Nope, but I have noticed once you dump a crewman you're again bound by the max # PO and O's designated to your type of ship when you try to recruit..
...BUT if you get some GOOD undesignated recruits you get the option after successful patrols to promote them and make them specialists (gunners not included). I've got almost 20 E6's and above on my crew mostly engineers and control room specialists. It works for officers as well.
You should see my efficiency ratings per section, FULL green on all stations, all watch sections. I never need to go to red alert.
