Most people talk about the True Ames 4C like it's the other Greenough fin. Same bloodline as the 4A, same vibe, different flavor. But if you've ridden both and thought these do not feel like cousins, you're not imagining it.
Here's the thing: the fin sold as the "Greenough 4C" didn't start as a Greenough template. On Swaylocks, Paul Gross wrote that the 4C "started out as a fin I made for myself, FROM SCRATCH." That's not drama—it's a practical clue. If you treat the 4C like a smaller 4A, you'll pick the wrong fin for the job.
The Origin Story
True Ames sells the 4C inside the Greenough universe, and most surfers experience it that way: a classic, more upright single fin option.
But Paul Gross' account is that the 4C began as his own late-80s template, made for his personal surfing. He describes having to adapt his original outline to work with standard 3/8" panel construction when it went into production. This fin didn't come from a design lab. It came from a guy solving a problem on his own board.
The 4C and the 4A aren't competing claims to a throne. They're different tools with different origins. Once you accept that, the choice gets easier.
What Makes the 4C Different
When people argue 4A vs 4C, they're usually talking about three things: rake, base, and flex.
Rake
The 4C is more upright than the 4A. Less rake means a tighter turning radius and more "pivot from the tail" feel. More rake means longer arcs and smoother drive through turns.
The 4C wants to turn now. The 4A wants to draw a line.
Base
The 4C has less base than the 4A. Less base means less projection, less drag, easier turning. More base means more hold and more push in soft waves.
This is why the same fin can feel different depending on the board. One Swaylocks user swapped to a 9.5" 4C and said it felt like the board was "dragging kelp." That's not a knock on the 4C—some hull-ish logs with rolled bottoms need base width to come alive.
Flex
Template is half the story. The other half is what the fin does under load. The 4A comes in a huge size range (6.5" to 10.5") and the Volan version has its own feel entirely. The 9.75" Volan specs at 7.09" base and nearly 40 square inches of area. That's a lot of fin.
The 4C is simpler: one primary size (9.5"), one clear intent, less universal fit.
When to Choose the 4C
Choose the 4C when you want tail authority more than free speed.
- Heavy logs and noseriders: If your goal is nose time and planted-tail trim, the 4C's upright feel makes sense.
- Surfing from the tail: If you like stepping back and pivoting rather than drawing long arcs, the 4C rewards that.
- When you want the board to wait for you: Some fins feel like they're always trying to accelerate. The 4C is calmer—less eager to run, more willing to hold position.
- If your board already generates speed: If the rocker and rails already have drive, you can afford a fin that isn't the engine.
With a 4C, small moves in the fin box matter. Don't jump inches—move a little, surf it, move again.
When to Choose the 4A
Choose the 4A when you want a fin that adds life to the board—especially in soft surf—and when you want to feel the board accelerate out of turns.
- Performance logs and mid-lengths: If you want to turn more than park, the 4A's balance is hard to beat.
- Boards that feel stuck without base: Some shapes need base width to wake up. A wide-based fin makes paddling, entry, and trimming feel easier.
- If you want one fin for multiple boards: The 4A's size range is the cheat code. Pick the right size instead of forcing one template to do everything.
- If you care about feel through the turn: The 4A's reputation comes from how it blends hold and release on rail.
Quick Decision
- Priority is nose time? Start with 4C.
- Priority is turning and speed in weak surf? Start with 4A.
- Board feels dead without a wide base? 4A.
- Board already has push and you want calmer control? 4C.
- Unsure? Get the 4A first. Add the 4C when you want a specific feel for a specific board.
Where to Get Yours
We stock both. The 4A is a benchmark for a reason. The 4C is the fin you reach for when you're done chasing "best" and you're choosing a feel.
Come by 4051 Judah and talk it out—board under arm, fin in hand.
Sources: Swaylocks Paul Gross discussion, True Ames Greenough fin guide