Paloma Cruises, Halong Bay Vietnam

Before I took off to Vietnam - at least 6 months before - I spoke to a number of my friends who had recently visited Halong Bay on their opinions about which junk cruise to pick. I was under the impression that the junk cruise would be anchored not too far from the pier. I was wondering how those who easily suffered from motion sickness would be able to stay on the cruise boat overnight. I was told to just go there and pick a junk cruise to join but I am quite the safe travel