A sail assembly includes a sail, a mast, a coupler, and a fastener. The mast is attached to a first side of the sail. The coupler is attached to the mast and is used to couple the mast to a handle portion of a paddle. The fastener is attached to the sail at a location opposite the first side of the sail and is used to fasten the sail to the blade portion of the paddle. The sail is held in an open position when the mast is coupled to the handle portion of the paddle at a right angle to the paddle and the sail is fastened to the blade portion of the paddle. Thus, when the mast is supported upright and the end of the sail is connected to the paddle, the sail is open and usable to propel the boat under power of the wind.