12-metre Class

12-metre Class

The 12 Metre Class is a rating class for racing boats designed to the International rule. It enables fair competition between boats that rate in the class whilst retaining the freedom to experiment with the details of their designs. The first 12 Metres were built in 1907. The 12 Metre Class was used in the Olympic Games of 1908, 1912 and 1920 but only few boats participated. The 12 Metre class boats are probably best known for their use from 1958 to 1987 in the America's Cup.

Rough equality between boats is ensured by requiring compliance with a formula that takes into account the length at the waterline, the girth (the measurement around the boat from one sideboard, under the keel and then back over the top on the opposite side back to the original side) and the sail area. The carefully specified measurements are then entered into the formula, and the result must be less than or equal to 12 Metres - hence the name of the class. Designers are free to change any of these variables (as well as other details, such as the size of the rudder and keel, etc.), with the understanding that for any change in any of the measured attributes, something else will have to be adjusted, in order to make the formula produce the required value.

The "12 Metre" in the class name does not refer to the actual length of the boats, which range from 65 to 75 feet (about 20 to 23 m) overall. They are all sloop-rigged, with their masts typically being about 85 feet (26 m) tall. The "12 Metre" yachts are also referred to as "Twelves" or "12 Metres" or even "12s".