Page 212 - Geoffrey Budworth, Jason Dalton "The Little Book of Incredibly Useful Knots"

Spar hitch

Besides attaching a rope’s end to a horizontal spar, tying this knot in the bight makes it possible
to fasten the standing part of a barrier rope or tape to a vertical post, at locations as diverse as

country fairs, road construction sites, and crime scenes.

Take the rope around the rail or post, picking up the rear portion and bringing it diagonally across
on top of itself (1). Pull out a small bight, twist it counterclockwise, and pass it over the end of the
anchorage (2). Then pull on both ends to tighten the knot (3).