It would help to know where you will be sailing from, and where you are headed.
Beth's information on Sunflower was pretty good. Some things that worked for me:
Ramen noodles - easy to prepare no matter how rough the weather. Add a little meat (packages of tuna, chicken, or leftovers), onion, garlic, other vegs., and it's a nice easy, filling meal.
Cabbages and carrots keep very well, with a little vinegar and mayonnaise you have a nice salad. Beans for sprouting.
Lentils for lentil stew ("menestras" in S. America)
Powdered whole milk is very economical and an easy way to carry milk.
Usually not available in the US except for Chinese groceries or on line, but pretty much available everyplace else.
You need to have some idea of people's likes, etc. I went through almost 20 pounds of onions and 7 dozen eggs in 3 weeks, 3 people, but I baked a lot of sweet breads (banana bread, orange cranberry, etc.).
More in my Cruising Dictionary: you can get a free download from: http://www.cruisingconnections.co.za/ebooks.htm