Fin Flex

We have covered some of the basics in our first fin article, so now let's continue and talk about fin flex. Fin flex is the amount of movement of a fin from side so side. The stiffer the fin is, the less movement from side to side it will have, and thus the less Flex.

Stiffer / Lesser Flex

• Reaches maximum flex during a turn.
• Releases quicker, leading to quicker turns.
• Has less drive.

Greater Flex

• Takes longer to reach maximum flex.
• Takes longer to release.
• Has greater drive.

Fin Foil

Fin foil is the curve of the fin from front to back and from tip to base. The foil and fin thickness determines how much and where on the fin that flex takes place when turning. Different foils give the fin its different performance characteristics.

The fin on a single-fin surfboard and the center fin on a tri-fin will have a foil on both sides. This ensures the fin reacts evenly when turning in both directions.

The outside fins on a tri-fin surfboard are a little different. They have a foil on the outside and will be flat on the inside. This flatness on the inside aids in a quick release when transferring from rail to rail.

Fin Brands

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  Guest

  on Jan 22, 2020

  i think there is a mix up! higher flex results in less drive, because the effective area "bends away" under the pressure of the water, just like loosening up the sail on a sailboat when a gust of wind comes in is not gonna get you out extra speed. In exchange you get an easier and more forgiving handling than keeping the sail tight no matter what.

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  Paul

  on Jul 27, 2020

  I completely agree with the comment above. More FLEX, less Drive.

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  Clark Matsont

  on Sep 22, 2020

  A have A-Flex 9" fin and Im getting these small cracks inside the fin, any ideas what's going on?