Ski

This article is about the sporting device. For the related activity, see Skiing.

For other uses, see Ski (disambiguation).

A shaped alpine ski with relatively little sidecut and classic camber: the tip and tail touch the snow while the midsection is in the air.

A ski is a narrow strip of semi-rigid material worn underfoot to glide over snow. Substantially longer than wide and characteristically employed in pairs, skis are attached to ski boots with ski bindings, with either a free, lockable, or partially secured heel. For climbing slopes, ski skins (originally made of seal fur, but now made of synthetic materials) can be attached at the base of the ski.

Originally intended as an aid to travel over snow, they are now mainly used recreationally in the sport of skiing.

Etymology and usage

The word ski comes from the Old Norse word "skíð" which means stick of wood or ski.

In Norwegian this word is usually pronounced [ˈʃiː]. In Swedish, another language evolved from Old Norse, the word is "skidor" (pl.).

English and French use the original spelling "ski", and modify the pronunciation. Prior to 1920, English usage of "skee" and "snow-shoe" is often seen. In Italian, it is pronounced as in Norwegian, and the spelling is modified: "sci". German and Spanish adapt the word to their linguistic rules; "Schier" (however there is a form- Ski) and "esquí". Many languages make a verb form out of the noun, such as "to ski" in English, "skier" in French, "esquiar" in Spanish, "sciare" in Italian, or "schilaufen" (as above also Ski laufen or Ski fahren) in German.

Finnish has its own ancient words for skis and skiing. In Finnish ski is suksi and skiing is hiihtää. The Sami also have their own words for skis and skiing. For example, the Lule Sami word for ski is "sabek" and skis are "sabega".

History

Main article: History of skiing

The oldest wooden skis found were in Russia (ca. 6300-5000 BC), Sweden (ca. 5200 BC) and Norway (ca. 3200 BC) respectively.

Nordic ski technology was adapted during the early twentieth century to enable skiers to turn at higher speeds. New ski and ski binding designs, coupled with the introduction of ski lifts to carry skiers up slopes, enabled the development of alpine skis. Meanwhile advances in technology in the Nordic camp allowed for the development of special skis for skating and ski jumping.

Design

Described in the direction of travel, the front of the ski, typically pointed or rounded, is the tip, the middle is the waist and the rear is the tail.

Skis have four aspects define their basic performance: length, width, sidecut and camber. 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.

Length and width

The length and width of the ski define its total surface area, which provides some indication of the ski's float, or ability to remain on top of the snow instead of sinking into it. Cross-country skies must be narrow to reduce drag, and thus must be long to produce the required float. Alpine skis are generally not designed to reduce drag, and tend to be shorter and wider. Skis used in downhill race events are longer, with a subtle side cut, built for speed and wide turns. Slalom skis, as well as many recreational skis, are shorter with a greater side cut to facilitate tighter, easier turns. For off-piste skis the trend is towards wider skis that better float on top of powder snow.

Sidecut

Main article: Sidecut

Sidecut is the subtle hourglass shape of the ski, viewed from the top. Skis have had some sidecut since before 1808, when it was invented by Norwegian artisans. Since that time, the straight ski with parallel edges is only used as a light cross country ski and for modern jumping skis. In alpine skis, sidecut shape has grown gradually deeper over the decades. Today deep sidecuts are used to help skis carve short, clean turns.

Many ski vendors allow selection of skis by turning radius. For a racing slalom ski, this can be as low as 12 metres and for Super-G it is normally 33 metres.

Camber & rocker

Modern powder skis are much wider than on-piste designs. This example has noticeable rocker shaping at the tip and tail, while retaining some camber and sidecut.

Camber is the ski's shape as viewed from the side. Typically skis are designed so that when the tip and tail are on the ground, the waist is in the air. Without camber, when the skier's weight is applied at the waist, the weight would be distributed on the surface closest to the foot, diminishing along the length. Camber distributes weight onto the tips and tails, extending the surface area bearing the skier's weight, and thereby improving the amount of ski 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 uses reverse camber with the tips and tails rising above the waist in an effort to improve floating on soft snow. Referring to the shape of the running on a rocking chair, these designs became known as rockers.

Today alpine skis often feature a combination of rocker and camber. This is often subtle, with natural camber at the waist, and rocker at the tip and tail. These designs often lack sidecut as well, relying on their interaction with the snow to provide the curving shape that causes the ski to turn smoothly.

Design by gender

Skis were once unisex, but today skis are designed to suit both men and women. Compared to men's skis, women's skis are built for smaller, less powerful frames, and have a waist that’s farther forward to better match a woman’s relatively lower center of gravity relative to a man.

Construction

Skis have evolved from being constructed from solid wood to using a variety of materials including carbon-Kevlar to make skis stronger, torsionally stiffer, lighter, and more durable. Ski manufacturing techniques allow skis to be made in one or a combination of three designs:

Laminate or sandwich

Laminated skis are built in layers. Materials such as fiberglass, steel, aluminum alloy, or plastic are layered and compressed above and below the core. Laminated construction is the most widely used manufacturing process in the ski industry today. The first successful laminate ski, and arguably the first modern ski was the Head Standard, introduced in 1950, which sandwiched aluminum alloy around a plywood core.

Torsion box

The Dynamic VR7 introduced a new construction method in which a smaller wooden core was wrapped in wet fibreglass, as opposed to pre-dried sheets of fibreglass being glued to the core (essentially replacing metal sheets). The result was a torsion box, which made the ski much stronger. The VR7, and its more famous follow-on VR17, was the first fibreglass ski that could be used for men's racing, and quickly took over that market. Over time, materials for both the core and torsion box have changed, with wood, various plastic foams, fibreglass, kevlar and carbon fiber all being used in different designs. Torsion box designs continue to dominate cross-country ski designs, but is less common for alpine and ski touring.

Monocoque or cap

During the 1980s, Bucky Kashiwa developed a new construction technique using a rolled stainless steel sheet forming three sides of a torsion box over a wooden core, with the base of the ski forming the bottom. Introduced in 1989, the Volant skis proved expensive to produce, and in spite of numerous positive reviews, the company never became profitable. In 1990, the Rossignol S9000 took the same basic concept but replaced the steel with plastics, producing a design they called "monocoque". Now referred to as the "cap ski" design, the concept eliminates the need to wrap the core and replaces this with a single-step process that is much less expensive to produce. Cap ski construction dominates alpine ski construction today.

Historical

The classical wooden ski consists of a single long piece of suitable wood that is hand-carved to produce the required shape. Early designs were generally rectangular in cross-section, with the tip bent up through the application of steam. Over time the designs changed, and skis were thinned out to the sides, or featured prominent ridges down the center.

Types

In the history of skiing many types of skis have been developed, designed for different needs, of which the following is a selection.

Alpine

Ski design has evolved enormously since the beginnings of the modern sport in mid-19th Century Norway. Modern skis typically have steel edges, camber, side cut, and possibly reverse camber. During the 1990s side cut became more pronounced to make it easier to carve turns. Specialised types of alpine skis exist for certain uses, including twin-tip skis for freestyle skiing, alpine touring ski, and monoski.

Nordic

In Nordic skiing the skiier is not reliant on ski lifts to get up hills, and so skis and boots tend to be lighter, with a free heel to facilitate walking. Styles of Nordic skiing equipment include:

• Cross-country skis are light and narrow, with a slight sidecut. Three binding systems are popular: Rottefella's NNN, Salomon's SNS profil, and SNS pilot. Ski bases are waxed to reduce friction during forward motion, and kick wax can also be applied for grip. Some waxless models have patterns on the bottom to avoid the necessity of grip waxing for classic technique.
• Skating skis are shorter than classic skis and do not need grip wax. The skating technique is used in biathlons.
• Ski jumping skis are long and wide.
• Roller skis have wheels for use on dry pavement, in the absence of snow.

External links

• Physics of skiing
• FIS equipment tolerances
• Hiking Ski Climbing Men's Gaiters