i agree with what FisherDave said, if you are fishing anything over 30ft deep, give the fish some time to adjust while you reel it in, or its swim blatter will be popping out its mouth!! LOL
I have never really caught anything deeper than 28′ probably, in all honesty i have poor luck in deeper water…..stuff over 20ft. But almost always fish @ night, and sometimes never get out until way past sundown. these fish could have moved out, or are feeding on the head/tail/edge of a hole and i was in the wrong spot.
But i have had my boat anchored in >18″ water and fished the snag which was in 3ft or so. Managed a couple fish, then it was time to move cuz it was a tiny snag.