The Turle knot is often used in Salmon fly fishing with up eyed irons. The actual knot sits at the top of the hook shank behind the eye with the line coming through the eye parallel to the shank. This helps the fly swim straight in running water in effect optimising fly presentation to the fish.
The Turle knot is ideal when tying on flies with turned-up or turned-down eyes to your leader. This gives your fly good action because of the way the knot causes the leader to pull away from the hook. It can be tied with one or two wraps of an overhand knot.
Step 1. Pass the leader end through the hook-eye. Take two wraps around the standing line and pass the tag end through the loops forming a simple overhand knot. Tighten it down.
Step 2. Pass the fly through the large loop formed and snug it against the hook-eye.
Step 3. Tighten down and trim off the excess.
Step 1: Slide the fly up the line and keep away from the knot.
Step 2: Form the first part of the knot as shown and pull this part tight leaving an open loop at the end.
Step 3: Slide the fly down the line to the knot and slip it through the loop. Hold the eye between the fingers and pull on the main-line closing the loop at the eye of the hook.
Step 4: The completed knot allows the fly to swim parallel and straight to the mainline. With other knots the fly often sits at an odd angle relevant to the mainline putting fish off the final take.