bowline

Bowline
Names	Bowline, Boling knot (archaic)
Category	Loop
Origin	Ancient
Related	sheet bend, double bowline, water bowline, Yosemite bowline, spanish bowline, triple bowline, bowline on a bight, running bowline, poldo tackle, Eskimo bowline, cowboy bowline
Releasing	Non-jamming
Typical use	Making a fixed loop in the end of a line
Caveat	While widely considered a reliable knot, when tied in certain materials or loading conditions it may not hold.
ABoK	#1010, #1716

The bowline (pronounced /ˈboʊlɪn/ or /ˈboʊlaɪn/^[1]) is an ancient and simple knot used to form a fixed loop at the end of a rope. It has the virtues of being both easy to tie and untie. Although generally considered a reliable knot, its main deficiencies are a tendency to work loose when not under load and the bight portion of the knot to capsize in certain circumstances.^{[citation needed]} To address these shortcomings, a number of more secure variations of the bowline have been developed for use in safety-critical applications.

The structure of the bowline is identical to that of the sheet bend, except the bowline forms a loop in one rope and the sheet bend joins two ropes. Along with the sheet bend and the clove hitch, the bowline is often considered one of the most essential knots.^[2]

History

The bowline's name has an earlier meaning, dating to the age of sail. On a square-rigged ship, a bowline (sometimes spelled as two words, bow line) is a rope that holds the edge of a square sail towards the bow of the ship and into the wind, preventing it from being taken aback.^[3] A ship is said to be on a "taut bowline" when these lines are made as taut as possible in order to sail close-hauled to the wind.^[4]

The bowline knot is thought to have been first mentioned in John Smith's 1627 work A Seaman's Grammar under the name Boling knot. Smith considered the knot to be strong and secure, saying, "The Boling knot is also so firmly made and fastened by the bridles into the cringles of the sails, they will break, or the sail split before it will slip."^[5][6]

Another possible finding was discovered on the rigging of the Ancient Egyptian Pharaoh Cheops's solar ship during an excavation, although this has not been proven in fact to be the bowline.^[7]

Usage

The bowline is used to make a temporary loop at the end of a line. Since it is tied with a rope's working end, the bitter end can be passed around or through an object before the knot is made.

The bowline is commonly used in sailing small craft, for example to fasten a halyard to the head of a sail or to tie a jib sheet to a clew of a jib. The Federal Aviation Administration recommends the bowline knot for tying down light aircraft.^[8]

A rope with a bowline retains approximately 65% of its strength at the location of the knot,^[9] although in practice the exact strength depends on a variety of factors.

Tying

A mnemonic used to teach the tying of the bowline is to imagine the end of the rope as a rabbit, and where the knot will begin on the standing part, a tree trunk. First a loop is made near the end of the rope, which will act as the rabbit's hole. Then the "rabbit" comes up the hole, goes round the tree right to left, then back down the hole. An alternative "lightning method" can also be used; see this animation.

The rabbit hole.	Out comes the rabbit,	runs around the tree,	and hops back into its hole.
Lightning method, tied on a ring. Pull per the blue arrows.

Security

As noted above, the simplicity of the bowline makes it a good knot for a general purpose end-of-line loop. However in situations that require additional security, several variants have been developed:

Double bowline

The double bowline is made simply by the addition of an extra turn in the formation of the "rabbit hole" before the working end is threaded through.

Water bowline

Similar to the double bowline, the water bowline is made by forming a clove hitch before the working end is threaded through. It is said to be stronger and also more resistant to jamming than the other variations, especially when wet.

Yosemite bowline

Yosemite bowline

In this variation the knot's working end is taken round the loop in the direction of the original round turn, then threaded back up through the original round turn before the knot is drawn tight. The Yosemite bowline is often used in climbing.

Notes and references

External Links

• Variety of methods of tying basic bowline knot
• Animated tying diagram