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the afx, 2013

The Asymmetic Fin Experiment, 2013

Thesis
1. When riding a surfboard while standing, the rider's stance is off-set, or asymmetrical, with a leading and a trailing foot.
The trailing foot is either the right foot (natural), or the left foot (goofy).
2. Ideally for the surfboard rider, from the intial cresting (the curl), waves break with lateral progression, either to the right or to the left.
Defined from the rider's perspective, a right is ridden to the observer's left; conversely, a left is ridden to the observer's right.
3. For the natural-footer, when riding to the right, their stance is forehand to the wave face, and when riding to the left, their stance is backhand to the wave face.
Alternatively, for the goofy-footer, when riding to the right, their stance is backhand, and when riding to the left, their stance is forehand.
4. When transversing a breaking wave, either to the right or to the left, the rider controls the direction by weighting the side of the board nearest to the wave face, that is the inside rail; the opposite side of the board is the outside rail.
5. When riding forehand, the inside rail is principally weighted and controlled by the rider's toes.
Riding backhand, the inside rail is principally weighted and controlled by the rider's heels.
6. While riding forehand, the surfer has unrestricted vision of the wave face; whereas, when riding backhand, vision is somewhat limited, particularly the curl, which is often outside the rider's periheral vision.

This asymmetry suggests that riding forehand is somewhat "more precise" (toe control and unrestricted vision) than riding backhand (heel control and limited vision), an observation supported by some annecdotal evidence.

Since the introduction of the lightweight fibreglassed surfboard with a fin in the early1950s, a number of surfboard shapers have experimented with asymmetric designs.
However, many have focused on building one-direction boards, that is, ridden exclusively on waves breaking either right or left; these were usually for the forehand stance and designed for particular locations.

During the late 1960s, the area of surfboards was progressively reduced, and in 1970 became standard sized (approximately the surface area of the rider's profile), facilitating the development of high performance surfing.
Now the rider no longer adjusted their position along the board, but rather took a fixed-stance, and, ideally, maintained board speed and adjusted to variation in the wave's lateral progression by linking together a combination of forehand and backhand turns on the wave face, effectively "break(ing) out from the straight line" (Bob McTavish,1967).
Despite the severely restricted avaiable wave face inside the curl, by the end of the decade, some riders, such as South Africa's Shaun Tomson, were "turning while inside the tube."
Performance surfing was significantly enhanced with the introduction of Simon Anderson's three fin Thruster in 1981.
The current study examines asymmetry in this context.

Asymmetric Design Predecents

In the early 1963, Australian and Makaha champion, Midget Farrelly designed the Off-set Square "with one side longer than the other ... designed to eliminate one of the surfboard rider's major problems - perfecting the backhand turn."

- Kevin Platt in Pollard: Australian Surfrider (1963) page 24.

Around the same time, Scott Dillon Surfboards, Brookvale, produced the Hook-tail, possibly derived from a California, where one rail had extended curvature.

Left:
Scott Dillon Surfboards: Hook-tail, 1963.
Photograph: Unaccredited
- Pollard: Australian Surfrider (1963) page 26.

According to Matt Warshaw, Karl Ekstrom developed "the first asymmetrical tail design in 1965, based on the idea that the board should match the rider's non-linear stance" at Nelson- Ekstrom Surfboards, La Jolla, California.
- Warshaw: Encyclopedia (2004-2008) page 180.

At the Tom Morey Noseriding Contest, Ventura, California, held at a righthand break in 1965, one designer introduced the Additional Control Skegs, apparently addng an off-set fin box, although the exact intention or operation of the design is unclear.

Left:
additional control skegs [Offset Fin Boxes], 1965.
Photograph: Unaccredited.
Bill Cleary: Nose Riding - A sport within a sport.
Surfer,Volume 6 Number 5, November 1965, page 33.

An experiment demonstrated at Tom Morey's Noseriding Contest, 1965.

The following year, Bob Cooper's Blue Machine for Morey-Pope Surfboards, featured an offset fin box.

Left:
a. Bob Cooper: Off-set Fin box, Blue Machine, Morey-Pope Surfboards, 1966.
b. Removable fin with Wonder Bolt, Morey-Pope Surfboards, 1966.

- Surfboards Shaped by Davenport, viewed 3 November 2013.
http://adamdavenport.blogspot.com.au/2011/07/blue-machine.html

With far less extreme positioning than the Noseriding Contest model, above, the finbox is only marginally off-set from the centre line.

In the 1970s, Nat Young produced his Backhand model in Byron Bay and at Bennett Surfboards, Brookvale.
The most subtle of the various asymmetic designs, Nat shaped each rail to a different profile, as specified by the client's stance.
(The combination of subtle and Nat in the one sentence is rare, possibly unique.)
In a brief article for Tracks, Young noted the limited vision when riding backhand:
"On your forhand (sic) you are able to follow your curves in both eye and movement ...on your backhand ... you can't see what the wave is going to do for sure, so you rely on instinct and knowledge."

Young also notes that "shapers subconsciously think of a board for surfing on the forehand," apparently suggesting that the designer/shaper conceives and shapes (their) forehand rail, then replicates that shape for (their) backhand rail.

This is a picture of my board for going left or backhand.
It's five to seven years old and is in fact the same one I
was riding on those lefts at the beginning of "Morning of the Earth".

Nat Young: Nat's Backhand Board
Tracks, January 1976 Number 64 Page 33.
Photograph (rotated) by Frank Pithers.

During the late 1970s, Bob McTavish designed a series of asymmetical templates, particularly for his favoured powerful North Coast righthand point breaks.

McTavish noted the asymmetry of the rider's stance:
"Forehand you apply pressure through knees, ankles and toes ... backhand the pressure goes much more directly ... pushing into heels."

Left:
Bob McTavish, daughter, and asymmetric surfboard, 1976.
Photograph: Bob McTavish Collection.

- Bob McTavish : The Asymmetric Story
Seanotes, August/September 1978, pages 38-39.

At the end of the 1970s, small wave performance surboard design was split almost evenly between the (original, but by now highly modified) single fin and Twin-fins, as ridden by Newcastle's Mark Richards, one of the elite surfers of the period.
In the early 1980s, Queenslanders, Peter Drouyn and Peter Townend introduced asymmetric twin-fin surfboards, with a small fin on (their) forehand rail and a larger fin off-set towards the backhand rail.

Right:
Peter Drouyn: Asymmetic Twin Fins, 1980.
Photograph : Jeff Hornbaker.
Surfing, Volume 19 Number 9, September 1980, page 87.

Right:
Peter Townend: Bi - Fin ,
Bronzed Aussie Surfboards/ G & Surfboards, 1981.
Photograph : Guy Motil
Surfer, Volume 22 Number 10, October 1981, page 42.

Asymmetrical board template and corresponding asymmetric fin placement.

Also see
Peter Townend: Two, Two, Two Boards in One
Surfing, Volume 17 Number 6, June 1981, page 27.

During the 1980s, asymmetric boards had a brief popularity with sailboard and snowboard designers.

The Assymetric Fin Experiment, 2013.

In May 2013, Ken Grieves donated a Bombora sailboard shaped by Mark Paul circa 1995, retrieved from a northern Sydney suburb kerbside, to my collection.
Unusually, it was fitted with four fin boxes and three fins.

The foot straps were removed, the fins replaced (photograph right), and a legrope attached before the board was ridden on four waves for a reasonable distance.
These were five foot (that is, the wave face, after Bascom, 1964) right handers, my forehand, and in a stron off-shore wind.

Despite the clear difficulty in adjusting to a "new" board, it felt "more precise" on my forehand and "losser" my backhand.

Encouraged by this initial test, I began collating and researching previous approaches to asymmetric design in surfboards and fins, which comprise much of this paper.
Applying the concept in 2013, such asymmetric fin experiments would be best carried out:
- by a team of skilled test pilots, of varying stance.
- over a range of conditions,
- on standard sized Thrusters, fitted with FCS, or similar, plugs,
- with the trailing fin offset approxinmately 1 1/2 in. to the rider's forehand rail.

Test pilot reports, which may vary for fore and back hand waves, offer three basic options:
1. Some improvement in performance.
2. Some detriment to performance.
3. No perceived difference in performance.

Unfortunately, such a program is beyond both my current resources, and my ability.
However, to demonstrate comittment to the concept, in November 2013, a second finbox was fitted to my current Malibu board, #214, by DSN Surfboards, Gerringong.
The new box was set 1 1/2 in. from the centre line, and re-set with the previous fin combination, which is in itself, mariginally, asymmetric.

Centre fin: (Unknown) sailboard fin, 10 1/2 in. x 4 in. b @ 8 in., with Canard fin, 2 in. x 1 1/2 in. b.
Left Fin: FCS TC Red Line, 4 1/2 in. x 4 1/2 in. b @ 16 in.
Right Fin: FCS Drive, 4 1/2 in. x 5 in. b @ 16 in.

Photograph, right.
( Yes, the FCS Drive fin is designed for the left hand rail)

The Surf Tests
1. #216
1. Two-three foot left and right peaks: felt tighter on forehand, little difference on backhand.
2. Two-three foot righthand walls: felt tighter on forehand, more stability/control on the nose.
3. In the same surf conditions, the board was also ridden in a "blind test."
Due to devious concealment on my part, the second test-rider, who had ridden the board previously, was not aware of the reconfiguration upon entering the water, and subsequently reported "no difference."

2. Other
Feedback is invited from any surfboard rider who carries out this experiment.

Conclusions

Geoff Cater (2013) : www.surfresearch.com.au : The Asymmetric Fin Experiment, 2013.
http://www.surfresearch.com.au/a_afx.html