SAIL FABRICS EXPLAINED
Nylon, Dacron, Kevlar, Mylar, Carbon……….what???
Nylon – Spinnaker Material
Nylon is used in spinnakers because of its light weight, high tensile strength, superior
abrasion resistance and flexibility. However, it has a low modulus allowing too much stretch to
be suitable for upwind sails. Nylon is more susceptible to UV and chemical degradation than
polyesters and its physical properties can change due to moisture absorption.
Polyester (PET) – Dacron & Mylar
Polyethylene terephthalate, the most common type of polyester, is the most common fiber
used in sailcloth; it is also commonly referred to by the brand name Dacron. PET has
excellent resiliency, high ...view middle of the document...
PEN laminates are an economical
alternative for higher performance sail.
Kevlar – Gold fibre strands in laminated sails
Kevlar, an aramid fiber, has become the predominant fiber for racing sails, since it was
introduced by DuPont in 1971. It is stronger, has a higher strength to weight ratio than steel,
and has a modulus that is five times greater than PET, and about twice as high as PEN.
There are two popular types of Kevlar: Type 29 and Type 49, the latter having a 50% higher
initial modulus than Type 29 but a lower flex loss. DuPont has developed higher modulus
Types 129, 149 and 159, but these have seen little use in sails, since generally as the
modulus increases the flex strength decreases. DuPont has recently introduced Kevlar Edge,
a fiber developed specifically for sails with 25% higher flex strength and a higher modulus
than Kevlar 49. Kevlar, along with other aramid fibers, have poor UV resistance (Kevlar loses
strength roughly twice as quickly in sunlight as PET) and rapid loss of strength with flexing,
folding and flogging. Minimal flogging and careful handling can greatly extend the life of a
Technora is an aramid, which is produced in Japan by Teijin, has a slightly lower modulus
strength than Kevlar 29 but a slightly higher resistance to flex fatigue. The fiber’s lower UV
resistance is enhanced by dying the naturally gold fiber black. Technora is most often used as
bias support (X-ply) in laminate sailcloth.
Twaron is an aramid, which is produced in The Netherlands by Teijin, is chemically and
physically similar to DuPont’s Kevlar. Twaron HM (High modulus) has similar stretch
properties to Kevlar 49, greater tensile strength and better UV resistance. Twaron SM is
similar to Kevlar 29. Like Kevlar, the fiber is a bright gold color.
Spectra is an ultra-high-molecular-weight polyethylene (UHMWPE) made by Honeywell,
which offers superior UV resistance (on par with PET), very high initial modulus numbers
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(second only to high modulus Carbon Fiber), superior breaking strength, and high flex
strength. However, it also exhibits permanent and continuous elongation under a sustained
load (AKA: creep). This results in a change in shape as the sail ages. Because of this Spectra
is only used in spinnakers on high performance boats where the sails are replaced regularly.
Equivalent to Spectra, Dyneema is an extremely strong fiber produced by the Dutch company
DSM. It is often used by European sailcloth manufacturers, is available in a wider variety of
yarn sizes than Spectra, and is growing in popularity. Dyneema DSK78 set a new standard
combining the typical high strength to weight ratio, excellent low stretch, abrasion and UV
resistance but added three times better creep performance compared to Dyneema SK75, and
nearly two times better than Dyneema SK90.
Hoechst Celanese produces Certran polyethylene similar to Spectra, with about one...