The International Monohull Open Class Association (IMOCA) manages the IMOCA 60 class, best known as the yacht of the Vendée Globe.

The association was founded in 1991 and recognized by the International Sailing Federation (now World Sailing) in 1998.

The open design of IMOCA monohulls sets parameters for sailors and designers to innovate in this rapidly developing class, while IMOCA defined rules are intended to limit costs, ensure safety, and create some degree of sporting equity for older designs of the yachts.

The basic parameters are that all IMOCA 60s must be between 59 and 60 feet (18m) hull length (66ft/20.12m LOA) with a maximum draught of 4.5 metres (15ft.)

Other parameters include a maximum mast height of 29m, and a wing mast design. The keel of new designs must be from a single design (although it is canting). There can be no more than 5 hull appendages, including 2 rudders, 1 keel and 2 foils. The rudders and keel must be in a high-visibility colour for safety.

There are also limitations on the number of sails that can be carried onboard in races.

Most IMOCA races are crewed single- or double-handed. The Vendée Globe race is restricted to the IMOCA class and a single skipper whilst events such as the Rolex Fastnet Race usually allows crews of two (or sometimes more) racing in the IMOCA class.