We were on Zenith this year, we left at the end of May came back beginning of June. Beautiful cruise, but it was very rough going down. We left NYC with a low pressure system coming in. For second nite dinner at least 1/3 did not show up for second seating. One table mate got a visit and shot from the Dr.
We took bonine the moment we boarded. We did feel the ship moving as we staggered down our hallway, but as long as we religiously took the bonine, it was more something to laugh about.
Take the bonine and enjoy the cruise because there is no guarantee during any season.