If you're talking about working on a cruise ship you actually have to agree to work for 9 to 12 months depending on the job. They run over here during the winter months and head to Europe in April and May. I think you will have to pass a Coast Guard physical. As far as passage on a freighter many foreign flagged vessels may not hire you if you cannot speak the crews language. Any US flagged vessels generally want you to have either had some experience, professional training at a Merchant Marine school, or both.