Rule number one for sea sickness and travel sickness. DON'T wear any man made fibers (Kinda confirms what Barry just said).

Also get up near the pointy end and look where you are going and RIDE the waves as they come to you.

We were crossing The Channel on a hovercraft in a force nine gale and everyone was throwing up. To avoid the stench we went up to the almost deserted observation deck and enjoyed the ride. It was like an hour and a half on a roller coaster but we were the only ones on the whole craft that were not sick.