The perfection loop
The perfection loop is a tidy fixed loop tied at the end of a leader, and it sits perfectly in line with the line rather than cocked to one side. That straight, in-line loop is what makes it the standard for loop-to-loop connections, joining a leader to the fly line. It is small, strong and clean, and it holds in mono and fluorocarbon.
Near the end of the leader, form a loop by crossing the tag end behind the standing line. Hold it where the lines cross. This first loop stays roughly where it is; the tag end carries on to make the second loop.
Bring the tag end round again and form a second loop in front of the first one, then bring the tag down and hold it between the two loops. The size of this second loop sets the size of your finished loop, so keep it small, just big enough to link another loop through.
Reach through the front loop, take hold of the back loop (the second one you made), and draw it forward through the front loop. The back loop becomes your finished loop; the front loop closes down into the knot. This is the step to get right, so make sure you pull the correct loop through.
Wet the knot. Hold the finished loop and pull it in line with the standing leader to draw the knot down, rather than pulling on the tag end, so the loop seats straight and in line. Pull it firm and check the loop sits square with the leader, not cocked to one side, then trim the tag close.
Four steps. Each one is a panel in the diagram above. Wet it before you pull it tight.
What it ties
A fixed loop at the end of a leader, sitting straight in line with the line. You use that loop for a loop-to-loop connection: a loop in the end of the fly line meets a loop in the butt of the leader, and the two link through each other so you can swap a leader in seconds without tying a knot at the water. The thing that sets the perfection loop apart is that it sits perfectly in line with the leader, not off to one side, so the leader turns over straight and the join runs clean. It holds in mono and fluorocarbon. For a bulkier, quicker loop you might use a double surgeon's loop, but the perfection loop is the one that sits truly in line, which is why it is the standard for leader loops.
When to use it
Use a perfection loop whenever you want a fixed loop at a leader end for a loop-to-loop connection. That is the classic way to join the leader to the fly line, and to build a leader system you can break down and swap, a fresh tapered leader looped on in seconds instead of a knot tied streamside. Keep the finished loop small, just big enough to pass the other loop through, so it stays tidy and in line. The thing to get right is which loop you pull through the front loop, and to tighten by pulling the loop in line with the standing leader rather than yanking the tag, so it seats straight. Tie it at home when you build your leaders, so it is ready before you fish.
Strength and tips
Tied well the perfection loop is a strong, tidy fixed loop, and its in-line shape is the whole point: a loop that sits straight with the leader turns over cleanly and joins loop-to-loop without hinging. Two things make it. First, pull the right loop through, the back loop comes forward to become the finished loop while the front loop closes into the knot; pulling the wrong one gives you a mess. Second, tighten by pulling the loop in line with the standing leader, not by hauling on the tag, so it seats square rather than cocked to one side. Wet it before you draw it down. Keep the finished loop small, just big enough to pass the linking loop through, so it stays neat. It holds in mono and fluorocarbon alike. Tie it at home when you build your leaders.
1Wet it
Wet every knot before you pull it tight. A dry knot drags against itself as it closes and the friction heat weakens the line.
2Seat it slowly
Draw it down slowly and evenly, then trim the tag end close, leaving a stub of a millimetre or two so it cannot slip back through.
3Test it
Pull the finished knot firmly against your hand or the rod before you fish it. Better it fails now than on the take.
Rigs that use it
The perfection loop builds the leader loops on the fly rigs. It makes the fixed loop that joins the leader to the fly line loop-to-loop on the dry-fly rig, the nymph rig and the streamer rig, so you can loop on a fresh tapered leader in seconds. It is the leader-system loop across all three.
Perfection loop questions
Making a tidy fixed loop at the end of a leader for a loop-to-loop connection, usually joining the leader to the fly line. It sits perfectly in line with the leader rather than off to one side, so the leader turns over straight and the join runs clean. It lets you swap leaders in seconds.
Because of how it is formed: the finished loop comes straight off the standing leader, so it lines up with it. A double surgeon's loop is quicker but sits bulkier and slightly off-axis. For a loop that turns the leader over cleanly, the perfection loop is the tidier, in-line choice.
Wet it, then pull the finished loop in line with the standing leader to draw the knot down, rather than hauling on the tag end. That seats it straight and in line. Keep the loop small, check it sits square with the leader, then trim the tag close.