I used those patches on our first 2 cruises, but the side effects were awful. I started taking meclizine/Bonine. I would take it each evening as I got ready for dinner since they speed the ship up then to make good time. I've never had issues with that. But our last 3 cruises, I didn't take anything, but I did take them with me in case. I know one cruise, we hit rough enough seas that stewards were putting out barf bags (never a good thing to see), so I hopped my happy butt back to the cabin and took another one! I could feel the movement but never got sick.
One thing I will say is that hydration is very important! Alcohol is the opposite of that. I learned this because altitude sickness is very similar for me but if I can hydrate properly before getting to certain altitudes (obviously, flying doesn't count - at least not for me), the sickness isn't as bad.