I don't mean to get too technical here but I thought I'd share my experience. I've been a pilot and been on the water for 30 plus years in everything from my 30 footer to an aircraft carrier. Motion sickness (plane/boat/car) otherwise known as Vertigo is caused by your brains inability to correlate what it's feeling your orientation is (from your inner ear) with what it's seeing with your eyes. The brain gets confused signals and you get nausea.
I've only been seasick once, as a kid, in 10-12 foot seas in a small boat (36 feet). My mother made me wear a coat cause it was cold out and she was afraid I'd get sick. What happened...I got hot and sweaty, my body temp rose and I was over the side for hours, so I learned what triggers it in me and have never repeated those conditions. The best thing you can do is learn what triggers it in you. Given the right conditions, we can ALL get vertigo.
How to prevent it. Technically you can't, but you can minimize the likelyhood you will get it. I've listed the ways below I know of and how they work.
Trans Scop patch (Scopolamine) - interferes with the signals from the inner ear - in a strong enough dose it's a psychedelic drug. 
Bonine and it's ilk - It's an antihistamine - Thought to interfere with the bodies histamine response when vertigo sets in, get all sweaty, etc. This can knock you out so be careful.
Wristbands - They put pressure on a nerve in the wrist that's thought to interfere with the nerve signals from the inner ear. I know, weird that a nerve in the wrist will interfere with signals from the ear. Other people (mostly western doctors) will tell you it's the psychological value that you THINK it's working that it does. 
Not sure about the Ginger root. First I've heard of that. Will have to look into that.
If you feel yourself getting woozy, get to a railing or a porthole you can see the horizon from and focus on whats not moving as opposed to what is.