I have found the sea bands that you wear on your wrists most helpful, even gale force 8 in Bay of Biscay.They work by accupressure, with small 'buttons' that go on certain point on the wrist. cost about £7. No drug side effects.I also found they aided sleep and have even used them on bumpy plane and bus journeys.
I have just been on my first cruise on the Ventura and the journey through the Bay of Biscay was absolutely awful and I am not a sea-going person - I get sick on car ferries. I bought "Sea-Legs" from the pharmacy, took them before going to bed and felt absolutely brilliant next day. Worked for me. Irene, Dunfermline.