Ellie, It might be a good idea if you brought some Bonine just in case. The cruise ships are pretty stable but when the seas are up there is some rocking. Most people are unaffected but there are others that aren't so lucky.
I agree with Robocop. My husband has an inner ear problem and gets seasick at the drop of a hat. He swears by Dramamine II, which has the same active ingredient (meclazine, I think) as Bonine. And few enough side effects to not worry about in the least.