Twinzers: The forgotten four fin design

Stu Nettle
Design Outline

Last week I was privy to a private conversation about surfboard design. Fittingly it was held in the carpark of my local pointbreak, the speakers stood near the tailgate of a late model ute while I, the lone audience member, sat quietly at the wheel of my van. Eavesdropping is the impolite term. The protagonists had just been for a surf and one of them was assessing the merits of his craft, a quad, while the other asked ever more probing questions.

Did it go alright?

How did it feel?

Mr Quad said, yes, it did go alright, and yes it felt good, he went on to describe the feeling of the board and its performance in florid language. Clearly he enjoyed surfing it. But then the line of questioning took a turn away from the sensory and toward the scientific:

Why was the board so fast?

Why did it perform differently than his last board?

...and the answers ceased to flow as freely. Mr Quad attempted to respond but he was obviously fumbling.

The conversation caused me to think how little surfers know about board design – and I include myself in that assessment. We may understand what particular design features do – pintails hold a line, twin fins are skatey, thrusters more stable – but we don't always understand why they work. I'm talking about the theory of board design here. The physics of water over fibreglass that makes each design feature behave in its own peculiar way. And in the case of fins, the more there are on a board the harder it is to understand why the board behaves the way it does.

An exception to this is the Twinzer, the fin configuration that's best described as an augmented twin fin. For those that don't know, the Twinzer is a standard twinny with two smaller fins sitting just forward and towards the rail of each larger fin. Early iterations also had a narrow tail for increased hold with a concave running out the back. But it was the fins that were the defining feature. The Twinzer was invented in the late-1980s, refined in the early-1990s, although the theory behind them had been used in aerodynamics for many years previous. Unlike most other surfboard designs the Twinzer incorporates a commonly understood physical concept.

will-jobson.jpgThe fin configuration was first placed on a board by Wil Jobson while shaping in Southern California in the late-80s. For arguments sake it'd be good to know Jobson's thinking when he placed the fins the way he did. Was it just trial and error experimentation, the method that led to breakthroughs such as the twin fin and Thruster, or did Jobson understand the laws of physics before he created the Twinzer? Unfortunately I couldn't get hold of Jobson for this article so the question remains unanswered.

However, for the time being we'll leave the physics and trace the short history of the Twinzer.

In 1988 Martin Potter was in Southern California and rode one of Wil Jobson's new designs. He liked it and took the idea to his shaper at the time, Glenn Minami of Blue Hawaii. Potter had success on twinnies in the early-80s and in the Twinzer saw a way to remove the “terminal skittishness” of twin fins. With a Twinzer among his armoury, Potter built up a head of steam in 1989 and went on to blitz the world tour winning six competitions and the World Title.

In Australia, Stuart D'Arcy was taking notice. In 1986 Pottz stayed at D'Arcy's Cronulla house during the Beaurepaires Open and the two remained friends. When Potter left Blue Hawaii in the early-90s D'Arcy not only offered to shape his boards but also to go shares in a new label, Pottz surfboards. The Twinzer thus became part of D'Arcy's shaping repertoire. In 1991, the Twinzer went into production at Pottz surfboards with some changes to the tail shape. According to Darc the design sold well.

Pottz Twinzer shaped by Stuart D'Arcy

Back in California, Wil Jobson travelled to San Diego and shared his design with Rusty Priesendorfer who was “blown away at the difference in feel from a conventional twin fin”. Rusty subsequently made “quite a few” Twinzer's paying Wil a royalty for his idea.

As well as being a shaper of principle - how many shapers voluntarily pay royalties? - Rusty is also the best person to explain the physics behind the Twinzer concept. To begin with, many people call the smaller outside fins 'stabilisers' or 'sidebiters' but the correct term for them is 'canards'. The canards, Rusty says, “help punch a hole in the water” before the main fins run through it. When turning a twin fin, the inside fin is pivoting and also holding the board in the water. By redirecting the water flow the canard “creates a wider effective base” on the main fin, thereby allowing a higher angle of attack - read: sharper turns - while lessening the chance of them spinning out.

In short, canards prime the water, allowing the main fin to work at its best – reducing drag and increasing foil efficiency. And the principle works across all fluid dynamics. The theory dates right back to the Wright Brothers; the Wright Flyer biplane had canards when it launched at Kittyhawk in 1903. The term 'canard' means duck in French, owing to the fact the French public thought another pioneering biplane, the Santos-Dumon 14-bis, looked like a duck with its stabilising control front wings.

In modern times canards can be seen on supersonic fighter jets, the most well known being the RAF's Typhoon  and the Mirage, used by the French and Australian air forces. Many commercial and private jets also employ the use of canards.

RAF Typhoon with forward canards that increase foil efficiency of the wings behind, the same principle is applied on Wil Jobson's Twinzer

In the mid-90s Rusty extended Wil Jobson's concept evolving it into the C-5. Where the Twinzer was an augmented twin fin, the C-5 was an augmented thruster: it had canards placed outside and in front of the forward fins in a standard thruster set up. Both the Twinzer and C-5 enjoyed a brief period of popularity in the mid-90s before being lost in the rush of retro designs that defined the late-90s marketplace.

However, Twinzers never fully went away, they've always remained around the periphery and with quad fins currently the source of much experimentation it was only a matter of time before shapers began investigating 'the other four fin' design. One of them is Sunshine Coast shaper, and Swellnet's local reporter, Mark Pridmore:

Swellnet: How did you come across the design?
Mark Pridmore: I remember seeing a few in the mags and then saw a Glenn Minami Pottz version about '89. I rode one a few times but didn’t think it went that great, but it was different and I have always been drawn to anything different in design, so I decided to revisit it.

Do you consider it an extension of the quad, or another design altogether?
Not really, although I do enjoy a good quaddy, it's more about being curious about other fin set-ups that offer different performance benefits.

dscn5361.jpgDescribe the feeling.
I think they feel free and fast, kinda like a twinny, but they have the drive and hold of a quad fin yet with exceptional manoeuvrability. They definitely aren’t slidey or too loose like a twinny usually is.

Why the Nubbin fin?
Because it adds hold, and with a wider tail or in bigger waves, or even if you just want to push harder through turns, the Nubbin allows that with no slipping.

Have you ridden it without it?
Yes, sure have I've ridden it with about 10 variations. I had to trial lots of things with the entire set-up to understand it and get my version of it to feel great.

What’s the difference?
Without the Nubbin it's looser and some lighter footed surfers don’t need the Nubbin, but I like to push on rail and the Nubbin allows me to do that. I don’t wanna nurse turns...

Best type of surf to ride it?
I ride mine in everything. My current fave is a little 5’5” wide-tailed thing with the Twinzer set-up but with two small nubbins, as I like the feeling of no centre fin, and it adds hold and drive on such a wide tail. I cant stop riding it, I even took it to Fiji and rode it in waves that were way too big for it. But once I got into 'em it went insane, it's just a magic board for me. It's a big call but it's the best board I have ever ridden and best thing I have ever shaped for myself.

Generally I ride it in head high and under waves, but that's thereality of living on this coast and not the limitations of the fin set up.

Where do you think this Twinzer design could lead?
Personally, I like it more than a quad or thruster, and they go insane, though they may be too different for many people.

Comments

zenagain's picture
zenagain's picture
zenagain commented Friday, 5 Dec 2014 at 1:43pm

Interesting article. I'm on the side of knowing very little about hydrodynamics, I really just go with what feels right for me. I've had some magic boards and quite a few pigs over the years.

I wonder if anyone has ever reversed the fin set up on a McKee quad? Kind of like a faux-twinzer? Be fun to see how that went.

Watashi wa metabo oyagi desu.

zenagain's picture
zenagain's picture
zenagain commented Friday, 5 Dec 2014 at 1:56pm

PS. Magret de canard rôti-

Mmmmmmm!

Watashi wa metabo oyagi desu.

memlasurf's picture
memlasurf's picture
memlasurf commented Friday, 5 Dec 2014 at 2:44pm

Another great article on design Stu. Love this stuff can never get enough of it. Always enjoyed different boards and have a 5'10" twinnie and 5'2" pier pony looking thing, a 6.0 I cut the back off and reset the fins further up (square back no nose I call it) and few other rodents. All good fun and once I get a bit of debt under control I will get one of these.

stunet's picture
stunet's picture
stunet commented Friday, 5 Dec 2014 at 2:55pm

Cheers Memla, was fun to write this one. It also got me pretty keen to try one again. The Twinzer I used in the breakout photo on the homepage is actually my board. I rode a few Pottz' Twinzers in the early-90s and got my normal shaper to have a shot at one. He got the back end right, you can see that in the photo, but the front end owes more to Webber banana boards which were popular at the time. Unfortunately the two ends don't go very well together!

Always loved the feeling of Twinzers though. Might see if I can get him to do another one with low rocker and full nose.

PS: Just realised I've been using the same shaper for over 20 years!

griz's picture
griz's picture
griz commented Friday, 5 Dec 2014 at 3:05pm

Little know fact....Peter Ware , Dale Ponsford & Dave Parkes of Friar Tuck kneeboards were producing the"Twinzer" fin configuration a least 10 years ( late 70's) previous to this " break through " design. Mostly using adjustable fin boxes to dial them in. Strangely with the same channel set up too.
Even mixing them up with reverse curve " ski tails " thanks to Rodney Ball influence .
An unheralded melting pot of original ideas and influence were born between these guys.

pointy's picture
pointy's picture
pointy commented Saturday, 6 Dec 2014 at 6:13pm

I had one of parkesy's with the ski tail.

It was an OK board but I didn't like the hard rails up the front end of it

steen's picture
steen's picture
steen commented Wednesday, 10 Dec 2014 at 12:09pm

Spot on Griz,
Stu you should have a chat with Peter Ware. Legend of the Friar Tuck label. He had this set up running in all his boards a good ten years earlier. He is a wealth of information, get on touch with him. I will send you a facebook link if you want?

steeno

skatement's picture
skatement's picture
skatement commented Friday, 5 Dec 2014 at 8:50pm

I really like my twinzer plus one.
Although mark made mine with the double step in the tail.
Prey for waves....

baldad.

Ellen's clam's picture
Ellen's clam's picture
Ellen's clam commented Friday, 5 Dec 2014 at 8:59pm

Pretty popular on the surfermag forums.

I've played withe the setup, but yet to get it going right. Very very fast though

indo-dreaming's picture
indo-dreaming's picture
indo-dreaming commented Saturday, 6 Dec 2014 at 7:45am

So is the actual fin plug set up different on a proper twinzer to say a standard wide tail quad? (doesn't look like it is)

Ive got to say I've never taken much interest in this fin set up, but this article has made me curious to give them go.

PS. Also love these board design articles.

Damothediver's picture
Damothediver's picture
Damothediver commented Saturday, 6 Dec 2014 at 8:18am

If the plugs are more or less in the same spot as a quad could you get similar effect by simply switching the larger front with the smaller rears??

stunet's picture
stunet's picture
stunet commented Saturday, 6 Dec 2014 at 8:22am

Yeah, it's very different ID. There are no rear fins on a Twinzer. The front fins sit in the same place as a standard twinny, with the small fins (canards) even further in front and closer to the rails. Also, the front fins are usually larger in area than those used on a quad.

If you're not interested in the twin fin feel then Twinzers aren't for you. However, if you like the speed and skatey-ness of twins then you'll love 'em; you get the loose back end feel with just a bit more bite.

wingnut2443's picture
wingnut2443's picture
wingnut2443 commented Saturday, 6 Dec 2014 at 7:00pm

" ... caused me to think how little surfers know about board design – and I include myself in that assessment. We may understand what particular design features do – pintails hold a line, twin fins are skatey, thrusters more stable – but we don't necessarily understand why they work the way they do. I'm talking about the theory of board design here. The physics of waterflow over fibreglass that makes design features – pintails, twin fins, thrusters, etc. - work in their own peculiar way. And in the case of fins, the more there are on a board the harder it is to grasp the relationship between them and so understand why the board behaves the way it does ..."

For me, it's a mind fuck and vertical learning curve, but I love it!.

It's part the reason why I started the FFW Surfboard journey and log my ramblings.

I've had this thought for a while, so throw it in here ... take a thruster set up, use more upright fins and a tad more fin cant for the front (side) fins, add canards. Align the inside edge of the front fins to a bonzer type channel. Cannard as a bonzer type fin, or nubster type fin (maybe a tad bigger) ... put some concave through the fins, so the whole lot sits inside a concave instead of vee like the usual bonzer ...

Impact? How would it go?

It would be a refined C5 (see more about Rusty's C5 here: http://us.rusty.com/us/blog/tag/c5/ )

Thoughts?

EDIT - when I say more upright front (side) fins, I'm thining say k2.1's or the shapers AP02's ... could go the more raked fins like on the C5, but I'm thinking more upright with better foil options will help to improve the overall feel.

Surfboard Design and Construction Kook. Evidence is here: www.ffwsurfboards.com.au
*FFW - Few Fun Waves ... that's what it's all about for me.

udo's picture
udo's picture
udo commented Saturday, 6 Dec 2014 at 9:14pm

Wingnut, going off track of twinzers here but Paul Neilson - encyclopedia of surfing has a short vid of Paul surfing a single fin with 2 almost keel looking front fins added with heaps of cant { 8 seconds] ,very early 70s at a guess...you seen the clip ....Blindboy or brutus any clues on what year ? Mex Sumpter film it I think.

velocityjohnno's picture
velocityjohnno's picture
velocityjohnno commented Saturday, 6 Dec 2014 at 9:18pm

Great article Stu, loved the history of the design write up. I remember talking with a local shaper about them in the mid 90's - never got further than that. The ones Pottz used incorporated a step deck in the tail, no?

singkenken's picture
singkenken's picture
singkenken commented Monday, 8 Dec 2014 at 11:54am

@ Pointy - Parkesey's boards were awesome, I had a Squashtail double channel with the twinzer setup, and the thing fairly flew. Turn on a dime (good for 360's), enough drive for a Kenworth truck, and when you hit the sweet spot in the rocker it would trim like a mini mal. One of the best pre-thruster boards I ever had !!. Mine had kinda 60/40rails forward of the mid-point (reasonably soft).

le-renard's picture
le-renard's picture
le-renard commented Monday, 8 Dec 2014 at 9:07pm

I can’t really see those acting as ‘canards’…Really can’t compare fighter design to surfboards so hastily, the canards on the Typhoon for example are linked to the performance peculiarities of it's delta-wing configuration. They are also (super) computer controlled...not static.

I see these dirtying rather than increasing the flow to the lifting surface of the main fin...(the only way they would 'increase foil efficiency.') Not worth their frontal area drag penalty...

I would suggest the increased drive felt is a function of the more-rearward positioning of the main fins more so than any efficiency of the fore-finlets.

'Trial and error' is still very much used in even the most advanced industries when complex fluid-dynamics are concerned.

the-roller's picture
the-roller's picture
the-roller commented Tuesday, 9 Dec 2014 at 4:54am

The latest from Hal's understudy, Dan Woods.

The best complement a student can give to their teacher is to outdo 'em. Yew!

http://iconosquare.com/tag/sikxzer

steen's picture
steen's picture
steen commented Wednesday, 10 Dec 2014 at 12:41pm

Spot on Griz,
Stu you should have a chat with Peter Ware. Legend of the Friar Tuck label. He had this set up running in all his boards a good ten years earlier. He is a wealth of information, get on touch with him. I will send you a facebook link if you want?

steeno

stunet's picture
stunet's picture
stunet commented Wednesday, 10 Dec 2014 at 5:52pm

Yeah, been looking at some of those fin configs. So different to what was under the hood of surfboards at the same time. Appreciate the offer of a hook up, Steen, maybe in the new year?

caml's picture
caml's picture
caml commented Wednesday, 10 Dec 2014 at 11:00pm

So is le renard correct that the bigger fins are set further back ? Thats not what was explained earlier by stu

stunet's picture
stunet's picture
stunet commented Thursday, 11 Dec 2014 at 10:27am

The fins are set in the same position as standard twinnies - at least they're in the same position as the twins in my collection. That puts them a bit further back than standard thrusters but nothing out of the ordinary.

I'd also like to add that Le Renard has twisted my words: the front fins ARE canards. Canards aren't defined by computers, no matter how super, or by any other advanced technology aspect. It is simply a forewing - or in this case, a forefin - that moves through the water before the main fin. I wasn't trying to compare performance but configuration.

caml's picture
caml's picture
caml commented Thursday, 11 Dec 2014 at 11:23am

By the looks of the pics they are further back than a twinny . Im guessing thats how it works its quite obvious if u think about it