Lead core trolling. Generally one color of lead core is equal to 5' of depth. I only use 8' of leader ,so 5 colors of lead core equal 25 ft plus the 8' of leader and the crank baits ability to dive. . I run lead core off of planer boards one rod 5 colors other rod 6 colors . In addition I use down riggers to pull worm harness. Usually deploy them after locating fish.. With the down riggers I try to keep the baits 3-5 ft above the fish. Walleyes look up to attack prey. Lead core is always a guessing game. I try to keep speed close to 2 mph in the summer time . Once you catch a fish remember how much line you had out and then vary it by small amounts. Always watch the fish locater as the fish will stage at different depths throughout the day . If you arn't using planer boards try tru trip deep divers. I deploy without lead core generally 4 colors of braid.