BREAKING STRENGTH 8 MM NYLON WITH CORE 12.57 kN — strongest 8 mm in the test
A nylon rope with a braided sheath and a twisted core: two constructions in one. Five samples were pulled to destruction to measure what actually happens when the stretch runs out.
The 8 mm nylon black with core broke at an average of 12.57 kN (1,282 kg) in our test — the highest result of all 8 mm ropes tested.
Sheath-core ropes typically break in stages: the core yields first, then the sheath, and the force curve shows this clearly. Or so the theory goes.
This 8 mm nylon rope with a white twisted core and black braided sheath behaved differently.
Every single time, it snapped in one go. How that is possible in a rope with two separate construction elements, and what it indicates about the stiffness of the curve, is explained further below.
Five measurements produced a spread of just 0.63 kN (lowest measurement 12.23 kN, highest 12.86 kN). For a rope with two separate elements — core and sheath — that consistency is notable.
The force curve itself was uneven: not a clean line but an undulating profile, indicating that fibres were breaking gradually before the rope failed completely.
Just before the final snap, the breaking was also audible.
The material8 mm nylon rope with twisted core and braided sheath
This rope combines two construction principles: a white twisted core of 2 plied strands and a black braided polyamide sheath.
The core carries the majority of the tensile load; the sheath provides protection and also contributes to strength. Nylon (polyamide) has the highest elongation at break of all synthetic fibres — 20–35% — delivering substantial shock absorption.
The downside: nylon loses 10–15% of its strength when wet, a factor that must be accounted for in safety-critical applications.
This rope is part of our Polyester rope collection.
The method - How we test
Breaking strength tests are conducted in-house by Otto Tromm on a universal testing machine with a capacity of 50 kN.
Two sets of purpose-built rope clamps are available for this machine, selected based on the diameter and material of the rope. These clamps allow rope to be tested without first needing to be spliced.
All tests are carried out in accordance with the guidelines of ISO 2307:2019. This includes testing five times and using a test speed of 20 mm per minute.
Each rope is secured so that it is taut. No pre-tension is applied, as elongation is not measured in these tests.
Two repeat recordings of each test are filmed with a Sony camera on a tripod. The exact progression of the graph is also recorded separately on video.
This allows the stress profile and break behaviour to be matched precisely to the graph from the breaking strength machine.
For each of the 5 tests, observations are recorded in writing by the tester, capturing details such as the degree of elongation, the manner in which the rope breaks, and the loudness of the snap at the break point.
Just before the final break, fibre failure was clearly audible — five times in a row.— from the test notes
The figuresTest results: 12.57 kN average
Five identical ropes were loaded to break at 20 mm/min. Results were closely grouped: lowest measurement 12.23 kN, highest 12.86 kN, spread 0.63 kN. A narrower band than expected for a rope with a loose core.
Notably, the rope snapped in a single event in all five measurements — without the gradual staged failure typically seen in sheath-core ropes.
The force curve was nonetheless uneven and not clean, indicating progressive failure of individual fibres.
The high elongation of nylon plays a role here: load is built up slowly and a large proportion of the energy is absorbed by the elasticity of the rope. Just before the final break point, fibre failure was clearly audible.
In perspectiveComparison with other 8 mm ropes
The 8 mm nylon black with core was compared with three other 8 mm ropes previously measured on the same testing machine. All values are averages over a minimum of three measurements.
The nylon rope with core (12.57 kN) scores higher than the nylon braided without core (12.07 kN, +0.50 kN), polypropylene (10.57 kN, +2.00 kN), and the polyester sheath-core with loose twisted core (10.17 kN, +2.40 kN). The difference versus the nylon variant without core is modest; the difference versus the polypropylene and polyester variants is substantial.
In practice: When to use — and when not to
The high breaking strength and excellent shock absorption make this rope suitable for dynamic loads. Elongation and wet performance define its limits.
✓ Suitable for
- Anchor lines and mooring lines — the nylon elongation absorbs shock under wave and wind loading, keeping peak loads on attachment points low.
- Tow ropes — the elasticity of the nylon absorbs energy peaks during starts or sudden loads; 12.57 kN provides ample reserve at 8 mm diameter.
- Lashing rope on tarpaulins — the black sheath is UV-resistant; nylon retains its properties under prolonged outdoor exposure better than polypropylene.
- Pulling work in DIY and garden applications — for temporary or semi-permanent use where elongation is acceptable and high strength is required.
✕ Not suitable for
- Static lifting with certified documentation — without a manufacturer MBL and certification, this rope is not suitable as a certified lifting line.
- Applications where elongation is undesirable — nylon elongates 20–35% at break; for precise positioning or low-stretch rigging, polyester or HMPE is more appropriate.
- Prolonged underwater use or permanently wet conditions — nylon loses 10–15% of its strength when wet; strength is recovered on drying, but this must be factored into safety calculations.
- Life-safety applications — without a validated working load and certification, this rope is not suitable for life-safety use.
Stronger, at 8mm - Alternatives to 8 mm nylon with core
Conclusion: highest breaking strength in the 8 mm comparison
The 8 mm nylon black with core broke at an average of 12.57 kN (1,282 kg) — the highest result of all 8 mm ropes tested in this series.
The combination of braided sheath and twisted core delivers a consistent result with a spread of just 0.63 kN.
The rope is best suited to dynamic applications where shock absorption and tensile strength matter: anchor lines, tow ropes, or heavy outdoor lashing work.
Where low elongation is required or minimising dry weight is a priority, the polyester braided variant or HMPE rope should be considered.
Otto Tromm personally pulled five ropes to destruction, described the sound of breaking nylon fibres as music to his ears, and then tidied up methodically. He notes that the snap did momentarily startle him, but that this was not relevant to the test.