I think they work a rotation but it's sort of a rolling rotation. The more or less ships they do the quicker they are back on top of the list. Also I think the newer pilots do more jobs that the senior ones.
Oops I misread I thought you meant the actual pilots. Ya they are 1 week on/off but they mostly have the apprentice pilots run the boats. However the Md pilots are next door and they have normal boat crews 1 on/off and alternate day and night shift.
Just look up the VA Beach stations phone number online and ask for the station manager. I applied there years ago but can't remember the guys name. The guy who answers will likely be one of the boat guys. Maybe he can answer your questions.