There is a book available, that tells how deep many lures will run, based on how far back they are. Believe it's called Precision Trolling. Lots of research went into putting it together, and they update it to keep up with new lures. It is a very valuable tool, if you want to add to your success. If you know how deep the fish are suspending, it will tell you how to get there. It's pricey, but it beats guessing how deep you're fishing.
