For bigger groups, I make fresh salsa, usually the first afternoon on the boat. It isn't that hard, and the ingredients were readily available, including fresh cilantro.

I made a ton of it and kept it in the fridge for use all week. We had chips & salsa, salsa on eggs, salsa with steak, wraps w/salsa...you get the idea! It was a great fresh side accompaniment.

I don't usually bring anything from home, but usually plan to make simple dishes for bbqing while on the boat, and usually one foul weather dish (pasta with sauce & sausage for example).

One of my favourites is to take out frozen chicken first thing in the morning, throw it in a zip-lock with Italian salad dressing (or olive oil, lemon juice and some herbs & fresh garlic), and by the end of the day, it's ready for the grill - whenever I into the cabin, I give it a flip to marinate both sides. I make extra chicken and use the left over the next day for lunch - either in wraps (using some of that salsa!) or in a Chicken Caesar salad.

We also always by lots of pepperoni, cheeses & crackers for a mid afternoon snack - we keep all the cheese in one big zip-lock so we aren't always rooting around for it.

I am sure there are a ton of ideas out there, but that's a few that come to mind.