Reference

Six fibres.Six sets of compromises.

There is no best fibre, only a best fit. Every entry below lists what the fibre is good at and — more usefully — the specific way it will let you down if you specify it for the wrong job.

Properties compared

Comparison of synthetic rope fibre properties
Fibre	Tenacity (g/den)	Specific gravity	Elongation (%)	Max temp (°C)	UV	Abrasion
HMPEDyneema® / Spectra®	35	0.97floats	3.5	70	Excellent	Excellent
AramidTechnora® / Kevlar®	23	1.44	3.6	200	Fair	Good
LCPVectran®	23	1.4	3.3	165	Poor	Very good
PolyesterDacron®	9	1.38	12	150	Excellent	Very good
NylonPolyamide 6.6	9.5	1.14	20	120	Good	Very good
PolypropylenePP multifilament	6	0.91floats	18	80	Fair	Fair

Tenacity is fibre-level, not rope-level: construction geometry and termination both reduce what actually reaches the load. Elongation is at break. Temperature ceilings are for continuous service and assume no sustained load — de-rate both together.

What each one is actually for

HMPE

Dyneema® / Spectra®

Best strength-to-weight of any commercial fibre: stronger than steel wire rope size-for-size at an eighth the weight, and it floats. Default where weight or safety governs.

Where it lets you down

Creeps under sustained high load, faster when hot. Specify a creep-resistant grade (SK78/SK99) for permanent moorings and de-rate above 40 °C.

Aramid

Technora® / Kevlar®

Holds its strength where HMPE softens. Near-zero creep and a 200 °C ceiling make it the fibre of record for hot work and standing rigging.

Where it lets you down

Degrades under UV and dislikes tight-radius flexing. Specify a jacketed construction for exposed service.

LCP

Vectran®

Effectively zero creep and excellent cyclic-load fatigue life. The fibre for holding a dimension for years under tension.

Where it lets you down

Very poor bare UV resistance — a jacket is mandatory. Costs more per pound than aramid at similar strength.

Polyester

Dacron®

The workhorse. Outstanding UV and abrasion life, negligible strength loss wet, controlled elongation without nylon's recoil. Best value per working hour.

Where it lets you down

Roughly a quarter the tenacity of HMPE. Sizes and weights climb fast on high-load jobs.

Nylon

Polyamide 6.6

The fibre for energy absorption: anchor rodes, tow springs, mooring pendants exposed to surge.

Where it lets you down

Loses 10–15% of strength wet. The energy that absorbs shock makes a failure dangerous. Respect snap-back zones.

Polypropylene

PP multifilament

Light, floating, cheap. For modest loads where buoyancy and cost govern: pick-up lines, buoy pendants, barrier rope.

Where it lets you down

Lowest strength and worst UV life of the group. Not a structural fibre.