I think I read somewhere if you stare at the horizon it helps.
Many years ago I got sick as a dog just going out to Catalina Island off the Cali coast, but I was hung-over that morning and when I got on the boat I ate some donuts and fell asleep...OMG when I woke up from my nap was I sick! Once I got on land on Catalina I was fine and I didn't get sick on the return trip.