They will definitely try to avoid any very rough seas by changing itineraries, but I cannot guarantee they will have a smooth ride just by doing that.
What ship are you on?
Now - take heart that ships are NOTHING like small boats. I also get sick on small boats but I cruise all the time.
I see a lot of people using the patches and they seem to tolerate them well. I have never tried them.
An alternative is Bonine (Meclizine) - which is an over-the-counter medicine for seasickness. Dramamine 24-hour formula should be the same (but not regular Dramamine).