If in fact the fish are on that drop off ledge ,go up and down it watching ur sonar verry close,and go verry slow,right on the top edge ,then on the deep side ,and then on the shallow side make your passes 10 to 20 yards apart,if you spot those big clumps of what you beleve to be CATFISH holding still eather on the top bottom or up on the ledge,stop and get on them with cut and live bait. If you dont have any luck on the ledge then switch to the flat shallow water fishin, or make a few drifts at difernt depts. you can put them biguns in the boat on rod and reel !!!!!!!!