Spec series

One-Design is a racing method which may be adopted in sports which use complex equipment, whereby all vehicles, gliders or boats have identical or very similar designs or models. In motor racing, it is also known as Spec series, and one-make racing.

As manufacturing technologies became more efficient and effective over the course of the 20th century, racers in a number of sports realized that there was an important need to equalize the design of the equipment that they were competing in. One-Design racing is the ultimate result of this. Most often, the members of a One-Design class are near identical as a direct consequence of all deriving from the same production line. Sometimes they are checked or measured at stages in their use to guarantee continuing conformity to the standard design. The important factors being measured in One-Design racing help to equalize the vehicles and put more emphasis on the skill of the competitors.

One-Design is utilized in a variety of racing sports.

It is heavily used in sailboat racing. All competitors in a One-Design race are judged simply on a 'first to the finish' basis using a single start time. Other approaches to racing involve either a handicapping process (adjusting each competitor's elapsed time over the course by a factor based on the handicap figure for their boat), or restricting participants to using boats of some recognised class or type, or allowing only boats which conform to some formula or other specification. In the United States, the One-Design Class Council creates, monitors, and enforces the rules that define what classes of sailboats are One-Design boats.

It can additionally refer to airplanes or motor vehicles, such as IndyCars, where teams are required to meet certain specifications such as vehicle weight, engine displacement, weight, fuel capacity, and a variety of other factors are measured and regulated, or classes limited to a single make, such as the Yamaha RD Cup.

In motorsport, this term is commonly known as one-make racing and this term is predominantly given to series for production based cars such as the Porsche Supercup.

There are two primary methods of competition in sailboat racing: One-Design and handicap (see: Portsmouth Yardstick,PHRF and LYS (Leading Yard Stick)). One-design refers to a racing class that consists of just one model or design of sailboat. In one-design racing, the first boat to finish wins the race. This is contrasted with handicap racing, where time is added or subtracted from the finishing times based on design factors and mathematical formulas to determine the winner.

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