A plurality of assembly sheets are placed on an upper surface of a substrate adsorption platform, and a pressing plate is placed on the plurality of assembly sheets placed on the substrate adsorption platform such that the plurality of assembly sheets are pressed by the pressing plate. Therefore, the mattress members are retained between the two frame holders to align the mattress surfaces of the mattress members to form a floating platform for supporting the user to rest thereon and to float on the water surface. The elements are temporarily coupled to the guide curve. The sleep state is entered for a remainder of the predetermined period upon determination of the initial timing offset. A method of monitoring weight of a person, comprising the steps of arranging one or more weight sensitive detectors underneath a foot of the person; processing signals from the detectors to determine weight; and wirelessly communicating the weight to a remote receiver. The sound source used is a highly directional parametric loudspeaker.