I use sea bands when cruising and they’ve worked great for me. I’ve used them on the Wonder out of San Diego in fact. I was quite worried about motion sickness before cruising the first time but the sea bands did the trick the first couple cruises.
On our last cruise on the Fantasy we either just had smooth water or I’ve gotten my sea legs because I stopped wearing them part way through as I really didn’t notice the motion onboard, which was not the case on our first couple cruises.
My recommendation is get sea bands, have a medication back up just in case as well but then don’t stress about it. It is really hard to predict how you will react onboard a large ship until you experience it.