ProBox Technical Title

Fin Setup Primer

Fin placement can have a dramatic effect on the performance of a surfboard and is one of the main reasons behind the design of our fin box. This primer is geared towards providing our customers with a better understanding of how the various adjustments to the fin setup can affect the performance. At best this is more art than science, but the beauty of an adjustable fin system is that you can go out and experiment for yourself to verify what effect a change in fin placement can have on the overall performance of a board.

This primer will use some terminology that is best explained up front so that we are all speaking the same language.

  • fin triangle or cluster - this is the set of fins, so for a thruster this is all three fins, for a 2+1 longboard setup this is still all of the fins
  • fin setup - this is position of the entire fin cluster as a unit, either all forward all back, spread apart, grouped together, etc.
  • cant - also referred to as fin angle, is the amount by which the side fins are leaning out from the centerline of the surfboard, bottom up
  • fore 'n' aft - this is the position of the fin in the box forward or backwards along the length of the board
  • spread out cluster - this is where all the fins in the cluster are spread as far apart as possible, side fins all the way forward, center fin all the way back, this generally makes the board stiffer
  • compacted cluster - the opposite of the spread out cluster, typically side fins all the way back and center fin all the way forward, makes the board looser and more pivotal

When experimenting with your fin placement always start with the fins centered in the ProBox, then start making adjustments from there, typically this is the position the fins will be in when on the shaper's marks. Keep the adjustments small to start out with as the effects can be quite dramatic. Also play with one adjustment at a time and then test the setup so that you can tell how each type of adjustment alters the performance of the board. Below is a table that attempts to catalog the different types of adjustment, characteristics of the setup, and what conditions the setup is geared towards.

Fin Setup Characteristics Conditions
spread out fin cluster longer turning arc, more common on longer boards or guns larger faster waves, situations where a gun would more likely be used
compacted fin cluster shorter turning arc, the common setup for smaller thrusters wide range, depending on skill and the shape of the board
fin setup forward looser, shortest arc, less hold pivotal surfing on small to medium waves
fin setup normal loose with control, typically the position designed by the shaper versatile wide range of conditions
fin setup back more control, shorter arc, bigger, tube/pocket waves, once again typical for situations for a gun
more fin cant looser with less drive, requires more turning to generate speed small to medium surf
less fin cant stiffer with more drive bigger, faster hollow surf, commonly used in twinnies, guns or toe-in boards

The above table is just a small sampling of the more obvious combinations, there are many more in between or with subtle variations. The intent has been to provide a little insight into the more general characteristics of fin placement.

Obviously, the position and cant of the fins are very important and greatly affect the performance of a surfboard. The smallest change can sometimes have a dramatic effect on the board, but it is not a magic bullet, sometimes the opposite effect can occur. The fin setup is just one piece in a complex dynamic system of shapes and curves that make up a surfboard. Each board is different, as is each surfer, so any changes could have different results depending on the board and the surfer!

Most of the information provided above is applicable to a 2+1 fin setup, except in that type of setup the size of the center fin has a more heavily weighted effect on the cluster. The smaller the center fin the more it will perform like a thruster. Placement of the center fin is going to be by far the more controlling aspect of the performance of a 2+1 setup.

Of course there are other factors that can affect the fin setup, such as the size and shape of the fin, and even the foiling of the fin. Also whether all of the fins in the cluster are the same size, or not. Which is why we believe the beauty of an adjustable system is that it allows the surfer to experiment for themselves to determine what works for them and to help them learn the significance of being able to adjust the fin setup on a surfboard.

This is why we designed our system to provide adjustability, so that it is easy to experiment hands on with fin adjustment.

Get a ProBox fin system and go experiment!