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 "12 Metre" in their name refers not to their length but to the sum of the components of the formula they're governed by. Typically 12-meter class boats range from 65 to 75 feet in length overall; they are sloop-rigged, with masts roughly 85 feet tall. 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 and the sail area. The carefully specified measurements are then entered into the formula, the result of which must be less than or equal to 12 Metres. Designers are free to change any of the component variables so long as corresponding changes elsewhere produce an ultimate sum of 12 meters. Wikipedia [ - ]

The 12 Metre Class is a rating class for racing boats designed to the International rule. It... [ + ]