Rocker

The Largest Surfing Encyclopedia

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Surfboard rocker, or bottom curve, is frequently singled out as the most important design feature of a given board. Well, it is and it isn't. Rocker has this reputation because it can be such a volatile component in any shape -- from a 5'6" Fish to a 12'6" tandem board.

Every (well-designed) surfboard is a complex balance of curves and straights; some enhance speed, others maneuverability. So, it really would be impossible to isolate just one specific feature and say that it was the most important.

And bottom rockers themselves are incredibly complicated. To describe that simple nose-to-tail bend in your surfboard, the following terms are bandied about by the shaper: nose rocker, tail rocker, entry rocker, rail rocker, deck rocker and so on and so forth. No one can agree on how rocker should be measured -- many shapers have their own method -- so each board builder's lifelong records often mean something only to himself. And even if it was generally agreed that a board with, say, 6 inches of nose rocker and 2.5 inches of tail rocker was arrived at with a universal standard of measurement, there may be a dozen completely different bottom curves that result in those numbers.

The understanding of how bottom rocker affects a surfboard has come relatively late in the development of the surfboard. It wasn't all that long ago that boards could have only the bottom curve that a given tree would allow. Things didn't improve much with the advent of the balsa surfboard, though some shapers did "scarf" extra pieces onto the nose deck area so that they could shape a little extra nose kick or "scoop" into the board. Still, the qualities of a given rocker were not really quantified until well into the foam era -- and probably not even identified as a key design point and measured repeatedly -- until the late '70s. (Bill Barnfield gets the most credit for this.) Nowadays, rocker design is a fundamental part of the manufacturing process at the major foam blank companies. Each blank may have dozens of intricate bottom rockers that the molded foam can be bent into; some of the more popular 'plugs' can have pages of varying rocker designs.

Some basic 'rules' concerning rocker are as follows: The more rocker or bottom curve that a board has, the looser (but slower) it will be. Water flow has to follow the excess curve, ends up pushing water, and drag is the result. Flatter rocker brings more speed but brings a decrease in maneuverability. Generally, boards with more rocker work better in larger, hollow waves where the added curve and drag can contribute to more control for the rider. Flatter bottoms are normally used on small-wave boards designed for slower, mushier surf, where the speed (and added leverage) help keep the board planing.

As with every other aspect of surfboard design, the best option lies in the happy medium of compromise. The better-designed surfboard steers clear of extremes and finds that an even, neutral rocker serves best: flat enough to be fast and efficient, but with enough curve to let the surfboard fit into the curved face of the wave and allow for the tight turns that are the mainstay of performance surfing. -- Dave Parmenter, February 2001