Materials used for Ropes:
Polyester is sometimes called Terylene, Dacron, or Trevira, these are trade names for the same material. Polyester is widely used for boat lines and for sail material because it combines good strength and durability, relatively low stretch and reasonable prices.
Polyester fibres are very fine and hair like, typically about 0.023 mm dia. These fibres are almost always white. It is virtually impossible to distinguish between nylon and polyester by appearance alone.
Polyester Physical Properties
Strength and Weight of Polyester Rope
|Inches||mm.||lbs per ft||kg per m||Pound||Kilogram|
|1/4||6.4||0.02||0.03||1 088||2 400|
|5/16||7.9||0.031||0.046||3 400||1 542|
|3/8||9.5||0.045||0.067||4 800||2 177|
|7/16||11.1||0.061||0.091||2 993||6 600|
|1/2||12.7||0.08||0.12||9 000||4 082|
|5/8||15.9||0.125||0.19||15 500||7 037|
|3/4||19.1||0.179||0.267||18 000||8 172|
|1||25.4||0.319||0.475||32 000||14 528|
Polyester Chemical Resistance
Advantages and Disadvantages of Polyester
- Good chemical resistance at regular temperatures
- Excellent UV resistance
- Polyester is slightly stronger than Nylon. Unlike nylon it does not lose strength when wet.
- Low Stretch
- Stiffer than Nylon
- Well suited to Static Loads
- Well priced and widely available.
- Polyester does not float.
- Some braids of polyester are quite stiff and don't work very well in blocks.
- Polyester is not suitable if the load is subject to jerking. It does not give as nylon does. In these applications it might only be used as the outside protective layer.
Among the conventional synthetic ropes available Polyester has the lowest stretch and best abrasion resistance, combined with good UV resistance.
It is commonly used for halyards and sheets. for example Novabraid supplies Marine lines: NOVABRAID XLE Double Braid Dacron Sheet Halyard Line 3/8" x 100' white/Blue and 1/2" X 100' Double Braid/Yacht Braid Premium Polyester Halyard Rigging Line
Polyester is the most common readily available sail material. The fabric is treated to improve rigidity and resistance to UV. It is often referred to as Dacron or Terylene. Sailrite sells fabric by the yard.
It also finds use for anchor rode. It is stiffer than nylon and not as stretchy.
There have been cases where nylon anchor lines have failed because high temperatures have been generated during strong weather, particulaly when it's hot. This caused the nylon anchor/mooring lines to soften and fail.
Polyester rope or polyester combinations are often found for winches, capstans and block and tackles. Its low stretch and low creep.
It is extensively used for cargo lifting straps, tow straps: CESS 3 Inch x 20 Ft Polyester Tow Strap Rope 27,000lbs Real Heavy Duty , and slings, where a stretch and bounce effect could destabilize a load.
There are a number of ropes offered that combine polyester outer braid with nylon inner core to get the low stretch and resistance to wear of polyester with the cushioning effect of nylon. It helps control the stretch of nylon in some climbing roopes: Samson Arbormaster Black/Red/White 16 Strand Climbing Rope (1/2") - 150' Hank
It is also combined with aramids again to provide protection and wearability in the outside layer, while the core provides more strength. Many such ropes are marketed as survival rope: Sleeved Spectra Kevlar Cord Durable Orange 100ft 325lbs Strength
The safe loading of a rope is a 1/10 to 1/12 of its breaking strength. Remember that knots weaken a rope as does age, wear, chemical attack etc.
I try to be accurate and check my figures, but mistakes happen. Check the suitability of any material against the technical information provided by the manufacturer.email me if you find mistakes, I'll fix them and we'll all benefit: Christine