Surgeon's Knot

The Surgeon’s Knot is a bend knot for joining two lines that is quite easy to tie. The entire knot consists of making two overhand knots while the main line and leader are doubled over, then pulling the entire leader through to complete the knot. The downside to the Surgeon’s Knot is that since the leader needs to pulled completely through the loop formed by the overhand knots, it is only suitable for joining leaders but not suitable for lines of arbitrary length.