Looks like a regular Accomodation Barge to me. Had to stay on one for awhile when shipyard crews had to basically split our ship in half for some modifications.
For anon entertainment, clip from documentary "Carrier" of 2005, tour of USS NIMITZ brig:
https://www.wearethemighty.com/articles/this-is-what-jail-is-like-on-an-aircraft-carrier