set your walleye gear out in 30 feet of water and troll until you get to 80 foot and mark waypoints on your electronics every time you mark a school of perch. pull up walleye gear and go to your waypoints for perch, simple. If you are in a hurry you should be able to search faster driving around 10 mph or less (depending on your setup) , set your ping speed to max and your cone to the wider 83 khz. if you dont leave a trail on your map, set it to leave one makes it easier to turn around and get back on them you can see where to retrace your path. Also if your bottom thickness changes from being thick to thin or shows up a different color you might want to follow that east or west, it is a change in bottom compsition mud/clay to shale rock which is a prime area for perch. good luck