HMS Pylades was a Satellite-class composite screw sloop of the Royal Navy, built at Sheerness Dockyard and launched on 5 November 1884.The iron framing, with wooden skin planking, admitted of considerable strength being obtained, and the possibility of sheathing the bottom with metal in order to avoid fouling, appeared to be another advantage in favor of the composite system.Soon, however, it was shown that the galvanic action set up between the copper on the "yellow metal" sheathing, and the iron frames tended to rapidly deteriorate the ironwork, and perhaps, sooner or later, hasten the loss of the vessel.So rapid, indeed, was this wasting of the frame found to be, that for some time past the composite system has been, so far as regards merchantmen, quite abandoned.Some ships, however, are still built "composite" for the Royal Navy, especially such craft as are intended for use on foreign stations, and whose duties would render frequent docking impossible.