Something like that needs to be in checked luggage, if brought at all. I assume you are talking about a Buck knife or something similar. Something like that is sure to get you some extra attention by security at the pier if it is in a carry on bag. I'd strongly urge him to leave the "pocket knife" home this time. There really isn't any need for it aboard a ship and carrying it in some of the ports of call could land him in serious trouble.