Why no hydrophone/sonar qualification?

[Incubus]

This has always puzzled me. Personally, I use the hydrophone a lot more than I use the radio/radar. Why is there a radio qualification and no hydrophone qualification?

What exactly does the radio qualification do?

Too bad you can't assign an officer to the radio/sonar room- in fact, that is the only part of the boat you CANT assign an officer. Odd...