Ski - Design

Design

Ski nomenclature is relatively simple. Examining the ski from front to back along the direction of travel, the front of the ski (typically pointed or rounded) is the "tip", the middle is the "waist" and the rear (typically flat) is the "tail".

All skis have four basic measures that define their basic performance: length, width, sidecut and camber.

Length and width

The length and width of the ski define its total surface area, which provides some indication of the ski's "float", its ability to remain on top of the snow instead of sinking into it. The width by itself also has a strong relationship to the amount of drag as it moves though the snow. Efficiency in cross-country skiing depends on keeping the skis narrow to reduce drag, and thus requires them to be very long in order to produce the required amount of float. Alpine skis are generally not as concerned about drag, and tend to be shorter and wider.

Sidecut

Sidecut is the shape of the edge of the ski as viewed from the top or bottom. Alpine skis are wider at the tip and tail than they are at the waist; when rotated onto their edge, known as "edging", this causes the ski to bend into a curved shape and allows them to "carve" a turn. Cross-country techniques use different styles of turns; edging is not as important, and skis have little sidecut. For many years, alpine skis were shaped similarly to cross-country, simply shorter and wider, but the Elan SCX introduced a radical sidecut design that dramatically improved performance. Other companies quickly followed suit, and it was realized in retrospect that "It turns out that everything we thought we knew for forty years was wrong." Since then, "shaped" skis have dominated alpine ski design.

Camber

Camber is the shape of the edge of the ski as viewed from one side or the other. Skis are traditionally designed so the tips and tails are naturally pressed down, and if laid on a flat surface, the waist will be in the air. Without camber, when the skier's weight is applied at the waist, the weight will be distributed on the surface closest to the foot, diminishing along the length. Camber presses the tips and tails into the snow, extending the surface area bearing the skier's weight, and thereby improving the amount of edge in contact with the surface. The technique was first introduced by ski makers in Telemark, Norway, and remained largely unchanged through the 20th century. In 2002, skier Shane McConkey led development of the Volant Spatula, an alpine ski developed for skiing deep powder snow. The Spatula featured "reverse camber" with the tips and tails rising above the waist, in an effort to improve the ski's ability to float on the snow. It was quickly realized that the design was superior in many snow conditions, and as was the case with radical sidecuts, modern alpine skis generally feature some sort of "rocker" design today. This is often subtle, with natural camber at the waist, and rocker at the tip and tail.

Skis also differ in more minor ways to address certain niche roles. For instance, mogul skis are much softer to absorb shocks, and powder skis are much wider to provide more float. These are discussed below.