Perimeter support for a waterbed mattress

Claim 1

In a waterbed having a flexible liquid-containing bladder, said bladder having upper and lower surfaces with a plurality of substantially vertical side walls interconnecting said upper and lower surface, such liquid within said bladder exerting lateral forces on said side walls, a perimeter support for said side walls, said perimeter support comprising: at least two sleeves connected to said upper and lower surfaces of said bladder to be co-extensive with at least two of said plurality of side walls respectively, said sleeves formed of a sheet of flexible material, of stable dimensions under tension, attached to the external surface of said bladder adjacent to the marginal edges of said upper and lower marginal edges of said surfaces so as to be coextensive with said vertical side walls; and at least two self contained chambers encasing a compressible medium, said chambers slidably retained within said sleeves respectively and bearing against said sleeves and said vertical side walls so that said sleeves urge said chambers against said side walls to counteract said lateral forces exerted by such liquid, thereby providing support for said side walls.