If you are running two lines off one rigger in the sound for BM, Silvers, or whatever you'll want the lower line further back than the top line by about 20-30 feet in distance behind the boat. With flashers or dodgers I space them at least 12-15 feet respectively on the downrigger cable. This is so that once a fish bites on the lower line he'll likley come up and away from the path of the upper, shorter line. When stacking you just have to manage your gear real quick once fish gets on so you lessen the chance of a tangle. Good teamwork is the key.