Selecting the right surfboard fin set can transform your surfing experience - giving you more speed or better control. Whether you're picking up a new board or shopping for a second-hand surfboard at Board Exchange, understanding your fins is just as important as picking the board itself.

 

What Do Surfboard Fins Do?

Surfboard fins are your steering and control system. By directing water flow beneath your board, they affect your ability to turn, maintain speed, and hold your line on a wave. Modern fins come in materials ranging from plastic and fibreglass to high-tech carbon fibre - each adding their own flex and responsiveness.

Types of Surfboard Fins:

Thruster fins: 

The go-to for most modern surfboards, the thruster uses two side fins plus one centre. This setup gives you a perfect blend of drive, stability, and manoeuvrability - making it ideal for everything from waist-high to well-overhead conditions. Thrusters allow for powerful bottom turns, quick snaps, and vertical surfing. No wonder you'll find this setup everywhere, from beginner boards to the performance quivers on the World Tour.

Best for: Everyday performance in all types of surf

Popular on: Shortboards and most all-round second-hand surfboards at Board Exchange

Single Fin:

One fin centrally aligned with the surfboard stringer

The single fin setup is commonly found on longboards and retro mid-lengths, delivering a smooth, classic feel. With only one fin centrally aligned, turning is slower and more drawn out, but the board offers steady control and predictability. Think long, arcing turns and unbeatable flow down the line, ideal for noseriding and smooth rail-to-rail flow. You lose a bit of “snap” for sharper moves, but gain classic trim and relaxed style.

Best for: Clean, mellow waves and cruisy lines down the wave.

Popular on: Longboards, gliders, and retro shapes

 

Twin Fin:

Two fins, one on each side of the stringer

Compared to single fins, they offer greater stability, high manoeuvrability, and excellent speed, particularly in smaller, playful surf. However, they can sometimes feel a bit loose or “squirrelly”, especially in steeper or more powerful waves, where the lack of a central fin can cause the tail to slide out during bottom turns.

This is where Twin Pin surfboards come in. These boards typically feature a narrower, more pulled-in tail, which helps counteract the tendency to slide out. By tightening up the tail area, Twin Pins offer better hold and control without sacrificing the speed and flow that twin fins are known for.

Best for: Small to medium surf, creative lines

Popular on: Fish boards, grovellers, and modern Twin Pins

Quad Fins:

Quads feature two fins on each side of the stringer but no centre fin.

Quads bridge the gap between twin fins and thrusters - offering the high speed and rail-to-rail drive of a twin, but with better hold thanks to extra fins. Quads are excellent for fast down-the-line surfing, especially in bigger or tube waves where extra grip matters.

Best for: Speed and hold in punchy beach breaks or quick reef waves

Popular on: Everything from fish shapes to high-performance shortboards

Bonzer:

Developed in the early 1970s by the Campbell brothers, the Bonzer setup features three or five fins: a central fin and two or four angled side fins called “runners.” This design channels water through specially shaped concaves in the tail, creating lift, grip, and speed. Its strengths are:

• Efficient water flow out the back generates natural acceleration.
• Side fins act like rudders, enhancing grip and control in turns.
• Known for smooth, flowing transitions and maintaining down-the-line drive.

Best for: Medium to powerful surf where you want to maintain speed through tight turns.

Popular on: Experienced surfers or those interested in alternative surfboard designs.

Basic Concepts:

Base: The bottom length of the fin

Fin's with a longer base length will give you more speed and predictability.

Fins with a shorter base allow for increased manoeuvrability, resulting in sharper, tighter turns. 

Depth: The vertical measurement from base to tip

The larger the fin, the more control and stability it will have. These large fins are perfect for beginners and less experienced surfers and/or more experienced surfers in bigger and more powerful waves. Shorter fins will allow for more manoeuvrability - typically used by advanced surfers looking to perform more ‘radical’ surfing tricks, offering a looser feel, easier release and more playful turns.

Sweep: The curve from front to back

The rake, or sweep, is how far back the fin tilts to the back.

• High sweep (laid‑back fin): produces “drawn‑out” turns - long, arcing lines down the wave face, great for open faces and point breaks.
• Low sweep (upright fin): enables tighter radius and faster pivot - ideal for quick snaps in pocket areas or messy surf. "More drawn‑out turns" therefore means slower, smoother arcs rather than rapid direction changes.

Foil: The fin's cross-sectional shape that influence how water flows

• Centre fins: 50/50 foil (symmetrical) offers stability and even flow.
• Side fins: typically convex outside and either flat or concave inside.
  • Concave inside foil: generates lift, maintains speed through weaker surf, smoother rail transitions.
  • Flat inside foil: balanced hold, speed and pivot.

Good foil design reduces drag, improves lift, and affects release out of turns. Essentially, more foil (concave inside) tends to enhance lift and smooth speed in weaker surf; less foil (flat) favours quick responsiveness and drive in stronger surf.

Choosing the Surboard Fin size:

Fin size can seriously change the way your board feels under your feet. In general, heavier surfers need bigger fins, while lighter surfers are better off with smaller ones. That’s because larger fins provide more hold and control, especially in powerful surf, while smaller fins give you more looseness and maneuverability. But it’s not just about weight, your surfing style and the type of board you’re riding matter too.

• If you love tight, snappy turns and surfing in smaller waves, go for smaller or medium fins.
• If you’re powering through solid surf or riding a board with a wider tail, larger fins will give you that extra drive and stability.

Most fin brands include a size chart based on weight - it’s a great place to start. But once you start feeling the difference, it becomes more about preference than rules.

Board Exchange Tip

If you’re buying a second-hand surfboard at Board Exchange, always check which fin system (FCS, Futures, single box, etc.) your board uses. Some boards come with fins included, while others let you customize with your ideal set.

The right fin set can completely change your favourite board - even one you’ve had for years. Experimenting with thrusters, twins, quads, and singles is one of the joys of surfing, and at Board Exchange you’ll find a range of boards and sometimes spare fins to help you test what truly works for you.

Whether you’re after all-round performance, classic lines, or something alternative, the best setup is the one that suits your waves, your style, and your stoke. Browse Board Exchange for quality second-hand surfboards and unleash your session’s full potential!