Duncan Loop

The Duncan loop takes the same sliding-knot construction most anglers already know as the uni knot and uses it to build a genuinely adjustable loop - one that can be slid larger or smaller along the standing line before being cinched permanently tight, letting the loop's final size be set by eye against the actual lure rather than guessed in advance.

The tying method is close kin to the standard uni knot: a loop of tag end wrapped repeatedly around both strands of a doubled line, but tied loosely enough at first that the whole assembly can slide freely along the standing line before the final full-strength pull locks it in place.

That sliding adjustability is the knot's real practical advantage over a fixed-size loop knot - an angler can thread the line through a lure's eye, form the loose Duncan loop, and then slide it to whatever size looks right for that specific lure's action before committing to the final tight pull, rather than needing to estimate loop size while tying from scratch.

Once that final pull is made, though, the knot behaves exactly like a standard uni knot - fixed and no longer adjustable - so an angler who wants to change the loop size afterward needs to cut and retie rather than simply sliding the existing knot again. That's a fair tradeoff for most anglers, since the adjustability matters most during the initial tying, not afterward.

This sliding property makes the Duncan loop particularly popular with anglers targeting species known for aggressive strikes at a specific retrieve speed or lure angle, since the loop can be dialed in against the actual lure sitting in the water rather than committed to blind. A crankbait that needs a slightly larger loop to achieve its full side-to-side wobble, for instance, can be tuned in real time before the final lock, something a knot without sliding adjustability simply doesn't allow.

Because the underlying wrap-and-cinch mechanic is identical to the uni knot's, anglers who already default to the uni knot for hooks and swivels find the Duncan loop requires almost no new learning - just a slight change in when the final full-strength pull is applied, sliding the loose assembly to size first rather than cinching immediately.

The number of wraps used in the sliding portion affects both how smoothly the knot slides before locking and how much strength it retains once cinched - four wraps is a common minimum for lighter lines, while heavier monofilament or fluorocarbon often uses five or six to generate enough friction and holding strength in the final lock. Too few wraps on heavier line risks the knot slipping under a hard hookset even after it's been pulled fully tight, since fewer wraps mean less surface area gripping against itself once locked.

A subtle timing detail separates a smoothly tied Duncan loop from a frustrating one: the wraps need to stay loose enough to slide freely right up until the size is set, but the moment the final full-strength pull begins, it should be committed to firmly and evenly rather than pulled in hesitant increments - a hesitant, stop-start final pull tends to let one side of the wraps cinch down before the other, leaving an uneven, weaker lock than a single confident pull produces.