My GG grandfather was called George Thomas Craddock, he was born in Sheerness in 1825 into a whole family of dockyard workers, mostly blacksmiths. He worked his way up through the apprenticeship system, and eventually moved to Portsmouth with most of his family, in about 1872.
His wife, Jane Pearce, was born in Pembroke but her father Robert had come from Devonport, and they met when Robert was posted to Sheerness.
From what I can gather, skilled workmen seemed to be posted to where they were needed fairly often - I've come across another lot, who moved from Woolwich, to Portsmouth, and back to Woolwich again. Presumably the chance of promotion would encourage you to move as well!
Cheers Veron