The ferry was the Blue Nose. It was horrible. The boat pitched and rolled so much that nothing would stay on shelves or tables, swinging doors wouldn't stay shut, and it was a considerable effort just to get anywhere without falling down. After that we took the Scotia prince, which was also a cruise liner. That was much, much better and far more comfortable.
It has been said that you can go to the very front of the boat and look at the far horizon will help. Anyway, it seemed to work for me.