Preheat the oven to 400°. Place the yams in a 12x12 inch baking pan. Pour in the water and vanilla. Mix the butter, both sugars, cinnamon, and allspice in a small bowl until blended. Sprinkle this mixture over the yams. Cover the baking pan tightly and bake for 45 minutes.
Sprinkle the raisins and pineapple chunks over the yams and baste them with the juices in the pan. Cover the yams and continue baking until very tender and the juices are bubbling, about 20 minutes. Serve hot from the pan.