I am no expert, but when I look for deep water crappie, I first hit the deepest brush I can find. Usually 30-35ft.
If it's not producing, I go get on my graph in open water and look for elongated bait clouds NOT BALLS. If they are still in a ball, the crappie aren't in them feeding on them. The best thing you can see is a long cloud with dots underneath (obviously). The bottom structure at this point makes almost no difference. Usually you're fishing by the dam in some deep water, around 35-45 ft. Think about chasing schools of bass except the crappie don't come to the top of the water. Stay on your trolling motor and try your best to keep that bait cloud on your screen. I use 3/4oz bell sinkers below my baits so I can keep on the move without my lines going sideways and losing their depth.
When you're fishing, use at least two poles to try different depths, I usually see where the bottom of the bait cloud is, and try one right at that level and the other about 5 ft deeper.
Another thing to look for while graphing is your bottom. Look CAREFULLY at the bottom because the crappie can almost hide in the bottom line on your graph. Sometimes they will look like little commas on the bottom. I've come across schools hugging the bottom that would wait til my bell sinker hit the mud to attack the bait.