This subject has been covered many times, so to sum it up.
Don't think about getting sea sick and you probably won't.
Don't get plastered the night before going out, and you won't.
Have a good breakfast, and you probably won't.
Keep your stomach occupied, and you probably won't. #( eat dry bikkies and fizzy drink ).
Keep yourself occupied and you probably won't.
But should all else fail.
There are a number of pills that should ( no gaurantee ) do the trick.
Others will post names here. #I used to get crook, but that was due to a inner ear prob. #That taken care of, I'm sweet.
Cheers # Phill