If you are indeed allergic to wheat, called celiac disease or sprue, you should not consider your food preferences to be just a strange food preference. For some more information, here's one link Sprue
Avoid wheat flour, barley, perhaps oats. You should read ingredient labels carefully, to be sure there's no wheat flour.
You can bring along rice flour in order to substitute it in preparation of various foods. Mix potato flour and rice flour and this can be a reasonable substitute for bread or cake-making. Of course, this means you need to practice baking before you try to impose this on your boat mates, though. Potato flour is very tricky to use. Combine rice flour and cornstarch (corn flour outside the US) for a substitute coating for fried foods. It's really better than wheat flour because it doesn't absorb as much of the cooking oil as wheat flour does. Corn flour (cornstarch) is better for a thickening agent than rice flour. NOTE: Real corn flour is hard to find, but for preparing fried fish I think it's the best. Corn bread made from scratch (not a packaged mix which will contain wheat flour) is quick and easy to make, and good.
Corn tortillas are good (DO read the ingredients label to be sure that there is no wheat flour included), and fortunately they are now pretty common most places in the USA. An added advantage is that in the areas with a large hispanic population you can find packages of them that have a long expiration date, and the packages need not be refrigerated until they're opened. I prefer tortillas to regular bread, and so stow a lot of packages when heading outside the US.
Most grocery stores now sell rice crackers, again something that I usually prefer. For a nutritional snack, most "Oriental" snack mixes contain nuts, dried peas, and rice snacks. Good snack food. Some have dried fruit.
I can go on all day, so think of some things that you like now that contain wheat flour and I'll try to come up with a substitute. That way the things that few people like, but I love, need not be mentioned.