Surgeon’s Join

Join two fishing lines with two passes through one shared loop.

One entire leader section passes through the loop. This is the fishing bend, not the surgical binding knot.

Step-by-step

Overlap the lines
Lay the main line and leader alongside each other with opposite standing ends.
Form a shared loop
Use both strands together to make a loose loop.
Pass through once
Pass the tag and the entire leader through the loop together.
Pass through again
Take the same paired ends through the same opening a second time.
Bring out the ends
Leave the two standing parts and the two tags free.
Dress the knot
Moisten real line. Pull all four strands evenly to seat the knot. Keep the turns aligned.
Inspect the double pass
Two passages through the loop form the fishing surgeon’s knot.