I tried the patch that goes behind your ear on our first cruise because I was afraid that I would get sick. I tend to get motion sickness from watching home videos if you can imagine that! And, I did get nauseated the first night at dinner. I mentioned it to my waiter and he told me that sometimes the patches make people feel sick. So I took the patch off and I was just fine within 30 minutes or so.
We went on our second cruise a year later - I did not take the patch and was perfectly fine.
The first night is a little bumpy when we go across the gulf stream. But after that, I can't even tell we were on a boat!