> but you wouldn't expect them to command a ship.

I know what you mean, but I don't think it would merely be unexpected if one did somehow. I'm pretty sure it isn't possible because, being specialists, they can't also be a line officer. It seems like logic stops them, but then leads me to wonder about the vague possibility of a horribly unfortunate event leaving only specialists on-board... what then? Would logic stop them from sailing, or inexperience and lack of expertise?