Page 81 - Patrick Moreau, Jean-Benoit Heron Marine Knots How to Tie 40 Essential Knots

To latch on to a ring, bar, or any other support with a bowline knot, rather
than creating a half hitch in the left hand, it can be done in a more free-form
way.

1 and 2 - Begin by tying a half hitch in the standing end, working end passing over.
Then transfer this half hitch to pass over the standing end.
This is achieved by pulling on the working end at the same time that you push the A-shaped
standing end in the opposite direction.