1Heat oven to 325°. Place ham, cut side down, on rack in shallow roasting pan. Pour water into pan until 1/4 to 1/2 inch deep. Insert meat thermometer so tip is in center of thickest part of ham and does not touch bone.
2Cover with aluminum foil. Bake 1 hour 30 minutes to 2 hours, uncovering ham after 45 minutes, until meat thermometer reads 135° to 140°. Let stand 10 to 15 minutes for easiest carving.
3While ham is baking, beat remaining ingredients in 1-quart saucepan with wire whisk until well mixed. Cook over medium heat about 10 minutes, stirring frequently, until cranberry sauce is melted and mixture is hot. Serve sauce with sliced ham.