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ROPE & CORDAGE

Polyester Rope

Low stretch, strong ultraviolet resistance — the working line for sheets, halyards and general rigging.

INSPECT BEFORE LOAD · NEVER EXCEED WLL

Rope, splices and hardware are only as good as their condition. Inspect before every use and retire on evidence.

Polyester Rope — nautical chart line drawing

Specification

FibrePolyethylene terephthalate (PET)
ConstructionDouble braid, or 3-strand
Specific gravity1.38 — sinks
Elongation at 20% MBL8–12%
Wet strength lossNegligible
UV resistanceExcellent
Abrasion resistanceGood
Typical useSheets, halyards, general rigging

Technical parameters

Diameter 8 mmMBL ≈ 1,900 kg
Diameter 10 mmMBL ≈ 2,900 kg
Diameter 12 mmMBL ≈ 4,100 kg
Diameter 16 mmMBL ≈ 7,200 kg
Safe working loadMBL ÷ 5
CreepLow under sustained load
SelectLoad

Overview

Polyester — sold as Dacron, Terylene or PET depending on where you are — is the balanced choice in cordage. It stretches far less than nylon, roughly eight to twelve per cent at a working load, and it holds that figure far longer in sunlight. Polyester is also effectively immune to the hydrolysis that shortens nylon's life in a marine environment.

A double-braid polyester line has a braided cover over a braided core. The cover takes the abrasion and the handling, the core takes the load, and the two are spliced separately. That construction is why a double braid can be spliced to near its full strength while remaining pleasant to hold.

The trade-off is shock absorption. Polyester has little of it, so a polyester dock line in a surge will shock-load a cleat where nylon would have absorbed the energy. Choose polyester where you need control, nylon where you need forgiveness.

Safety notes

  • Low stretch means high shock load. A taut polyester line has almost no give — never use one as a fall-arrest or energy-absorbing element.
  • Cover damage exposes the core to ultraviolet light; a line with a breached cover should be shortened past the damage or retired.
  • Check splices after the first heavy load — a settling splice can draw up and leave the tail short.

Using it well

  • Whip or heat-seal every cut end immediately; a braided polyester line unlays fast once it starts.
  • Mark the cover where the line leaves a clutch or winch so you can spot migration.
  • Wash in fresh water once a season — salt crystals abrade the fibres from the inside.

Suited to

SheetsHalyardsGeneral riggingControl lines

Typical applications

SailingRiggingGeneral purpose
Figures are typical catalogue values for new equipment, quoted for comparison and planning. They are not a guarantee for any specific product or any specific load. Always work to the manufacturer’s stated working load limit and to the regulations that apply where you sail.

Related tools

Halyard — nautical chart line drawing

Halyard

The line that hoists a sail — low stretch, spliced at both ends, sized to the winch.

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Sheet Line — nautical chart line drawing

Sheet Line

The line that trims a sail — handled constantly, so grip and abrasion resistance come first.

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Eye Splice — nautical chart line drawing

Eye Splice

A permanent loop spliced into the line itself — the strongest way to terminate a rope.

Knots & Splices Tie
Cleat — nautical chart line drawing

Cleat

The fitting a line is made fast to — horn, cam or jam, each with its own way of holding and releasing.

Rigging Hardware Select

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