A better solution would be to leave it home and ask the room steward to provide you one. The only reason I profer that suggestion is that some of the "no-no's" differ between plane and cruise. On a plane, as long as your "weapon" is checked, you have no access to it and you are not a danger to anyone. When that same air-checked bag arrives at the port and proceeds onto the ship it will be x-rayed again. I have known of people being called to the service desk to have their checked bags opened after it is discovered that a knife or corkscrew is contained. They ask permission to lock it up and return it to you at the end of the cruise. This makes sense from a danger point of view because now the item that is considered dangerous is now available to you....not inaccessible in the hold of the plane.