i fish a shallow river, 16ft max. i dont look for the deepest water necessarily. i look for deep water next to shore with lots of timber. i have a milk run of spots i have narrowed down over a lifetime. if i cruise by one of my spots and the finder reveals a lot of shad marks, i turn around a probe the cover there. the shad seem to move up n down the river to different sections and the big crappie fallow. go jig deep in some steep banked cover and try areas out. then remember the ones you score at and look for more like that. be very stealthy while doing it too, they spook easy.
tight lines to ya