When I was running charters, it was pretty much a set pattern:
The party would arrive the night before, get drunker than Cooter Brown, arrive at the dock late and hungover, eat a bunch of sweet crap and slam some soft drinks. It never surpised me they were puking before we cleared the jetties.
Here is how you can go offshore and not get sick:
Don't try and drink until 3:00 am when the boat is leaving at 6:00AM.
Don't drink or eat anything sweet; eat a rib-sticking breakfast like bisquits, gravy and ham(eggs are not a good thing either), or a couple of breakfast tacos.
Do not go below. Stay on deck, as near to the center of the boat as possible, the bridge is the best place, if there is room.
Do not crack a beer at 6:30. Our suggestion/boat rule was no beer till the first fish is on the boat or 11:00AM, which ever happens first.
Stay busy! Do something, anything, except for reading.
Sea-sickness medications work by making you sleep. Save yourself a thousand bucks if you want to sleep and stay at the hotel.