Screwed, Blued and Tattooed: The last Trifecta

Ponderings of an idiot, I looked this up.  What could it possibly mean?

There seems to be two camps: A) a Navy term relating to the rite of passage in becoming a sailor, with "screwed" and "tattooed" being obvious (no word on whether the sex is necessarily hetero), and "blued" having something to do with getting your uniform. Hmmm ... thought swabbies wore whites, and B) (from urban dictionary):

Unlike the imaginative explanations given, the definition goes way back to early machinists. After inspecting a finished manufactured or repaired part, the Toolmaker/machinist would:
1 tighten all parts and screws (Screwed)

2 Use Blueing a blue paint-like stain that stuck easaly to metal (blued) and

3 Put his inspectors mark through the blue paint with a sharp scriber (tattooed)

I have to say the Navy explanation seems to be in the reverse order of how I'd imagine such a ritual, but I'm a landlubber.    The manufacturing explanation seems like post-hoc theory. 

Let the mystery be ....