Page 156 - Buck Tilton - Outward Bound Ropes, Knots, and Hitches 2 ed.

Take the double end up through the loop, again

as if a basic bowline was being tied.

Bowline on a bight, bowline in the bight, bowline upon the
bight—they are all names for the same knot. This knot can

be tied near a working end of a rope but more often appears
away from an end. Historically, this knot served as an

improvised seat, the seated person shoving one leg through
one loop, the other leg through the other loop. The person in
the seat held on to the line and was then lowered or raised,

as over the side of a ship. When a double loop is tied in the
middle of a rope, a weight (such as a person) can be

lowered or raised from two points, allowing for more
security and control during the process. Because devices

such as harnesses now exist to aid in moving a person via a
rope, the bowline on a bight is not recommended for such

use except in emergencies. This knot first appeared in print
in 1795 in Allgemeines Wörterbuch der Marine by Johann
Röding. It is often used by campers and climbers who need

to secure gear to the middle of a rope. Note: The bowline on
a bight reduces the strength of the line by as much as 40

percent.