Just to give you an idea...when we cruised I turned on the tv every morning in our room and there's a channel that gives updates on where you are plus other info. such as wave heights etc... Anyway's when we cruised the wave heights averaged approx. 13 feet and you would have thought you were on a lake.
We didn't feel any effect from the waves. You would think you would at that height but the ships stabalizers are awsome! Once in awhile you could feel it when walking down the halls or when you were in the shower etc... but it only lasted for a second. It's like a quick rush. we never took any dramamine or anything and we were perfectly fine.
What I don't know is what wave heights other people have had. I would like to know how high the waves have to be to REALLY feel the effect of the sea?