Being that I was Army I wasn't aboard very many ships But I was detailed to travel from Germany to Sydney For prisoner escort in 75 to bring back a couple guys who had stayed there after their leave was over from Vietnam in 1969 To get there and back it was available military only. which wound up being several various sized Naval vessels and a couple of C 130 s. On the trip down the 3 of us learned real quick how not to get rolling sickness. Like Marv said when on deck if possible get somewhere where you don't see other objects if possible especially anything that was moving about the ship in a back forth motion. I found that after a couple of days I had gained my sea legs pretty well. Moderately rough seas didn't bother me near as much as the calmer times.