Mix the dry rub ingredients in small bowl, and the barbecue sauce ingredients in a small bowl, set aside.
Put the ribs on a large cutting board, flip them over so the curved side is up. Remove and discard the silver skin, I do this but getting my fingers under middle edge on one side and pulling up, most of the time I can get it off in one piece. Cut the ribs into 4 even portions. I do this because it fits nicely in the slow cooker.
Using your hands rub the dry rub on the ribs on both sides. Place the rib pieces into the slow cooker that has been sprayed with non-stick cooking spray. Take half of the barbecue sauce and spread over the ribs (being careful not to contaminate the rest of the barbecue sauce with the raw meat, that sauce will be used later when the ribs are cooked.) Add the 1/2 cup water around the ribs.
Cover and cook on Low for 8 hours without opening the lid during the cooking time.
Brush the remaining barbecue sauce on the ribs.