According to my professional photographers (this is the business I am in) here is the scoop. The machines used by security to scan your carry ons (both at the airport and at the cruise ship terminal) will not damage your fim unless you have either very fast film (800 speed or higher) or run the film through a whole bunch of times. Two or 3 scans will not hurt it.
THE SCANNERS USED FOR CHECKED BAGGAGE WILL DO SERIOUS DAMAGE TO YOUR FILM. These are 10 times more powerful than the ones used for carry on.
DO NOT PUT FILM IN CHECKED BAGGAGE. Put your film in your carry on, take it out of the boxes and put it in a clear plastic bag. Ask if they will hand check your film, they should, and having it in the plastic bag makes it easier. If they won't, the xray for carry on will not ruin it. Over 800 speed film, you MUST have it HAND CHECKED or it will get ruined.
Other solutions, get the film processed on the ship, xrays will not damage photos, bring mailers with you and mail it to the processor between the ship and the airport or mail it home to yourself.
Ultimate answer, go digital.