The Offshore swivel knot is used to attach a swivel or even a hook to a main line. Commonly used to provide a place to attach a hook or sinker off of another short line. But also comes in handy if you want to attach a swivel or hook to a double line.
To Tie an Off-Shore Swivel Knot:
Slip the loop of double-line leader through the eye of the swivel. Rotate the loop 1/2 turn to put a single twist between the loop and the swivel eye.
Pass the loop with the twist over the swivel. Hold the loop end, together with both strands of double-line leader, with one hand. Let the swivel slide to the other end of the double loops now formed.
Still holding the loop lines, use the other hand to rotate the swivel through the center of both loops. Repeat this at least five times.
Continue holding the strands of double line leader tightly, but release the end of the loop. As you pull on the swivel, the loops of the line will begin to gather.
To draw the knot tight, grip the swivel with pliers and push the loops toward the eye with your fingers, still keeping the strands of leader pulled tight.