You haVE 2 CHOICES........!
have (2) alcoholic drinks as you get on board, medium strenght or take a pill call bonnie or dramamine..for motion sickness...if you are on a big ship you have nothing to worry about...
what you will get is "sea legs " after the first or second ports of call.... you will feel like your at sea with slow movement, but your not. this will go away after your in land for more than 24 hours
you'll be fine if you try to relax...your not going to Mars..!
HAPPY SAILING BABY! : )