Mid-summer walleye often suspend at the thermocline, well off the bottom — and trolling at a precise, repeatable depth is the most effective way to keep a lure in front of them for extended periods. This guide covers lead core line (the most precise depth-control tool), snap weights (a simpler alternative), and planer boards (for spreading lines across open water and covering more fish).
This guide is part of our Walleye Fishing Cheat Sheet — head there for seasonal patterns, live bait, electronics, and gear setups.
Jump to a section:
- 🚤 Planer Boards
- 🎣 Lead Core Trolling — How It Works · Full Setup · How to Fish It · vs. Snap Weights · Snap Weight Basics
🚤 Planer Boards — Spreading Your Trolling Lines
Planer boards are torpedo-shaped floats that attach to your fishing line and swim out to the side of the boat as you troll. Instead of all your lines trailing straight behind in the boat's wake — which puts fish down — planer boards spread lines 30–60 feet to the sides, covering far more water and keeping lures away from motor noise and boat shadow.
When they matter most: Mid-summer suspended walleye on big open lakes (Mille Lacs, Leech, Lake of the Woods). When fish are spread across a flat and boat pressure is a factor, boards let you cover 4–6 lines across a wide swath of water simultaneously.
Basic setup: Clip the board to your line after letting out the desired amount of line behind the boat. The board planes out to the side as you move forward. When a fish hits, the board either trips flat (inline boards) or your rod loads up — reel in until the board reaches the rod tip, remove it, then fight the fish on light line.
Two board styles:
- Inline boards (clip directly to the fishing line) — simpler, good for one or two rods, trip on a bite
- Mast-system boards (run on a fixed line from a mast on the bow) — more complex, can run more lines, standard on serious walleye trolling boats
Beginner note: Learn to troll with straight lines and a line counter reel before adding boards. Boards add complexity — tangled lines and release issues are common until you have the basics dialed in. But once you get them, you'll wonder how you fished without them.
🎣 Lead Core Trolling
Lead core is the most effective tool for targeting suspended mid-summer walleye at a precise depth — specifically when fish are holding at the thermocline and crankbaits can't dive deep enough on their own. It's not beginner territory, but it's not complicated once you understand the system. For where and when to find suspended fish in the first place, see our Mid-Summer Suspended pattern in the Seasonal Patterns guide.
Jump to: How It Works · Full Setup · How to Fish It · vs. Snap Weights · Snap Weight Basics
How Lead Core Works
Lead core line has a braided outer sheath with a lead wire core running through the center. The lead makes it sink at a predictable rate as you let it out. Line is manufactured in distinct color segments of 10 yards each. Every color you let out equals approximately 5 feet of depth at average trolling speeds (1.5–2.0 mph).
| Colors Out | Approximate Depth | Notes |
|---|---|---|
| 1 color (10 yds) | ~5 ft | Very shallow — rarely used alone |
| 2 colors (20 yds) | ~10 ft | Shallow crankbait zone |
| 3 colors (30 yds) | ~15 ft | Early summer weed edge depth |
| 4 colors (40 yds) | ~20 ft | Prime thermocline range on most MN lakes |
| 5 colors (50 yds) | ~25 ft | Deep thermocline, late summer |
| 6 colors (60 yds) | ~30 ft | Late fall deep structure |
| 7–10 colors | 35–50 ft | Big water, deep suspended fish |
Important: These depths are approximations at standard trolling speeds. Speed, lure drag, and current all affect the actual depth. Verify with a depth-checking device or by watching your electronics when you mark fish.
The Full Setup
Main line: 18–27 lb test lead core spooled on a dedicated reel. You need enough capacity for the colors you plan to run plus a backing.
Backing: 50–100 yards of 20 lb mono or braid before the lead core — this gives you something to fight the fish on after the lead core is retrieved, and fills the reel spool.
Leader: 15–25 ft of 10–15 lb fluorocarbon tied to the end of the lead core with a double uni knot. A long leader keeps the lure away from the sinking line and lets it swim naturally. In clear water, go longer (20–25 ft); in stained water, 15 ft is fine. See our Rod, Reel & Line Setup Guide for how to tie the double uni knot.
Rod: 8'–8'6" medium moderate action trolling rod. The length keeps lines separated when running multiple rods; the moderate action cushions the hookset so you don't tear the hook out of a fish that's been following behind the boat.
Reel: Low-profile line counter baitcaster. The line counter is not optional — it's how you know exactly how many colors are out. Without it you're guessing.
Lure: Any crankbait that runs true at trolling speed. The lead core does the depth work; the lure just needs to be in the right zone and running straight. Check your lure with a rod sweep before dropping it back — a lure that doesn't track true catches weeds, not fish.
How to Fish It
- Find suspended fish on your sonar — note the depth they're holding (e.g., 22 ft)
- Calculate colors needed: 22 ft ÷ 5 ft per color = ~4.5 colors. Round to 4 or 5 and adjust
- Let the lead core out to that color count, watching your line counter
- Note your trolling speed on your GPS — keep it consistent (1.5–2.0 mph is the standard range)
- When a fish hits, note the exact color count and speed — repeat it on every rod
- When retrieving, slow your boat before reeling — pulling lead core through the water at speed creates enormous drag and can strip gears on a smaller reel
Lead Core vs. Snap Weights — Which to Use
| Lead Core | Snap Weights | |
|---|---|---|
| Best for | Precise repeatable depth, running multiple lines at different depths, big open-water trolling | Simpler setup, occasional use, targeting a single depth |
| Depth control | Excellent — color system is repeatable and consistent | Good — but varies more with speed changes |
| Setup complexity | Higher — dedicated reel, backing, leader system | Low — clip on anywhere on existing line |
| Line twist | None | Can cause twist over time |
| Cost | Higher (dedicated reel + lead core) | Low (just the snap weights) |
| Beginner friendly | No — learn snap weights first | Yes — great starting point |
The short version: If you occasionally want to troll deep, start with snap weights on your existing trolling setup. If suspended fish are your primary summer target — especially on big lakes — lead core is worth the dedicated setup. Many serious walleye trollers run both: lead core rods for the primary depth and snap weight rods to cover other zones simultaneously.
Snap Weight Basics (The Lead Core Alternative)
Snap weights are weighted clips that attach to your line at a set distance above the lure. They dive the lure deeper without needing a dedicated rod or spool.
How to use them:
- Let your crankbait out 50 ft behind the boat on mono or braid
- Clip a snap weight onto the line at the rod tip (common weights: 1, 2, 3 oz)
- Let out another 50–100 ft of line — the weight pulls everything down as you release line
- A 1 oz snap weight adds roughly 8–12 ft of depth depending on speed; a 2 oz adds 15–20 ft
- When a fish hits, reel in until the snap weight reaches the rod tip, unclip it, then land the fish normally
Snap weights are imprecise compared to lead core — depth varies more with speed and line diameter — but they get the job done with gear you already own.
Related Reading
- Walleye Fishing Cheat Sheet (Hub) — seasonal patterns, lure colors, electronics, and more
- Walleye Seasonal Patterns: A Season-by-Season Depth & Structure Guide
- Walleye Rod, Reel & Line Setup Guide
- Best Walleye Lakes in Minnesota: A Data-Driven Guide