Surfboard Fin Details
7 commentsFins are the bits that poke out from underneath the surfboard. The purpose of the fin is to help steer your surfboard. They all have a similar curved appearance but come in a variety of shapes, sizes, and types of flexibility depending on a surfer's needs. There are two general types of fins: glassed-on and removable. The only difference between the two is that you can take out your removable fins when you like; all other performance properties are based on their measurements. Let's take a look at the fin in detail.
Fin Measurements
Depth
The depth is the measurement from the tip of the fin to the base of the surfboard (not the end of the fin plug), and it is essentially how far the fin goes into the water. The fin depth effects how the board "holds" in turns. The deeper the fin goes, the better the control is in the turn.
Remember: depth = how far the fin goes into the water!
Base Length
The fin's base length is measured at the widest point of the fin, where the fin meets the bottom of the board. The base length determines the board's speed and drive. Fins contribute more speed and greater drive with longer base lengths. Want to go fast? Think long base!
Remember: base length = how much speed and drive the fin provides!
Fin Plug (Removable Fins Only)
Fin plugs slot into the fin box on the base of the surfboard. The fin can then be secured in place for surfing. Fin plugs come in different shapes and sizes depending on the type of removable fin system. Below is a close-up image of an FCS™ Fin System showing the fin plug, fin box, and fin screw. (The fin screw is used to tighten the fin into place once it has been slotted into the fin box.)
Remember: fin plug = the plug used to attach a removable fin!
Removable Fin and Fin Box
Glassed-On Fin
Rake / Sweep
This has nothing to do with gardening, I'm afraid. Rake — also know as sweep — is the distance the fin tip curves away from the base. The rake affects the turning ability of the board. The smaller the rake is (i.e. the greater the tip is offset from the base), the less maneuverable the board will be and the longer and more drawn out the turns will be. The larger the rake is, the greater the pivot and the more maneuverable the board will be. Rake is also referred to as Sweep.
Remember: rake = fin offset, not gardening implement!
Next we talk about flex, replacement fins and fin positioning. Why not find out more about fins.
Don't forget to get more information on the underside of a surfboard, including the different bottom contours.
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How much more performance should I expect if I go from a bottom of the line FCS glassflex (M3) to something like the Composite PC3?
Like should I see any difference in the actual feel of the board if they have the same shape?
make your own fins
Where do you start? Are there fin kits available?
I'm 70 yrs old and riding my 1st single fin log since the early sixties. It's really heavy, wide and thick; and since I ride mostly beach break waves with steep and very quick takeoffs, I have a heck of a time getting into waves, not like back in CA where I could just cruise into waves, especially point surf waves. When the waves are big, I can get in early and turn off the wide and thin foiled diamond tail and walk up to trim. I'm using a 9.75" Greenough flex fin with a longish rake. Would a longer pivot fin help or should I get rid of the board and go back to riding a performance 2 + 1 hydro hull (Stewart) now that I'm in surfing shape again?
@ ElKayWitz : a pivot fin is going to help you turn with more ease, makes your board more responsive and reduces your turning ark. i think that fits to bumpy beach breaks! from a bigger pivot finsize you can expect even more output in reactiveness, drive and acceleration down the line but could soon feel too "bitey". Just like driving backwards with the car too fast, you might experience the steering to responsive once you cross a certain speed level. going slow the higher manouverability helps you well to steer confident into the parkinglot (or wave).
there is a mixup in the article! more rake makes your board less manouverable. the off-centered tip stabilises and resists the turning movement