Parting the Water: Part 2 - Fin Shape

Stu Nettle picture
Stu Nettle (stunet)
Design Outline

In Part 1 we looked at the placement of fins on the board and how that caused each design - twin, Thruster, quad etc - to ride the way they do. In this instalment we’ll look at the shape of fins and how that affects water flow and in turn the way fins ride.

Since first being put on the underside of a board, fins have been made in a myriad of shapes - D-fins, hatchets, half-moons and many more - however we’ll only look at the most common modern shapes.

Profile Shapes

When viewed in profile, most modern fins assume a shape similar to a tuna fin: raked backwards with a wide base tapering to a narrower tip. Even keel fins, which we’ll include in the discussion, are a bloated version of the same.

George Greenough in 1970 with a classic fin of the era (John Witzig)

If you recall from Part 1, a board with a fin closer to the middle of the board will be loose though it will lack drive, while a board with a fin near the tail will be the opposite, it’ll be stiffer and have more drive.

The same spectrum from pivot to drive is traversed when considering fin shape: An upright fin will have more pivot, while a raked fin will have more drive. That’s the simple rule, and though fins come in a range of shapes the same principle always applies. However, it’s also worth considering why that’s the case, and there are two reasons.

Rake measure the degree to which a fin is swept backwards

The first is that upright fins - measured from the leading edge where the base meets the board to the trailing edge tip - sit in a narrower column of water, so there’s less resistance when it swivels through a turn. In contrast, a raked fin disturbs a larger column of water when turning; they’re hard to initiate into a turn - hence stiffer - but have more hold when moving through the turn.

The second reason is that raked fins generally have more fin area so there’s more surface to drive off when pumping a board. The opposite is also true, something the author can attest to after recently testing a batch of boutique upright fins that, while very fast and responsive, often slipped while the board was being pumped for speed.

Cheyne Horan's EZ3 fins are an extreme example of upright fins, having no rake at all

Keel fins are a wide base version of the classic tuna fin shape, and they’re predominantly used on fish outlines in a twin fin set up. Keels tick both of the above points: Being long fins they occupy a wide column of water, and they also have a large surface area. The result is a stiff fin with lots of drive, an ideal choice for shorter boards with less rail in the water - such as fish. The keels can provide the drive and control that the shorter rail line can’t.

Another fin worth analysing is the C-Drive. Designed by Troy Clutton, they’re a clever mix of outlines, having both a wide base and a narrow tip. The wide base provides drive, especially through the beginning of turns, while the narrow tip allows for release towards the end. C-Drives still have more surface area than many orthodox shapes, and they also occupy a wide column of water, so all things being equal they tend towards the drive side of the equation. For this reason some surfers choose to ride their C-Drives a size down.

C-Drive fins have both a broad base and a narrow tip

When considering the rule about fin shape - upright equals pivot, raked equals drive - it’s worth considering how this could be toyed with in multi-fin boards. For instance, though Simon Anderson put three fins of equal shape on his board and called it a Thruster, what about if the rear fin was more upright so it had less drag and was looser? What if the front fins were upright and the rear fin was raked..?

Don’t ask me, try it yourself. Report back with your findings.

Cross-Sectional Shapes

From viewing fins in profile, let’s now tilt the axis 90 degrees and look at the shape of fins in cross-section.

George Greenough is generally credited with popularising and refining the tuna fin shape on surfboard fins, and he can be similarly credited with introducing foil to the fin’s cross-section. With sandpaper in hand, Greenough reduced fin thickness, particularly along the trailing edge, and at the same time introduced flex - something we’ll touch upon later.

Cutaway diagram to show the cross-section of a fin and its streamlined shape

From ‘67 onwards, most fins had a rounded leading edge, tapering slowly to a thin trailing edge, the design mimicking the shape of pelagic fish when viewed from above, and for single fins considered the most efficient way of slicing through water.

Despite Greenough’s refinement, many 70’s single fins still had fins up to half an inch thick. In some situations this was desirable as the thickness created drag, and hence control. Cheyne Horan’s attempt to surf large Waimea Bay on a 5’8” single fin is a classic example. The thick fin shaved yards off Horan’s speed but it gave control to a board measuring half the length of a standard Waimea gun. It's worth noting that, not only do modern tow boards measure a similar length to Horan's Waimea board, but specialised tow fins are also thicker than normal to induce drag and provide control.

Cheyne Horan's 5'8" Waimea 'gun' - note the thickness of the single fin

By the time Mark Richards popularised the twin fin a more potent feature was built into the cross-section of fins: asymmetric foil for side fins.

It’s not known who first came up with the idea, however it’s based on the same principle that gives flight to airplanes. That being, a shape that’s flat on one side and bulbous on the other, so fluid flows slower across the bulbous side generating a force towards that side. On an aircraft wing it causes lift, while on a surfboard fin it creates a force perpendicular to the water flow - which results in acceleration towards the outside of the board when turning.

Importantly, not only does a foiled fin accelerate a surfboard into a turn, but it can also generate lift. If the perpendicular force that’s generated is greater than the combined weight of rider and board, the board will want to rise out of the water, thereby reducing drag from surface area and creating yet more speed.

Used on multi-fin boards - which have their fins off the centreline, hence increasing response time - foiled fins turbocharged surfing. Once concaves came along in the early-90s, which also generate lift and drive, surfers had enough speed to take their boards anywhere on a wave, including above it.

On both twins and Thrusters, there was agreement about how fins were shaped. Two asymmetrical foils on twin fins, same again on Thrusters but with a symmetrical fin in the back. But what about quads? What shape works best in quad rear fins..?

Having asymmetric foiled fins in both the front and rear fins of a quad amplifies its accelerating and lift qualities, though sometimes to an excessive level. If you have four asymmetric foiled fins in a quad and struggle to contain it through big turns, it may be harnessed through symmetric fins in the rear which will provide forward drive without an overabundance of lift.

However, with so many factors at play, fins, rocker, volume and everything else, the choice of shape in rear quads comes down to personal preference. Find your favourite set and experiment with flat foiled and double foiled, and keep in mind there’s also 80/20 foils and 70/30 foils that both sit somewhere between flat foils and symmetrical foils.

Before we drop over the clifftop of esoterica, it’s worth mentioning one more design built into fin foils: the inside foil.

When any fin cuts through water it creates drag, which as was noted in Part 1 can be a good thing. However, sometimes it’s not. Sometimes, a surfer will believe their board already offers enough control so will seek to eliminate as much drag as possible.

Whereas foiled fins create a force perpendicular to the water flow, the drag from the same fin runs parallel with the water flow. Inside foils create a pocket for disturbed water to flow, hence minimising the overall drag quotient.

Of all the popular fin configurations, quad fins create the most drag so it’s also the design where you’ll most often see fins with an inside foil used.

Flex

When a fin flexes it causes a distortion of its shape. Many shapers have experimented with flex though the original idea and inspiration flows back, once again, to George Greenough who was seeking to mimic the movements of tuna fins through the water. Unlike tuna fish, however, surfboard fins can, and indeed should, only flex through one plane. Fin-making specialists lay the fibreglass to control this movement.

There's a lot of misinformation around flex, and I hope to avoid it here, however it generally works around the idea of stored energy. When water cuts at an angle onto a fin, it can overcome the stiffness of the material and distort its shape away from the water flow. When the turning weight is released it snaps back into shape. As this generally happens around the tail and the tip of the fin - the thinnest areas - it helps propel the board forward. The effect is often very subtle.

Fin flex is best harnessed by front foot surfers who like to unweight three-quarters of the way through turns. It's also better served in small to medium-size waves. Bigger boards need stiffer fins.

Too much flex, or even uncontrolled flexing, can result in indecisve turns, such as a double pump off the bottom, or a board that's unwilling to drive through a turn on its rail.

Comments

ryder's picture
ryder's picture
ryder Monday, 20 Sep 2021 at 8:37am

Greenough 4A - nuff said...

bbbird's picture
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bbbird Wednesday, 22 Sep 2021 at 8:00pm

"Greenough is credited for the design of the modern surf fin as well as with influencing modern surfing's more radical maneuvers." In 1961 a massive 10 inch protrusion, with a smaller (almost by a third) flexible swept-back model he had copied from the shape of the rear dorsal fin of a tuna. This design had the effect of reducing drag and increasing the handling capabilities of the board; the new surfboard fin, which Greenough called a "high aspect ratio fin", was an elegantly functional piece of equipment, but took around three years to become popular... (& thanks to reshaping Nat Young's fin & then winning the US world championship in 1966)
Nat "Young described Greenough as "The greatest surfer in the world today,"
Source: https://en.wikipedia.org/wiki/George_Greenough

Ronreo's picture
Ronreo's picture
Ronreo Monday, 20 Sep 2021 at 9:22am

Building flex into fins is indeed a fine art. Early 70's fin makers often produced a "humming" vibration that could be felt and heard when turning or at high speed.

Reform's picture
Reform's picture
Reform Tuesday, 21 Sep 2021 at 11:21am

The humming was a fairly common occurrence from a newly foiled fin, due to the back edge of the fin not being foiled to a fine point. ie a flat back of fin edge. This created a vortex where turbulence builds behind the fin and creates the vibration and humming noise and also slowed the board speed considerably. This was remedied by foiling the fin further to where both sides of the taper meet. Ronreo, some of the fins were indeed a work of art. Midget, loved the art of fin making, by layering the fins with varying colours and when foiled produced some pretty nice grain effects, Called rainbow fins (I think off memory) were also much thicker than normal. He would advocate the efficiency of the even taper without any flat spots within the taper. Much like the foil of an airplane wing. These fins had 'bugger all' flex though. Your point about the flexible fins is also a valid one I assume would be unstable and therefore be affected at speed. Thanks.

memlasurf's picture
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memlasurf Friday, 1 Oct 2021 at 9:46pm

I changed some fins over the other day and they hum quite loudly. Not flat at the back, very refined can’t work it out.

Ronreo's picture
Ronreo's picture
Ronreo Saturday, 2 Oct 2021 at 11:51am

Before fin boxes, all we could do was keep sanding the fin down until the humming stopped or side slipping started. Maybe that's how Twizzle began his act.

udo's picture
udo's picture
udo Saturday, 2 Oct 2021 at 12:06pm

Off to Swaylocks memla
Fin Humming or similiar into their search function....

memlasurf's picture
memlasurf's picture
memlasurf Thursday, 7 Oct 2021 at 11:01pm

No luck Udo, sent an email to Noel Salas who designed them but nothing back yet. Put the very similar, though thicker and of fibreglass Futures in and no hum.

blackers's picture
blackers's picture
blackers Monday, 20 Sep 2021 at 9:28am

I know this is all about the fins, but how thin is the tail on Greenough’s board in that first pic?

philosurphizingkerching's picture
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philosurphizing... Monday, 20 Sep 2021 at 12:35pm

spoon

radiationrules's picture
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radiationrules Monday, 20 Sep 2021 at 10:38am

Where do those "swiss fins" - FCS - H4 - fit into the above analysis?

82shoes's picture
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82shoes Monday, 20 Sep 2021 at 11:52am

Stu - "What if the front fins were upright and the rear fin was raked..?
Don’t ask me, try it yourself. Report back with your findings."

I used to have a Chris Garrett "rocket fish" quad. Great board, so fast down the line I could make it around previously unmakeable sections. However, in more peaky, pockety waves sometimes I was frustrated about not being able to get more vertical so i mentioned it to Chris. He suggested trying more upright front fins ..... It worked really well.
It was my first personal experience and insight into how much influence fins have. It was like owning two boards

YoungOne's picture
YoungOne's picture
YoungOne Monday, 20 Sep 2021 at 2:29pm

As always, interesting reading. Thanks Stu.
Just checking one point, though: "That being, a shape that’s flat on one side and bulbous on the other, so fluid flows slower across the bulbous side generating a force towards that side." My understanding is that the fluid flowing past the bulbous side needs to travel faster (not slower) so as to retain the principles of hydrodynamic flow. Using the aeroplane wing as the best example, the air flowing faster over the top of the wing (the bulbous side) results in a reduction in air pressure (as the air particles become more spread out) on the topside of the wing, whilst the air pressure beneath the wing remains more stable. This creates the pressure imbalance that results in lift - i.e. the wing is forced up into the area of lower pressure above the wing, which is how an aeroplane can fly.
Is this wrong, or is it different for surfboard fins underwater?

Craig's picture
Craig's picture
Craig Tuesday, 21 Sep 2021 at 8:28am

That's correct, and applies to all fluids, be that air or water. They're just different densities.

This is a good example.. [edited - poor example as discussed below]

https://static.scientificamerican.com/sciam/assets/Image/2020/XXsaw0220R...

gearoid's picture
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gearoid Tuesday, 21 Sep 2021 at 7:08pm

Not sure about the whole fin thing, but this nicely produced 'flawed classics' thing is complete bollocks.

I would like to know the source, if you don't mind. I have a feeling it could be from someone that has a vested interest in discrediting well proven scientific principles.

Cheers!

Craig's picture
Craig's picture
Craig Tuesday, 21 Sep 2021 at 7:13pm

Oh really? It's from here..

https://www.scientificamerican.com/article/no-one-can-explain-why-planes...

To me it seemed a well balanced and though out piece.

gearoid's picture
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gearoid Tuesday, 21 Sep 2021 at 8:06pm

Cheers Craig,

as you would be aware, there are certain sections of society that are quite visible these days with their distrust of conventional scientific methods. Climate change, vaccines, moon landings etc etc. I think you know what I'm talking about.

Anyway, you will note in the article it says science definitely does know how wings work:

"One exists as a strictly mathematical theory, a realm in which the analysis medium consists of equations, symbols, computer simulations and numbers. There is little, if any, serious disagreement as to what the appropriate equations or their solutions are. The objective of technical mathematical theory is to make accurate predictions and to project results that are useful to aeronautical engineers engaged in the complex business of designing aircraft."

It then goes on to say:

"But by themselves, equations are not explanations, and neither are their solutions. There is a second, nontechnical level of analysis that is intended to provide us with a physical, commonsense explanation of lift."

This is where it gets messy. The author says 'equations are not explanations and neither are their solutions' and I have a fundamental problem with that. The equations and their solutions are the explanation expressed in its most concise and accurate way. If there is a perceived problem with intuitively understanding the concepts that isn't science's problem.

I'm not sure what the article is about, to tell you the truth. It seems like the author is acknowledging the science that explains the concepts but he is saying there is some sort of issue because people can't intuitively relate to the explanation.

Let me know if you seriously think it is a mystery how wings work and I will break it down for you.

Craig's picture
Craig's picture
Craig Tuesday, 21 Sep 2021 at 8:10pm

Yep, gotchya!

I found it a little weird reading it as well. Might get rid of the image.

gearoid's picture
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gearoid Tuesday, 21 Sep 2021 at 8:13pm

No harm done really

I have always thought there is enough magic and wonder in the world without having to make up fake stuff!

If you are the weather guy you will know there is plenty of other stuff science can't really explain.

udo's picture
udo's picture
udo Monday, 20 Sep 2021 at 3:00pm
Taprobane's picture
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Taprobane Monday, 20 Sep 2021 at 4:11pm

That's reminding me of High School Math's lessons.
My head hurts.

udo's picture
udo's picture
udo Monday, 20 Sep 2021 at 4:30pm
memlasurf's picture
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memlasurf Tuesday, 21 Sep 2021 at 1:27pm

Geoff is still experimenting Udo, he shaped this wild looking banana thing with a massive concave last summer for super hollow waves. Had a good local surfer to give it a whorl - think it was a bit of a challenge a bit schizo. Geez he is young there I have only ever known him as one of the tribal elders of the surf crew on the Peninsula with a mop of grey hair.

Taprobane's picture
Taprobane's picture
Taprobane Monday, 20 Sep 2021 at 5:33pm

I rode a set of Greg Webber curved fins for about 2 years. They seemed to go great ,not sure why I stopped using them.

udo's picture
udo's picture
udo Monday, 20 Sep 2021 at 5:41pm

Huge amount of Toe in on those Fins

Taprobane's picture
Taprobane's picture
Taprobane Monday, 20 Sep 2021 at 5:54pm

Thanx for that input Udo. I will have to return to Lesson 1 to remind me how " the toe " affects performance.

brutus's picture
brutus's picture
brutus Monday, 20 Sep 2021 at 5:35pm

Stu, check this out as one of the best single fins made...I actually used them , incredible that we used a much smaller fin but heaps of drive...incredible 1" thick base....I have ordered some from the USA as I think the original idea based on a dolphin fin......like the grand daddy of C-drives which I still rate as one of the best fins , but they work best if you place them 1/2" forward than your normal thruster measurement...
https://www.swaylocks.com/groups/dorsal-fin-plan-shape-dolphin-resource-pic

udo's picture
udo's picture
udo Monday, 20 Sep 2021 at 6:02pm

Bruce Raymond used to make Timber Fins for a Living...?

vbaaccess's picture
vbaaccess's picture
vbaaccess Monday, 20 Sep 2021 at 7:42pm

Kneeboard riders have been experimenting with different fin designs for many year. Hanalei have a extensive range of unique fins on their website. I use Q2 quad fin setup on a David Parkes kneeboard and the drive and hold these have are outstanding. Designed in Hawaii by Robert Mair and made in Australia by Lancelot Pearson. Hanalei fins are leading the way with innovated fin design.
https://hanalei-fins.surf/fins/hrd-kore/

memlasurf's picture
memlasurf's picture
memlasurf Tuesday, 21 Sep 2021 at 1:45pm

They are really weird fins look like they were inspired by Antoni Gaudi's architecture. Have you tried them?

vbaaccess's picture
vbaaccess's picture
vbaaccess Tuesday, 21 Sep 2021 at 3:57pm

I have a pair of Hanalei Q2 Large/Medium quads. They have a wide base but a lots of rack. The Q2 have inside curved foil on all the fins. The Q2 have heaps of drive and hold through turns. A lot of kneeboarders swear by Hanalei Fins including Neil Luke and many others.

Sheep go to heaven's picture
Sheep go to heaven's picture
Sheep go to heaven Thursday, 23 Sep 2021 at 7:42am

Yep good call on the Hanalei fins vb . Plenty of standup surfers using them as well and loving them , The Q2 are amazing fins . They feel like very minimal resistance when passively going along and as soon as you turn and engage the fins they kick in ! Very very fast as quads in down the line hollow surf . I've ridden them in super fast indo freight trains , and they fly

vbaaccess's picture
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vbaaccess Thursday, 23 Sep 2021 at 8:17am

Thank you for your comment regarding Hanalei Fins.

chook's picture
chook's picture
chook Friday, 24 Sep 2021 at 11:41am

I received my new Neil Luke freak model kneeboard this morning, with Hanalei fins. they forgot to include the knee pads, so it's gong to be a few days before I get to try them out.

vbaaccess's picture
vbaaccess's picture
vbaaccess Friday, 24 Sep 2021 at 11:49am

David Parkes pads I guess?

chook's picture
chook's picture
chook Friday, 24 Sep 2021 at 11:54am

yeah... Parkes pads. Neil does his boards through Dave Parkes, it's a bit frustrating...having the a new board sitting there, some decent swell and can't ride it.

Leebo20's picture
Leebo20's picture
Leebo20 Monday, 20 Sep 2021 at 10:57pm

Geoff and Cheyne.
What a combination.
Any reports on how those EZ3 fins go?

udo's picture
udo's picture
udo Tuesday, 21 Sep 2021 at 10:52am
bbbird's picture
bbbird's picture
bbbird Wednesday, 22 Sep 2021 at 8:23pm

Cheyne at Waimea Bay swell of 1983 @1min
https://eos.surf/video/entry/swell-of-1983-waimea-bay/

radiationrules's picture
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radiationrules Tuesday, 21 Sep 2021 at 9:42am

&ab_channel=FCSFINS

anyone tried these? i've heard good reports. design theory sounds logical?

Yippee's picture
Yippee's picture
Yippee Tuesday, 21 Sep 2021 at 10:34am

I have used H Series fins for many years.
Set up ATM is a pair of large H4 front & pair of medium H4s back in a quad setup ('cause they don't offer a quad set yet so have to buy 2 sets).
It has always surprised me that foil technology is very well researched and available, (including CAD modelling programs) yet that info has not been applied to surfing, nor has surfing adopted the empirical methods (tank testing, the hydro version of aeros wind tunnel) that would yield hard info. Well accepted tech in aero & marine industries.
Exceptions include Simmons towing shapes behind a speed boat in the Ala Wai channel (1930s I think?) with a simple device between boat & board to measure drag- (a fishermans' hand held scale, I believe), and FCS's claim with the original H series fin that they were tested in the Tasmanian facility.
Surfing industry is content with the old "shape it and see" method - which works too, just slower to advance.
BTW interesting to note the resurgence in bio mimicry in design, ref GG & tuna/dolphin fins!

seaslug's picture
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seaslug Monday, 27 Sep 2021 at 4:57pm

Yippee, you can buy H4 quad rear fins which are designed to work with both medium & large H4 sets

Yippee's picture
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Yippee Monday, 27 Sep 2021 at 6:40pm

Thanks mate!

udo's picture
udo's picture
udo Tuesday, 21 Sep 2021 at 11:40am
memlasurf's picture
memlasurf's picture
memlasurf Tuesday, 21 Sep 2021 at 1:32pm

Stu didn't you do an article on some professor fella from the Gong doing more scientific investigation some years back?

Craig's picture
Craig's picture
Craig Tuesday, 21 Sep 2021 at 3:12pm

Here you go Melma.. The science of flex with Professor Marc in het Panhuis: https://www.swellnet.com/news/swellnet-dispatch/2018/07/11/science-flex-...

udo's picture
udo's picture
udo Tuesday, 21 Sep 2021 at 2:09pm

Prof Mark Panhuis
----------------------------------------------------------------------------------------

gearoid's picture
gearoid's picture
gearoid Tuesday, 21 Sep 2021 at 7:30pm

From my observations, most recreational surfers get the best result with a set of PL4C380's.

They come in all colours and configurations and you can find a set that has been endorsed by your favourite pro or shaper if you look hard enough.

You can use then in twins, thrusters, quads. They work in shortboards, fishes, mid-lengths and guns. Regardless of your skill level, in fact the less skilled you are ,the better your PL4C380s will feel - especially if you have paid over $100 bucks for them!.

I would have to say that unless you're a semi pro or better, your favourite fin set up will be PL4C38Os.

dastasha's picture
dastasha's picture
dastasha Wednesday, 22 Sep 2021 at 8:27am

SShhhhhh they are hard enough to get already you dont give that away on the forums.

Anything with carbon in will suffice.

udo's picture
udo's picture
udo Tuesday, 21 Sep 2021 at 7:50pm


Craig's picture
Craig's picture
Craig Thursday, 23 Sep 2021 at 10:19am

Regarding that first vid, be great to see the follow up vids he mentions that apparently show the reduction in drag from the base, but alas there are no more on his Youtube page.

udo's picture
udo's picture
udo Thursday, 23 Sep 2021 at 10:01am

Craig's picture
Craig's picture
Craig Thursday, 23 Sep 2021 at 10:20am

I thought this wasn't very scientific. Comments like "you could see the large amounts of spray coming off the fin" are very subjective. How about some flow tanks etc.

udo's picture
udo's picture
udo Thursday, 23 Sep 2021 at 10:27am

Thought the same -Red Fluid Dynamics on there other fins

https://futuresfins.com.au/blogs/news/c-f-d-research-design

brutus's picture
brutus's picture
brutus Thursday, 23 Sep 2021 at 10:52am

here Udo...this is probably the best rundown of fins I have seen, thought you might appreciate....

https://www.surfresearch.com.au/f.html

stunet's picture
stunet's picture
stunet Monday, 27 Sep 2021 at 6:55am

Well that was comprehensive. There may have been something he missed but I can't think of it.

brutus's picture
brutus's picture
brutus Monday, 27 Sep 2021 at 1:12pm

Stu , great article you wrote...I have been doing nothing but test new fins and positions for the last mth or so.......am researching finshapes/foils , fin placements...and a lot of history of where did it all come from.....when I saw that link from the swaylocks Dolphin series...blew me away how comprehensive , informative and a foundation of knowledge for the next generation of fins...more drivey , more faster , more grippier.....more betterous....keep up the good work...

stunet's picture
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stunet Monday, 27 Sep 2021 at 2:56pm

Testing them for a special project? Got something on the boil..?

brutus's picture
brutus's picture
brutus Monday, 27 Sep 2021 at 3:55pm

yeah for now just keeping it quiet.....but you will see my creative best coming soon....new fins and managed to cross a reverse vee with a deep concave Metro......film and book project will keep ya posted....

stunet's picture
stunet's picture
stunet Monday, 27 Sep 2021 at 4:14pm

Looking forward to it.

morg's picture
morg's picture
morg Thursday, 23 Sep 2021 at 11:09pm

Has anyone got any info on those old aeroplane tail shape surfboard fins with straight leading and trailing edges. I had a couple of thrusters with them in the early 80’s and found a photo of one that I recall was a good board. Wouldn’t mind putting a set on a current board to see how they go.

morg's picture
morg's picture
morg Thursday, 23 Sep 2021 at 11:09pm

Has anyone got any info on those old aeroplane tail shape surfboard fins with straight leading and trailing edges. I had a couple of thrusters with them in the early 80’s and found a photo of one that I recall was a good board. Wouldn’t mind putting a set on a current board to see how they go.

morg's picture
morg's picture
morg Thursday, 23 Sep 2021 at 11:09pm

Has anyone got any info on those old aeroplane tail shape surfboard fins with straight leading and trailing edges. I had a couple of thrusters with them in the early 80’s and found a photo of one that I recall was a good board. Wouldn’t mind putting a set on a current board to see how they go.

udo's picture
udo's picture
udo Monday, 27 Sep 2021 at 2:59pm
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udo Wednesday, 29 Sep 2021 at 6:15pm

simba's picture
simba's picture
simba Friday, 8 Oct 2021 at 10:38am

mate sent me this...different concept,sort of.........

&feature=youtu.be&fbclid=IwAR28IyVLPyPziDFpCbP8IxSQXRPwgg7MCIXzqlJsHXF0O8kmYnCVr3QxWWQ&ab_channel=MathieuCrepel

stunet's picture
stunet's picture
stunet Friday, 8 Oct 2021 at 10:43am

That was unreal. I imagine ol' Mick Mackie would dig it too. He's been playing around in that realm for a while.

stunet's picture
stunet's picture
stunet Friday, 8 Oct 2021 at 2:52pm

Thanks for the heads up on this, Simba.

simba's picture
simba's picture
simba Friday, 8 Oct 2021 at 3:48pm

no worries i will pass it on to my mate Bryan.......ol eagle eye