Like skinny jeans and fluorescent items of clothing, four finned boards (aka "Quads") aren't a new thing. They first appeared in the late 80s, before they were re-popularised over the last 5 years by Bill "Stretch" Riedel and other progressive shapers and surfers, all looking to four-fins in their quest to push the boundaries of the possible in waves big-or-small.
Anthony Tashnick, eyeing the paddle out at Mavericks
Yet despite a large number of pros (particularly the currently injured Nathan Fletcher) experimenting with quads during free-surfing sessions, Anthony Tashnick's victory in the 2005 Mavericks big wave contest and CJ Hobgoods victory in the 2007 Surfbout contest (held at Lower Trestles in tiny conditions) remain the only major surf contests which have been won on quads. The reasons for this are simple: The vast majority of pro-surfers still prefer to ride thrusters, especially when it comes to trying to impress the judges. But are they doing so out of a lemming-like desire to copy the world championship winning trends of Slater, AI, Fanning and co., or do they genuinely believe that 3-fins offer significant performance advantages over 4?
One point, on which Kelly Slater, Jeff Clark and most other pros and shapers who have experimented with four-fins agree upon is that quads are faster than thrusters. This is because they generate more drive through a turn and are able to hold a higher line (whether being pumped or not) on steep wave faces. This performance advantage quads have is due to their greater-fin surface area, which results in quads slipping sideways through the water less easily than thrusters (they "hold" more), resulting in more of the riders energy being redirected into forward momentum. In other words; quads are simply more efficient and so better than thrusters when it comes to holding a high line and doing rail turns.
This means that quads perform well in particular conditions where a surfer needs as much speed as possible, such as in big waves, deep barrel sections and tiny, "gutless" beach breaks. Which also goes someway to explaining why CJ Hobgood was by no means the only competitor to ride a quad in the 2007 Surfbout, why a large number of the 2008 Eddie Aikau invitees brought along there quad guns to the opening ceremony and why Kelly Slater opted to ride a round tail quad in his first round heat on the Gold Coast last week.
The Quad's efficiency in turns also makes them particularly suited to power-surfers who want to hack-n-hold their way through full-rail turns, cutbacks and lip-smashes like Taylor Knox. However they're not so good in conditions which favour a new school approach. This is because their extra-speed and fin-surface area makes it harder to perform release-and-recover manoeuvres such as tail-slides, air reverses and any other moves which require the board to slide side-ways or backwards. In comparison, the thruster's relatively inefficient fin-set-up makes it tail much freer when the weight is taken off it, allowing riders to perform new-school moves with greater ease.
So if you're a big wave rider looking to maximise the chances of you making a giant section, a committed competitor searching to gain the edge in 2-foot slop, a power-surfer-and-proud-of-it or more likely a local simply looking for faster ways to go down-the-line at your local break, four-fins (or even five) might just be the way to go. But for all other applications, three still simply hasn't been bettered.