a lighter - than - air device comprises a buoyant element containing lighter - than - air gas , and a flexible surface having a length and height forming a usable area . the flexible surface has a bottom edge that is not connected to the buoyant element . the length of the flexible surface is connected directly to the buoyant element . the flexible surface is operable to use an area defined by the buoyant element and the bottom edge of the flexible surface to , among other things , condense water , move a vessel , and block material from entering an area .