Hi Katejoy, if living aboard cooking was *really* different it would feel too much like camping out, and that would be no good! So if you already like to cook, use your favorite recipes. That said, here's a few thoughts I've had about the differences after 5-1/2 years aboard fulltime. Don't know what's in your galley, we have a fridge but no freezer, a stove & oven & broiler but no microwave. (And no grill CD! You'll have to provide advice on that
You're probably more constrained by fuel and water than you are on land. For example, boiling a big pot of water for pasta isn't as efficient as couscous, where all the water is absorbed.
We use a pressure cooker a lot, for various permutations on beans and rice plus whatever veggies are handy. Less water, and cooks faster. We do lots of one-pot meals, soups and stews. BTW, serve them in big deep bowls only half-full, so they have room to slosh if its rough and not spill on the unlucky diner. And nothing greasy or very spicy if anyone's prone to seasickness.
We don't use the oven as much as we did on land - especially in summer. It has less insulation than a home oven and really heats the cabin. If you've gotta bake, do it early morning or late evening. We substitute lots of stovetop things - an omelet uses about the same ingredients as a quiche, and fill the same niche on the brunch table without so much waste heat.
Revisit your appetizer recipe collection, you'll want a few on hand always for the many cruiser happy hours you'll enjoy with your fellow liveaboards; and your sandwich/wrap collection for when you're at the helm thru lunch.
I know this isn't exactly what you asked for, but hope it helps point you in a direction. Give us a few more specifics and maybe I or someone else can tailor a response a bit more - are you planning to be in a marina? cruising? what kind of boat and what part of the world?
Someone on the site, T37Chef?? was considering building a cooking class with categories like "things to eat while underway" and "things to bring to a raftup" perhaps s/he can also help?