Place ham in roaster. Add 2 cups water, and cover roaster. Bake in a 325 F oven, allowing about 21 minutes per pound for a large ham, about 25 minutes per pound for a smaller (up to 12 pounds) ham or half ham. If the ham has an exposed bone, cover this with foil. Keep an eye on the ham as it cooks and spray occasionally with olive oil during the first part of the cooking.