Yes, it's different from existing
surfboard fins, but by design. Yet compared to today's boats, planes,
submarines, race car spoilers, etc., the technology of the Wavegrinder is
very normal, and at the forefront of technology. See
Wikipedia article about winglets.
Helps you turn better (more lift
(horizontally)). Helps you go faster (less drag).
Riders report more "pop" in turns, and
more snap. Others report the ability to ride into the mush further,
especially on East Coast waves. Riders report a sensation of floating
higher in the tail when dropping in. Probably this is because typical fins
are partly in stalling mode when dropping in, slowing the board, and
dragging down the tail. See testimonials.
See video of stalling.
Fins are not magic. Basically they
do two things, they help you turn (or resist turning) and they slow you
down. These are the forces of lift (horizontal) and drag. If you
have enough turning force (this is lift, it's horizontal force), then you
want the smallest fin area you can get away with, so you get more speed.
Winglets are there to help the fin turn
better but with less-than-typical surface area, which means less drag, and thus a
more efficient faster fin.
The idea is to get better turns and more speed. We designed this as a
performance fin. Yes, you can turn large-radius turns as with older,
larger, heavily raked "carving fins." But you also can make
short-radius turns with a lesser likelihood of stalling during the quick,
short turns. Just as BMWs and Ferraris can make both long and
short-radius turns whereas buses cannot, this is quite a versatile and
performance-oriented fin. You can always slow down with a performance
fin, but you can't always speed up if you have a fin with lots of drag.
Lift is the turning force — acting
horizontally, not vertically — that turns the board, or that resists
turning. This fin is not designed to raise or to lift you out of the
water. It is not a hydrofoil. The winglets are way too small to
lift a person out of the water — a little more than one inch of surface
area. The winglets are there to keep the water on the fin flowing
smoothly across both sides to make the fin more efficient, so that it gives
more turning force per square inch of wetted surface.
We designed it for performance
longboards. But surfers have been buying and using these for any board
they fit -- shortboards with single fin and bonzer setups, classic
longboards, standup paddleboards --anything that has a regular fin box --
and have reported excellent results. Hobie Alter bought two for his
standup paddleboard. One guy bought a couple for a one-person
submarine.
The fin is 9.25 inches in height, about
30 square inches in surface area.
But keep in mind that it has winglets, that make the water think it a larger
fin as when turning, but with a smaller drag penalty, and thus speed.
As a general rule of thumb, you can
expect performance gains when going to a fin or to a fin system that has
less surface area (i.e. a smaller fin or less total fin area) provided you
still have the turning force (horizontal lift) that you want.
We have thruster fins for shortboards
(and for longboard side fins) in the works, and plan to have them available
soon. If you'd like to be on our mailing list to receive an email when
these are released, click here.
We did not design the fin specifically to
promote noseriding, or as training wheels for noseriding. But many
surfers report the best noserides of their lives -- excellent ability to
plant a rail and hold in the pocket -- and still it turns great.
Many riders tell us the
same thing —the tail has a feeling of
lift, of riding high in the tail, and super-fast turning, especially when
dropping in and when doing bottom turns. Some have said that the fin
works great for performance longboards, but even better in single-fin
shortboards. See the testimonials page
for more.
I tried my
fin today, and I was thrilled! --Dan
I've gotten the best noserides of my life! --Matt
I've gotten the best rides of my life with this fin! It is
incredible! --Bill, Longboard House
"It
felt really fast and accelerated out of turns but it had this much
looser feel to it, especially in a vertical plane."
--Allen
"I was surprised by how my board 9'
surftech, epoxy, Takayama, snapped off the top, and there was some speed
to the bottom turn. Yesterday I got it in head-high Torrey Pines. The
board seemed faster down the line, the snaps off the top and bottom were
no problem." -- Pete
It fits "standard" fin boxes.
The fin base itself of tapered slightly to tighten itself when screwed down
into the box. But do not overtighten, you could break the fin or the
screw.
Unfortunately fin boxes vary by a few thousandths of an inch between
manufacturers. Boxes from the same manufacturer even vary slightly too
sometimes, and with wear and use, boxes will loosen up over time.
Roughly 90 percent of the time this fin fits just right, tightly, moveable,
yet no slop. 10 percent of the time you might need a few swipes of the
fin base with 180 or higher grade sandpaper on the fin base. But be
careful, three swipes with sandpaper can go from too tight to too loose — we
are talking about thousandths of an inch.
So sand slowly, and test it every few swipes. Also, focus on the heel
of the fin, where the heel pin fits, as this is what allows it to be
adjusted for and aft when angled within the box. Up close, you'll see
a small step built into the fin for this purpose, focus any sanding here
first.
9.25 inches tall. But we should all
start thinking in terms of surface area, not height. This is about 30
square inches, less than most, but with lift-enhancing features that make it
feel bigger than it is, without the drag penalty.
Want a thruster? We are developing
new thrusters for shortboards and for longboard side fins. You can
add your name to our list, and
we'll email you when these are available.
Because the fin will go faster and turn better with less effort,
so you can catch more waves and surf longer. In short,
winglets make the surface area of a fin more efficient, which means you can
get away with a fin that has less surface area and thus less drag. Less
drag means a faster, better-turning fin.
Here is a more scientific explanation.
When a surfboard fin moves through the water, and
especially when it turns, water wants to move from one side of the fin to the
other, from the high-pressure side to the low-pressure side. Water moves
sideways in a circle -- from one side to the other around the tip of the fin.
As the fin goes through the water, the circle elongates or stretches into a
vortex.
This process is called a downwash. The larger the
vortex, the more drag created, and the less and less effective the fin
becomes, because the turbulent vortex decreases the fin's lift.
Winglets are designed to prevent that movement of water from one
side of the fin to the other. In the process, we reduce drag
and increase lift. The fin becomes more effective, so we can use a fin
with a smaller area
surfing with less drag
surfing to produce the same or better turning
ability.
Drag is the resistance to forward and to
turning movement, and is to
be avoided. Think of drag as what you're dragging though the water. Less
drag is better.
The less drag a surfboard fin has, the faster it goes through
the water, the easier it is to catch waves, and the longer a surfer can paddle. The Wavegrinder fin has
winglets to decrease drag. Think of those great waves you've just barely
missed surfinglike by a half a stroke. Don't you wish you had had less drag,
so you could have caught the wave?
Downwash, incidentally, is what accounts for birds flying in
V-shaped formations. As birds fly, gravity is pulling them downward, and air
moves from the high-pressure side of their wings around their wingtips, creating
an upwardly directed vortex off of their wingtips. Other birds know this of
course, and fly immediately behind the leading bird's wingtips to ride
the uplift, as do birds behind them, ultimately forming a V-shaped flock.
Airplane designers are aware of the adverse effects of wing-tip vortices, which accounts
for many airlines now using winglets. Think about their use of winglets
next time you're at the airport.
When a fin turns, it creates downwash by pushing sideways on the
water. This bigger
vortex is a turbulent flow of water that robs lift from the
area near a fin's tip, causing a loss of lift,
which is a loss of turning force. Fins with a big tip vortex are basically
just brakes.
Think about those times where you catch a great wave, you make a
sharp turn, but then the board grinds to a halt and the wave slides by under
you, leaving you behind. Don't you wish you'd had a fin that turned
better and had not become a brake?
The winglets are designed to be in the same plane as the
fin box and bottom of the board to minimize drag. We rejected winglets
angled upwardly and downwardly, especially larger winglets, finding that
such angled surfaces slowed the board, increased drag —
the angled surface fought against the board bottom that the water travels
past. The winglets are there for
speed and for turning, not for vertical lift, and thus are quite small
— but large enough to perform the
intended function.
Put the Wavegrinder fin
about two inches back from where you place your typical swept-back, sickle-shaped fin. This
puts the center of effort where you are most used to it with your typical
swept-back fin. See the diagram below, and click for a close up.
Both sickle-shaped fins and the Wavegrinder have a center of effort
(actually a center of lateral resistance), the
location on which the turning force is deemed to act. To be able to compare apples to apples and
turning ability in your old fin the Wavegrinder, we suggest that you line up
the centers of effort for comparison purposes, which requires the two-inch
back Wavegrinder placement. See above (1.8 inches in the photo (click for larger image)).
But note that once you've tried it against what you're used to, you can
adjust this fin further forward and aft because it has a shorter fin base,
so it can travel further in the box than most other fins.
Winglets are smaller than wings. Wings are unnecessarily
large, and create too much drag because they add surface area
onto a fin. Properly designed winglets
allow us to actually reduce fin surface area, decreasing drag.
Back in the 1980s, boat designers experimented with wings
attached to keels, most notably Ben Lexcen's Australia II
designthat won the 1983 America's Cup. In
that design and thereafter, wings were relatively
large. Initially, wings often gave little to no performance advantage
because they added surface area, rathen than reducing it. The wings
were just too big.
But winglets are different because they
are small, and typically stretch only
part of the distance between the leading edge and
trailing edge of the fin. The WavegrinderTM winglets are attached
at the rear of the fin
and stretch forward to the point of maximum fin thickness.
Winglets are better than full-chord-length
or large wing projections because the vortex affects primarily the back two-thirds of the
fin, not the front or leading edge of the fin.
Boeing and NASA agree.
Another factor that increases drag by increasing the tip vortex
is rake, or sweepback angle, combined with a high aspect-ratio. The more
vertical and the thinner the fin, the smaller the turbulent vortex becomes.
Those of you familiar with boat design have seen the evolution
in keels and sails from low aspect, heavily raked keel, rudder, and sailplan designs in the early to mid
1900s to the high-aspect more vertical designs over the past 20 years or so.
But surfboard fin design did not similarly evolve.
Until Now.
Decrease the sweepback angle. Increase aspect ratio. Create a fin shape
(planform) with an elliptical lift
distribution. Add an endplate, wings, or winglets.
Turning ability is a question of leverage, or moments.
Leverage or moment is a force
acting over a distance that imparts rotation.
First, the WavegrinderTM fin is more adjustable in the fin box than
is a
typical fin, meaning that it can go further forward and further back in the fin
box than a typical, longer-rooted fin, giving surfers more leverage and control
options. See the photos page for the array photo demonstrating the
adjustability.
Second, the WavegrinderTM
fin generates more lift than the typical high-sweepback fin of similar size.
This is in part due to the NACA foil shape, a high-lift foil shape.
The WavegrinderTM fin thus is less prone to stalling
—losing lift
— because of its NACA
foil shape. When you've turned too sharply and lost a wave, probably it
was because your fin stalled, and acted like a brake, just like a canoe paddle
placed sideways in the water stops a canoe.
When a fin stalls during a turn, as
occurs in high-sweepback fins, turbulence is robbing the
high-sweepback fin of lift, and the
center of effective lift actually moves forward because the back half of the
high-sweepback fin no longer is producing lift. See the picture below, and
note the stall pattern of
airplane wings.
The WavegrinderTM fin has a shape
similar to planform shapes B and C that will stall evenly, whereas traditional high-sweepback fins prevalent
today are similar to the wing depicted in F, that will stall at the tip
first, moving the working, lifting area of the fin dramatically further forward.
In our opinion, we have found
that the WavegrinderTM fin retains maneuverability at the limits
better than any traditional fin that we've tried. It has a greater range
of speeds and better maneuverability than traditional fins. But try it yourself,
side-by-side with your favorite fin, and let us know what
you think.
Well, if that kind of question or thinking made sense, we'd still be
listening to music on black vinyl, riding in cars without seatbelts, sailing
J-Boats or 12 meters in the America's Cup, and flying biplanes.
Check out the 1973 boat design below, and compare
typical sidebites and raked fins to that 34-year-old design.
Ask your local surf shop if they have one you can demo so
you can try before you buy, or just buy a fin directly from us.Until you've tried one of these WavegrinderTM fins, you'll simply
have to wonder!
Basically it is the best there is. It is clear, forms a
consistent shape exceedingly well, and is basically bombproof. Well, maybe
not bombproof, but Lexan is a polycarbonate used in bulletproof glass, and in other
applications requiring great strength. Many ocean-going boats rely on
Lexan for the windows and portlights, as it is capable of standing up to
punishing ocean waves..
