Lost a fin at the lake, or not sure which one to order? Good news: picking the right fin is easier than it looks. It comes down to three things: how the fin attaches, where you paddle, and how many fins your board uses.
One Fin Box on Every Inflatable Board Since 2021
Since 2021, every iROCKER and BLACKFIN inflatable paddle board uses the same fin box: a clip-in flip-lock fin that locks in place with a lever. No screws, no tools, just slide it in and flip the lever.
On our iROCKER 8.0 and BLACKFIN 7.0 boards, the fins are also tethered to the fin box, so a fin that slips loose stays with your board instead of sinking to the bottom of the lake.
Boards made before 2021 used other fin types, and we no longer carry fins for those older boards.
Regular Fins vs. River Fins
Once you know the fin box, the next question is where you paddle.
- Regular fins are a little longer. They help your board track straight and feel steady in regular and deep water, like lakes, bays and the ocean.
- River fins are a little shorter, made for shallow water. The shorter fin means fewer run-ins with rocks and underwater tree roots, and less chance of getting stuck in the sand.
3-Fin Setup: Classic iROCKER and BLACKFIN Boards
Most paddle boards, including our classic iROCKER and BLACKFIN inflatables, use a 3-fin setup:
- Center fin for tracking, so you glide straight with fewer corrections.
- Two side fins for stability. Side fins are shorter than the center fin, so they steady the board without making it harder to turn.
The two side fins are optional on our classic boards. Many riders paddle with just the center fin, and most riders skip the side fins altogether when they use a river fin.
Want to go deeper on fin setups? Read 1 Fin vs 3 Fin Explained.
Twin-Fin Setup: ULTRA™ Boards
ULTRA™ boards pack down differently from our classic boards. A classic board rolls up from the nose to the tail. An ULTRA™ board first folds in half the long way (taco style), then folds from the nose to the tail. That fold is what makes ULTRA™ boards so compact, and it is also why they use a twin-fin setup instead of three fins.
ULTRA™ side fins are designed differently from regular side fins. With no center fin, they handle both jobs: tracking and stability. They are a great middle ground that works in both shallow and deep water.
Quick Fin Finder
| Your board | Fin setup | Fins to look for |
| iROCKER or BLACKFIN inflatable, 2021 or newer | 3 fins: 1 center + 2 side | Flip-lock center fin (regular or river) and flip-lock side fins |
| ULTRA™ board | 2 fins (twin-fin) | ULTRA™ fins (look for “ULTRA™” in the product name) |
| Board made before 2021 | Older fin types | No longer available |
Shop the Fins collection.
How to Install a Flip-Lock Fin
- Open the lever on the fin box.
- Slide the fin into the slots and push it all the way to the end.
- Lower the fin and close the lever.
- Give the fin a gentle pull to check that it is locked.
Fin will not lock? Rinse any sand and dirt out of the fin box, and if it is cold out, let the fin box warm up before trying again.
Good to Know
- Lost fins are not covered under warranty. Tethered fins on iROCKER 8.0 and BLACKFIN 7.0 boards add extra protection, and a spare in your bag never hurts.
- If the fin you need is out of stock, click “Notify Me” on the product page and we will email you when it is back.
