A flotation device for water aerobics comprising a single piece of foam shaped to form a main central member having positive buoyancy and a pair of float arms having positive buoyancy. In some embodiments, the invention relates to devices and methods of generating a gas enriched in a specific component. The permanent magnets may also extend within the stator teeth on an angle or diagonal, thereby allowing use of magnets which are wider than the teeth themselves to produce greater flux. Remote sensing units according to the invention can be used for a variety of purposes, including water quality or electrical power monitoring, and data from such sensing units is preferably transmitted to a secure host terminal via a communications link. For ride owners the ride gives a large patrons-per-hour capacity in a relatively small operating area.