Solution designed to solve the connection of a sheave to the furling mainsail clew efficiently. The block is contained within the size of the sail, thus allowing a larger surface of the mainsail to be used. The choice of materials guarantees the least weight as well as a very good mechanical resistance to the environment. Particular care has been taken over the ease of connection which is obtained by normal webbing. This ensures moreover a very good distribution of the load on the sail.