Ernest Shackleton claimed his ponies got miserably seasick in rough weather on their voyage to Antarctica. And though I am skeptical, a German scientist supposedly proved fish in a mini-aquarium in zero gravity exhibited human signs of motion sickness.
I do know, Jackie, that you can't get seasick if you are steering, no matter if it be a boat, car, or plane. So if we theoretically a fix DM's nice new tiller to the bronze bathtub, you should be fine.
Speaking of gripping a tiller in a bathtub, in the early 90's WILDFLOWER coincidentally arrived in Nanaimo, BC, Canada, at the same time as the finish of the Vancouver-Nanaimo Bathtub Race, 40 miles across the Straits of Georgia. And you thought the 3BF exhibit indications of insanity?