Quad Fins: How They Actually Work and Which Set to Buy

Pemulis Water & Power
2026-04-29T00:27:53-07:00

How Quads Actually Work

The marketing version of quad fins goes something like: "four fins provide the speed of a twin with the hold of a thruster." That's not wrong, exactly, but it describes the outcome while skipping the mechanism. Here's what's actually happening under the water.

A thruster's center fin sits directly in the turbulent wake of the board's stringer line. Water flowing off the tail hits that center fin at a bad angle — it's catching disturbed flow, generating drag in the most inefficient spot possible. Remove that center fin and you eliminate this specific source of positional drag. That's where the speed comes from.

What the marketing version leaves out: four-fin configurations actually produce more total drag than a thruster, per CFD (computational fluid dynamics) studies. Four fins means more surface area in the water, more skin friction, more induced drag. But the center-fin position is so costly that removing it offsets the added drag from the fourth fin — and then some, in most conditions. The net effect is a faster board, but not for the reasons people usually cite.

Drive in a quad comes from both rail fins engaging the wave face simultaneously during a turn. In a thruster, you pressure one rail fin at a time, pivoting around the center fin. In a quad, the inside rail pair loads up together — front fin generating lift, rear fin providing bite. This creates a wider, more arcing turn radius. You can't snap a quad the same way because there's no single center pivot point. You can, however, drive through a turn with remarkable velocity because both fins on the engaged rail are working for you.

This is also why quads feel different bottom-turning. In a thruster, you pivot off the center fin at the bottom of the wave and redirect vertically. In a quad, the bottom turn is more of a drawn-out arc — you carry speed through it rather than pivoting out of it. Surfers who love quads usually love this feeling. Surfers who hate quads usually hate exactly this feeling.

The Hold Debate — Resolved

Ask ten surfers whether quads hold and you'll get ten different answers. Half will tell you quads hold better than thrusters. The other half will tell you they're skatey and unreliable. They're both right. They're just describing different axes.

Lateral hold — the ability to resist being pushed sideways by the wave face — is where quads dominate. Two fins on the rail that's engaging the wave creates redundancy. In a barrel, both rail fins are locked into the face. On a steep, open face, the same thing happens. This is why quads excel in hollow waves: the lateral force vector is what matters, and two fins handle it better than one.

Vertical hold — the ability to maintain grip during a top turn, snap, or any maneuver where you're redirecting vertically — is where quads struggle. A thruster's center fin acts as a pivot point for vertical redirection. Remove it and there's nothing to anchor the tail during sharp vertical changes. The tail slides. You can't carve a tight arc off the top the same way. Surfers describe this as "skatey" or "slidey," and it's a real phenomenon, not a technique issue.

This resolves the debate: quads hold better laterally and worse vertically. Both camps are describing real experiences. The surfers who love quads tend to surf hollow, powerful waves where lateral hold matters — barrels, steep drops, open-face carving. The surfers who find quads unreliable tend to surf beach breaks where pocket turns and vertical snaps are the primary maneuvers.

Once you understand this, the "quads are for tubes" consensus makes mechanical sense, not just anecdotal sense.

Four Schools of Quad Design

Not all quads are built the same. Fin placement — where the rear fins sit relative to the stringer, rail, and tail — changes the character of the board as much as the fins themselves. Four distinct design philosophies have emerged.

McKee System

Rich McKee's approach places the rear fins closer to the stringer and further back toward the tail. This is the most thruster-like quad setup. The rears act almost like a split center fin, providing pivot and hold in vertical maneuvers that other quad setups lack. If you've ridden a "quad that doesn't feel like a quad," it was probably a McKee-style placement. Good for surfers transitioning from thrusters who want quad speed without giving up vertical surfing.

Rail-Oriented / Split-Twin (NPJ, Rich Pavel)

Neil Purchase Jr., Rich Pavel, and others in this school place the rear fins close to the rail in a tight cluster with the fronts. The quad effectively becomes an "enhanced twin" — the rear fins add bite and control to what is fundamentally a twin-fin drive pattern. As NPJ puts it: "Fins that are spread out tend to work against each other through a turn." By clustering them tight to the rail, both fins on each side work as a unit rather than fighting each other. This produces the most twin-like quad feel — lots of speed, lots of flow, minimal pivot.

Performance Quad (CI, Standard FCS/Futures)

The default. Channel Islands, most stock FCS and Futures quad boxes, and the majority of off-the-rack quad boards use a moderate placement — rears neither hugging the rail nor sitting on the stringer, positioned at a middle distance behind the fronts. This is the compromise position: some vertical ability, some twin-like flow, nothing extreme. It's the right choice for a board that needs to work in varied conditions, but it doesn't excel at any single thing the way the other placements do.

Hydrodynamic Architecture (Tomo / Thomson)

Daniel Thomson's boards are designed as integrated hydrodynamic systems where fin placement, bottom contours, and outline all work together. Deep concaves channel water between the fins in specific ways. The quad isn't an afterthought bolted onto a conventional hull — it's the reason the hull looks the way it does. These boards are the hardest to generalize about because the fins only work as intended in the specific concave architecture they were designed for.

What the Variables Do

Six variables define a quad setup. Here's what each one controls.

Rear Fin Size

This is the single most impactful variable. Larger rears provide more hold and control. Smaller rears provide more release and speed. Simon Anderson's original formula — and it holds up — was to use thruster side fins as fronts and scale the rears down by roughly 1/4". Most quad sets follow some version of this ratio, with front fins in the 4.5"–4.75" height range and rears in the 3.5"–4.25" range.

The ratio matters more than the absolute size. Equal-sized fronts and rears (like the Pavel Speed Dialer at 13.44 sq in front / 13.56 sq in rear) create a very different feel than a set with large fronts and tiny rears. Equal sizes mean both fins contribute equally — more drive, more hold, less release. Large ratio differences mean the fronts do the work and the rears just provide a touch of guidance — more release, more speed, less hold.

Rear Fin Placement

Further back = more hold, more thruster-like. Further forward = looser, more twin-like. Closer to stringer = thruster-like pivot. Closer to rail = twin-like flow. This is where the four schools of design diverge most dramatically. The fin placement your board was designed for matters — you can't turn a rail-oriented quad into a McKee system by moving fin boxes, because the outline and rocker were designed around specific placement assumptions.

Cant

Cant is the angle the fin tilts outward from vertical. Front fins typically run 6–9 degrees of cant. Rear fins run 2–5 degrees. More cant = more maneuverability through turns (the fin engages at a better angle when the board is on rail). Less cant = more straight-line drive (the fin is more efficient when the board is flat). Most quad sets have less cant on the rears than the fronts, which makes sense — the rears are for tracking and stability, not for turning.

Toe

Toe is the inward angle of the fin relative to the stringer. Front fins typically toe in 3–5 degrees, directing water toward the stringer. Rear fins toe in less — usually 1.5–2.5 degrees — because their job is more about tracking than redirecting flow. Less toe on rears means more drive and less drag. Sets designed for speed (like the Speed Dialer) often have minimal rear toe.

Foil on Rears

This is the one most people ignore, and it matters. Rear fins near the rail (rail-oriented setups) work best with an 80/20 foil — the thicker side facing outward, like a thruster side fin. Rear fins near the stringer (McKee-style) work better with a 50/50 foil — symmetrical, like a center fin. This makes intuitive sense: a rear fin near the rail is acting like a side fin, so it should be foiled like one. A rear fin near the stringer is acting like a split center fin, so it should be foiled like one.

Front Fin Template

Front fins in a quad do most of the heavy lifting — they generate lift, initiate turns, and provide the primary hold. Upright templates with a straight leading edge (like a standard thruster side) pivot quickly. Raked templates with a curved leading edge (like a keel or semi-keel) carve wider arcs. The front fin template determines the basic character of the quad; the rears refine it.

The True Ames Quad Lineup

True Ames makes more quad templates than anyone. Here's what each one does and who it's for.

Pavel Speed Dialer

for fish & alternative boards

$128

Timmy Patterson Quad

for performance shortboards

$128

Ellis Ericson Feathers

for mid-lengths & alternative shapes

$128

TA Quad

The house quad. Medium area, moderate rake, general-purpose. This is the fin you reach for when you don't know what you need. It works in everything from waist-high beach break to overhead reef, won't blow your mind but won't let you down. Available in solid fiberglass, FCS, and Futures.

Best for: your first quad set, all-around use, boards that see varied conditions.

Pavel Speed Dialer

Rich Pavel's masterpiece. This is a deconstructed keel — "a traditional keel style fin split in two." The fronts are 13.44 sq in, the rears are 13.56 sq in. That's nearly equal, which is unusual. Most quads have significantly smaller rears. The equal sizing means both fins drive together as a unit, producing the keel-like speed and flow that Pavel is known for, but with more maneuverability than an actual keel because you have two independent pivot points instead of one continuous foil.

The Speed Dialer works best in fish and fish-derived boards — anything where you want keel speed with more control. Available in solid fiberglass, FCS, and Futures.

Best for: fish boards, retro quads, keel converts who want more turn.

Timmy Patterson Quad

Performance-oriented with the numbers to prove it: 14.78 sq in fronts, 11.73 sq in rears. That's a steep ratio — the fronts do the work, the rears just guide. This produces a responsive, maneuverable quad that handles well in the pocket. Patterson designs these for performance shortboards and step-ups, not for fish. The smaller rears release easier, which means you can break the tail free for snaps and cutbacks in a way that most quads resist.

Available in solid fiberglass, hexcore, and Futures fiberglass.

Best for: performance shortboards, punchy waves, surfers who want thruster-like responsiveness in a quad.

Ellis Ericson Feathers Quad

Greenough-inspired and unlike anything else in the lineup. The Feathers use an inside concave foil — the same principle George Greenough applied to his Stage 4A and Edge fins, where the concave face creates lift by accelerating water across the surface. Front fins run 7 degrees cant, rears at 3 degrees. The result is a neutral, pivot-oriented quad that turns from the center of the board rather than the tail.

These are strange fins. They feel nothing like a conventional quad. The Greenough influence means they want to be ridden with a light touch — subtle weight shifts rather than aggressive foot pressure. In the right board (mid-length, alternative hull, anything Ericson-adjacent), they produce a gliding, frictionless feeling. In the wrong board, they feel like the fins aren't there.

Available in Futures solid fiberglass.

Best for: mid-lengths, alternative hulls, Greenough devotees, surfers who prioritize glide over grip.

Tyler Warren Quad

Tyler Warren's quad set is designed for the versatile boards he shapes — performance-oriented but with more flow than a pure competition template. Slightly more area than the Patterson, slightly less than the TA Quad. The balance point is maneuverability with enough hold that you can push through turns without the tail washing out. Warren's fins reflect his surfing: smooth, stylish, capable in good waves but not dependent on them.

Available in solid fiberglass, hexcore, Futures solid fiberglass, and FCS solid fiberglass.

Best for: all-around performance, good waves, surfers who split the difference between fish and shortboard.

Mandala AK4

Another strong all-around option. The AK4 is designed for versatility — not a specialist for fish, not a specialist for shortboards, just a well-balanced quad that works across board types. Moderate rake, moderate area, moderate cant. If the TA Quad is True Ames' house quad, the Mandala AK4 is the premium general-purpose alternative with a bit more refinement in the foil and template.

Available in solid fiberglass and Futures.

Best for: all-around, multiple board types, surfers who want one quad set that works everywhere.

Lovelace Piggyback Quad

Ryan Lovelace's take on the quad is the Piggyback — an alternative setup where the rear fins sit in an unusual piggyback position relative to the fronts. This is a fish/alternative quad, not a performance quad. The Piggyback produces a smooth, flowing feel with less drive than a conventional quad but more maneuverability than a keel. It's designed for Lovelace's retro-modern shapes and works best in boards with some volume and a relaxed rocker.

Available in solid fiberglass, FCS, and Futures.

Best for: fish, alternative shapes, retro quads, Lovelace boards.

Other Quad Options We Carry

Beyond the core True Ames templates: the Album Quad for Album boards, the Danny Hess Noriega Quad for Hess shapes, the John Simon Quad Type I and Type II for different performance niches, the Mackie Quad, the McCallum Quad, the Tappy Quad, and the Valaric Quad. Each was designed for a specific shaper's boards — if you ride the board, ride the matching fin.

For rear fins sold separately, the 6-4 Rear Quad Fiberglass and 6-4 Rear Quad Hexcore pair with various front fins for custom setups.

How to Choose

Start with two questions: what waves do you ride, and what board are you putting these in?

Hollow / Barrel Waves

Lateral hold is everything. Larger rear fins, placed further back. The Timmy Patterson Quad with its large fronts provides the drive to get in early and the hold to set a line. The TA Quad is the safe choice. Avoid tiny rears — you need the hold.

Small / Gutless Waves

Speed generation matters most. Smaller rears, closer to the rail. The Pavel Speed Dialer produces speed in conditions where thrusters bog. The Tyler Warren Quad provides good flow in weak surf. The Ericson Feathers generate speed from almost nothing, though they require a particular board and approach.

Fish Boards

The Pavel Speed Dialer was built for this. "A traditional keel style fin split in two" — it gives you fish speed with more control than actual keels. The Lovelace Piggyback is the alternative choice for Lovelace-style fish and retro shapes. Both feel more like enhanced twins than conventional quads, which is what you want in a fish.

Performance Shortboard

The Timmy Patterson Quad or Tyler Warren Quad. Patterson for sharper, more vertical surfing. Warren for smoother, more flowing surfing. Both have the front-heavy ratio that performance quads need — big fronts generating hold and lift, smaller rears allowing release when you want it.

Alternative / Mid-Length

The Ellis Ericson Feathers are the clear choice for mid-lengths and alternative hulls. The Greenough-inspired foil generates speed and glide that conventional quads can't match in these board types. If you want something more conventional, the Mandala AK4 works well in alternative boards without requiring the Feathers' specific technique.

Don't Know / First Quad Set

The TA Quad or Mandala AK4. Both are general-purpose, both work in varied conditions, both forgive mistakes. Start here, figure out what you want more or less of, then specialize.

Our Top Picks

Debunking the Venturi Myth

Dozens of quad fin guides — including some from major fin companies — claim that water "accelerates between the quad fins via the Venturi effect," producing speed. This sounds scientific. It's also wrong.

The Venturi effect describes what happens when fluid flows through a constriction in a closed channel — a pipe, a nozzle, a narrowing tube. The fluid has nowhere to go except through the constriction, so it speeds up. This is basic fluid dynamics and it's well-established.

Quad fins in the ocean are not a closed channel. Water can flow around the fins, over the fins, or not through them at all. There is no constriction because there's no enclosure. The gap between quad fins is open on all sides. Water doesn't accelerate through it any more than wind accelerates between two trees standing next to each other.

The speed advantage of quads is real, but it comes from removing the center fin's positional drag — not from any acceleration between the remaining four fins. This matters because the Venturi myth leads people to obsess over the gap distance between front and rear fins, when what actually matters is rear fin size, placement, and foil.

If someone tells you their quad is fast because of the Venturi effect, they're describing the right outcome for the wrong reason.