You can be buoyant with plastics

When swimming there are four forces acting upon the body. Moving forwards is the thrust provided by the swimmer’s paddling and kicking movements, in the opposite direction moves the drag or resistance caused by the flow of the water. Affecting how high in the water the body sits are the opposing forces of the person’s weight as they are pulled down by gravity and their level of buoyancy pushing them up. The higher their level of buoyancy, the higher they will float within the water.

Plastics materials can help a person float higher in the water by increasing their buoyancy to weight ratio. This Crewsaver jacket (1) is made of supersoft PVC foam which is very buoyant and extremely light weight.  Similarly, the Speedo kick board (2) made from ethylene vinyl acetate provides the training swimmer with the ability to hold their arms high and still in the water whilst they concentrate on building their leg technique. The PVC arm bands (3) are used by children to increase their confidence in the water by providing extra floatation at the head and shoulders and therefore helping them keep their head out of the water.