I catch big crappie all winter long no matter how cold and if I hardly ever fish in more than 12 fow. Usully the averay winter depth for me is 6-8 fow but last year I found them in 3 fow or less fishing 18 inches deep. I had VERY little company. No one seems to fish that shallow when it's cold. Years of trial and error is why my usual average was 6-8 fow until I got the side scan and started seeing schools of fish super shallow.