A class 6 supply ship has a crew of 26 and not meant to risk combat. While U.S.S Thera has been a class 6 supply ship for a while, she will again take the role as a medium cruiser with a 220 strong crew. So my "just passed..." comment is for a chief engineer that is out of the comfort zone. To actually be ready for the position would require a lot more training and experience for the character.
I'll PM you about your character concept to bounce some thoughts.