In response to Rolf

(A lot of what I wrote came from Charlie's after dinner speech at GBCC.)

Yes, they are using Cuben( I added it to my spell checker). Cuben is more of a process than a fiber. They take a woven material, compact it or modify the weave and then laminate one or both sides. They make fabrics from many types and combinations of materials, Kevlar, spectra, carbon, Dacron, etc.

I heard about a Cuben Dacron fabric as an industrial balloon/inflatable material a while back, but I never thought about it for sails.

I have looked at Cuben fibre a couple of times in the past. In the same weight as normal sail cloth, Cuben is much more durable. in a 20% lighter version, it should be at least as durable as dacron/pentex. My only experience was cuben spectra for a club racing jib. For 40% more money we got about 3 times the life. It's expensive but, it doesn't blow out, in fact the spectra version doesn't give at all until it just disintegrates.