[mikesn9]

I have 'lurked' at times. With radar, watch for contacts.
When you don't have radar, dive and run the sonar around, watching for that green light. You can sometimes pick up a faint sound before the sonar man.
I usually check sonar now and then, even with surface radar, just because.

I have sat at all stop, but usually wander around at 2/3 bell, occasionally less.
With air search radar, even from all stop, you can dive in time to avoid being shark bait.