Square Fisherman’s Knot

The Square Fisherman’s Knot is used to tie two ropes together for rappelling. It’s basically a square knot backed up with double fisherman’s knots on either side. If you use this knot, always use the backup knots or risk it coming untied. A square knot alone is never a good knot for rappelling or any other climbing purpose.

 A square fisherman's knot is used to tie two ropes together for rappelling.