How to Install FCS Fins: FCS II and FCS I Guide

FCS makes two fin systems, and the install process is different for each. FCS II is the toolless push-in system you’ll see on most modern boards. FCS I (sometimes called FCS Original) is the older two-screw system. Figure out which one your board has, then follow the right steps below.

Not sure which system you have? Look in the fin box. FCS II boxes have a single long slot with a spring-loaded catch. FCS I boxes have two small round holes that take tab screws.

FCS II (toolless install)

1. Pull the FCS II key (included with every fin set) and slot it into the back of the fin box to depress the catch — or skip this and just push the fin in; the catch releases on its own if you press hard enough.
2. Angle the fin forward and slide the front tab in first.
3. Press down on the back of the fin until you hear and feel a click. That click is the catch locking behind the rear tab.
4. Tug the fin to confirm it’s locked. If it lifts out, push it down harder — it wasn’t seated.

To remove: insert the FCS II key into the back slot, press to release, pull the fin up.

FCS I (two-screw install)

1. Back out both grub screws in the fin box with the FCS hex key. A few turns is enough.
2. Check orientation — the rake sweeps back toward the tail on side fins.
3. Drop both fin tabs into the box holes. The fin should seat flush with the board.
4. Tighten both set screws evenly. Snug, not cranked.

Common mistakes

• FCS II fin pops out while surfing — it wasn’t fully clicked in. Always tug-test after install.
• FCS II catch feels sticky — rinse the box with fresh water. Salt and sand gum up the spring.
• FCS I set screw won’t bite — the grub screw is backed out too far and has dropped out of the threads. Remove the fin, re-thread from above.

Care tips

Rinse boxes after every session. For FCS II, occasionally push the catch with the key and check that it springs back cleanly — a seized catch is the #1 failure mode. For FCS I, a light wax on the screw threads keeps them from corroding.

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