How do fins change the way a surfboard feels?

Different fin configurations

Thruster — Three fins. The familiar all-round setup on a huge number of modern boards.

Twinny — Two fins. Usually looser and faster, with less hold than a thruster.

Quad — Four fins. Somewhere in between the thruster and the twinny, looser than a thruster set-up but can still give you speed and drive without a centre fin.

Single fin — One larger centre fin. Common on longboards and some mid-lengths, with a very different feel from a thruster or quad. Single fins can be tricky for beginners to master.

Five-fin setup — A board with five boxes gives you the option of changing between different configurations. This is a common setup on many modern boards and gives you a chance to experiment.

There are plenty of variations, but you don't need to understand all of them before you start surfing.

Shape

Fin shape changes how the board feels. A more upright template can make a board feel quicker to turn, while a longer, more swept-back fin can give more hold and drive through a turn. Bigger fins generally give more hold and stability, while smaller fins can feel looser.

Flex

Some fins are stiff and some have considerably more flex. That changes the way they load up and release through a turn. Different materials and constructions are used to create those differences.

Beginner boards often come with plastic fins. That's fine to start off with but you'll probably want to upgrade to some fiberglass ones once you know you're going to stick with it.

So what should a beginner buy?

Usually, the fins that came with the board are a perfectly good place to start. If you're still learning, there is probably more to gain from having the right board to catch waves than spending a fortune experimenting with fins.

Once you know how your board feels, changing fins can be a useful way to fine-tune it. That's when size, template and flex are worth thinking about but don't get overwhelmed about it just yet.

What are FCS, FCS II and Futures?

This is the boring but important bit. The fin needs to fit the box in your board. Futures uses a different base from the FCS systems. FCS I uses the familiar two-tab fin, while FCS II uses a different insertion system. If you're buying fins separately or second hand make sure you know that they match the system in your board.

FCS I fins can be used in FCS II boxes with compatibility inserts and grub screws. So an FCS II board doesn't necessarily make an existing collection of FCS I fins useless. But remember, FCS II fins won't fit in FCS I boxes.

FCS II fins are designed to click into the box without screws, but it's not a bad idea to use some grub screws anyway. A hard knock can loosen a fin and send it on its own little adventure, and you don't want to lose an expensive fin halfway through a surf.

Useful bits to keep around: FCS I/FCS II compatibility inserts, spare grub screws, a fin key or multi-tool, and the right fins for your board. These are small purchases compared with replacing a lost fin.