International Rule

The "International Rule" in yacht racing is a measurement formula used to classify sailboats of different designs, allowing them to compete fairly. These rules consider factors like a yacht's length, beam, displacement, and sail area to estimate its potential speed.1

Early rules focused on sail area and waterline length, leading to specific hull designs. Later, rules like the Universal Rule and the more complex International Rule (adopted in 1906) were introduced. These rules penalized certain dimensions while retaining key factors. While some International Rule classes, like the Metre classes, were popular, many were eventually superseded by one-design classes where all boats are identical.1

Long-distance races often use handicap systems based on measurement rules, such as the International Offshore Racing Rule, which combined aspects of earlier rules. The Bermuda Race, for example, uses a handicapping formula to determine its winners.12