There are so many variables (including the use of umbrellas vs. lures with less drag) that the charts are not really reliable, but the "rule of 5's" I talk about in the Chesapeake Guide is about as close to an average as you can come - at 5mph, 5 ounces, 50 feet, you're looking at around 5 feet of depth. So at 3 knots with 12 ounces and 50 feet of line, 12' to 17' would be where I'd expect it to run. That said, I wouldn't ditch the deep rigs. There are days (especially when the bay is crowded or when a front is moving through) that the deep rods catch - and on those days, the ones up top usually don't. On the flip side, it doesn't sound like you have any running close to the surface, and you should. There are other days (and it happens more often) that board lines running short, in the top 5 to 7 feet of water, catch the lion's share. Of course, we haven't even talked tidal cycle, water clarity/stratification, or light levels yet!!!