As you can see from this table of yarns characteristics, there is a wide variation in the strength and stretch resistance of the various yarns. Besides the type of yarn, there is also a choice of the size of yarn to be used.
Other factors may be important too. Some yarns are impervious to UV rays (carbon for example) while others degrade rapidly when exposed to sunlight.
The durability of a yarn may be a consideration. Experience has shown that Technora (usually died black to protect it from UV) is the most durable of the aramids while Spectra or Dyneema is the best when it comes to bend and flex strength.
BELOW: An all carbon laminate on a Twaron scrim.
LEFT: A Kevlar laminate with a taffeta on one side. For performance cruising boats, MatriX is available with taffeta on both sides. RIGHT: A laminate made with a blend of Twaron and Carbon yarns on a black polyester scrim.
Yarn Layout and Distribution
Last but not least is the yarn layout and distribution. AccuCut gives the designer complete flexibility to tailor the yarn layout exactly to the predicted load map of a particular sail. In this process, the sail is typically broken into sections. Then depending on the size and intended use of the sail, the designer will determine the DPI (denier* per inch) each section of the sail requires. Armed with a DPI and a yarn type and size selection, he lays out the yarn paths and their spacing (concentration). This is a time consuming and critically important step that results in putting strength where strength is needed while eliminating weight and cost (yarn) where it is not needed.
* Denier is used as a measure of the size of a yarn. Specifically, denier is the weight in grams of 9000 meters of a given yarn.
Each section and each reef (in mainsails) is done separately before the combined layout is fed to the computer.
