North Sails

  • Cuben Fiber

    What is Cuben Fiber sailcloth?

    In 2007 North Sails acquired the Cuben Fiber Sailcloth business based in Mesa, Arizona.  Cubic Technology, the original parent of Cuben Fiber, continues to independently develop, manufacture and sell spread-filament tape based composite products for non-sailing applications.  The Cubic Tech team, led by Heiner Meldner and RJ Downs, acts as technical consultants to North Cuben Fiber – a superb addition to North Sails’ resource base in leading edge materials and manufacturing capabilities.  Mike Dunn, a longtime employee of 3DL, joined the Cubic Tech team as VP for new business development in 2008, and remains a key liaison for North Sails in Mesa.

    Mesa Arizona© North Sails

    Cuben Fiber is a proprietary material in which fiber that is originally manufactured as a yarn (many small filaments bundled together in a larger thread) is spread into a flat tape of side-by-side filaments. These tapes are typically produced from Dyneema, but are sometimes made using other fiber types such as carbon and aramid.  These tapes are arranged in various layouts and combinations between outer layers of film.  Film choices are polyester (“Mylar”) which Cubic Tech refers to as “K” type, or Fluoride “FC” film.  The material is autoclaved to ensure lamination that is extremely well consolidated and as light as possible.

    Cuben Fiber looks different from the usual taffeta or scrim based laminated cloth, with a distinctive standard grey color (other colors are available on a custom order basis) and a mottled “high tech” appearance.  Cuben Fiber is very strong for its weight.  Because the fiber tapes can be laid up in varying directions, strength performance can be enhanced in warp, fill and intermediate directions.


    What are the styles and how do I select the appropriate material for a specific sail?

    Because Cuben Fiber is produced in multiple combinations of film and tape layouts, specifications and pricing are admittedly complex.   Here are a few key points of reference in selecting a Cuben Fiber fabric for your project.

    © North Sails“K” Type Polyester (Mylar) Film Types are well suited to lighter Cuben Fiber styles (CN13 and lower) – especially the K.08 and K.18 films.  The number refers to the film thickness in mils for each side of the laminate, so a K.18 style has .36 mils total polyester film.  In general, it is better to save weight by selecting a higher “CN” number (which equates to fiber content) and a lower film spec than to use heavy film in a style with fewer filaments of Dyneema.


    © North Sails“FC” Fluoride Film is often preferred to polyester in middle (CN18 to 29) and heavy (CN36 and above) weight Cuben Fiber materials. All laminated sailcloth (in which film is bonded to another type of material) suffers shrinkage with use to some degree.  It is generally agreed that Fluoride film Cuben has a modest advantage over K styles in reduced shrinkage.  

    “HB” designates a style with extra plies of filament tape in the intermediate directions between warp (0 degrees) and fill (90 degrees).  HB styles most often feature plies in the +/- 30 degree directions, with some special styles also featuring plies at +/- 6 degrees.  HB styles consume a lot of material and require significant extra time to manufacture so the prices per meter are high.  In lower load applications (wider apparent wind angle sails) HB styles are “overkill”, but for heavier load applications HB is advisable.

    © North SailsLight Weight “Offwind” Sail Materials: Cuben Fiber offers a unique opportunity to supply very light and easily pressurized sails with enough strength to handle inevitable and sudden high loads well in excess of those seen in static sailing conditions.  There is simply no other super light material in the world that offers the strength needed to absorb the energy of an asymmetric sail refilling after a gybe, or the loads generated when sailing in lumpy seas - at cloth weights in the 12 to 20 grams per square meter range!  Super light Cuben Fiber styles (CN.03 to CN1K.08) weigh one third to one half of the lightest coated nylon spinnaker cloths.  A Cuben Fiber A1 spinnaker will stay pressurized and will load the spinnaker sheet at significantly lower apparent wind angles than any other material, providing a significant net VMG gain. The advantage is most pronounced in small/medium size boats of course where “traditional” 36+ g/m2 fabrics are, to scale, somewhat overweight by nature.  

    Very light Cuben Fiber should make a superb windseeker headsail, and it has already tested very well in staysails.

    For more information on Cuben Fiber sailcloth contact:

    Jody Kiraly // North Cloth // 125 Old Gate Lane // Milford, CT 06460
    Ph: 01-203-783-4244 // Fax: 01-203-878-9045