The Vela al terzo is the traditional form of sail used by fishing boats and small transport on both shores of the northern Adriatic from the eighteenth century until the middle of the last century. It is characterized by the trapezoid shape and dyeing with earth in bright colors, always marked with a design referring to the family of the owner of the boat, as a kind of folk heraldry.
It owes its name to the fact that the upper flagpole that supports it is fixed to the mast at a third of its length.