Abstract: A marine antifouling material providing an antifouling surface for use in sea water comprises a layer of inert, water-insoluble, flexible and extensible elastomeric carrier material having embedded therein a single layer only of a plurality of copper or copper alloy particles of substantially uniform size and shape exposed at the outer surface of the material to provide a multiplicity of generally evenly sized discrete copper areas in the inert material continuum surface thereof. The particles are insulated from each other and from an opposed inner surface of the material.

Abstract: A submersible or semi-submersible structure, such as a boat, oil rig or pipeline, has an anti-fouling covering secured thereto. The covering comprises a mesh of copper or copper alloy embedded in a carrier, preferably of plastics material. The mesh has knuckles which on one surface are close to or protrude from the carrier so as to be accessible to sea water. The knuckles are spaced from the other surface so as to prevent contact between the structure and the mesh. A sea water permeable coating may be provided on the outer surface.

Abstract: In a sifting machine having a driven vibratory screen assembly comprising a so-called sifting basket of which a screen forms the base, the screen is releasably located by a plurality of spaced bars which extend across the screen and project at their ends through side walls of the basket. The projecting end portions of the bars are bolted to external supports on the side walls, and the bars carry spring-loaded plungers which press the frame of the screen against internal ledges on the side walls.