Carbon Fibre Carbon fibre is a black fibre which has the highest strength and lowest stretch of all of the fibres we use. Carbon is used where light weight and low stretch are essential for sail performance. Carbon is often combined in the GPX laminate with either Twaron, Kevlar or Technora for added durability. The modulus and tensile strength of carbon fibre used in Stratis membranes exceeds that of all the other fibres but comes at a price with the brittle nature of the material resulting in far lower resistance to flex fatigue, which is why it is predominantly used in race sails. It is however virtually impervious to UV degradation, and when used appropriately it is a very useful fibre.
Twaron/Kevlar These yellow coloured fibres are also very high in strength and low in stretch and have been used in sails for many years. Kevlar and Twaron are suitable for most mid range racing applications, and while they are not as high performance as carbon they are better performing than any other fibre. Kevlar and Twaron have the advantage of better resistance to flex than carbon. Both Kevlar and Twaron are native to Stratis GPX where they are used alone or combined with carbon fibre. Twaron will also be available as a dope-dyed black fibre late in 2011, for those looking for a higher modulus fibre than Technora, but still wanting to retain the look of a full black fibre sail.
Technora Technora is a black coloured fibre originally developed to replace steel belting in tyres. It is a very durable fibre and is resistant to breakdown from either flex or UV. Technora has low stretch characteristics but does not out perform carbon or Kevlar in this field. It is particularly suitable for combining with carbon or Twaron in a sail to increase durability. Technora is another tool in the Stratis GPX tool box and works well in synergistic combinations with carbon fibre, where the membrane must go the extra mile. It’s one of our favourites for offshore racing applications.
PEN PEN provides a reasonably significant increase in modulus over PET, so it is very useful in those classes limited by Class Rules to lower modulus fibres (or simply “polyester” fibres). One cosmetic issue with PEN is that the naphthalate in the polymer is prone to yellowing on exposure to UV light. The yellowed polymer is only a few micron thick, and if you poke underneath you’ll find the virgin white polymer unharmed as the yellowed material actually acts as a sunshield. There is an associated loss in mechanical properties proportional to the amount of yellow sun-shield material, which is not really that significant, but is pretty ugly – so more expensive measures are needed to protect it from UV damage. Due to its cost PEN is found only in Stratis GPX sails where it is used in conjunction with UV blocking films and/or taffetas on Class restricted sails. Proven offshore and inshore, Stratis continues to fill the trophy shelf.