Submersible or semi-submersible structures

An anti-fouling panel for attachment to the surfaces of a submersible or semi-submersible structure, said panel comprising a layer of a water-insoluble, inert carrier material having first and second opposed surfaces and, embedded in said material, a layer of thin flexible woven wire mesh comprising wires of copper or a copper alloy, the mesh size being in the range 3 to 60 mesh per inch, and wherein the woven wire mesh comprises warp and weft wires forming knuckles at their crossover points, the knuckles being upstanding from the two opposed faces of the mesh layer, the said mesh layer being completely buried in the inert material except for all the knuckles on one face only of the mesh layer, all said knuckles being exposed at the first surface of the plastics layer to provide thereon a multiplicity of tiny, regularly-spaced, discrete evenly-sized metal areas in the inert material continuum surface, the said areas being spaced by 0.25 to 7 mm., the total area of the spaced metal areas being between 13 and 50% of the total area of the first surface of the plastics layer, and wherein the knuckles on the other face of the mesh layer are buried in said layer whereby the second face of the layer has no metal exposed thereat, and wherein the second surface of the layer can be attached to a said structure whereby the said first surface of the layer is accessible to sea water and the multiplicity of tiny regularly-spaced metal areas thereon retard or prevent marine growth on said first surface.