Trim fat from meat. If necessary, cut meat to fit into a 5- to 6-quart slow cooker. Set aside. In cooker place carrots, celery, onions, and, if desired, raisins. Add meat.
In a small bowl combine water, vinegar, brown sugar, salt, and pepper. Pour over mixture in cooker.
Cover and cook on low-heat setting for 10 to 12 hours or on high-heat setting for 5 to 6 hours.
Transfer meat and vegetables to a serving platter, reserving juices. Cover meat and vegetables and keep warm.
For gravy, pour juices into a glass measuring cup; skim off fat. Measure 3 cups juices. Pour juices into a medium saucepan; stir in gingersnaps. Cook and stir over medium heat until thickened and bubbly. Serve meat and vegetables with gravy. Makes 8 servings.