Blacksmiths produced metal items needed for ships including anchor chains and stoves. They worked mostly with iron. Unlike founders who pour molten metals into moulds, blacksmiths used hand tools to hammer, bend, cut and shape heated, but not molten metal, into finished items.
In the early part of the twentieth century blacksmiths were the main trade under the shipwright. The early metal ships were built using frames which were bent on great iron slabs. The shipwrights would prepare moulds and the blacksmith would hammer out and bend the plates to the mould made by the shipwright. The blacksmith was a highly skilled craftsman. As welding developed welders began making items which the blacksmith had previously forged. It was easier and cheaper for welders to pre-fabricate fittings from steel plate.
Blacksmiths worked in special workshops which in the Royal Dockyards are called smitheries. These were no different to smithies outside the Dockyards. The words both come from the same Anglo-Saxon route. People used the words smithy and smithery interchangeably. Once uniformed spelling became the norm in the nineteenth century, the Royal Dockyards called their blacksmith shops smitheries whereas blacksmiths outside the Royal Dockyards called their shops smithies.