I get it every time we spend a prolonged period on a boat -- but then again, I never get seasick, no matter how rough the water is, and I figure that's the better half of the equation. The comments about "the more accurate the brain's model, the less likely seasickness" certainly applies to me. But I wobble for several days after getting off the boat. It isn't particularly pleasant (and the only time I've ever been really motion sick was in a Chinese restaurant in San Juan, Puerto Rico -- stale grease and a pitching restaurant don't make for a happy tummy) but it doesn't last that long.