PURPOSE: To obtain the full capacity of sailing by providing a plurality of blade- shaped members with gaps to each other in the whole length of a mast for keeping the shape of blades without reference to the tension of a sail.

CONSTITUTION: Blade-shaped members 5 are fast fixed on a mast 2 by bands 53 to cover the mast 2. A plurality of them are arranged almost in the whole length of the mast 2 with small gaps to each other. Each blade-shaped member 5 is constructed of a plastic plate, and a core material 50 made of foam plastics is arranged inside between the front and the mast 2. The core material 50 is provided with a concave 52 to permit the bending of the mast 2. The mast 2 is fastened at its lower end to be rotatable round the axis. The direction of the blade-shaped members 5 can be changed by the rotation of the mast 2.