I just bought new units with the NVB (preloaded maps) but the maps don't include the great lakes. I don't fish them much but I do have one tournament on green bay. It will cost 199 to get the USA-Great Lakes & maritines, has anyone used this one before. I would only need it for one tournament to help find the reefs and humps, the sales man at bass pro didn't know if it had the reefs or not.