What is a Twinny? The Ultimate Guide to the Twin Fin Surfboard

Last Updated on November 29, 2023 by Matt Hapgood

8-10 Minute Read

Originally made popular during the 70’s, the twinny or twin fin surfboard is having a bit of a resurgence of late.

Don’t know where to start, or don’t know what a twin fin surfboard is? Read on and find out all about twinny’s in our ultimate guide!  

When we refer to a twin fin, we are basically talking about any surfboard with just two fins (just to set the record straight).

When most surfers think about twinnies – we tend to think, FUN!

In this Ultimate Guide to The Twin Fin Surfboard, we will take a closer look at the beginnings of this fin set-up, examining the main events and characters in the consolidation and dissemination of what eventually became a revolutionizing design-feature come board model.

WHERE DID TWIN FINS COME FROM?

The surfing world began to change radically the moment trailblazer Tom Blake, at his home in Honolulu in 1935, bolted a foot-long, four-inch-deep speedboat metal keel to the bottom of his surfboard. But it wasn’t until the 1940s that surfers across Southern California began to tinker with this new apparatus, creating their own wooden versions of fins and attaching them to their boards to see just how far they could push the limits.

Among them was Bob Simmons, an innovative surfer and board designer from Los Angeles.

Simmons started experimenting with twin fins (or the “dual fin” design, as he called it) in the late ’40s and early ’50s, mainly as a way to improve the stability of his renowned, wide-tailed balsa surfboards. The development of the double-finned surfboard received an important boost in 1967 when brothers Nick and Bear Mirandon of Surfboards La Jolla in San Diego came up with the split-tailed, Twin-Pin model.

But it wasn’t until the turn of the decade when the word “fish” came into the surfing lexicon, that twin-fin surfboards became a thing.

HOW THE FISH MODEL HELPED POPULARISE TWIN FINS

Noticing how his swim fins caused drag when hanging off the sides of his pintail kneeboards, Steve Lis, a kneeboarder from San Diego, felt compelled to think up a solution.

In 1967, Lis reshaped the pintail of one of his stumpy, blunt-nosed boards into a split tail, and added a pair of keel fins to the bottom, thus creating a design of his own – the Fish.

Having been invented with kneeboarding hollow waves in mind, the model remained in the shadows for a while. It was only when some Californian surfers started trying to ride the fish whilst standing that the thought of adapting it for stand-up surfing emerged.

The first watershed for the Fish – and, consequently, twin fins – was the outstanding performances of Jim Blears and David Nuuhiwa at the 1972 World Championships in San Diego, during which they placed 1st and 2nd respectively, both riding Lis-inspired boards.

And whilst their performance put the fish under the spotlight, the fact that it transpired in tiny surf and that this particular design was incredibly difficult to tame in anything over four feet, caused the fish to be labeled a small-wave design, thus hindering its potential popularity.

Nowadays, although still a predominantly small-wave board, we also tend to see the fish as a user-friendly craft. This is due to the micro-adjustments the model has been suffering since the 1990s when shapers like Matt Biolos of Lost… Surfboards began directing the concept toward a more marketable and modernized path.

This not only reignited interest in the original Lis model, but also set off a wave of experimentation that led to the creation of fish-like crafts surfed by the likes of Rob Machado, Craig Anderson, and Dave Rastovich.

MARK RICHARDS AND THE PERPETUATION OF TWIN FINS

The second major turning point for the Fish – as well as for twin fins as a design feature – occurred in 1976, when Hawaiian Reno Abellira brought a Steve Lis model along on a trip to Australia.

He met future world champ Mark Richards, who in the following year made some modifications to the 5’3″ fish Abellira used during the competition season.

Assisted by Hawaiian shaper Dick Brewer, Richards increased the board’s length to 6’2″, narrowed and refined the swallow tail, and, more importantly, switched the twin-keel fin set-up for a pair of more upright, six-inch fins, placing them along the rails, roughly eleven inches from the tail.

The result was the iconic MR twin-fin model, the one he used to win four consecutive world titles from 1978 to 1982.

After Richard’s first world title win, the notion of surfing a dual-fin surfboard stopped seeming so absurd. This version of the twin fin, described by its creator as “the ultimate small-wave board”, compelled surfers to overlook its pitfalls and focus on its potential.

It also made the MR model a best seller, with tens of thousands of reproductions sold worldwide. And even though the design still wasn’t the easiest to be tamed, Richards’ refinements potentialized the twin-fin configurations so that it allowed for a wider range of turns and maneuvers.

Which, in turn, led to a push in the limits of performance whilst also teasing the idea of introducing yet another fin.

WHY ARE TWIN FIN SURFBOARDS IMPORTANT? 

Now that we know a bit more about how the twin fins came to be, it is important to underscore the reasons why they came to light. And in surfing, design features only endure when they offer something unique – and that has been tried and tested by myriad surfers, of various levels, in wide-ranging conditions.

Otherwise, they remain a niche choice – or they die away altogether. In the case of twin fins, their tenacity is a combination of the right-place-right-time scenario in which they were invented with the right amount of versatility and charisma.

The first example relates to how, despite modifications in specs and materials, the concept of a dual-fin surfboard – and, to a large extent, its performance spectrum – remains pretty much unchanged since the 40s.

Even before Mark Richards transformed the twin-fin from a mere design feature into an actual board model, two fins had always been synonymous with speed and stability – both factors that owe to the placement of the fins and the way the water channels between them, and promote rail engagement as well as that gliding feeling.

This is exactly what surfers had been looking for/needed. This is exactly what makes all twin fin surfboards the same.

The second example has to do with its mutations – or rather, its propensity to mutate. Proto double-finned surfboards featured two keel fins placed pointing forward, which created less drag and improved the board’s potential to track down the line; the MR twin fin had both fins angled inward (toe-in) and leaned outward (cant), which reduced its tracking potential but was in line with Richard’s desire to carve powerful, drawn-out arcs.

Nevertheless, both versions used two fins to achieve something that couldn’t be done with single fins, namely to redirect the board with more ease by using one fin as a pivot point for the other.

All twin fins benefit from the aforementioned properties in one way or another, which makes this kind of surfboard an ideal go-to for small-to-medium surf. At the same time, all twin fins also share the same drawbacks, in that their pivoting tendency makes them less and less reliable the bigger and more powerful the waves grow, particularly when bottom turning.

Given the evolution of materials and design, the performance of twinnies has improved, and many surfers like Craig Anderson and Ozzie Wright have been taking them out when the waves are overhead and hollow – check the clip below.

TWIN FIN PERFORMANCE 101

After drooling over and caressing a newly found, soon-to-be-tested surfboard, the first thing most surfers think about is how it will feel in the water.

If the board on your radar happens to be a twin fin, there are two main things to bear in mind. First, this (usually) is more of a small-to-medium wave sort of board. And second, it is more about fun than high performance. It is both special and specific.

It is a different style of surfing altogether.

Regarding the first point, it is worth noting that the ideal conditions for a twin fin are dependent on the type of twin fin you are riding. But generally speaking, the majority of twinnies will show their true colors in point-break kind of waves; waves that have open faces; waves that break slowly and/or weakly; chubby, summertime waves.

Sure, you may use them in bigger, more powerful surf. However, there is a high chance they will be harder to control. But if you are adamant, try to pick a twinny with enough volume to ensure you will make the drop, and with a slightly more pronounced rocker to avoid nose-diving.

As for the second point, it boils down to the most prominent feature of twin fins: at least when compared to your traditional thruster, they feel a lot looser under the feet. This skittishness is a byproduct of both the dual-fin setup and their placement and size, which, in turn, induces the surfer to review his notion of high performance.

It will be more about rail-to-rail surfing. It will be about drawing wider arches. It will be about grace – not aggressiveness, which, I think is part of the appeal to a huge majority of surfers. 

Watch this clip of Rob Machado surfing his twinny in France below – Hands up who wants a fun little session like this? 

THE UPSIDES

To put it simply, most twin fins are awesome at speed-generation. And if tapped into correctly, speed results in flow – and flow is the ultimate sign of twin fin mastery.

What you want is to take advantage of the fact that there are no centre fins to restrain the tail and indulge in releases such as fins-free hacks and off the tops. Because twinnies have deeper/larger fins when you put one on rail and carve, the board really holds – but only up to a certain point, which can result in you wildly skipping out! 

Which brings us onto …

THE DOWNSIDES

The scenario changes when the surf gets bigger. Ironically, the very looseness so many cherish on twin fins becomes their greatest enemy when the waves are double-overhead and/or super hollow.

Without a centre fin, the tail doesn’t have enough teeth to bite the water, so to speak. And at higher speeds, any small change of direction can result in a big change of motion, which means it is likely to slip out in critical sections, thus increasing the chances of a (bad) wipe-out.

That said, many other factors need to be taken into account to determine how well a twin fin will perform in bigger surf. Things like the softness of the rails, the shape of the tail, and the steepness of the rocker come into play. But the main elements are the type of twin fin setup you have and the dimensions of your board – both of which we unpack below.

CAN YOU SURF A TWINNY BACKHAND?

Another potential downside of a traditional twin, is how difficult they are to surf on your backhand. Personally, I agree that they can be hard to surf backhand, but only if you are using your thruster approach.

You need to remember you’re riding a different type of board and adjust your lines to the wave accordingly. 

Listen to these guys talking about backhand surfing on your twinny.

TWIN FIN SETUPS

Although twin fin surfboards will not deviate too much from their inherent idiosyncrasies, a way of adjusting their “personality” to fit your style of surfing and/or the type of wave you will ride is by fiddling with different fins.

In the case of twinnies, there are three main setups: keel fins, pivot fins, and twin+stabilizer.

• Keel Fins: This setup is ideal for surfers who seek the more classic twin fin experience; that is, speed, drive, and stylish, drawn-out turns. A standard in the Fish, keels feature a larger surface area than your standard fin. They are also shorter, which means they don’t sit as deep in the water. And their wider base helps with increasing the hold in the water, especially when trimming and bottom turning.

• Pivot Fins: A pivot fin is essentially an upright fin; the most common setup in more modern twinnies. They have both a narrower base and smaller surface area than keel fins. They are also longer, and, as such, sit deeper in the water, which gives surfers more control when putting pressure on the tail. This feature makes pivot fins the go-to option for twin-fin aficionados who don’t want to compromise on performance.

• Twin Fin + Trailer/Stabilizer: Maybe not for the purists, but one thing that frustrates many twin fin surfers is not having that extra bit of hold during take-off in bigger, hollower days. The best remedy for that is to have a removable fin system on your twinnie, and add a stabilizer fin when needed. That way, you can still get the most out of your twin fin and only have to morph it into a pseudo-thruster when the swell picks up and you need that extra bit of bite.

TWIN FIN DIMENSIONS 

Twin Fin surfboards have always varied in shape and size. The most popular design is, and probably always will be the Fish – the epitome of performance, style, and aesthetics. But as of late, with the resurgence they have been going through, dimensions have been varying even more to accommodate high-performance-oriented versions.

Needless to say, the dimensions of your twin fin board will depend on your own height and weight. But as a rule of thumb, smaller, wider, and thicker twin fins (especially Fish shapes) lend themselves to small, mellow surf, where improving paddle-ability and ride duration might be the priority.

To size your board, for intermediate/experienced surfers, aim for around 2-4 inches shorter than your height. If you are more of a beginner, size your board closer to your own height.

As the length of your twin increases and width/thickness decreases, twinnies become more suitable for larger waves and/or higher performance. If that’s the case, the dimensions will usually be complemented by specific tail shapes and more rocker.

MODERN-DAY TWIN FINS

Some newer models onto the market in the last couple of years allow for more high-performance surfing, while still keeping the ‘feel’ of two fins.

These boards tend to work well in a huge range of conditions – they have the free-flowing feeling of a twinny, but the more performance outline and rocker allow you to surf top to bottom in hollower steeper waves. Check out this modern take on the twin from Pyzel – The Wildcat (admittedly surfed by a super-talented guy, Jai Glinderman).

When choosing your twin fin, it is important to consider the type of surfing you will be doing and the kind of waves you will be surfing.

If you seek to glide on clean waves and draw wide arcs, a more classic style of twin fin such as the Fish might be the best option. But if your wave of preference is a beach break and you are into pulling more aggressive turns, opt for a modern-style, hybrid twinny.

And of course, if you can, add both to your quiver!

OUR TOP 3 TWIN FIN SURFBOARDS FOR 2023

If you’re in the market for a twinny you need to check out these boards below – we’ve chosen one modern twin, one classic, and one high-performance. 

CLASSIC TWIN FIN: Channel Islands CI Fish

Anything Channel Islands needs no introductions – and the CI Fish is no different. This model reworks the classic twin-keel design into a modern craft that not only gives the speed and forgiveness of a Fish but also opens up a space for performance usually not associated with the traditional version.

They have done so by blending state-of-the-art concave and foil with the classic ’70s outline and rocker, measuring it to sit between bulky and skinny, thus enabling the drive and responsiveness contemporary boards are known for. And to top it up, Channel Islands partnered with Futures to develop a whole new fin template for this particular model.

MODERN TWIN FIN: Haydenshapes Hypto Krypto Twin

Added to the Hayden line up the Hypto Krypto Twin is a super fun modern take on a classic twinny. Only available with two fin boxes, the HK Twin will excel in small to medium-sized waves.  A fast and playful shape that will put a smile on your face no matter what the conditions. A highly rated twin to add to your quiver. 

PERFORMANCE TWIN: Album Twinsman

If you want to maintain your high-performance approach to the waves but want to try a twinny, the Album Twinsman has got to be on your list. Touted as one of THE best twin fin surfboards, and ripped to bits by Josh Kerr and Asher Pacey in all manner of conditions. 

They are getting pretty expensive these days, and quite a wait on production, but if you are lucky enough to try one, we would thoroughly recommend getting your feet on one of these boards. 

FINAL THOUGHTS

The popularity of the twin fin surfboard will never fade away – and if a design can really stand the test of time like the twinny has, then it’s cleary an awesome design.

Have you recently ridden a twinny? Or been riding them your whole life?  

Hit me up on Twitter and let me know!