Home / Seamanship / Knots and ropework on board / Tying a bowline: the loop under load
The bowline, step by step
If you learn only one knot on board, learn this one. The bowline makes a loop that does not close under pull and that still comes undone afterwards, even when a tonne has hung on it.
What it is for
A mooring line into a ring or around a bollard, a sheet into a clew, a line onto someone else's anchor. Anywhere you need a loop that keeps its size.
How it is formed
Make a bight in the standing part, bring the end up through the bight, around behind the standing part and back down through the bight. The old aid: the rabbit comes out of the hole, around the tree and back down the hole.
The most common mistake
The bight made the wrong way round. The knot then looks almost the same but does not hold and slips under load. You can check it by one mark: the short end lies inside the loop, not outside.
Where it does not belong
Not as a join between two lines, that is what the sheet bend is for. And not where the load changes constantly and the knot can work loose, such as on a fender that chafes for hours.
How to tie a bowline: six steps
Most bowlines go wrong before the end ever moves, at the moment you twist the small loop into the line. Hold the standing part, the side that will take the load, in your left hand and the working end in your right. That is how most people learn it and how the steps below are written.
Go slowly at first and watch how the rope lies rather than what your fingers are doing. Once you have seen a correct bowline clearly, a wrong one stands out at a glance.
- Twist a small loop into the standing part with your left hand, making sure the working end side lies on top of the standing part, not underneath it.
- Decide how big the finished loop should be. The rope between the small loop and the end becomes the eye.
- Pass the working end up through the small loop from underneath.
- Take the end around the back of the standing part.
- Bring it back down through the small loop, alongside the strand that is already there.
- Hold the end and the eye together in one hand and pull firmly on the standing part with the other. Only now is the knot properly set.
Checking your bowline before it takes a load
A correctly tied bowline shows three things. A small collar wraps around the standing part. The tail comes out on the inside of the eye, lying next to one of its legs. And pulling on the eye does not change its size. If any of these is missing, untie it and start again.
Leave a decent tail. A good hand's width is a sensible minimum on board, and more on a heavy mooring line. A tail cut too short can creep back through the knot when the load comes and goes.
Slippery or stiff rope, such as modern lines with a very smooth cover, holds a bowline less well than soft polyester. Back it up with an extra half hitch around the leg of the eye. It takes seconds and stops the knot shaking loose when it goes slack.
The double bowline and the bowline on a bight
People asking about a double bowline usually mean one of two knots. The first starts with two small loops instead of one, laid on top of each other, with the end passed through both. It looks almost the same as the standard knot but grips harder and is less inclined to loosen, which makes it a good choice in slippery line or where the knot works for hours.
The second is the bowline on a bight. It is tied with the rope doubled, not with the end, and gives two loops side by side. That lets you put an eye in the middle of a line without reaching an end. Traditionally it has also served as an improvised seat for lifting someone, with one loop under the thighs and the other under the arms.
For everyday use the plain bowline is enough. The doubled forms earn their place where you do not quite trust the single one: in slick rope, in a line that flogs for hours, or whenever a person is hanging on it.
A bowline on the pontoon: bollards, rings and shared posts
On a bollard the bowline is quick: make the eye on board, hand it ashore or drop it over yourself. If another boat's eye is already there, do not simply drop yours on top. Pass your eye up through theirs from underneath and then over the bollard. That way either boat can leave without lifting the other's line.
A bowline through a ring is secure, but you cannot release it from the deck. If you want to cast off without anyone stepping ashore, rig a slip line instead: doubled through the ring with both ends made fast on board, then let one end go and pull the line through.
Watch where the eye bears. A bowline sitting right on an edge chafes exactly where the rope is already under the most strain.
Tying a bowline one-handed and around yourself
There is a method of tying a bowline with one hand, typically around your own body when someone throws you a line. You pass the end around your waist or under your arms, flick the small loop into the standing part with a turn of the wrist, and take the end around and back in one movement. It sounds like a party trick but it is simply practice.
Practise it on dry land, sitting down, then with your eyes shut. Nobody ties a knot in cold water with numb hands that they have only ever read about. The point is that the loop around your body stays the same size and does not tighten under load, which is exactly what a bowline does.
Frequently asked questions
How much strength does a bowline cost?
Every knot weakens a rope because the fibres are bent sharply inside it. As a rough rule of thumb, a bowline reduces the breaking load by something like a third. The exact figure depends on the rope. Where every kilo counts, a spliced eye is the better choice.
Can you untie a bowline under load?
No, it stays shut while the line is loaded. Once the load is off, push the collar around the standing part forward and the knot breaks open, even after it has taken a heavy strain.
Why does the bowline on my headsail sheet keep loosening?
Because it switches between load and slack all the time and flogs in the wind. An extra half hitch or the double-loop version helps. Check the knot after a few tacks.
What is a left-handed or cowboy bowline?
A variant in which the tail finishes outside the eye. It holds under a straight pull but is less dependable when the eye is loaded sideways. On board the version with the tail inside is the usual one.
Bowline or figure-of-eight loop?
The figure-of-eight loop is very secure and is what climbers use, but it is hard to undo after a heavy load. On a boat, where lines are made fast and cast off all day, the bowline is usually more practical.
What is the quickest way to learn the bowline?
Keep a short length of line in your pocket. Tie the knot a few times every day, then with your eyes closed, then around a chair leg or your own leg. Within a few days it comes without thinking.
What this has to do with insurance
A bowline in a mooring line is good. A bowline that pulls the line across a sharp edge is not: that is where it chafes through, and a chafed mooring line is wear, not damage. Wherever a line runs over an edge, it needs chafe protection over it.
