Scopolamine has saved my life. Put on the night before, eat something light in the morning on the way to the boat. Absolutely zero issues regardless how rough it gets. I can use the head, I can eat... doesn't matter. On the days that I might feel a little uneasy, it's maybe ~ 5% but I can usually get that to go away just walking to the back.
I used to get so sick I wasn't sure if diving was for me (from boats anyway).
Can order from ebay without a prescription for fairly cheap.
@doctormike, great article!