it is normally 33 metres. Sidecut is the extent to which a ski or snowboard is narrower at the waist than at the tips. It is the arcing, hourglass-like curve that runs along a ski’s edges from tip to tail. This curve dictates how skis turn: the deeper the curve, the tighter the turn. Straighter skis with less sidecut have a larger turning radius and are more stable at high speeds. The sidecut radius is the radial measurement of the curve that matches the inner curvature of the ski, snowboard, or skiboard. For instance, with a radial sidecut, a circle with a particular radius will perfectly fit the curvature of the sidecut. This particular radius is the given specification from the manufacturer. However, it is not necessary that the radius be constant. Mathematical functions, such as a parabola or a clothoid, are often used to describe the curvature of a sidecut. Also, multiple radii are stitched together in a piecewise fashion as well. Alpine skis have undergone three distinct changes in sidecut design. The earliest skis from the 1800s all the way to modern examples in the late 1990s featured a very small amount of sidecut that produced a ski that was almost rectangular in profile as seen from the top. Starting with the Elan SCX in 1993, and very rapidly thereafter, these designs dramatically increased sidecut, a design known as the parabolic ski, or later known as a shaped ski. With the exception of competition mogul skis, shaped skis continue to dominate wherever skis are used on packed snow or in powder with a firm base underneath. Following the introduction in 2003 of the Volant Spatula, designed by Shane McConkey, "rocker" skis became popular in the North American market. European skiers generally remained committed to full-cambered skis designed primarily for carved turns. Snowboards and skiboards have generally had much more sidecut than alpine skis, roughly similar in layout to a parabolic ski. These designs evolved independently and were engineered from the start to select a design that produced smooth turns. Alpine skiing had previously been based on a skidding style of turns known as "stemming" that did not require much (or any) sidecut, and did not experiment with other designs as styles changed. Snowboards had to invent their equipment and techniques fresh, and found the deep sidecut was best through experimentation. Alpine skis were for many years shaped similarly