when deployed there are no gaps to the sail plan enabling each spar's sail plan to work as a single sail. The sails, when not deployed, furl into the mast. The sail is trimmed to the wind direction by rotating the mast. As there is no rigging the yards have no restriction on rotation and this taken together with the curved (shaped) yards, low windage and effective single piece sail combine to give the rig improved aerodynamic efficiency compared to a traditional square rigger.