I get car sick very easy, I used the patch and I did just fine with the motion. They even hand out bonine at the pursers desk if you need it.
As far as the heights just don't look over the side and you should be okay.
Try to keep food on your stomach that also helped and we tried to stay busy to keep our minds off of the rocking. It really is not that bad.
I think you will have a blast!
Let us know how your trip was when you get back.