Shelby was a lt. cmmdr.
I agree on every point. Shelby was an excellent character. Not only did she "shake things up" a bit among the crew, she did it in a way that was respectful, and did not rob anyone's dignity away.
At the time of this episode, I remember speculating that she would become a permanent member of the cast. It was a bit of a shame that she didn't.
And yes, she was a competant professional, AND pretty damn sexy!