Experimental Quad Fin Surfboard – Speed, Drive & Diamond Tail Design

Sometimes the most interesting surfboards come from making something for yourself.

There’s no customer brief to follow and no need to fit the board neatly into an existing model. You can take a few ideas that have worked on different boards, blend them together and see what happens in the water.

This 6'0 experimental quad fin is exactly that.

Dimensions: 6'0 × 19 7/8 × 2 3/8 – 30 litres

It sits somewhere between a performance shortboard and a more user-friendly hybrid. I wanted plenty of speed and drive, but without making something that only works when the waves are perfect.

And then there's the colour.

The bright pink, grey and black resin tint certainly makes it hard to miss.

I've built thousands of surfboard files in AKU over the years. One of the benefits of that is being able to look back at different boards and recognise little design elements that worked particularly well.

With this board I wanted to bring some of those ideas together rather than simply reproduce an existing model.

The deck is relatively flat, helping distribute foam without making the board feel excessively thick.

Through the front half I've kept the rails softer and more forgiving. Moving towards the tail they transition into a harder, boxier rail, with a clean edge beginning just forward of the fins.

The idea is to have some forgiveness and flow through the front of the board, then increasingly more release, response and bite as you move onto the back foot.

 

Why a Diamond Tail Quad?

I've always liked diamond tails.

A diamond effectively shortens the rail line compared with carrying the outline all the way into a square or squash tail. That can give a board a really nice combination of drive and release.

Pairing that with a quad-fin setup was something I particularly wanted to experiment with.

Quads can generate serious down-the-line speed because you've removed the centre fin, but I didn't want this board to feel excessively stiff or locked into its line.

The goal was speed and drive without sacrificing the ability to break the line and turn.

That's where the combination of the tail, rails, rocker and bottom shape becomes important.

First Surf Feedback

It's still early days with this prototype, but so far I'm really impressed.

The standout has been the drive.

I've been riding twins quite a lot, so I was interested to see how going back onto a quad would feel. Surprisingly there hasn't been that adjustment period where you're fighting the board or trying to figure out where it wants you to stand.

It immediately felt natural.

There's plenty of speed, it turns easily and so far I haven't experienced the feeling of the quad becoming too tracky or locked in.

The waves I've tested it in haven't exactly been perfect either, which in some ways makes the early feedback even more encouraging.

I'm looking forward to getting it into some clean, powerful surf and seeing where its limits are.

The board even though a prototype does everything I want from it and some , stoked straight of the bat it goes unreal and next stop Indonesia. For some more surfing it in good waves .

Design of the bottom shape

 The bottom contours run from a single concave into a double concave, finishing with a subtle amount of V through the tail.

The single and double are there to help generate and maintain speed, while the V helps the board transition from rail to rail.

Rather than designing a quad that simply wants to race down the line, I wanted something I could push into a turn and redirect easily.

That's been one of the most encouraging things about riding it so far.

The rocker is balanced but slightly flatter than what you'd normally see in a high-performance shortboard.

Again, that's deliberate.

A little less rocker gives the board more natural speed, better paddle power and helps it carry through flatter or weaker sections of the wave.

There's still enough curve to fit into better waves and surf in the pocket, but I didn't want to sacrifice everyday usability chasing a highly specialised performance rocker.

For me, that's where modern surfboard design gets interesting.

It's relatively easy to make a surfboard fast.

The harder part is making a fast board that can turn, release, change direction and then regain its speed without interrupting your flow.

Surfboard Design Never Really Stops

After shaping surfboards for a long time, I still think experimentation is one of the most important parts of progressing.

Computer design gives us incredible accuracy and the ability to revisit thousands of previous designs, but there's another part that is much harder to quantify.

It's experience.

Shaping boards, riding them, listening to other surfers and gradually developing an intuition for how seemingly small changes to rails, rocker, bottom contours, tail shape and foam distribution affect the way a surfboard feels.

This board is really a combination of all those things.

For now, this diamond-tail quad prototype has plenty of speed, heaps of drive and a surprisingly loose feel.

And that bright pink resin tint isn't exactly hurting it either.

More testing to come. Stay Tuned .