Dave Parmenter |
 The Largest Surfing EncyclopediaA-Z: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Advertisement
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The first things you feel when you lean into a turn on a surfboard are your rails. Their shape will determine whether your turning leverage is crisp and directional or spongy and sluggish.
The refinement of the surfboard rail over the past half-century has been the most important aspect of design progression. Had the shortboard revolution stood only upon the introduction of reduced length and improved fins, we would certainly have not gotten very far toward the levels of high performance seen today. Most armchair design history buffs would agree, if pressed, to name the application of the hard down rail as the most important (non-material) innovation in surfboard history. The down rail, with the apex lowered from the midpoint of the rail to nearer the bottom (later to be further improved with the addition of the tucked under edge), represents the continental divide in surfboard development. As we reached that peak and pushed over it, we entered our own sort of jet age, as surfboards began to become flat planing hulls rather than round-bottomed displacement hulls. The old egg-shaped 50/50 rails were suited to the bottom shapes of the pre-shortboard revolution equipment. Generally speaking, bottom shapes tended toward the rolled, convex school of thought cribbed from the centuries-old example set by boat or canoe hull design. But with the advent of the shortboard, specifically the new flat-bottomed Brewer mini-guns, more sensitivity and leverage were needed. And drag had to reduced if the lightning-fast reaction times -- necessary if surfers were going to ride deeper in the curl -- were to be obtained with the new boards. The shape of your surfboard's rails determine how much of the board's thickness, or volume, is brought out to its extremities. Since much of modern surfing consists of sinking and unsinking the rails to turn and gain speed, it is possible to calibrate how much resistance and leverage the surfer will feel by using a specific rail shape. Most rails in use today represent some variation of the down rail. This type of rail best suits the modern surfboard, as the soft, round part of the rail grants holding power in turns. The drag and suction of the water wrapping around the rails keep the board from spinning out easily. The tucked-under bottom edge enables the board to plane faster when driving down the line, as the water flow off of the bottom has a harder time bending over and around the firm edge; it releases straight off at that point, thereby reducing drag. An over-simplified primer on rail shapes would probably contain these main premises: the lower and harder a rail is, the faster and stiffer it will be. The softer and rounder, the slower and more neutral-handling it'll be. Fuller, boxier rails are harder to sink, so have more potential for leverage. Thinner, tapered rails sink easily, but with less stored energy, are not as likely to leap out of turns. Naturally, there are many examples of hybrids and compromise applications of the above-named rail types that can be exploited for specific board designs, and each surfer should be encouraged to explore the whole range so that they are familiar with the basic feel and potential of each type of rail. -- Dave Parmenter, March 2001
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