The number one reason boats drag anchor isn't a bad anchor — it's not enough rode out for the depth and conditions. Scope ratio accounts for the fact that your anchor line needs to pull at a shallow enough angle to set the anchor into the bottom rather than just yanking it straight up.
Anchor Scope
Scope is the ratio of rode length to total height (water depth plus bow height above the water) — too short and you'll drag, especially anchoring up current on a river for walleye.
SCOPE 5:1 – 10:1
Inputs
Rode to Let Out
70
feet of rode/chain
Scope ratio used7:1
Total height (depth + bow)10 ft
All-chain rode can run slightly less scope than rope/chain combos since it lies flatter on the bottom. If you're anchoring two points (common for river walleye fishing bow-and-stern), each line can usually come down a notch in scope since the second anchor is doing some of the work.