Talking Design with Rusty: Quadrophenia – Part I

Four fins are faster than tri fins.
Four Fins are looser than tri fins.
Four fins ride the barrel higher and tighter than a tri fin.
They drop in easier.
They come out of the gate quicker.
Accelerate on cutbacks.
Do better airs.
Can be ridden shorter.
Draw new and different lines.


Josh Kerr is one of the half-dozen or so of the ASP World Tour who regularly experiment with quads.

So why isn't every surfer on the planet riding one?

It's all Hype?
Different strokes?
The pros don't so I won't?

Maybe shapers don't have it right...yet?

Perhaps if there were a ubiquitous effort, a Manhattan Quad Project, the design would evolve at a faster rate and all would enjoy the benefits.

Sorry, somebody has to win a major friggin contest on one first. (Biggest win? CJ won the Body Glove Surfbout on a quad in '07.)

So at this point, who seems to like them and who doesn't? And why?

Typical first impression of a quad is this: fast and loose, but not confident without something directly under the back foot. It takes a few sessions to trust the setup -- and run with the positive attributes.

The lack of an auto-centering sensation seems to be a common complaint from most detractors. Without a center fin, a lot of surfers miss the instant feedback from the back foot and the ability to do quick adjustments. With quads there is an information gap in rail change that varies widely depending on fin (rear especially) position.

Backhand performance is also a concern of 3-fin loyalists. Going heelside, the rider delivers more power through the rear foot and specifically the heel. Visualize foot angle and where the energy is going...for most surfers pretty much in line with the rear fin, three inches and change from the back end.

Early days of the 3-fin, I'd put rear fins way back on some rider's tail blocks. It was necessary to do this to keep more powerful, rear-foot surfers from blowing their tails out on acute direction changes. Occy's were set at 2 3/4" and some of Tom Carroll's trailers were as far back as 2" from the end of the board. As rockers and outlines evolved, the rears crept up to 3 1/4" to 3 1/2" on an average shortboard.

If a rear fin on a tri is moved up an inch or two from the placement most people are used to, the board loses drive, hold, and moves the pivot point further forward. A surfer would have to completely readjust his rear foot placement. Same holds true with a quad.

Which leads to probably one of, if not the single most important detail in designing a 4-fin surfboard: fin positioning. Not weird-ass tails. Not crazy bottom contours. Fins. How big they are, outlines, and foils. Where they are, their relative positioning with respect to each other, cant and nose vector.


Jamie Sterling is a fan of quads in the barrel at Teahupoo 'cause they go fast and hold at speed. Photo: Tyler Cuddy

Early on I took a fairly simplistic approach to it.

Early quads were an attempt to add drive and control to twins. In 1980/81, Twins were de rigueur. Since 1982/83, tri-fins were most surfers' experiential basis. In my mind, I'm starting with a tri-fin. So I took the rear fin on a tri, and was theoretically splitting it in half. The more the rider wants the feel of a tri, the further back and closer together I'd keep the fins. If a rider was after more of a twin-fin feel, I'd move the rears towards the rail and the front fins.

My common middle ground: for argument's sake, a 6'2" tri-fin has fronts at 11" and rears at 3 1/4". A lot of designers go half the distance on a quad, so that would put the rears at 5 1/2" and the same distance from the rail, about 1 1/8". In my humble opinion, I feel this is a little on the neutral side. I split the difference on distance from the tail (tri vs. quad: 2 1/4"), which would be 3 1/4" plus 1 1/8"...or 4 3/8". Easier math: 7' board. Fins at 12" and 4" on a tri. Half the distance is 6". Split the difference, 5" for a quad. On average, I try to keep my rears about 2" in from the rail. That's a generalization. It becomes a more complicated depending on tail width and board length.

Fin size: Fronts are similar to tri-fins, perhaps slightly smaller. Rears: profiles similar to fronts reduced approximately 10% in overall area. You can adjust drive by swapping out rears with different aspect ratios. More upright fins for tighter arcs. More rake to add length and draw to turns.

Foils: Your preference on fronts...your favorite tri fin fronts are a good starting point. If you are a fan of cambered fins -- stay with them. If you prefer flat-sided fronts, you will probably like them in the trailers as well. Smaller, weaker surf; flats are probably the go as they react a little quicker and provide instant feedback. Bigger, more powerful surf -- most prefer cambered or dual (full) foil trailers. Less prone to cavitate and let go. Some prefer full-foil trailers in everyday surf, citing more "feel"...smoother, cleaner, etc. Not as fast.

Cant on rears: Typically, I halve the angle of the fronts. It can vary according to intended use. Smaller softer surf; a little more cant will add some lift and looseness. Conversely, less tilt will increase speed, hold, and drive.

Nose vector (line towards nose): I typically point all four fins to approximately the same place, which depends on board length and type of surf the board is intended for.

Another shaper's insight into quads and fin positioning: Bruce McKee has done nearly 30 years of homework for all of us and he's quite happy to share it here.


Why not chuck a quad in the back with the rest of your quiver? Photo: Tyler Cuddy

So back to...why aren't more surfers embracing this design?

I suspect that there were probably a lot of takers that might have had a go early on before a lot of work had been done. They may have had a less-than-satisfactory experience and shared it with others that may have at one point been interested.

Some of it may be due to negative stigma. The print media. In an incredibly myopic and disappointing "Surfboard Issue" last year the polyurethane/polyester tri-fin was declared the winner and still champ in a fizzling technology push.

Thankfully, we have the Internet.

Search and you will find. There are quite a few board builders offering quads. Even Simon Anderson himself rides and enjoys quads and has several models in his product line.

My suggestion is that if you are interested, search out a builder who embraces the design and has a solid history with the setup. It's not as easy as just sticking four fins on a board.

More often than not when I let someone demo a quad they are pleasantly surprised.


Check back later this month for "Part Two: A History of Quads," with words from Simon Anderson, Jeff Clark and more.



Last month's blog on tails, we received a question in response to the Simon Anderson story:

So Rusty - did you build a thruster later that same night? --Munga

Rusty answers:

I tripped on the experience for a couple of days, wrestling with the thought, was it the board or the surfer? My mind said it was 90% Simon.

After a few days, wtf, I stuck a trailing fin on my favorite twin. My first surf on the jury-rigged tri-fin was in decent surf but it was not nearly as good as Blacks on that day I watched Simon. First impression: board was noticeably slower but had a tentative short burst of speed out of turns on the better waves. It felt like the parking brake was on but when I drove off my back foot hard enough the board would come back up to the speed it had as a twin...just briefly, and as soon as I let off, it would slow down again.

I shelved it.

The next board I made myself after the twin to tri-conversion was a 4 fin round-tail. It was a super fun board. It had the speed of a twin but with more drive and a bigger sweet spot. I vividly remember it doing swooping cutbacks at full speed, almost effortlessly. I rode it for a few months.

Thanks to .

One Response to “Talking Design with Rusty: Quadrophenia – Part I”

  • bird November 14, 2009

    I want a new board BIG MAN!