Surfboard Fins or Bust was written on location in the Mentawais by Mike Psillakis of Psillakis Surfboards (lucky Mike).
The surfboard fin. Without question, one of the most important design features in a surfboard that is often overlooked. Fins can make or break a board when it comes to performance.
Here I have broken down just a few aspects of the humble fin, so you can have a better understanding of them and can therefore get the most out of your surfboard.
The fin area is the surface area of the fin. The area needs to be right for your weight, length of board, type of rocker, concaves and so on. Basically speaking, find out the right area for you, and you’re half way there. Fin area can be decreased in the size of the board. For example, in step-ups or guns wherein the tails are narrower and you are using more rail. And vice versa, shorter, wider tailed boards need more area for hold. Same applies with highly rockered boards which need more area for drive.
Fin shape will determine how the fin will react. Fins that are shaped with an upright rake (the leading edge to the tip is of a short distance). These fins will surf loose, with a shorter turning circle. Great for top to bottom surfing, and generally good on small beach breaks. Fins that are shaped with a long rake (leading edge to the tip is of a long distance). These fins are generally stiffer and will work well in down the line point type waves. They generally have more hold and are great for larger waves.
Having said that, you can still have upright fins that offer hold and drive by increasing the base size while maintaining a small tip, such as the TC range. It’s all about personal preference on how you surf, or the type of wave that will determine what fins to use.
The foil of a fin is very complex, and sometimes overlooked. The foil of a fin is determined by how the thickness flows from the leading edge (the front of the fin) to the trailing edge (the back). The leading edge is usually rounded with the thickest part of the foil being around 1/3 back from the leading edge, foiling to a fine trailing edge.
Different types of foils will determine how a board will react. Generally speaking, a thicker foil fin will work well in smaller waves with water flowing around the full foil, creating lift and also turning in a shorter radius. Fins with a lower foil on the other hand, will have less lift, feel stiffer and will handle speed better as water flow will be more efficient around thinner foil.
Inside foils are when the inside of the side fins are concave. Inside foils are great for lift in small waves generating speed through the lift. Great for boosting airs. Sometimes these foils can feel unstable as there can be too much lift in bumpy or more powerful surf. Again, this is a personal preference and I guess, if you can handle it, go for it.
The flex in a fin is how it bends under pressure when applied with force. The flex at the base (bottom) of the fin is generally stiff, and progressively has flex as it reaches the tip. This is helped by the fin being thicker at the base, and foiling thinner to the tip. Other materials such as carbon can manipulate stiffness in certain areas of a fin. Again, having the right flex all depends on the surf/board/riders.
Generally speaking though, a stiffer fin works better in larger surf as there is more force against the fin, so it doesn’t wash out too much. Fins with more flex work well in smaller waves or where a tighter radius of surfing is required. Having some flex is great for loading up your bottom turns like a spring effect. Too much flex, on the other hand, can cause the board to have no drive and hold.
The right balance is optimum for a good all round feel.
Fin placement plays a big part for shapers in positioning the markings. This can be a make or break moment. A board’s dynamic can change totally by as small of an increment as 1/8” when it comes to fin placement.
The fins as a unit, whether it is a thruster or a quad, have to work together. Spreading the fins apart so that the forward fins are at a greater distance than the trailing (rear) fins, can give the board a more drawn out feel through turns – works well for point waves. Having the unit closer together can give you a shorter radius of turning which is generally better for smaller waves. Again, all this can be manipulated by the shaper to suit the board/surfer/surf conditions.
Just so you can have a bit more of an understanding, a flatter tail rocker in a board generally means that the board will surf at a longer radius through a turn, so the shaper will place the fins so that the leading edge of the forward fins are closer to the trailing edge of the trailing fin (rear). So the drive of the board is more from the actual board shape itself. The fin setup can afford to be looser in this respect. On the other hand, a heavily rockered board, where there is maximum curve, the fins need to be spread apart to compensate for looseness that the board design gives. This is when the fins need a little more drive.
Each shaper has their own setups when it comes to fin placement. Having the right combination is key.
The side fins are pointing towards the nose of the board. This is called Tow. The more Tow, the looser the board will feel and turn in a shorter arc, for small beach break type surf. The straighter the Tow means more drive and longer bold turns. Finding the right Tow for the board design/wave condition is key.
The tip of the side fin is generally closer to the rail in relation to the base of the fin. This is known as the cant. The more cant in the fin, the looser the board will feel, ease of rail to rail feel and loss of drive. The straighter the cant, the stiffer the board will feel, added hold, but response is lost. A combination of the two extremes is optimum in finding the perfect balance.
Get real surfboard reviews from a weekend warrior. Independent. Objective. For you.