Besides everything described by
bigboywooly, all qualifications do matter if you are using a fatigue model. I am using RuB model and it really helps to have a qualified officer with Maschinist ability when you are trying to get back home after 30 day long patrol with exhausted crew. Being unable to complete enough workforce to keep diesel engines running can be a real pain in the ass.
In situation like this even Helmsman ability can be useful.
BTW, I didn't check it, but it may be that having unfilled green bar at helms station affects diving, turning and accelerating times.