Bowline on a Bight
Double bowline mid-line
A pair of fixed loops mid-line when both ends are already occupied.
Loop · Intermediate · Polyester / Nylon rope / Polypropylene / Natural fibre · 4 steps
ApplicationsHow to tie itFinished structure
Drawn from a rope model of this knot: which strand passes over which comes from where the rope actually lies.
Move 1 of 1Form a long bight in the middle of the rope where the two loops must sitYou should now see: Both rope ends remain standing; only doubled rope is in the working area. Step 01
Fold the rope double at the point where you want the loops, so the doubled section is long enough to make both loops and still pass around the whole knot.
You should now seeTwo parallel strands running back to the standing parts, joined at a U-shaped bight, with no twist between the strands.
If it goes wrongStarting with a bight that is too short. At step 3 it will not stretch over the two loops, and you end up forcing it or shrinking the loops to make it fit.
Fix: Pull more rope into the bight before going on. Allow for the size of both loops plus enough to pass around them.
Why: The folded end of the bight does not become one of the loops. It becomes the collar that wraps around the standing parts, so it needs its own length on top of the rope used for the loops.
Move 1 of 1Make a loop in the doubled rope and pass the end of the bight through itYou should now see: The bight end is through the doubled loop and still remains one continuous folded bight. Step 02
Make a small eye in the doubled rope by laying the bight side over the standing parts, then push the end of the bight up through that eye from underneath.
You should now seeA small eye with the bight side lying over the standing parts, a long bight standing up out of it, and a double loop hanging below.
If it goes wrongDrawing only a short tip of the bight through the eye. You find out at the next step, when the bight will not open wide enough to go over the loops.
Fix: Hold the eye so it keeps its shape and draw more of the bight up through it until the bight is longer than the loops hanging below.
Why: This is the eye and tuck of an ordinary bowline, made in doubled rope. If the standing parts lie on top of the bight side, the eye is mirrored; shake it out and make it again before you tuck.
- 1Collar around both standings2Two fixed loops
Move 1 of 1Open that bight and carry it around the entire knot until it surrounds both standing partsYou should now see: The finishing collar surrounds both standing parts, not just one of them. Step 03
Open the bight wide, bring it down over the double loop hanging below, then up behind the knot until it lies around both standing parts above the eye.
You should now seeThe opened bight forms a collar around both standing parts just above the eye, and no part of it is left hanging among the loops.
If it goes wrongThe collar ends up around only one standing part, or stays caught on one of the loops. Look at the collar: both standing parts should pass through it together.
Fix: Slacken the knot, lift the bight back off, and pass it over both loops again so it comes up around both standing parts.
Why: The collar around the standing parts is what locks the eye. Until the bight has gone over the whole knot, it is only tucked through the eye and can pull back out under load.
- 4
step 04 · schematic Two eyes of equal size, collar seated.
Step 04
Adjust the two loops to the size you need, then hold the standing parts and pull the loops downward to tighten. Put the load on both loops together.
Two eyes of equal size, collar seated.
You should now seeA firm knot with the collar snug around the standing parts, and two loops that keep their size when you pull on them together.
If it goes wrongHanging the load from one loop only. The knot can slip when just one loop is loaded, and you may see that loop lengthen while the other shortens.
Fix: Pass the hook, shackle or line through both loops. If the line will be pulled from both ends as well as from the loop, tie an alpine butterfly instead.
Why: Both loops come from the same doubled rope, so they can be set to different sizes before tightening, such as a seat loop and a back loop for a bosun's chair. Once loaded it does not bind and is reasonably easy to untie.
When this family fails, it fails as these. The recovered end still outranks the name.
Fixed eye whose lock is a collar seated on the standing part.
- !Open collar — the eye capsizes under cyclic load
- !Cowboy / wrong-direction loop
- !Tail too short to backup, or a Yosemite finish on an unfinished bowline
- !Only one loop is loaded. The knot can slip, and that loop lengthens while the other shortens.
- !The bight is tucked through the eye but not passed over the whole knot, so it can pull back out under load.
- !The collar sits around only one standing part or stays caught on a loop, so it does not lock the eye.
Bight never encircled both standings
One loop collapses or the knot capsizes
The opened bight must pass around the whole knot · step 03
Unequal undressed loops
One eye walks; the other takes all the load
Both loops must be dressed after the wrap-around · step 04
Used for three-way mid-line load
Structure was not built to take load on both standings plus the loops that way
Three-way load is an Alpine Butterfly job · step 04
One loop collapses or the knot capsizes
Check
- ?Bight around both standing parts
- ?Two open loops
Then
- →Retie and finish the wrap-around
- →Use Alpine Butterfly for three-way load
Bight never encircled both standings
Check
- ?One loop collapses or the knot capsizes
- ?Inspect step 03
Then
- →Retie. Do not dress a defective structure and call it seated.
Unequal undressed loops
Check
- ?One eye walks; the other takes all the load
- ?Inspect step 04
Then
- →Retie. Do not dress a defective structure and call it seated.
Used for three-way mid-line load
Check
- ?Structure was not built to take load on both standings plus the loops that way
- ?Inspect step 04
Then
- →Retie. Do not dress a defective structure and call it seated.
Same failure class, different geometry. Open the plates — Diagnose still starts from the symptom.
Why this knot
What it earns its place with, what it costs, and what to reach for instead.
- A single end-loop (use a bowline)
- A mid-line loop that must take three-way load (use Alpine Butterfly)
- Starting with a bight too short to pass over both loops, then shrinking the loops to make it fit.
- Drawing only a short tip of the bight up through the eye, so it will not open wide enough to go over the loops.
- Leaving the collar around one standing part, or caught on a loop, instead of around both standing parts.
- Hanging the load from one loop instead of passing the hook or shackle through both.
- Alpine ButterflyIntermediate
A fixed loop in the middle of a line that can take load on the loop or along the rope from either end
- BowlineBeginner
A fixed loop in the end of a rope, such as a mooring line to a ring or post