On that ocean crossing, the class system of the military was especially evident. Our nine-man crew, who had become good friends - no saluting, no "yessir and nosir" - were separated on board ship. The five enlisted men in the crew ate in the huge mess room, the usual grubby army food. We, the officers, ate in what must have been the first-class dining room of the Queen Mary - linen tablecloths, white-jacketed waiters, magnificent chandeliers, steaks and roasts. It was bizarre, with us sailing through submarine-infested waters on the way to a war.
I imagine that Zinn would have been surprised to learn that he and his fellow officers actually dined in the pre-war Tourist (Second) Class restaurant. The "huge mess room" that he wrote of (which would also be the setting for a defining moment in his life) was originally meant for the Cabin (First) Class passengers.
Regardless, however, this passage gives an idea of the way that soldiers were divided up on a wartime crossing aboard the "Grey Ghost."
References: Howard Zinn, You Can't Be Neutral on a Moving Train: A Personal History of Our Times (Boston: Beacon Press, 2002), 92.