Surfboard design theory

The surfboard design process can be described as building a bridge between shape and context, based on function. According to this approach, the designer is concerned with two sides of a relationship. On one side, there is the shape of the surfboard itself. On the other side is the surfboard’s context, which is every external condition that influences its function.

The most obvious factors that play a role in a surfboard’s context are physical in nature; from the surfer’s weight to the size and shape of the wave. These are taken into consideration when deciding on a surfboard’s length, width and thickness/volume. The design process thus builds a bridge between shape and context, based on function. However, the ultimate aim of surfboard design is to build a bridge between shape and purpose, since the ideal is a surfboard that becomes absorbed into the surfer’s intentions. So, the surfer’s intentions are also part of the surfboard’s context, making it part of the design process, too.

In considering the surfer’s intentions, the designer analyses how the surfer’s movements affect the response of the surfboard. Basically, the surfer turns the surfboard by leaning his body and extending his legs and feet to varying degrees. However, it is not the mechanics of the human body that concerns the designer, but the net affect. So, the designer reduces the surfer’s influence to a set of rotational axes. At this level of abstraction, the surfer’s intentions can be represented diagrammatically, enabling the designer to more easily visualize the different phases of a maneuver, as well as the transitions between them.

Whatever the axis of rotation, maneuvers can be divided into two phases, a penetration phase and a release phase. The penetration phase is characterized by the inward rotation of the surfboard, while the release phase involves its outward rotation. By visualizing each phase in terms of its rotational axis, or sequence of axes, the designer can identify which portions of the surfboard come into play for a given maneuver.

Having established a link between the surfer’s actions and the under surface of the surfboard, the designer is ready to include the notion of resistance. The focus here is on the degree of drop-off allowing the water to escape. So, a straight line is drawn across the bottom surface, depicting the flow of water. From this, a cross-section of the bottom contours is drawn on a piece of graph paper. The curve of this cross-section determines the force generated during the penetration phase of the maneuver. For example, a concave curve is more responsive than one which is convex.

For the sake of simplicity, the greatest amount of resistance is achieved by rotating the surfboard sideways, since the bottom curve aligned with this plane of rotation provides the least drop-off. Subsequently, the penetration phase of a maneuver tends to be characterized by rotation of the board in or near to this plane. By contrast, the release phase is characterized by a transition from this rotational plane toward either the center plane, by directing the water out through the tail, or into the horizontal plane, by sliding the tail out. The horizontal plane obviously provides the least resistance, since it is limited to the surface area of the fins. However, the loss of resistance felt in the central plane results from the surfboard’s rocker, since the greatest amount of surface drop-off is directed through the tail.

The blending of these curves, which fan out from the center of the board, influences the transition from rail-penetration to release through the tail. Although curvature from nose to tail and from side to side, by themselves, determine the extent to which penetration and release contribute to a surfboard’s performance, it is the blending of curves between these two extremes that ensures that the board enters and exits turns smoothly and with minimal loss of speed.

There is no ultimate shape. Designs ought to vary just as much as surfers vary in their style and approaches to a wave. But, in our quest to imagine new designs, we mustn’t be fooled into thinking that competition leads to progress. Competition is the self-centered offspring of marketing. While it facilitates the distribution of a new design, it is a double-edged sword, simultaneously narrowing the market’s interpretation of what is acceptable in design.

It is not hard to see that the surfer-shaper is the Sufi of naval architects. He understands a good deal more than he can put in words. However, the mystery surrounding his talent serves no purpose beyond the status it gives him. Today, anyone with a CAD program and an inquiring mind can get into the game. But, it’ll be a surfer, rather than a designer, who pulls all the threads together.

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