Double bowline (round-turn bowline)

In the ordinary bowline you form a small loop in the standing part, pass the end up through it, around the standing part and back down. Under load the loop tightens around the two strands of the end and holds them. In the double bowline this loop consists of two identically twisted turns – a small round turn.

Two turns mean more contact area and more friction on the end. So the end is held more firmly, especially in slick or stiff rope, where a single bowline is more likely to give. Even so, it remains a bowline: it does not jam after loading and usually unties easily. And it shares the weakness of all bowline variants of loosening when shaken back and forth while unloaded.

First look at the two turns on the standing part: they must be twisted the same way and lie neatly side by side. If they are twisted in opposite directions, one turn simply falls out when you set the knot, leaving an ordinary bowline – or a messy tangle. The end runs up through both turns, around behind the standing part and back down through both.

Second, check which side the end lies on. In the usual bowline it lies on the inside of the loop. If it lies outside, that is the left-hand form, which is regarded as less reliable. Dress the turns before setting, then pull all strands snug one after another and leave a long tail. Backing up the tail for serious purposes belongs in training; this page does not teach it.

In camp and on board the double bowline is a good choice for a fixed loop in slick or stiff rope, and for loops that should untie again after loading – for example to drop a line over a post or to make a rope fast to a tree.

It is not suitable when the loop is loaded crosswise, that is when the two sides of the loop are pulled in opposite directions (ring loading). Bowline variants can lose their shape that way. Nor is it a replacement for a tie-in knot: many training schemes prefer the figure-eight follow-through for tying in because it is easier to inspect.

Bowline variants are used in some climbing. There, a mistied or poorly checked knot can be fatal. Life-safety use only after proper training with certified equipment, guided by qualified instructors and with a partner check by a second trained person.

In everyday use too: leave a long tail, check the knot before every load, and remember that it can loosen when it dangles or flaps unloaded for a long time. Typical mistakes are turns twisted in opposite directions, a tail on the wrong side and a tail that is too short. Use the Yosemite finish common in climbing only after instruction by trainers – tied wrong it can weaken the knot.

'Double bowline' is an ambiguous name. It usually means the round-turn bowline, but sometimes the bowline on a bight, which has two loops. When you learn a knot from a book or video, always go by the picture, not just the name.

To practise, tie the single and the double bowline side by side in the same rope and compare them. Count the turns around the end, check which side the end lies on, and set both. This way you learn to see the difference at a glance.