I enjoyed the suggestions from everyone, even though I was not the one who posed the question. My contribution to the list is "don't worry about it." I have been diving for a long time, been a profession more than 10 years, and I would say that on boats between dives , I chum the waters as often as not. If I am near engine fumes on an idling boat that is rocking,... thar she blows! If the boat is moving I am less likely to lose my stomach contents. My wife has never gotten motion sickness on a boat, not even when we spent a day in 12 foot seas on a 37 footer and she was 5 moths pregnant! I chuck between dives, and have not ever remedied it. What is important is to know the proper etiquette if you are going to be sick on the boat, so herewith, one of the rules from our book, The Scuba Snobs Guide to Diving Etiquette.
PUKE ONLY WHERE APPROPRIATE
Never puke on another diver. Never puke on the boat. Don’t puke in the camera bucket either. Puke over the side of the boat. That’s about all there is to it. Fish love puke, other divers do not. Also, try not to be too obvious when you puke. Dennis quite often pukes at the end of a dive. But he can be so subtle that on occasion even Debbie, who is sitting and gearing up right next to him, has to ask if he in fact puked. It’s a gift.
--------------------------------
I should have added that if you are a puker, you should have a big water bottle for rinsing, and mark it well so others don't inadvertently drink from it!
DivemasterDennis