My younger brother was in a similar situation last year, but nowhere near as bad as yours. He went offshore fishing for marlins with a few buddies of his. The plan was to go several hundred miles south onto the Caribbean sea and fish for about two to three days. My brother got really sea sick pretty much the entire trip. He didn't have the stomach(pun intended) to ruin everyone else fishing trip so he had to suck it up and stay on the boat quarters throwing up; it was a nice yacht so it wasn't that bad. Nevertheless, he says it was the three most miserable days he's ever had.
Being sea sick is not life threatening provided that you drink enough water, but a salmonella poisoning may be pretty dangerous, you're a brave man for staying. ...Man, doing that trip twice must have sucked big time :-)
