Page 30 - Joseph B. Healy "The Pocket Guide to Fishing Knots"

Arbor Knot

This is another foundational knot that you can use to secure backing on a

fly reel or braided, monofilament, or any fishing line to the arbor of any
fishing reel.

1. Bring the line around the arbor of the reel. Tie one overhand knot
over the standing line, and tie another at the very end of the line, as
shown here.
2. Moisten the knots and draw both knots tight, and pull on the

standing line to tighten the small knot into the knot around the line,
thereby jamming the knots together and securing the line.