How to Choose Fins for Your Surfboard

by Central Coast Surfboards Admin February 14, 2022

What's the most important feature of your surfboard? The foam? The quality of the glass job? The traction set-up? While all crucial to performance, these things can be less than perfect and you'll still be able to surf: but without fins? There are only a few surfers out there who can surf with control on a board lacking fins. Plus, once your board is shaped, glassed, and cured, there's no way to adjust the core (foam) or shell (fiberglass/etc.) to reduce weight or change flex to alter its feel. But, throw some new fins in the bottom, and you've got an entirely differently behaving board.

Choosing the right fin set-up can seem overwhelming. But if you want to properly dial-in your board for a variety of conditions and surf better than you thought you could, keep reading, and check out Central Coast Surfboards' fin breakdown.

How to Choose the Fin You Want

Template/Shape - For waves where you have room and time to set up for and complete turns, think swept-back, or "raked." In hollow beach breaks, more of an upright, "pivot" shape will let you fit turns into a tighter, smaller curve. A "neutral" or "balanced" template performs somewhere in between, allowing you to make turns with any kind of arc rather than a square corner feel more natural, while still enabling big snaps under the lip when the mood strikes.

If you live to get vertical in the pocket, and/or surf waves where you need to get from the bottom to the top and back down again as quickly as possible, tend toward Pivot.

Keep in mind that drawn-out doesn't exclusively mean burying twenty-yard roundhouses. If you're wrapping carves in the pocket and trying top -to-bottom full face carves, a fin with some rake to it will feel more natural. Go for a neutral template for average waves and a rake template for steeper and/or faster waves.

Template Equivalencies

Futures	Captain Fin	FCS
Rake	Drive	Accelerator/Carver
Pivot	Pivot	Reactor
Neutral	Balanced	Performer
Keel	Keel	Keel

Construction and Flex - Aggressive, powerful surfers will benefit from a stiffer fin, while surfers who like to flow and finesse their waves should try a fin with more flex. The stiffer the fin, the more leverage a surfer has to put on it in order to get speed.

Performance Characteristics - If you like the way a fin turns but it's just too much work, try the same shape/foil in a construction with more flex. If you're overpowering your fins so they're mushing out in or feel sluggish out of turns, try stepping up the stiffness.

Fin Performance

A fin's performance can be defined by its ability to provide drive, how easily it releases, and how it turns. Drive can be defined as acceleration and maintaining speed throughout a turn. Generally a longer base provides more drive. Fin release indicates how easily a fin will break free from its turning arc, ie. allow a tight snap at the end of your set-up turn. Several factors, including fin size, rake/sweep, and fin array affect release, but a rule of thumb is that less area in the fin tip equals more release. How a fin turns, or pivots, refers to how tight an arc the fin wants to draw: tight and snappy, or longer and drawn-out.

Fin measurement terms

Area - A measurement of how much two-dimensional space a fin's template takes up, translating to the familiar "large," "medium," "small" when talking about fin sizes. Fin area can be distributed differently, so two fins measuring the same in area might have unequal bases, heights and rakes, and thus will perform differently. Generally larger fins have more hold and are better suited to heavier surfers, while smaller fins have less hold and are intended for lighter surfers.

Base - The length of the bottom of the fin parallel to the bottom surface of the board. A longer base provides more drive enabling drawn-out turns with more arc. Less base makes a board easier to turn quickly but sacrifices drive through longer turns.

Height (depth) - How far the fin reaches into the water from the bottom of the board. Measured from the base of the fin to its tallest (deepest) point. Taller fins will hold better, but won't release as well as shallower fins for tail drifts and fins-free turns.

Rake - Rake is the horizontal distance from the trailing tip of the top of the fin to the rear point of the base. With more rake a fin appears "swept-back" compared to an "upright" fin with less rake. More rake equals more hold, allowing you to make longer, carvier turns more easily, but makes snappier turns less fluid. A more upright, or "pivot"-style fin is great for tight, quick, short-radius turns and snaps, but will not hold longer turns as easily as a raked fin.

Foil - The fin foil is the profile of the fin that water flows across, and influences the fin's overall performance. A 50/50 foil is typically found on single fins and rear thruster/tri fins. Flat foils are usually used on the inner surfaces of the leading fins of thruster and quad sets. A curved inside surface, called inner foils sometimes used on the leading fins of thruster and quad sets, is used to generate lift and speed, making inner foils well-suited for smaller surf.

Flex - How much a fin bends from side to side is called flex. When a fin flexes and snaps back to its original position, speed is generated. Flexier fins tend to make a board feel looser, while a stiffer fin has more hold and feels more secure. Flex patterns are manipulated to create fins that have any combination of drive, speed, response, and hold.

Basic Fin Set-Ups and Types

Single or Double Tab - Most surfboards with removable fins have either FCS/FCS II or Futures fin boxes, and are only compatible with that type of fin interface. FCS and FCS II (or twin tab) fin boxes have two slots with a set-screw in each, while Futures (single tab) boxes have one slot running the length of the box with a set-screw at the leading end only. Single-fin boxes have one slot running the length of the box also but are much longer than a Futures/single tab box and do not have a set screw.

Terminology

Thruster (tri): Three fins of roughly the same size. Some thruster sets have a smaller center fin for more release. The center fin has a 50/50 foil with the two outer fins having a flat or curved foil in the inner surface. The thruster is the most common fin set up, balancing speed and control.
Quad: Four fins, grouped in twos on the four forward fin boxes. The center fin box is not used. Quad set-ups provide more speed than a thruster with more hold than a twin.
Twin: Two fins in the forward outer boxes. Twin set-ups are known for speed and looseness.
Twin + 1: Two larger fins in the forward fin boxes and a small trailing fin in the rear fin box. Fast and loose with more hold than a regular twin set-up.
Single: One large fin in the center of the board. Single fin boxes are specific to the single fin design, not to a brand's interface. Generally, single fins should be as tall in inches as the board is in feet. Although for mid lengths, going smaller makes the board more responsive and maneuverable.
2+1: A single fin with two smaller forward fins, called side bites, on either side of the board. Similar to a thruster fin box set up.

Number of Fin Boxes - surfboards with removable fin systems will have anywhere from one to five fin boxes. Five fin boxes allow thruster, quad, twin, and twin + 1 set ups. All five fin boxes are not usually intended to be used at once. Some fins are sold in sets of five, allowing for thruster and quad set-ups to be swapped out. 2+1 set-ups use a long single fin box in the center and two FCS/FCS II or Futures fin boxes forward and closer to the edge of the board.

The best way to really understand how different fins behave is to try them. Swap with friends, and buy a new set every new board or two. Eventually you will know what to expect from any fin just by looking at it and knowing a little about its flex.

Once you have a few different fin set-ups and have a handle on how they perform, try running them together. Mix the front fins from one set with the trailer of another. By shaking up the system, you may discover the secret combination that magically transforms you into the surfer you always knew you could be.