Post a gunnery qualified officer on the watch station with 3 regular n00b sailors manning the deck gun. Then post a non-gunnery qualified officer on the watch station with 3 regular n00b sailors manning the deck gun. Watch what happens.
(P.S. Same works for Flak Gun qualified officers too. The only thing officers are useless at being qualified in is Radioman. And Helmsman, from what I can tell. But then again, I believe the Helmsman qualification is useless for everyone.)