The IMOCA gauge was created after the first Vendée Globe in 1991. The aim of this gauge was to imagine sailing yachts driven by a single man (or with a reduced crew) capable of sailing in the Southern seas. It is a fairly open box rules gauge leaving a large creative part for architects.
Regularly modified in order to improve safety conditions for sailors, it only defines a few parameters of the boat:
- The sailboat must be a monohull
- Its hull length must be between 59 feet (17.98 m) and 60 feet (18.26 m)
- Overall length (with bowsprit and rudders) must be less than 66 feet (20.12 m). If the boom exceeds the length of the hull, it is taken into account in the measurement.
- The maximum width must be less than 5.85 m
- To avoid scow type hulls (as seen in the Mini Class), the maximum width, taken 1 m behind the bow, must not exceed 1.12 m
- The maximum draught is fixed at 4.50 m (empty vessel)
- Only 5 appendages are allowed (generally tilting keel, 2 rudders and 2 daggerboards or foils)
- The sail surface is free. The number of sails is limited to 9 (including a compulsory storm).
- The sailboat must be built with five watertight bulkheads (6 watertight compartments)
