My Dad got seasick enough that he had to quit commercial fishing in '50's because of it. He loved to go fishing on the salt and got sick almost every time. Poor guy tried most everything but it wasn't until he tried the wrist bands and the ginger pills from the health food store that he had any success, so that's what I'd suggest you try along with rest, no hangover, ginger ale and saltines. Even at that, it may not help.
Here's an old sea story for you - I've been sick once - on the tailend of a typhoon in the South China Sea. We took a 44 degree roll in a 250 foot ship. It was a bit rough and that ship was tossed around like it weighted nothing.