A Carrick Bend is a symmetrical interwoven knot that joins the ends of two ropes — typically heavy hawsers — into a single working line. The knot appears in Ashley's Book of Knots as #1439 and was standardised in Royal Navy rigging manuals by the late 1800s. Two rope ends form opposing loops that weave over-and-under in a basket pattern, so under load the knot collapses neatly into a compact capsized form that grips itself but never welds shut. That non-jamming behaviour is why tug crews still tie it on 80 mm towing hawsers — it carries the load and unties cleanly afterwards.
Carrick Bend Interactive Calculator
Vary rope breaking strength, knot efficiency, applied pull, and safety factor to see the effective Carrick Bend capacity and load margin.
Equation Used
The calculator applies the article equation F_knot = eta x F_break, where eta is the Carrick Bend knot efficiency. The allowable load divides the effective knot capacity by the selected safety factor, while utilization compares the applied pull with the calculated knot capacity.
- Carrick Bend is correctly dressed and capsized under load.
- Efficiency eta represents the retained rope strength after tying the knot.
- Loads are treated as steady tensile loads, not shock loads.
The Carrick Bend in Action
The Carrick Bend works because of geometry, not friction. Each rope end forms a loop, the two loops cross at right angles, and each end then weaves alternately over and under the opposing loop in a four-corner basket pattern. When you pull the standing parts in opposite directions, the flat woven shape capsizes — that is, it collapses into a tight pretzel form where every crossing pinches its neighbour. The capsize is the working state of the knot. A Carrick Bend that hasn't capsized under load is just decoration.
The reason crews trust this knot on heavy hawsers comes down to two things. First, capsize distributes load across four bearing crossings instead of two, so peak fibre strain at any single point stays below the breaking limit — typical knot strength efficiency runs 60–65% of straight-line rope strength, which beats most other bends on stiff laid line. Second, because the knot capsizes rather than welds, you can untie it after a 20-tonne pull. A Bowline-on-bowline or a sheet bend in the same hawser would jam permanently.
Get the weave wrong and you have problems. If the over-under sequence is broken at any of the four crossings, the knot becomes the so-called "false" or "Granny" Carrick — it still looks symmetrical flat on a deck, but under load it slips, capsizes irregularly, and can shed up to half its rated holding. The other common failure is seizing the ends to the wrong standing parts on the full carrick bend (the seized variant) — cross-seizing reverses the load path and the knot opens. The fix is the diagonal symmetry rule: the two working ends must exit on opposite sides of the knot, not the same side.
Key Components
- Standing Parts: The two load-bearing rope sections that exit the knot and carry tension to the load. On an 80 mm towing hawser these take the full bollard pull of the tug — typically 40-70 tonnes for a harbour tug. They must exit on diagonally opposite corners of the woven square.
- Working Ends: The two free tails that complete the weave. Standard practice leaves 8-10 rope diameters of tail beyond the knot — for 24 mm line that means 200-240 mm minimum tail length. Shorter tails will pull through during capsize.
- Four Crossings: The over-under intersections that form the basket pattern. Each crossing must alternate strictly: if you have two adjacent overs or two adjacent unders, the knot is tied wrong and will slip under load. The crossings are where load distributes during capsize.
- Seizings (full carrick bend only): Optional whippings of marline or seizing twine that lock each working end to its adjacent standing part. Used when the knot must hold its flat decorative shape and not capsize — for example on a ceremonial heaving line bend or a permanent hawser splice substitute. Without seizings the knot will capsize on first load.
Real-World Applications of the Carrick Bend
The Carrick Bend earns its place wherever two heavy, stiff, or wet ropes need joining and the joint has to come undone afterwards. You see it most often in marine work, but it shows up in arboriculture, heritage rigging, and even architectural cable assemblies. The non-jamming bend property matters more as rope diameter goes up — at 60 mm and above, a jammed sheet bend is essentially permanent.
- Harbour Towage: Joining two sections of 80 mm polypropylene towing hawser on Svitzer harbour tugs working out of Felixstowe — the bend takes the bollard pull and unties on the foredeck after the job.
- Sail Training: Bending the messenger to the heavy mooring pendant on the STS Tenacious during dockside handover, where the messenger is 12 mm and the pendant is 32 mm — Carrick handles the diameter mismatch.
- Arboriculture: Joining two rigging lines for a heavy limb takedown using Samson Stable Braid, where Husqvarna-trained climbers prefer Carrick over a Zeppelin bend on stiff 5/8 inch double-braid.
- Heritage Rigging: Re-rigging the bowsprit gammoning on the HMS Victory restoration at Portsmouth Historic Dockyard, where the full carrick bend with seizings is the historically correct joining knot.
- Ceremonial and Decorative: Forming the centre motif of the Royal Navy boatswain's call lanyard, where the flat (uncapsized) seized full carrick bend is worked into the lanyard as a flat decorative element.
- Heaving Line Joints: Joining a 10 mm heaving line to a 28 mm mooring line during ship-to-shore line passing at the Port of Vancouver, where the bend must transfer load and then run free through a fairlead.
The Formula Behind the Carrick Bend
Knot strength is the practical number you care about — not the rope's catalogue breaking load, but how much of it survives once you tie a Carrick Bend in the line. Knot strength efficiency η runs from roughly 0.50 at the low end (poorly dressed knot in stiff wet polypropylene) up to about 0.70 at the high end (well-dressed knot in supple nylon double-braid). The sweet spot for working calculations on marine hawsers is η ≈ 0.62 — that is what experienced riggers plan around when they size a hawser to a known bollard pull. Push above 0.70 and you are kidding yourself; below 0.50 means the knot is tied wrong or the rope is the wrong material for the job.
Variables
| Symbol | Meaning | Unit (SI) | Unit (Imperial) |
|---|---|---|---|
| Fknot | Effective breaking load of the rope with the Carrick Bend tied in it | kN | lbf |
| η | Knot strength efficiency (dimensionless, typically 0.50 to 0.70 for Carrick Bend) | — | — |
| Fbreak | Straight-line catalogue breaking strength of the rope | kN | lbf |
Worked Example: Carrick Bend in a coastal salvage tow rig
Your salvage outfit is joining two lengths of 32 mm 8-strand nylon hawser to extend a tow line for a stranded 180-tonne fishing trawler off the Cornish coast. The rope's catalogue straight-line breaking strength is 280 kN. You need to know what the line will actually hold once a Carrick Bend joins the two sections, and whether that figure leaves enough margin against the expected 45 kN peak surge load during the tow.
Given
- Fbreak = 280 kN
- ηnominal = 0.62 —
- Fsurge = 45 kN
Solution
Step 1 — at the nominal efficiency of 0.62, which is what a well-dressed Carrick Bend in supple nylon delivers, compute the knotted breaking load:
Step 2 — at the low end of the typical range (η = 0.50), which is what you get with a wet stiff hawser tied in a hurry on a pitching deck:
Even at this worst-case figure, the knotted line still carries roughly 3 times the 45 kN surge load. That margin is why the Carrick is the bend of choice for rough-weather salvage — it degrades gracefully rather than failing catastrophically.
Step 3 — at the high end (η = 0.70), achievable only with a perfectly dressed knot in dry pre-stretched nylon, capsized cleanly under a controlled pre-load:
You should never plan against the high-end figure on a salvage job — sea-state and rope condition will pull you down toward the nominal or below. Designing to 173 kN with a 45 kN working load gives a safety factor of 3.85, which sits comfortably inside the 3:1 to 5:1 range the IMO recommends for emergency tow gear.
Result
The nominal knotted breaking load is 173. 6 kN against a 45 kN surge — a safety factor of 3.85, which is well inside acceptable salvage practice. At the low end (140 kN) the factor drops to 3.1 and you're still safe; at the high end (196 kN) the factor climbs to 4.4 but you should never bank on it because rope condition rarely cooperates. The sweet spot is the nominal 0.62 figure for working calculations. If your measured breaking load in a test pull comes in below 140 kN, the most likely causes are: (1) the knot was tied as a false Carrick with two adjacent overs or unders in the weave, (2) working ends shorter than 8 rope diameters pulled through during capsize, or (3) the hawser is contaminated with diesel or salt crystals which stiffen the fibres and prevent clean capsize, dropping efficiency below 0.50.
When to Use a Carrick Bend and When Not To
The Carrick Bend competes with the Sheet Bend, the Zeppelin Bend, and the Double Fisherman's. Each has a place — the question is what rope diameter, what load, and whether you need to untie it afterwards. Here is how they compare on the dimensions that actually drive the decision.
| Property | Carrick Bend | Sheet Bend | Zeppelin Bend |
|---|---|---|---|
| Knot strength efficiency | 60-65% | 55-60% | 60-70% |
| Best rope diameter range | 20-100 mm hawsers | 3-20 mm general line | 6-40 mm climbing/marine |
| Jam resistance after heavy load | Excellent — capsizes then unties cleanly | Poor — jams on stiff line above 16 mm | Excellent — designed specifically not to jam |
| Tying speed (trained hand) | 15-25 seconds | 3-5 seconds | 10-15 seconds |
| Performs with unequal rope diameters | Yes, up to ~3:1 ratio | Yes, up to ~2:1 with double sheet bend | No — requires similar diameters |
| Suitable for stiff wet hawsers | Yes — primary use case | No — slips and jams | Marginal — works on supple line only |
| Decorative/ceremonial use | Yes — full carrick with seizings | No | No |
Frequently Asked Questions About Carrick Bend
This is almost certainly a false Carrick — the over-under sequence is broken at one or more of the four crossings. A correctly tied Carrick alternates over-under-over-under around all four corners. If two adjacent crossings are both overs (or both unders), the knot still looks symmetrical on the deck but under load it capsizes asymmetrically and can shed 30-50% of its holding power.
Diagnostic check: lay the knot flat and trace one rope end with your finger. It must alternately go over, then under, then over, then under as it crosses the four corners. If you ever pass under twice in a row, retie it.
Let the load do it, but apply the load progressively. A pre-capsized knot done by hand often capsizes incompletely — you get a half-collapsed shape where one or two crossings are loaded and the others are slack, which is exactly the condition that drops efficiency to 0.50.
Standard practice on tugs is to take a slow strain on the hawser at low engine power, hold for 30 seconds while the bend capsizes evenly, then ramp to working load. If you watch a tied Carrick during this process you'll see it audibly snap into its capsized shape — that's the sound of the knot finding its working geometry.
Zeppelin wins when the ropes are similar diameter, supple, and the joint will see cyclic shock loading — climbing rigs, dynamic mooring snubbers, that sort of work. The Zeppelin's interlocking loop geometry doesn't depend on capsize, so it holds its rated efficiency from first load and resists shock unloading and reloading without working loose.
Carrick wins on stiff laid hawsers above ~30 mm diameter, on unequal-diameter joins (up to about 3:1), and on any application where the knot might sit dormant under load for hours and then need to come undone. Pick by rope stiffness first, diameter mismatch second.
Rule of thumb is 8 rope diameters minimum, 10-12 for stiff or slippery line. On 32 mm nylon that's 256 mm minimum tail; on 80 mm towing hawser you want at least 800 mm. The reason: when the knot capsizes under load, the working ends shift 2-4 diameters into the knot body as the weave tightens. Anything shorter than 8 diameters can disappear into the knot and exit the tail end — at which point the knot unravels.
If you're tying on stiff polypropylene or new pre-stretched nylon, go to 12 diameters. The stiffer the rope, the more the ends migrate during capsize.
If the weave is genuinely correct, the next suspects are rope condition and capsize completeness. UV-degraded nylon loses 20-30% of its breaking strength after 5 years of deck exposure, which pulls the catalogue Fbreak down before the knot efficiency factor even applies. Diesel or hydraulic-oil contamination stiffens fibres and prevents clean capsize, dragging η below 0.50.
Quick check: cut a 1-metre sample from the same hawser and pull-test it straight. If the straight-line breaking load is already 20% below catalogue, the rope itself is the problem, not the knot.
No — and this is a common mistake on mixed-construction tow gear. Wire rope has effectively zero compressibility at the strand level, so the four crossings can't redistribute load through the elastic deformation that makes the synthetic-on-synthetic Carrick work. Efficiency drops to roughly 0.30 and the wire abrades the synthetic at every crossing.
For synthetic-to-wire joins use a properly swaged thimble eye on the wire and a soft eye splice or a Tugmaster-style mantled connector on the synthetic, joined by a shackle. Knots between dissimilar materials are not the right tool.
Slightly stronger in static load — efficiency rises from about 0.62 to perhaps 0.68 because the seizings stop any micro-movement at the crossings — but the gain is rarely worth the cost. Seizing two ends with marline takes 5-10 minutes, and once seized the knot is effectively permanent. You can't untie it after the job without cutting the seizings and re-capsizing.
The full carrick is the right choice for permanent or semi-permanent rigging — bowsprit gammoning on a heritage vessel, a long-term mooring strop, or a decorative lanyard. For working tow gear, stick with the standard bend and let it capsize.
References & Further Reading
- Wikipedia contributors. Carrick bend. Wikipedia
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