Hopefully he bought one that is a little larger than he needs. One of the bad features of a cruise is the fact that all of my clothes seem to shrink when we get back. It may be time to buy a new washing machine or drier and find a new dry cleaner that does not abuse my clothing. I am not sure but I would swear that the salt in the sea air makes them shrink.
Have a great time and be sure to write about your trip.