Wash, core and stem the apples, but don't peel them. Stand them in a buttered mold and stuff them with 2/3 C. of the brown sugar, and the raisins. Fill the tops of the core cavities with butter and sprinkle the remaining sugar over the tops. Place the mold in the slow cooker and pour the hot water into the cooker (not in the mold). Sprinkle the orange juice concentrate over the apples. Cover and cook on low for 3-5 hours, or until the apples are tender.