It is important to note that cruise ships are registered in foreign countries. Less than 1% are US flagged vessels. You are subject to the laws of that country once you are on board. Your scanner is not allowed. It doesn't matter what is permissible under US law because you aren't in the USA anymore. Probably they would take the radio and give it back to you at the end of the cruise. By the way, even though licensed ham radio use is allowed, it is subject to reciprocal regulations of the country under whose flag the ship operates. The ARRL has info on this.