Combine the flour, salt, and water in a bowl. After mixing, scoop the dough onto a floured countertop. The dough will be sticky at first. Knead until mixed thoroughly. Roll out about 1/2 inch thick into a rectangle shape. Use a sharp knife to cut the sections evenly about 3-inches apart. I used a ruler to keep them square. Use a nail or something with a sharp point to make the holes. Preheat the oven to 375 degrees. Place the hardtack pieces on an ungreased cookie sheet and bake one side for 30 minutes. After 30 minutes turn the hardtack over and cook the other side for an additional 30 minutes. After baking place the cookie sheet on a cooling rack.