Ginger or lemon or both are fantastic remedies for an upset tummy any day of the week. Being a yacht racing person I saw many people affected by motion sickness, I learnt the trick is to stop it before it starts.
The sickness is all to do with the brain, inner ear, and points of reference. The frequency of the waves, the hills in the road or the ups and down of the aircraft are the reasons we feel sick. For example, if the time between being on top of the wave, going down, and then back on top again is 4 to 5 seconds then expect trouble. It is scientific fact that the brain hates movements with this attribute. The brain needs a visual or physical reference to match what the brain expects, other wise the person can become woozy. The brain thinks you've ingested or eaten something, which is affecting the way you see the world — it's some sort of poison or toxin or drug so the body's defense mechanism for that is to vomit it up.
I'v learnt if a person is vulnerable then the point of reference (orientation) needs to be corrected before the sickness starts. Some ways to achieve this are:-
Look at the horizon
Steer the boat or car
Walk it you are in a big vehicle
Look out of the windows all the time
Opposite actions, like reading a book, reading a map, closing your eyes or going below deck will bring on motion sickness.