Bonine for us too. We have it in car, purse and home. Kids used to get car sick lots. We found the bonine chewable worked best for all of us. Very cheap at Wal-mart. Target never has it. Some other name drugstores don't either. Take several boxes in case. 8 tabs to box, I believe. We have sailed for several years now with the kids and just some times feel little dizzy first day then usually don't have anymore problems. Body adjusts. It works quick because chewable. I would wait to see if any trouble, but if have cruised before and did have trouble, would take 1 day as preventative.
We tried wrist bands on kids for car sickness when younger, didn't work.