard side main protrusion. The port side main
ridge 614 and starboard side main ridge 616 lie substantially
parallel to the base 606 and equidistant to the base 606. When the
fin is mounted to a surfboard with mounting blocks 608 secured in
FCS.RTM. plugs in the board, the port side main ridge 614 and
starboard side main ridge 616 also lie substantially parallel to
the bottom surface of the surfboard, at least at the location the
fin is mounted.
[0165] The port side main ridge 614 and starboard side main ridge
616 produce a kite or diamond shape when viewing the front of the
fin or through a cross-sectional front view. The kite or diamond
shape having a truncated base at the fin base 606, and an elongated
port side main ridge upper side 618 and starboard side main ridge
upper side 622.
[0166] The main ridges in the fin of the invention do not comprise
sections of a standard fin attached or protruding from either or
both sides of the fin.
[0167] In alternative embodiment, the kite or diamond shape is
instead a bulbous shape, torpedo-like shape, or tear-drop shape,
with a truncated base and an elongated top, when viewing the front
of the fin or through a cross-sectional front view where the ridge
sides comprise convex surfaces.
[0168] In another means for describing the shape produced by the
port side main ridge 614 and starboard side main ridge 616 of the
fin of the invention, the front view or a cross-sectional front
view shows the port side main ridge 614 and starboard side main
ridge 616 protruding from the sides of the fin. The port side main
ridgeline 615 and starboard side main ridgeline 617 at the crest of
each ridge are at substantially right angles or at right angle
planes to the centreplane 603 of the fin (shown with a symbol for a
right angle superimposed over the illustration of the fin in FIG.
1C), the centreplane 603 on a plane that passes through the leading
edge 602 and trailing edge 604 of the fin.
[0169] The port side main ridgeline 615 and starboard side main
ridgeline 617 meet at the leading edge 602 and at the trailing edge
604.
[0170] The port side outer fin surface 610 either side of the port
side main ridge 614 comprises a port side main ridge upper side 618
and a port side main ridge lower side 620.
[0171] The starboard side outer fin surface 612 either side of the
starboard side main ridge 616 comprises a starboard side main ridge
upper side 622 and a starboard side main ridge lower side 624.
[0172] In this embodiment, the port side main ridge lower side 620
and starboard side main ridge lower side 624 comprise a slight
curve; however, they may also comprise more curvature, or less
curvature, or comprise at least a portion that is flat.
[0173] In this embodiment, the port side main ridge upper side 618
and starboard side main ridge upper side 622 comprise flat and
curved portions; however, they may also comprise curved portions
with no flat portions, and the curved portions may have more or
less curvature.
[0174] The ends of the port side main ridge 614 and starboard side
main ridge 616 meet at the leading edge 602 and trailing edge
604.
[0175] A port side minor ridge 626 (i.e. a "third ridge") protrudes
laterally from the port side outer fin surface 610 above the port
side main ridge 614. The port side minor ridge 626 is smaller than
the port side main ridge 614 and is positioned further from the
base 606. The port side minor ridge 626 does not extend to the
leading edge 602 or the trailing edge 604. In the embodiments of
the fin that are adjustable and contain a knob, the port side minor
ridge 626 can comprise the knob.
[0176] A starboard side minor ridge 628 (i.e. a "fourth ridge")
protrudes laterally from the starboard side outer fin surface 612
above the starboard side main ridge 616. The starboard side minor
ridge 628 is smaller than the starboard side main ridge 616 and is
positioned further from the base 606. The starboard side minor
ridge 628 does not extend to the leading edge 602 or the trailing
edge 604 though may in other embodiments. In the embodiments of the
fin that are adjustable and contain a knob, the starboard side
minor ridge 628 can comprise the knob.
[0177] The port side minor ridge 626 and starboard side minor ridge
628 may be parallel to the main ridges, but in this embodiment, the
port side minor ridge 626 and starboard side minor ridge 628 have a
slight angle of attack towards the base at the ends closest the
leading edge 602 as shown in FIGS. 1A and 1B. The port side minor
ridge 626 and starboard side minor ridge 628 may also be tapered in
shape towards their ends or evenly shaped throughout their length.
The ends of the port side minor ridge 626 and starboard side minor
ridge 628 may be rounded as shown or end in a relatively sharp
point, or even squared ends, for example, at the rear end of the
minor ridges. Alternatively, the minor ridges may be the shape of
inverted flat foils with the flat surface of the foil facing the
direction of the base 606.
[0178] In another preferred embodiment, the fin according to the
invention may not comprise one or more port side minor ridge and/or
starboard side minor ridge. Alternatively, the fin according to the
invention may comprise additional minor or major ridges on one or
both sides of the fin, similar or different to the ridges shown in
these preferred embodiments.
[0179] This embodiment of the non-adjustable fin is made in a mould
constructed in one part, though could be constructed from more than
one part.
[0180] FIG. 3 shows in 3A and 3B a three fin `thruster` arrangement
similar to how the fins would be positioned once mounted to a
surfboard. The centre fin 630 is set back from the side fins, and
the side fins positioned with a slight inwards toe towards the
centre of the arrangement and on a slight outward cant. The right
or `starboard` fin 632 of the thruster arrangement and left or
`port` fin 634 of the arrangement may be identical to the centre
fin 630 or may comprise differences. FIG. 3C shows the right side
of the starboard fin 632, and FIG. 3D shows the left side of the
starboard fin 632.
[0181] FIG. 4 shows a fin according to the same embodiment except
the mount at the base comprises a single mounting block 636 which
can mount the fin into a Futures.RTM. finbox in a surfboard. FIG.
4A shows a mounting block 636 with one shape of mounting block
holes 638. However, other mounting block hole shapes or cutouts,
including triangles, ovals, or circles, amongst others, are also
within the scope of the invention. Alternatively, there may be no
cutouts, or holes in the mounting block 636 though the benefit of
such holes is to reduce weight and the amount of material required
to manufacture the fin which can be a cost saving.
[0182] FIGS. 4B and 4C show a front and side view, respectively, of
a further embodiment of the fin with dimensions in mm shown. As is
shown from the dimensions in FIG. 4B of the front view of the fin
according to a preferred embodiment of the invention, the thickness
of the fin between the first main ridgeline and second main
ridgeline (i.e. at its widest point of the major ridges) is 21.28
mm. The thickness of the fin between first outer fin surface and
second outer fin surface above the main ridges and ridge sides at
its widest point is 6.38 mm. Thus, the maximum width of the main
ridges when compared to the maximum thickness of the (non-ridged
portion of the) fin above the ridges equals a factor of
approximately 3.33 (i.e. 21.28/6.38=3.33). The factor would be
approximately the same if there was only a main ridge on one side,
for example, for a flat foil version of the fin according to the
invention.
[0183] The distance between the main ridgeline and base (where the
fin meets the mount) is approximately 7 mm. Thus, the distance of
the main ridgeline to the base is approximately 6% of the distance
of the base to the tip of the fin.
[0184] The maximum thickness of the minor ridges at 19.29 mm, when
compared to the maximum thickness of the (non-ridged portion of
the) fin at 6.38 mm, equals a factor of approximately 3 (i.e.
19.29/6.38=3.33). The distance between the minor ridge and base
(where the fin meets the mount) is approximately 18.31 mm. Thus,
the distance of the minor ridge to the base is approximately 16% of
the distance of the base to the tip of the fin.
[0185] The distance between the front of the fin where the leading
edge meets the base and mount, and the front end of the minor ridge
is 31.74 mm. Thus, the minor ridge starts approximately one third
of the distance of the total fin behind the front of the fin. The
distance between the rear of the fin where the trailing edge meets
the base and mount, and the rear end of the minor ridge is 40.12
mm. Thus, the minor ridge ends approximately one third
(approximately 36%) of the distance of the total fin from the end
of the fin.
[0186] The shape of the minor ridge is of FIG. 4C is substantially
a flat foil with a flat upper surface facing away from the base.
The maximum height of the minor ridge is approximately 5 mm. The
`angle of attack` of the minor ridge towards the base is
2.61.degree..
[0187] The distance from the base to where the upper ridge sides
merge into, meet, or become, the outer fin surface is approximately
30 mm. Thus, the portion of the height of the outer fin surfaces of
the fin comprising ridges is approximately one quarter
(approximately 26.5%) of the height of the fin from base to
tip.
[0188] FIG. 5 shows a fin according to the same embodiment except
the mount at the base comprises a base attachment plate 640 as a
further means for mounting the fin to a surfboard, as already
described herein. The base attachment plate comprises a
substantially flat base attachment surface 642 for contacting to
the external bottom surface of a surfboard to which it is to be
mounted (FIG. 5E). Cavities 644 (which could also be referred to as
indents) which are oval-shaped in this embodiment but may comprise
a variety of different shapes, are locations for adhesive which
will be one means by which the fin can be attached to the external
bottom surface of a surfboard. Preferably, the adhesive is injected
into each cavity 644 through an injection conduit in the form of a
tunnel or injection hole through the base attachment plate 640 (not
shown) once the base attachment plate 640 is placed in the desired
position on the surfboard to which it is to be mounted. A second
injection conduit (not shown) in each cavity 644 would enable air
to be released from the cavity 644 as the adhesive is injected into
a first injection conduit and spreads throughout the cavity 644.
Thus, the formation of air bubbles and therefore weaknesses in the
adhesive attachment can be avoided. Once the cavity 644 is full of
adhesive, excess adhesive will exit the second injection conduit
indicating that the cavity 644 is full, and the excess adhesive can
be wiped away before it dries. Preferably, screws are driven
through injection conduits and into the surfboard prior to, or
after the adhesive has dried, to provide additional strength in the
attachment of fin to the surfboard to which it is mounted.
[0189] The portion of the fin relative to the base attachment
surface 642 may be created at a specific cant for use as side fins
in a thruster set up.
[0190] FIG. 6 shows a left or port side fin 634 as shown in the
thruster arrangement of FIG. 3 with mounting blocks which can be
secured into FCS.RTM. plugs in a surfboard in the port side
position of a thruster or quad arrangement. Front the front view,
the port side fin 634 is asymmetric as opposed to the centre fin of
FIG. 1 and FIG. 2. This asymmetric configuration aims to benefit
from both: (i) the effect of having both the main ridges and minor
ridges on both sides of the fin to reduce the size of trailing
vortices to reduce drag; and (ii) a substantially flat portion on
the starboard side outer fin surface 612 of the port side fin 634
(that is, facing towards the centre line or stringer of the
surfboard) and a curved port side outer fin surface, which can
generate the known thrust experienced with flat foil side fins in a
thruster arrangement on a surfboard as already described
herein.
[0191] FIG. 6 shows the port side minor ridge 626 and starboard
side minor ridge 628 are of a similar size and equidistant to the
base. However, the starboard side main ridge 616 and starboard side
main ridge upper side 622 and starboard side main ridge lower side
624 are all smaller than the port side main ridge 614 and port side
main ridge upper side 618 and port side main ridge lower side 620,
respectively. The starboard side main ridge upper side 622 merges
into the substantially flat starboard outer fin surface 612.
[0192] Support plates 645 have been attached in this embodiment to
the port side main ridge lower side 620 and starboard side main
ridge lower side 624 to provide additional strength to this portion
of the fin. Such support plates 645 may, or may not be part of the
fins of the invention. Support plates 645 may be a metal or metal
alloy including those already described herein. In a preferred
embodiment, the support plates are made from titanium alloy.
[0193] Gaps are produced between the support plate 645 and the
surfboard onto which the fin in this embodiment is mounted, between
the mounting blocks 608 and the front and rear of the fin where the
leading edge 602 and the trailing edge 604 meet the bottom surface
of the surfboard. These gaps assist to provide additional
beneficial effects on the vortices created as water passes the fin
according to the invention during use on a wave as shown in the
modelling and analysis below.
[0194] In this respect, the fin according to the invention can
comprise one or more gaps between the base of the fin and the
surfboard onto which it is mounted. These gaps may vary in shape,
size, and height between surfboard and base, according to the
desired vortices to be created around the fin as water passes the
fin according to the invention.
[0195] Without wanting to be limited by any one theory, a benefit
of elevating a fin section from the outer surface of a surfboard on
which it is mounted is to allow creation of additional vortices,
when compared to a fin section which abuts or aligns flush with the
outer surface of a surfboard.
[0196] A starboard side fin (not shown in FIG. 6) will be the
mirror image of the fin shown in FIG. 6.
[0197] FIG. 7 is the same as the port side fin of FIG. 6 but with a
mounting block which can be secured into a Futures.RTM. fin box in
a surfboard in the port side position of a thruster or quad
arrangement. A starboard side fin (not shown in FIG. 7) will be the
mirror image of the fin shown in FIG. 7.
[0198] FIG. 8 is the same as the port side fin of FIG. 6 but with a
base attachment surface for mounting the fin to a surfboard as
described herein in the port side position of a thruster or quad
arrangement. A starboard side fin (not shown in FIG. 8) will be the
mirror image of the fin shown in FIG. 8.
[0199] Initially, the inventor introduced the main ridges either
side of the fin of the invention to increase the width of the fin
to accommodate an internal mechanism for adjusting a fin section
relative to a base. The minor ridge was formed to accommodate the
locking mechanism in order to reduce drag created by the protruding
locking knob. However, during testing of the fins by expert
surfers, surfing waves on surfboards to which fins according to
these embodiments of the invention were mounted, additional
velocity was experienced by the surfers on waves, particularly
during turns, when compared to standard flat fins. Upon further
analysis, it was considered that the shape of the fins was causing
the increase of speed due to reduction of drag forces. This was
predicted to be taking place through affecting vortices adjacent
where the fin is mounted onto the board. It is understood that
where large vortices are created behind an object moving through
water, or air, these large vortices create drag or a `sucking`
effect, therein reducing velocity. Disruption of the formation of
large vortices by instead creating smaller vortices around the base
of the fin either sides of the main ridges, resulting in a
reduction of drag forces behind the fins was predicted to be
causing the observed effect. Thus, computational fluid dynamics
modelling and analysis was performed to confirm the benefits
provided by these fin configurations when compared to standard flat
fins.
[0200] Computational Fluid Dynamics Modelling and Analysis
Background
[0201] Comparative computational fluid dynamics (CFD modelling of a
three-fin `thruster` arrangement of: tins of the invention (the
"Inventive fins" or "INV"), compared to standard, commercially
available flat fins (the "Standard fins" or "STD") as shown in FIG.
9, was conducted by Aurora Offshore Engineering (Aurora). The
modelling software used was the widely documented, validated and
accepted open-source numerical modelling tool OpenFOAM.RTM., which
is a general-purpose CFD modelling code for solving the Reynolds
Averaged Navier-Stokes equations for fluid flow.
[0202] The geometries modelled are shown graphically in FIG. 9A
featuring a sectional component of a conventional modern shortboard
surfboard coupled with either the Inventive fins or Standard fins,
Two waterlines have been considered as shown in the FIG. 9A. The
flow velocity combinations are given in Table 1. The flow direction
is always parallel to the waterlines as given in FIG. 9A.
TABLE-US-00001 TABLE 1 Flow velocity combinations modelled. INV
Fins STD Fins Waterline 1 10 m/s 10 m/s Waterline 2 7 m/s 7 m/s 4
m/s 4 m/s
[0203] The numerical model of the fluid flow was constructed using
a rectangular domain containing the relevant board and fin sections
as shown in FIG. 9B. The position and orientation of each fin
system is shown in FIG. 9C and a view of the surface mesh on the
base of the board, the main ridge (comprising the first and second
ridges), and the minor ridge (comprising the third and fourth
ridges) shown in FIG. 10.
Results
[0204] The analysis of the results focuses on investigation and
identification of the flow fields around the different fin systems
and differentiation of their resulting performance. FIG. 11 gives
the velocity vector field normal to the board velocity and located
on a cut-plane down through the side fins as shown in FIG. 11c. The
secondary velocity field as generated by (Ux, Uz) shown in this
figure demonstrates how the influences of the Inventive fin
features on the local flow field compared to the Standard fins,
showing (1) that both fins generate a similar trailing wake vortex
around the fin tip, while (2) the Inventive fin main ridge and
minor ridge also generate division of the longitudinal flow near
the base of the fin. These rotational flows appear to be more
apparent at the locations of geometry change along the Inventive
fin, as shown in (3).
[0205] FIG. 12 gives the velocity vector field normal to the board
velocity and located on a cut-plane down just aft of the side fins
as shown in FIG. 12c. The secondary velocity field as generated by
(Ux; Uz) shown in this figure demonstrates how the influences of
the Inventive fin features on the local flow field compare to the
Standard fins, showing (1) that both fins generate a trailing wake
vortex around the fin tip, while (2) the Inventive fin main ridge
and minor ridge also generate a significant change in the flow
behaviour against the board surface adjacent to and inboard of the
fin. Comparing the flow at (3) in FIG. 12(iii), the Inventive fins
cause changes in not only the direction of the flow, but also in
the magnitude of the velocity.
[0206] The effect of flow past the rear central fin is shown in
FIG. 13 which gives the velocity vector field normal to the board
velocity and located on a cut-plane through the aft fin as shown in
FIG. 13c. The secondary velocity field as generated by (Ux, Uz)
shown in this figure demonstrates how the influences of the
Inventive tin features on the local flow field compare to the
Standard tins, showing (1) that the prevailing flow at this
location is upwards towards the free water surface and board, while
(2) the Inventive fin main ridge and minor ridge also generate
division of the longitudinal flow near the base of the fin, which
are similar to those features in FIG. 11.
[0207] Differentiation of the flow behaviour between the Inventive
and Standard fins is also investigated by considering a cut-plane
parallel to and slightly below the board surface as shown in FIG.
14c at the elevation of the gap between the Inventive main ridge
and the board. As can be seen by comparison of the lateral velocity
(Ux) between figures (a) and (b), the flow immediately adjacent to
the board differs significantly between the Inventive and Standard
fins, with (1) the Inventive fin frontal gap under the main ridge
enabling significant inboard flow, followed by (2) the rear gap
enabling significant outboard flow which is not possible with the
Standard fin which has continuous contact with the board surface.
The downstream wake behind the fins (3) shows significant
continuation of the wake from the Inventive fin which is much
stronger than for the Standard fin.
[0208] To further assist in understanding the response of the flow
to the presence of the key design elements of the Inventive fin,
streamlines are generated down either side of each fin system as
illustrated in FIG. 15, looking forwards from behind the lateral
fin. The streamlines demonstrate the formation (1) of a persistent
downstream longitudinal wake vortex with its axis of vorticity
centred around the longitudinal axis of the main ridge (which is
predicted by the inventor to act in a manner similar to a caudal
keel of some fast fish). This wake vortex is located adjacent to
the board surface and is therefore anticipated to have a
significant influence on the flow past the board downstream of the
fin.
Forces in Tables
[0209] The hydrodynamic forces extracted from the CFD model for
each of the fins are presented in Table 2.
TABLE-US-00002 TABLE 2 The ratios of change in lateral forces of
Inventive fins compared to Standard fins. Lateral Force on Fin
Board Speed Waterline f(x) [N] [m/s] (FIG. 9A) Fin INV STD
.DELTA.f(x) 4 2 Port -2.71 -3.98 -32% Centre 0.09 0.18 -50%
Starboard 2.63 4.55 -42% 7 2 Port -17.86 -12.03 48% Centre 0.24
0.52 -54% Starboard 17.87 13.72 30% 10 1 Port -11.84 6.72 -276%
Centre -0.54 1.65 -133% Starboard 13.27 -3.76 -453% Note: The sign
convention is that the forces are the water force on the fin, which
is oriented so that (for 4 and 7 m/s) the forces are towards the
inner side of the board as shown in FIG. 16.
[0210] The key observations from this are that: [0211] The lateral
fin forces are considered as giving the best indication of how much
of an effect the fins are having on the flow over the board; [0212]
The centre fins have very low forces and therefore are expected to
have very little effect since they are aligned with the flow;
[0213] The lateral fins (both types and at all speeds) produce
roughly equal and opposite forces--this is expected since the board
is travelling straight ahead. There are subtle differences in the
geometries which can be seen in the differences between left and
right forces; and [0214] The lateral forces increase as speed
increases for waterline 2, but the change in waterline and velocity
results in a change in the direction of the forces on the Standard
fins.
[0215] In general, lateral forces increase greatly on the Inventive
fins, compared to the Standard fins, which is anticipated to be
important in the observed speed increase with Inventive fins. It
will also be very important in the performance and stability of the
board during turning manoeuvres, one of the most frequent actions
needed to be taken during surfing.
CONCLUSIONS
[0216] The results of the CFD modelling show a significant change
in the flow of water immediately adjacent to the board and
downstream of the fins of the invention when compared to the
standard fins in a thruster arrangement. These flow changes are
potential causes for the observed speed and stability increases
observed for boards using the fins of the invention.
[0217] Prior to the modelling, the additional thrust was predicted
to be due to the disruption of the formation of large vortices by
instead creating smaller vortices around the base of the fin either
sides of the main ridges, resulting in a reduction of drag forces
behind the fins. However, the results of the modelling showed that
while part of the additional forward thrust experienced was due to
the effect of disruption or reduction of trailing vortices which
reduced the negative `sucking` effects (but maintained the area of
high pressure), the main effect was that the ridges created a
vortex as a result of the combination of the surfaces of (i) the
lower surface of the surfboard adjacent to the fin, (ii) the lower
main ridge surface adjacent the board, and (iii) the minor ridge.
This vortex created a measurable area of lower pressure surrounding
the lower portion of the fin and in front of the fin when compared
to surrounding water and the high pressure measured behind the fin.
Incredibly, an area of low pressure created in front of the fin was
shown (video not able to be included) to be up to 500 mm long
beneath the surfboard. This effect is believed to be the cause of
the additional thrust (towards the area of lower pressure)
experienced by surfers using fins according to the invention when
compared to standard fins without the major or minor ridges.
Detachable and Adjustable Fin
[0218] FIG. 17 shows a detachable and adjustable version of the fin
of FIG. 5. The fin comprises a base portion 646 engaging a fin
section 648 to form the detachable and adjustable fin, wherein a
planar member 650 attached to the base attachment plate 640 to form
the base portion 646 is located within an internal cavity within
the fin section 648. The planar member 650 is secured to the fin
section 648 within the internal cavity by screws 652 that are
accessible from the outer fin surfaces and pass through the fin
section 648 into the internal cavity and can engage with the planar
member 650 at locking cavities 654. To adjust the position of the
fin section 648 relative to the base portion 646, screws 652 are
unscrewed out of a set of locking cavities 654 at a first locking
position, thereby un-securing the fin section 648 from the base
portion 646, the fin section 648 is slidably moved toward the
leading edge or trailing edge, and the screws 652 are screwed into
locking cavities 654 at a second locking position, thereby
re-securing the fin section 648 to the base portion 646 at the
second position. The more locking cavities 654 on the planar member
650, the more locking positions are available for adjusting the fin
section 648 relative to the base portion 646.
[0219] Removing the screws 652 also enables the fin section 648 to
be removed and separated from the base portion 646. This can be
beneficial for transporting a surfboard to which the base portion
646 is permanently attached so that the fin section 648 is not
damaged or in the way when stacking boards or other equipment on
top of the surfboard. It also allows a fin section 648 to be
replaced by a fin section of, for example, a different shape, size,
colour, material, amongst others as the user requires or if the fin
section 648 on the board becomes damaged.
[0220] A detachable fin according to the invention may or may not
also be adjustable in a direction towards the leading edge or
trailing edge of the fin. Likewise, an adjustable fin according to
the invention may or may not be detachable in the fin section being
separable from the base.
[0221] FIG. 18 shows collapsed views and FIG. 19 shows exploded
views of a further detachable and adjustable version of an
embodiment of the fin of the invention, wherein the base comprises
mounting blocks 202 that can attach to FCS.RTM. fin plugs for
mounting the fin onto a surfboard. In this embodiment, the knob 300
comprises the minor ridge. The outer fin surface 106 adjacent to
the base of the fin forms main ridge on either side 107 as in the
non-adjustable version of the fin of the invention.
[0222] This embodiment further comprises an upper fin section
attached to the bottom portion of the fin section, the upper fin
section comprising a titanium alloy (comprising approximately 4%
vanadium and approximately 6% aluminium) upper fin 500 covered with
an overmolding 510 of protective safety polymer. The titanium alloy
upper fin section is up to approximately 2 mm to 2.5 mm thick in
the widest section 505.
[0223] The upper fin 500 shown in FIG. 19B comprises upper fin
attachment members 520 which are received and restrained in
cavities 525 to attach the upper fin 500 to the bottom portion of
the detachable and adjustable fin. Adhesive may be used to restrain
the upper fin attachment members 520 in the cavities 525. The
embodiment shown in FIG. 14B comprises 5 upper fin attachment
members 520 and 5 matching cavities 525. However, more or less than
5 upper fin attachment members may be used, and they may comprise a
variety of different shapes and sizes with matching cavities that
can receive and restrain the members.
[0224] The upper fin 500 shown in FIG. 18A also comprises circular
holes 515 or cut outs of various sizes. These cut outs reduce the
weight of the upper fin 500 further and assist in providing the
beneficial flex characteristics for the detachable and adjustable
fin of the invention. While the cut outs are circular in this
embodiment, they may comprise a variety of different shapes.
[0225] Across the profile of the upper fin section is varying
thickness to create a single or double sided fin foil as is known
in the art and common to the shapes of surfboard fins, with a
thicker section 505 toward the leading edge of the fin section
which decreases in thickness with closer proximity to the trailing
edge.
[0226] In the embodiment of the detachable and adjustable fin shown
in FIGS. 15 and 16 and as shown in FIG. 19A, the base 400 and
mounting blocks 202 form one piece and do not comprise separate
components that have been attached. Thus, the base can be separated
from the fin section with the base left attached to a surfboard or
removed from the surfboard.
[0227] A further detachable and adjustable version on an embodiment
of a fin according to the invention is shown in a collapsed form in
FIG. 20, and an exploded form in FIG. 21. This embodiment is
similar to the embodiment of the detachable and adjustable fin in
FIGS. 18 and 19 with the exception that instead of mounting blocks
attached to the base, the base 400 is attached to a base attachment
plate 420 for mounting onto the external bottom surface of a
surfboard with adhesive and/or rovings, screws or other mechanical
attachment means. Thus, similar to the fin of FIG. 17, the fin
section can be removed from the base for storage, transport, or
replacement of the fin section with a new fin section of the same
or different template, shape, size, and/or material.
[0228] The underside of the base plate is shown in FIG. 21C showing
the base attachment surface 424 and large recesses or cavities 426
for accommodating adhesive.
[0229] When mounted to a surfboard, the base of the embodiment of
the detachable and adjustable fin of FIGS. 20 and 21 points away
from the surfboard at an angle of approximately 90 degrees when
measured from the external bottom surface of the surfboard on to
which it is mounted. While being otherwise the same as the
embodiment of FIGS. 20 and 21, the base of the embodiment of FIG.
22 points away from the surfboard at an angle of approximately 86.5
degrees (or approximately 3.5 degrees off `centre` or 90 degrees)
when measured from the external bottom surface of the surfboard on
to which it is mounted, i.e. at a different cant. That is, the base
400 is 3.5 degrees off pointing in a direction perpendicular to the
base attachment surface 424.
[0230] A further detachable and adjustable version of a preferred
embodiment of a fin according to the invention is shown in FIG. 23.
This embodiment is similar to the embodiment shown in FIGS. 20 to
22 with a key difference that side shut-off cavities have been
replaced with front and rear facing shut-off cavities 160. Another
key difference is the presence of injection conduits 428 for
injecting adhesive into the cavities or releasing air from the
cavities as the adhesive fills the cavities 428, and/or for use as
screw holes for attaching the detachable and adjustable fin to a
surfboard with screw-type fasteners such as screws.
[0231] An exploded view of the parts of the lock used in some
adjustable versions of preferred embodiments described herein is
shown in FIG. 24. The lock, which may also be referred to as a
"locking means", comprises a cam 304.
Propeller for Watercraft Propulsion
[0232] A preferred embodiment of a propeller 700 for providing
propulsion through water is shown in FIG. 25 and FIG. 26. The
propeller 700 combines features and benefits of a propeller and an
impeller. In this respect, a propeller assists a vessel to move
through water by providing a thrust force. The propeller 700
comprises a revolving hub 702 with rotating propeller blades 704
that convert rotational motion into forward thrust. This is due to
the pressure differential that is created between the front and
rear surfaces of the propeller blades 704. This pressure
differential pushes water behind the propeller blade 704 in
accordance with Newton's laws of motion and Bernoulli's
theorem.
[0233] An aperture 706 through the hub 702 comprises impeller
blades 708 that rotate with the revolving of the hub 702 to create
a sucking force to draw water through the aperture therein
increasing the pressure of the fluid and thus its flow through the
aperture 706.
[0234] The combined forward thrust provided by the rotating
propeller blades 704 and impeller blades 708 forces the propeller
700 of the invention through the water and the vessel to which it
is attached.
[0235] The rotational force applied to the propeller 700 of this
preferred embodiment is via a motor which turns a sprocket 710
interlocking with a first end of a loop of roller chain 712. At a
second end, the loop of roller chain 712 interlocks with teeth 714
on the hub 702, and the turning of the sprocket 710 by the motor
therein rotates the loop of roller chain causing the propeller 700
to also rotate.
[0236] The propeller blades 704 comprise outer blade surfaces 716.
A ridge 718 protrudes generally laterally from each outer blade
surface 716 as shown in the cross-sections of FIG. 26A. At the
crest of each ridge 718 is a ridgeline 720 which comprises a
relatively sharp edge. Each side of the ridge 718 between the
ridgeline 720 and where the ridge 718 protrudes from the outer
blade surface 716 is a curved sloped inner ridge surface 722
adjacent and facing the hub 702, and a curved sloped outer ridge
surface 724. These sloped inner ridge surfaces 722 and outer ridge
surfaces 724 comprise curved portions, substantially flat portions,
and comprise steeper curves where ridge 718 meets outer blade
surface 716.
[0237] The inner surfaces 722 of the lateral ridges 716, and the
ridgeline 720 comprise a similar curve to the curved shape of the
hub 702. The end of the ridgelines 720 meet at the blade edge 726.
The blade edges 726 and ridgelines 720 are relatively sharp edges
which assist in cutting through the water.
[0238] The impeller blades 708 are relatively short blades compared
to the propeller blades 704. The impeller blades 708 on the inner
aperture surface 728 of the hub 702 are curved (spirally similarly
to rifling in a barrel) assists to cause water passing through the
aperture 706 and the impeller blades 708 to spiral in the direction
of the revolving hub 702. A cross-section of the impeller blades
708 as shown in FIG. 26 and FIG. 27 shows an almost diamond-shape
with concave impeller blade surfaces 730 and a wide impeller base
732 where the impeller blade 708 meets the inner aperture surface
728. This cross-section of the impeller blade 708 may also be
considered as also showing two lateral impeller ridges 734
protruding from the sides of the impeller blade 708 with concave
sloped impeller blade surfaces 730 either side of the impeller
ridgelines 736. The impeller ridgelines 736 are at substantially
right angles or at right angle planes to the centreplane of the
impeller blade 708, the centreplane from between the middle of the
impeller base 732 where it meets the inner aperture surface 728, to
the impeller blade tip 738.
Keels
[0239] A preferred embodiment of a keel of a boat (or yacht)
according to the invention is shown in FIG. 28 and FIG. 29. The
keel 800 of this embodiment is located in the common location for a
fin keel on a boat, projecting below the centreplane 802 of the
vessel hull 804, the centreplane 802 between bow 806 and stern 807
of the boat.
[0240] The keel 800 comprises two main ridges 808 protruding
laterally from the sides of the keel 800 adjacent where the keel
800 meets the vessel hull 804. An upper minor ridge 810 protrudes
laterally from each side of the keel 800 just above the main ridges
808. A lower minor ridge 810 protrudes laterally from each side of
the keel 800 just below the main ridges 808.
[0241] The rear 818 of the keel in FIG. 29B shows the diamond-like
shape with elongated top and bottom ends produced by the main
ridges 808 in the keel 800. At the crest of each main ridge 808 is
a ridgeline 814. As is shown in FIG. 29, the main ridges 808 and
the ridgelines 814 extend from the front 816 of the keel where they
meet, to the rear 818 of the keel where they end at the flat
surface of the rear 818 of the keel 800. In other embodiments, the
ridgelines 814 may meet at the rear 818 of the keel 800 where the
rear 818 of the keel 800 ends along an edge similar to the front
816 of the keel 800.
[0242] Each side of the ridge 808 between the ridgeline 814 and
where the ridge 808 protrudes from the outer keel surface 820 is a
curved sloped ridge surface 822. These sloped ridge surfaces 822
may comprise curved portions, substantially flat portions, and
steeper curves near the ridgelines 814 and/or where main ridge 808
meets the outer keel surfaces 820.
[0243] The ridgelines 814 of the main ridges 808 are at
substantially right angles or at right angle planes to the
centreplane 826 of the keel 800 (see, for example, FIG. 30), the
centreplane comprising a plane from between the middle of the keel
800 where it meets the vessel hull 804, to the keel tip 824.
[0244] The upper minor ridge as shown in FIG. 29B comprises a
configuration similar to a flat foil protruding from each side of
the outer keel surface 820 adjacent where the outer keel surface
820 meets the sloped ridge surfaces 822 above the main ridges 808
(see for example, FIG. 30B). The flat side of the flat foil
configuration for the upper minor ridge faces up whilst the more
curved side of the upper minor ridge faces down.
[0245] The lower minor ridge 812, is a similar shape and
configuration to the upper minor ridge 810 except the flat foil
shape of the lower minor ridge has the flat side facing down away
from the vessel hull 804.
[0246] The upper minor ridge 810 and lower minor ridge 812 extend
only part way between front 816 and rear 818 of the keel 800.
[0247] While these upper minor ridges 810 and lower minor ridges
812 of the preferred embodiment comprise a configuration of a flat
foil, the upper and lower minor ridges may be differently shaped or
not even present in other embodiments of the keel of the invention.
For example, the upper and lower ridges may not be present; or one
or both of the upper or lower ridges may be present; the upper
and/or lower ridges may extend from the front 816 of the keel 800
to the rear 818; or the upper and/or lower ridges may comprise more
evenly shaped ridges similar to, though smaller, than the main
ridges 808. The upper minor ridges and/or lower minor ridges may
comprise relatively sharp ridgelines at their crest, or they may
comprise rounded, or even squared edges, or a combination of both
or other shapes at their ridgelines. The upper minor ridges and/or
lower minor ridges may also not comprise flat foil shapes, but
comprise more even configurations with similar or the same sloped
sides either side of straight or (curved) ridgelines on the upper
minor ridges and/or lower minor ridges. The upper minor ridges
and/or lower minor ridges may be similarly shaped or may comprise
different shapes.
[0248] While a fin keel according to the invention is shown in FIG.
28 and FIG. 29, the keel according to the invention may be another
type of keel, for example, a full keel or ballast keel, a skeg,
bilge keel, deep keel, dagger board, lee board, centre board, pivot
board, winged keel, twin canting keel, folding keel, or lifting
keel, amongst others. In this respect, the keel according to the
invention shown in FIG. 30 is a full or ballast keel. A keel
according to the invention may have one or more ridges only on one
side surface, for example if it used on one side of the boat.
[0249] A catamaran or trimaran may use the keel according to the
invention on the bottom of one or more hulls as shown in FIG.
31.
* * * * *