The first knot in creating a smooth French/ European Nymphing system is a Nailess Nail knot. We will use this knot to construct the upper portion of our French/Euro leader out of 30lb and 20lb monofilament that you see in the diagram above. This knot allows the lines to be connected with a strong and slender knot that will pass through rod guides easily, which is important because this upper section of line is the shooting part of your French/Euro leader. This part of the leader is 18ft long and needs to pass through the eyes easily to avoid problems while casting and landing fish. As with learning any new knot, at first you may have to take a few deep breathes and try not to curse, but with practice comes perfection.
Tip: Twist the lower poundage line around the heavier line (like you were tying a clinch knot) and leave enough tag end to loop up and around the turns you created. (4-5 turns is plenty here and keeps the knot profile small)
Tip: I hold my thumb and forefinger over the loops as I unwrap them keeping them straight and well aligned for step 3.
Tip: Pull on the ends of the lighter line with snug pressure while your hand is still holding the loops, then remove your hand and check the alignment of the loops, you may be able to move them around a bit and tidy up. I would pay special close attention to this part of the knot because the cleaner you make these loops the smoother your leader will slide through the guides on your rod.
This is not your run of the mill knot and may take a little practice to pull off, but once you have it down, any breakdown of any leader or loops in the field can be quickly fixed, and get you back in action. (Example) : You break the loop in your dry fly line fishing setup. This would normally require you to go back to the shop and form a new loop, whip finish, and cement to construct a new loop. Not with a Nailess nail knot, this will allow you to connect the butt section of your leader directly to your fly line the way the Ol’ Timers did but without carrying the nails around in your pocket! Take care and I hope to see you on the water soon.