Keels, centreboards, rudders and foils
World Sailing · 2025–2028Hull appendages are equipment attached below the defined hull boundary that affect stability, leeway, steering or related functions. A centreboard retracts by rotating, while a daggerboard retracts without rotating. A rudder primarily steers; a hydrofoil can reduce leeway or produce vertical lift. These distinctions help identify the correct class restriction and measurement.
The rule
Hull appendages are equipment attached below the defined hull boundary that affect stability, leeway, steering or related functions. A centreboard retracts by rotating, while a daggerboard retracts without rotating. A rudder primarily steers; a hydrofoil can reduce leeway or produce vertical lift. These distinctions help identify the correct class restriction and measurement.
In practice
The equipment definitions describe components rather than authorising every design on every boat. Class rules decide permitted appendages, movement and dimensions. Appendage weight and assembly weight are separate measurements because associated fittings may be treated differently. Under the ordinary racing rule, movable appendages are operated by crew power, subject to any valid change allowed by the applicable rules.
Sources & approach ↗