page_title: Sailcloth
section_title: Kevlar
hierarchical_section_title: Sailcloth / Modern fibers / Kevlar
caption_attribution_description: I Kevin Murray took this photo and release it to the public domain
context_page_description: Sailcloth encompasses a wide variety of materials that span those from natural fibers, such as flax, hemp or cotton in various forms of sail canvas, to synthetic fibers, including nylon, polyester, aramids, and carbon fibers in a variety of woven, spun and molded textiles.
context_section_description: 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 Kevlar sail.
caption: Aramid (Kevlar) sails, showing the typical color of the fabric.
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