Agreed on the first point. Passing the conn/switching roles is one situation where using (nick)names may make most sense.
Re: Hydro/sonar, a few reasons:
- The sub doesn't currently have active sonar, but some german submarines did have active sonar installed, and so this naming is "future proof" if that's introduced.
- "Sonar" is a single word, while "hydro" is just part of a longer word, and "hydrophones" is rather long.
- Last but not least, "rule of cool". "Sonar" just sounds cooler.
