An assembly for converting a non-sailing boat to a sailboat comprises a sailing keel adapted to be removably attached to the keel of a boat, a first and a second support frame, one or more straps connected on a first end to the sailing keel and connected on a second end to one or both of the first and second support frames, a steering support frame, and a rudder attached to the steering support frame or stern of the boat. The first and second support frames and steering support frame are adapted to extend across the boat from one side of the boat to an opposite side, and the first support frame is adapted to support a mast in an essentially vertical position. A method for converting a non-sailing boat to a sailboat utilizing this assembly is also provided.