The Keel Fin: From Forgotten Experiment to Hottest Setup

If you walk down any popular surf beach today, you’ll see them. Large, flat, raked-back fins that look more like a piece of vintage aerospace hardware than a modern surfboard accessory.

The keel fin is having a moment. But to understand why it’s the hottest setup in 2026, you have to go back to 1967, a San Diego kneeboarder, and a problem with swim fins.

The San Diego Origins

In the late 60s, Steve Lis was a talented kneeboarder surfing the heavy reefs of San Diego. At the time, high-performance boards were mostly pintails. But for a kneeboarder wearing swim fins, those narrow tails had a flaw: the swim fins would drag in the water, slowing the rider down.

Lis’s solution was radical. He split the tail into a wide "swallow" shape, giving his swim fins space to hang off the back without creating drag. To make such a wide-tailed board work in steep waves, he needed fins that could hold a line.

He looked back to the work of design pioneer Bob Simmons (who was experimenting with twin keels as early as 1948) and fitted two large, long-based fins near the rail.

The "Fish" was born.

The "Dark Ages" and the Thruster Revolution

For a few years in the 70s, the twin-keel fish was a cult favourite, especially in California. It was fast—faster than almost anything else in the water.

But then came 1981. Simon Anderson showed up at Bells Beach with three fins, and the "Thruster" changed everything. Suddenly, the world wanted vertical surfing, tight pivots, and the predictability of a centre fin. The keel fin was pushed into the "retro" corner, seen as a beautiful but limited experiment for old guys or hipsters.

The Great Resurgence

So why did it come back?

Because most of us don't surf like pros on the World Tour. We surf 2-foot beach breaks, sectional point breaks, and fat summer swells. We want glide. We want speed. And we want to stay in trim without working ourselves to death.

In the early 2000s, a new generation of shapers and surfers (led by guys like Rob Machado and Dave Rastovich) started rediscovering the "Fish" and its signature keels. They realized that while the Thruster is the ultimate tool for a contest, the keel-fin fish is the ultimate tool for fun.

Why It Works: Drive vs Pivot

Technically, a keel fin is all about surface area and base length.

A standard upright twin fin is built for pivot—turning on a dime. A keel fin is built for drive. That long base acts like a tracking rail. Every time you push through a bottom turn, the keel projects you forward. It’s a "slingshot" feeling that a thruster just can't replicate.

Today, you’ll find keels on everything from traditional 5’4” sub-surface fishes to 8’0” mid-lengths.

The Fin Blanks Take

At Fin Blanks, we love the keel because it represents exactly what we believe in: that different is fun. Swapping your upright twins for a pair of keels doesn't just change the look of your board—it changes the lines you draw on the wave.

It’s the cheapest way to get that "new board" feeling. And in our Ocean Blue or Salmon fibreglass? It looks as good as it feels.

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Next steps for Nic:

1. Review the history and technical claims.

2. Copy-paste to `/blogs/journal/`.

3. Link to the Keel Fins collection once live.