It means that all the other ships have a full complement of crew members. It's not a common usage, but it makes sense. 'Crew' can be a verb in the context of manning a ship or taking a crew on board, and the particle 'up' indicates a completion of a task. The implication is probably that this particular ship is a last resort for crew members looking for work. The man would only resort to taking work on this ship if he hadn't been able to find work elsewhere.

Crew up : To prepare your crew. This type of phrase/sentence is sometimes used in other contexts. Most often by Americans. It is usually an instruction (or challenge) - activate !! Do it !! Begin !! Stop talking. Lawyer up : Notify your lawyer. Cash up : Present the cash. Gear up: Put on your equipment. A: Our supplier charged us 10% extra for no reason. B: Did you get it back. A: Yes, I told the manager to either refund us immediately or lawyer up for a long and expensive court case. A: We don't know if the hockey game is starting. B: Gear up anyway, its better to be ready. A: Will you take the bet or not. B: Yes I will take the bet. A: Ok, cash up or leave.

i think its a spelling mistake. its 'grew up'.