If my experience in the offshore industry is anything to go by, a crew cabin will be 8-10sqm (100sqft-ish), with either one or two bunks (Pro tip: try to get dibs on the lower one), a small table or desk if you are lucky, a couch two people can share if they are really good friends, a couple of small cabinets for clothing and personal items, also two drawers under the lower bunk.

Oh, and with any luck, a porthole.

A head, 2sqm/20sqft or so, shower, toilet, sink.

Neat and tidy, but by no means luxurious.