PS, If you do not have a Side scan, another tactic to find the fish would be to set your lines up high and see what happens. Experiment with the presentation if you are not catching them. You can also set some lines up high, some lines towards the middle and some deep.
If you can see them on the sonar, always try to set your lines so the bait runs just above the fish. Walleye feed up... so one should always present the baits just above the leve the fish are suspending at.