Hardtack is a simple bread that could last long on voyages. When it gets hard, you soften it up by dipping it in seawater, soup, rum... whatever you have on-hand. In fact, cooks may have used seawater instead of regular water (though we wouldn't recommend this).
11/2 c flour
1/2 tsp salt
1 tbsp butter (melted) or shortening
1/3 c water
Preheat your oven to 325 degrees.
Mix together your dry ingredients, then add the liquids. Add a little water if needed so that the dough becomes lightly sticky.
Line a cookie sheet with foil; press hard tack in so that it's about 1/2 inch thick.
Bake for an hour or until it turns light brown.
Now that it's a little harder, cut it into small squares; or use a pirate cookie cutter and make your favorite shapes!
Puncture the surface of each cracker multiple times with a fork, then flip them over and cook them until the other side is light brown.
And now you're set for your sea voyage! This will mix quite well with your daily ration of beer, 1 gallon per day, per sailor.