Bring some Red Hering with you in your bag. Oh, and just bring a pack of cigarettes with you, and unpack the cigarettes, and replace a few of them with bud, and then put some tobacco at the very end so they can't see the bud. Last time I went on a cruise, I don't really remember getting checked. Since you're on international waters, I think it wouldn't be the biggest problem in the world if you got caught smoking, since they offer drinks to people that LOOK 18 (meaning kids get them all the time).