You can, butit will cost you some cash to do so. Usually, "the shot" referred to is the product Compazine. I would try the follwoing interventions:
1. Stay out on open deck as much as possible, and if need be, cast your eye on the distant horizon.
2. Give ginger products a stab. You can take 2 ginger caps three times a day, and augment this by sipping gingerale and sucking on ginger candy. You can find ginger products at a health food store or a homeopathic pharmacy.
3. SeaBands...products deigned on the premise that accupressure may help.
I also really enjoy peppermint or wintergreen candies when I have a roiling stomache, but don't feel like I have to vomit.
I hope that you find something that works for you!
Happy cruising!
John Burns, RPh