Covering or blanketing liquid surfaces and float members for effecting same

A float member, for side-by-side nesting relationship with similar float members for substantially completely blanketing or covering the surface of a liquid for reducing evaporation loss of the liquid and for reducing transfer of thermal energy between the liquid and atmosphere, the member comprising a body having a peripheral wall at its midportion of hexagonal shape and having a maximum transverse dimension of about 4.0 inches and a depth of at least about 0.2 inches, and wherein the hexagonal wall is located between opposed integral elements each of identical protuberant shape, the protuberance in each element terminating in the hexagonal wall and tapering inwardly away therefrom such that each protuberance presents sloping sides terminating at the wall, the sloping sides defining an angle to the horizontal of less than about 45.degree. so that wind blowing across the member tends to urge it downwardly, and wherein the depth of the hexagonal wall is at least one-eighth of the total thickness of the float member measured in the direction axially of the hexagonal wall and said depth being between 12.5% and 40% of the maximum dimension across the hexagonal configuration of the float member, and said float member having a weight in relation to its size such that its hexagonal wall is disposed at the surface level of, and partially immersed in, the liquid.