Fins are sold separately on most hard boards, and the first thing to know is which boxes your board has. The second is what setup suits the waves you surf.
FCS II boxes have two small slots per fin and the fin clicks in without screws. Futures boxes have one long slot and a single screw at the front. They are not interchangeable. Older boards may have the original two-tab FCS, which takes FCS II fins with an adapter or screw-in FCS I fins. Longboards usually have a single center box that takes any standard longboard fin.
| Setup | Fins | Feel | Typical board |
|---|---|---|---|
| Thruster | 3, equal or near equal | balanced drive and control, the default | shortboards, hybrids |
| Twin | 2 larger side fins | fast and loose, less hold in steep waves | fish, retro shapes |
| Quad | 4 | fast with more hold than a twin, drives down the line | fish, small-wave boards, big-wave guns |
| 2+1 | center fin plus two small sides | stable with some turn | midlengths, eggs |
| Single | 1 center fin | smooth, drawn-out turns | longboards, logs |
Most boards ship with the boxes for their intended setup, so buy that: a thruster set for a three-box shortboard, a quad set for a four-box fish. Medium size suits 65 to 80 kg; go large above that. Five-box boards take either a thruster or a quad set and let you try both.
More guides: Beginner board size · Soft-top or hard board · How many liters is too many · Foamie to fiberglass.