Inflatable swimming pool cover system

An air supportable structure for a swimming pool having peripheral side walls, said structure comprising:

• a central cover having a floating position and a raised position and made of two sheets of plastic material bonded together to form an air space there between cover is itself buoyant, when inflated said material being configured and dimensioned to closely approximate the configuration and dimensions of the swimming pool and thereby substantially completely cover the swimming pool water surface and float substantially flat upon the said surface in said floating position of said cover;
• a peripheral skirt made of sheet material of lesser buoyancy than said central cover and having upper edge margins attached to the edge margins of said cover, said skirt being free of attachment to the structure of said swimming pool whereby, in said floating position of said cover, said skirt extends downwardly in submerged relation below the swimming pool water surface;
• ballast means attached to the lower edge margins of said skirt, said ballast means being freely movable upwardly and downwardly in the swimming pool water and of sufficient negative buoyancy to maintain said skirt below the swimming pool water surface in said floating position of said cover;
• and
• means for introducing air beneath said cover at a pressure sufficient to lift said cover to said raised position such that a space is provided between said cover and said water surface sufficient for swimming and recreation, said skirt being located generally above the swimming pool water surface in said raised position, with said ballast means located in the swimming pool water.