The walleyes are in an area at some depth. You chuck planer board out and your lure starts sinking down to the level of the walleye. Depth isn’t set; that depends on how thick your line is, how heavy it is, how fast you are going, etc. Depth without a depth finder is largely guesswork.
Trolling is a changing process for most anglers who think it is steady. Get a handle on all those variables and you can control what’s happening. The main lever you pull is speed. Speeding up will raise your lure higher in the water. And slowing down will lower it down into the water. That seems counterintuitive as gravity should of pull it down and not up. But water resistance is the driver there.
How to Control Depth When Trolling
The harder you push the throttle, the harder the drag on the line and board tries to pull it up out of current. The faster you go the shallower you will be running and vice versa. So you can go slow and cover less water but get deeper or go fast and cover more water but shallower. It’s a choice based off where the fish are showing on the fish finder.
It’s a tradeoff: speed is important, but so is weight. The weight of the sinker opposes the line drag and forces the lure downward. If you has to move quickly to cover water well, use a heavier sinker to keep the bait in the strike zone longer. But don’t go adding lead willy nilly.
Your line diameter is another thing that frequently stumps beginners. Thinner line has lower resistance when cutting through the water, so the sinker pulls harder and pushes the lure farther down. Thick monofilament acts like a brake in the water. So lighter line (braid included) immediately adds several feet of depth. Physics reduces drag.
How does it change your approach? The board you opt to use will completely alter everything. Mini boards pack well in tight little streams or small river. Mast systems is powerful on big lakes. They allow for multiple points from one place, letting you run multiple lines out to cover acres of water spreading wide. Inline boards are direct and simple with no elaborate rigging required, making them great for the solo angler who wants something that deploys quickly and easily.
Once rigged up, it’s time to dial-in your depth. For example, shallow running spoons is deadly on salmon feeding high. Meanwhile, deep diving crankbaits (long bill) dive all the way down into dark shadows where lurking lake trout wait in cold water. Staggering your lines, perhaps one spoon fished close to the boat, a deep running crankbait at mid-depth and a spinner rig even deeper, is best done with a simple five-line spread. It layers your coverage so nothing goes untouched in any given depth zone.
Locate the fish with sonar. Vary the weight and speed until you get the lure down to the exact depth of the fish. Keep notes: Record what lure, how heavy, how fast each fish are caught on. Eventually you have your own reference log. Takes practice but when you dial-in, they start biting quick. No more guessing where the fish are hiding, just put bait directly in front of them.