Surf fins are when enable a surfboard to generate speed (known as drive), influence turning radius and how much grip you will have in the wave face and when performing turns.
Yes, surfboard fins matter. The shape of the fin, the angles of the fin and the materials used can give a surfboard a completely different feel. They can add life to what was a lifeless surfboard or make an otherwise surfboard that is too loose have more stability.
It’s difficult to separate one aspect of a surf fins from another given how the characteristics of a surf fin interact with each other. Let’s understand the anatomy of a surf fin and why surf fins matter. A lot.
The Surf Fin Base Length
The fin base is the length (from nose to tail) of the area of the fin that sits directly on top of the surfboard. The longer the length of the fin base, the more drive you can get out of your fin.
A narrower fin base will allow you to do sharper turns.
The Surf Fin Height (or Depth)
The height of a surf fin is the distance from the base of the fin to the top if the fin. The height of the surf in determines the hold a surfer will have when they perform turns.
Greater fin height provides more hold, decreasing the risk of your surfboard sliding out from under you.
Shorter fins don’t provide the same grip but allow for easier tail sliding and for sharper turns.
Surf Fin Size
The width x height of a surf fin make up what the majority of the fin size. The fins size refers to the surface area of entire fin and influences the drive and hold that the fin contributes to the surfboard.
A smaller fin will have less drive and less hold and will allow for sharper pivoting and sliding, while a larger fin will provide more hold and drive.
Surf Fin Rake (or Sweep)
The rake of the surf fin refers to the top of the fin (if the surfboard is upside down) that angles towards the tails of the surfboard. This the “swooping part of the find that makes surf fins look like the dorsal fin of a dolphin or shark.
The rank of the fin impacts the surfboard’s ability to turn. The more rank the drawn-out turns will be. Less rake will make for snappier turns.
Some surfers prefer more rake in their fins for bigger days to help them control speed and their arc when they turn on big open-faced waves.
Surf Fin Foil
The fin foil refers to the width and shape of the surf fin from its leading edge closest to the nose to its trailing edge closest to the tail.
Fin foils are an aerodynamic shape, or in our case it is a hydrodynamics shape, similar to the shape of and airplane wing. The fin foil shape directly affects the flow of water over the surface of the sides of the fin.
Fin foils are either symmetrical or asymmetrical. A fin used on single-fin surfboard will have a symmetrical shape while other fins set up will may have a either a symmetrical or asymmetrical shape to them.
Surf Fin Cant
The cant of the fin is the angle at which the entire fin leans towards the bottom of the surfboard. The more cant a fin has the more turn it tends to give surfer due to the angling of the cant.
The more straight up and down the cant of the fin has the more the fin will provide drive.
Surf Fin Toe
The fin toe pertains to surf fins closer to the rails of the surfboard and not to the a center fin.
The fin toe is the angle of which the fin is place relative to the stringer of the surfboard. A fin tow that is parallel to the stringer will enable a surfboard to go in a straight line fast.
Most fins are toe-in meaning if stretched out the forward portion of the fin it would angle toward the center of the surfboard and will meet the center of the surfboard at the tip of the nose. Essentially the lines of the side fins create a triangle shape with the center point of the tip of the nose of the surfboard.
Surf Fin Flex
The flex of the surf fin comes from the material used in to make the fin.
Plastic stock fins tend to bend when there is pressure put on them through a turn and bend slowly back to their original shape without much benefit to the surfer. Overall, plastic fins will help direct the surfboard but will do so with a sluggish feel.
A fiberglass fin and/or a fin made with higher quality material on the other hand will be rigid and will feel like a natural extension of the surfboard. These fins need a good amount of pressure to flex and when they do they will recoil when pressure is released giving a surfer a boost of speed through their turns.
Summary: Surf Fins
We’ve covered quite a bit so let’s review. When it comes to surf fins there a few things we can sure of more than not. We know that the shape of the fin and the material used matter a lot. Use your newfound knowledge to get yourself a quality set of surf fins if you haven’t already.
If you are looking to build up a quiver of surfboards, consider getting a surfboard with glassed-in fins. The most common surfboard with glassed on fins is most likely a twinny fish. If you don’t have a fish in your surfboard quiver, consider getting one. They are a ton of fun if you take the time to learn to surf it.
When it comes to the surf fin set ups, we know that single fins have their own feel as do twin fins. But when it comes to thrusters and quads the debate of which set up is better is very much active. Decide for yourself and experiment with your surfboards. It’s all part of the fun. Isn’t that why we surf in the first place?