Place ham in a very large container; cover with cold water. Soak ham overnight. Pour off water, and scrub ham thoroughly with a stiff brush. Rinse.
Place ham in a large stock pot; cover with water, and add vinegar. Bring to a boil; reduce heat. Cover and simmer 3 1/2 hours.
Remove from heat; cool ham in cooking liquid. Remove ham from cooking liquid, reserving 2 cups; discard remaining cooking liquid.
Remove tough outer skin from ham, and discard. Place ham, fat side up, in a shallow roasting pan. Score fat in a diamond pattern. Add reserved cooking liquid. Bake at 350° for 1 hour or until browned.
Remove from oven. Place whole cloves in points of diamond pattern. Combine brown sugar and sherry in a small mixing bowl; spoon over ham. Return to oven for 15 minutes or until glazed. Cool completely.
Transfer ham to a serving platter. Cut into thin slices to serve.
Note: Remaining ham may be covered and stored in refrigerator for later use.