A sparless altitude sail is controlled by the shroud ropes of the sail being surrounded by a reef ring (9) which is fastened on a rigid rod or a bar (8). The bar (8) is connected to the fly lines (5) of the sail so that an actuation of the fly lines brings about a movement of the rod/reef ring arrangement in such a manner that the shroud ropes are separated or drawn together, as a result of which the sail cap (3) opens or draws together. <IMAGE>
