The darker the uniform, the higher the rank they are. There are working ranks. Seaman does normal jobs Shift officer or S.O, command small groups of seamen, usually about 5, and are also used as shock groups if there are raiders on the ship. Officer, they command everyone, and also drive the boat. They usually give the orders to fire at will and help with disciplining the crew They all have an LF or Lifter Floater. This is like a small life vest. They also were under neath a tank top called a gravlert. The seamen also usually sleep on the decks of the ship if it isn't freezing or very cold outside. While S.O and officers sleep inside.
These groups mainly apply for bigger ships. If on a ship with only a few personnel (under 20), they have an S.O. in charge.