If you are referring to any ill-effects you might experience in your cabin I would imagine the degree of vibration,if any,depends on both deck and cabin position. If you are on a low deck at the stern of the ship,maybe there could be a problem.I was on Arcadia in June/July in a midships cabin on deck 9 and never felt or heard a thing.As for the motion of the ship in general,I didn't notice anything untoward.My wife suffers from the same degree of sea-sickness as your husband.She was ill at the beginning of our voyage but that was more to do with the sea-state than undue vibration.