Knot to Join Two Ropes

The Unit's clothesline came up short, and someone joins it with the first knot they ever learned: the square knot. That night, with wet towels swinging in the wind, the join slips and everything ends up on the ground. Picking the right knot to join two ropes (sailors and climbers call it a bend) prevents that kind of surprise, and the choice depends more on looking at the two ends in your hand than on memorizing names.

This guide sorts 15 bends from the catalog by the decision you need to make: which knot to use in each case, when it fails and how to test it. The step-by-step video is on each knot's page.

🧭What is the best knot to join two ropes?

No knot wins at everything. Some bends hold a lot and jam after the load; others untie with your fingertips but need similar ropes. So the choice comes down to five questions about the ropes and what the join is for.

First, thickness: different ropes call for the Sheet Bend. Next, material, because slick synthetic rope needs knots with interlocking turns. Flat or tubular webbing has knots of its own. If the join will hold a heavy load and has to come apart later, it can't jam. And if the joined rope has to run through a pulley, no knot will do: the answer is a splice.

The table sums up the 15 bends in this guide. For the basic knots of each job, see the guide to essential knots and lashings for Pathfinders.

Difficulty from the knots and lashings catalog; uses checked against Animated Knots and the Manual de Especialidades de Desbravadores (in Portuguese).

🚫Why is a square knot not safe for joining two ropes under load?

The Square Knot, also called the reef knot, is the first knot almost every Pathfinder learns, and it is on the official Friend class list published by the South American Division (SAD) of the Seventh-day Adventist Church. The Manual de Especialidades de Desbravadores, a Brazilian honors manual compiled by Gerson Boiko dos Santos and available on the Arquivos Adventistas website, sums up its place: tying parcels and finishing lashings. In first aid, it also ties off a bandage over a dressing.

As a bend for ropes that carry a load, it fails. All it takes is one end being pulled away from its own rope (a branch that snags it, a hand on the wrong side) for the knot to capsize and slide until it comes undone, and with ropes of different thicknesses or textures this happens even more easily. Clifford Ashley, author of The Ashley Book of Knots (1944), the reference work that numbers the knots, warned that the square knot used as a bend has probably caused more deaths and injuries than the failure of many other knots put together.

The Surgeon's Knot, also on the Friend class list, is its reinforced cousin: an extra turn in the first crossing adds friction and holds the knot while you finish it, which helps with slick string and fine line. In fishing, the same double turn gives its name to a join for lines of slightly different diameters. Even so, it inherits the square knot's flaw and also capsizes if an end is pulled outward.

🪢Which knot is used to join two ropes of different sizes?

The Sheet Bend is the classic answer, and it appears on the Friend and Companion class lists. The Brazilian honors manual records its use in a single line: joining two ropes of different diameters. It also works with similar ropes.

The bight, the U-shaped fold, always goes in the thicker rope; the thin one wraps around it and passes under itself, and both loose ends finish on the same side of the knot. If the difference in thickness is large, take two turns with the thin rope: that is the double sheet bend.

Its weak spot shows when the rope goes slack and flaps, because without tension it can shake loose, just like the bowline. On a flag on a pole or a tarp snapping in the wind, check the join now and then. In strength tests it ranks among the weaker bends: great for camp, never for holding a person.

The weaver's knot is the same sheet bend under another nickname, inherited from textile mills, where weavers used it to join threads that broke on the loom.

🔗What is the best knot to join two ropes of the same size?

For two ropes of the same thickness under load, three knots lead the pack. The Double Fisherman's Knot puts together two double overhand knots, each one tightened around the other rope. The Brazilian manual recommends it for joining thin ropes with extra strength, and it is the standard way to close the accessory cord loop for a Prusik knot. After a heavy load, though, it is practically welded shut.

The Figure 8 Bend uses the figure eight from the Companion class and is easy to check by eye: in every part of the knot, the two ropes run side by side, like rails. It is not for ropes of very different thicknesses, and it needs long tails.

The Alpine Butterfly Bend comes from the alpine butterfly loop, which the manual names as the best knot for a fixed loop in the middle of a rope. Both are tied by wrapping the rope around your hand, and the bend unties with your fingers even after a heavy load. Watch the crossing: passing the end through the wrong spot produces a look-alike knot that you cannot rely on.

🧲What is the best knot for joining nylon rope without jamming?

Synthetic rope, such as nylon and polyester, tends to be slicker than sisal and calls for knots with interlocking turns. The choice depends on whether you need to untie it later.

If the join can stay, the Hunter's Bend is the one the Solent branch of the International Guild of Knot Tyers recommends for joining slippery ropes, with the warning that after a heavy load it sometimes has to be cut. It became famous in 1978, when the British newspaper The Times credited it to Dr. Edward Hunter, although the American Phil Smith had described it earlier. The Ashley Bend, which Clifford Ashley regarded as his own creation and dated to 1934, hardly slips when properly dressed, but in David Delaney's tests cited by Animated Knots it jammed just like the Hunter's Bend.

If the join has to come apart, use the Zeppelin Bend, two overhand knots interlocked symmetrically: it is stable, resists shaking and does not jam (just don't try to untie it while the rope is still taut). In 1976, a boating magazine reported that U.S. Navy officer Charles Rosendahl required this knot on airship lines; Rosendahl himself later said he did not know the knot. For thick, stiff lines, the traditional choice is the Carrick Bend, from the heavy cables of ships, which deforms under load, unties with your fingers afterward and needs the ends coming out diagonally.

🎗️What is the water knot for, and who can join rappel ropes?

The Water Knot is an overhand knot tied in one end and retraced with the other along the same path, the classic bend for flat or tubular webbing. The tails should be at least 7.5 centimeters (3 inches) long, because with repeated loading and unloading the outer end can creep until it pulls out, and a snag on an edge can also open it. A webbing sling that will hold a person is safety equipment and stays with the instructor.

The Beer Knot feeds one end of tubular webbing inside the hollow of the other. It is smaller and has no visible tails, but one of the tails is hidden, so you cannot check its length by eye.

The Flat Overhand Bend is an overhand knot tied with both ropes held together. Climbers use it to join two rappel ropes, because both ropes enter the knot at the same point and it slides over obstacles more easily. Even in that use, it needs tails of about half a meter and must never be swapped for the figure-eight version tied the same way, which can roll with little load and has already caused deaths, according to Animated Knots.

🧵How do you join two ropes without a knot?

When the join must never loosen or has to run through a pulley, the way out is a splice: the strands of a laid (twisted) rope are opened and woven into the other. Learn from someone experienced before you trust it with a load.

The Short Splice is the strongest and works for a permanent join, such as lengthening a tow rope, but it ends up about twice as thick and will not run through a pulley. In synthetic rope, Animated Knots recommends at least five full tucks on each side, against the three that are enough in natural fiber. The Long Splice keeps almost the original diameter and runs through pulleys, at the cost of more work and a little less strength.

The effort pays off. According to Paul Dyer, technical manager at rope maker Marlow Ropes, a well-made splice generally keeps 90% of the rope's rated strength, against 50% for a knot in polyester or nylon. On a hypothetical rope with a breaking load of 1,000 kg, that would be 900 kg against 500 kg.

✅How do you test a bend before trusting it with weight?

Before you load it, check four things. The shape, compared with the knot's page: in the figure eight, the ropes run in pairs; in the sheet bend, the ends come out on the same side; in the Carrick, they come out diagonally. The dressing, pulling all four strands until everything settles. The tails, because a short end escapes with the back-and-forth. And a load that increases gradually, with the join close to the ground and no one underneath.

Do not join damaged rope to carry a load: a torn sheath, a core showing through or a burned section calls for new rope. The Brazilian honors manual advises that rope past its expiration date be kept only for carrying gear that poses no danger if it breaks. See how to care for a rope and, for rope that will hold someone, the guide to rescue knots, always with an instructor.

At the Unit meeting, the Counselor can hand out pairs of different ropes (thin and thick, smooth and rough, a piece of webbing) so each Pathfinder chooses, ties and explains the knot. That prepares them for the Knots and Lashings Honor, which asks them to know the uses and limitations of each knot; check the Knots and Lashings Honor requirements and the list of Pathfinder knots by class.