Surf Equipment Series: Twin Fins Explained

“What fins do you recommend?”

This is the most asked question by my friends and anyone that orders a twin fin from us.

It’s a GREAT question and the answer can be very COMPLEX.

This week is the start of a NEW SERIES. For the next few weeks, we’re going to be exploring our surfboard equipment.

I did the math today and I’ve been surfing for close to 24 years and within those 24 years, I had a time of surfing nearly every day for probably close to 10 years. 

With that said, I haven’t fully immersed myself in the fin world until recently. 

I’ve been riding futures fins for the majority of that 24 years and I’ve pretty much only stayed with 2-3 different sets of thruster (3 fin) fins. 

Those would be: 

The AM-2 (Al Merrick) - My go-to for steep/good waves in CA.

The TP-1 (Timmy Patterson) - My go-to for pivot in quick beach-break surf.

The Tokoro: My go-to for Hawaii boards.

This week we’re going to unfold some parts about twin fin design. I’m hoping to simplify and help open up a new world for us to explore. This won’t be everything but it’s a START.

Per Greenlight Surf Supply:

“The overall Size of the fin will make a big difference in the performance. A larger fin will have more hold and provide more control in bigger surf, where a smaller fin will be loose and somewhat more forgiving, but lack the drive and control needed in bigger surf.

The Base is the part of the fin that is attached to the board. A wide, or long fin base will help to produce more drive and will allow you to draw out your turns. A narrow, or short fin base will be a little easier to turn, but will produce less drive.

The Depth of a fin is how tall, or how deep into the water the fin goes from the bottom of the board. A deep fin will have more hold and stability, whereas a shallow fin will provide more release when throwing your tail around in turns.

The Rake of the fin is how far back the fin tilts or sweeps. The more rake you have in your fin, the more drawn out your turns will be, and are preferable on bigger days or when there is a long wall to work with. An upright fin will pivot a little more and will be more useful on weaker or junky days.

The Foil of a fin is the aerodynamic shape of the fin from front to back (much like an airplane wing), and help to create some lift under the board. Fins are usually thicker around the center and taper out towards the edges. There are a few basic foils and many variations of these. Side fins (found on twins, thrusters and quads) are usually flat, or sometimes curved inward on the inside, with it’s foil on the outside. Center fins usually have equal foil or double foil, on both sides. Usually found on single fins, the center fin on a thruster, or sometimes the rear fins on quads and some keel fins on traditional fishes.”

NOW I know that’s a lot, especially if it’s your first time diving in…

Take a second and try to retain what you can for now.

Below I’m attaching a few images to help you break down what set of fins my best suit your situation. 

Ie: If you surf points everyday, maybe a keel fin (more base, more rake) might make more sense for those fun clean days. Or maybe you surf Huntington Beach everyday and you need a fin with more pivot (less base, more upright, with added foil for lift). 

Given all this information, my best advice is to grab 2 different sets and journal your sessions. Keep track of the type of waves you’re surfing, the wind conditions, the board you’re placing the fins in and how they feel. 




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