How do you know how deep "deep is"

[billr12]

You always hear the pro's say I am trolling so many feet down. How do they know how deep they are when the lure is behind them up to 100 feet or more. Is there a way you can know that a specific lure and weight combination will give a specific depth. With all the variables like: Line weight, lure type, bill size and shape, line distance, boat speed, and others I suppose, I don't see how they can say so accurately. Maybe they say that because they are on TV, LOL.

[Jerry Blake]

One way of knowing how deep a crankbait is running is to troll parallel to the bank and gradually move shallower keeping an eye on your depthfinder until your lure starts bumping the bottom.

[cody]

maybe they use the trolling bible. mine is very handy.

http://www.precisionangling.com/

Cody.

[hogfaninla]

another theory is the weight, some bass fishermen i know will throw a bait ,count to a certain number (depending on the depth they want) then reel in. I believe it is all in the experience with different lures and how they work. and then there are the trollers. They definately after losing a few high dollar baits know exactly what they will do and how deep and motor speed and all that jazz.