Regarding Silvers timber leg Silver specifically says that he learned his craft as a sailor while in the navy In fact he specifically mentions that he was a master mariner which indicates he was an officer on a warship yes the pirate could have been lying regarding his former rank and that he lost his leg in battle which would doubtlessly lead to his retirement from active naval service However with the skills of a former naval officer incidentally who would have been trained in navigation he would have had an easy time joining up with a pirate crew He was likely lying about serving under Captain England given the dates Also Silver was Flints quartermaster which in the Royal Navy is the helmsmans position Given that his onelegged status does not seem to make him any less lethal a pirate  he takes down a man by nailing him in the spine with his crutch  there is no reason to suppose that he retired from the life of a gentleman of fortune because he had one leg He retired because Flint died