you have convinced me, too. Now I'm down to two options: this 92g polyester you recommend, or the Outguard 190.

But which one... That seems a harder choice than I thought.

Would you trust the 92g in F7-8 winds?

If I were at all interested in lightweight junk rig racing sails (which I'm not), I'd be investigating Code Zero fabrics like this and this.

Jami Jokinen wrote:

Whoa,
your tip of 90g/sqm, silicone-coated ripstop-polyester has to be the cheapest option available anywhere: only 1,70 eur/m (less than 2 pounds).

This is a very interesting option, if I just find something a bit stronger and yellow/orange -coloured (for visibility) for the upper two panels!

(And no, I'm not restricted to this one cloth provider website - if better options are to be found inside the EU, please bring them up!)

The only thing that ripstop construction does is to enable the manufacturer to get more strength into a given weight of fabric. Stretch will depend on other factors in the way the cloth is woven and then processed post-weaving.

No, I don't think you should use the PU-coated fabric. We've established that coatings and impregnations break down, in the case of Odyssey certainly, resulting in a loss of stability and strength. PU coating is for waterproofing only, and adds nothing to the properties of the fabric, in terms of sailmaking. It's not useful to have a coating on one side only, as we have to be more careful not to reverse pieces of cloth, so as to get a consistent appearance on each side of the sail. 

If you are looking to get your fabric only from that website, I would prefer to choose from the 'uncoated' section, and there, the only one I would use is the Cordura. Unfortunately 120 gm is out of stock which leaves 185gm. In the 'coated' section, I see silicon coated polyester 75 denier 75gm and silicon coated polyester 75 denier 90 gm  which I would prefer over the silicon coated nylon balloon fabric. I also see three different  Dacron 170gm sailcloths which, let's face it, are the right thing from which to make sails, as they have been designed precisely for that purpose.

Luckily, I have some silicone-coated nylon similar to Jami's sample, and some Odyssey. Both of them are stretchier across the width of the cloth than across its length. This is not surprising, as the warp will be under some tension during the weaving process, and will stay straighter than the weft, which must crimp somewhat as it goes under and over the warp. The Odyssey is about three times less stretchy across its width than the silicone-coated nylon, which is not surprising either, as it's about three times heavier. 

There are some sailcloths that are deliberately made with different characteristics in each direction, for specific uses, so this "unbalanced" kind of cloth is not unknown in sailmaking. It does mean, though, that you have to be very careful about way the cloth is laid. Those unbalanced Dacron sailcloths are woven with a heavier weft than warp, so that the cloths can be laid perpendicular to the leech (for reasons specific to bermudan sails). We have the opposite situation, as we are using cloths that are not specifically intended for sailmaking, and do not have the benefit of a weave that is ideal for being laid perpendicular to the leech; in a junk sail, made with fabrics like this, the cloths have to be laid vertically, parallel with the leech. If the cloths are laid horizontally, there will be stretch inside the stiffer tabling, resulting in a "hooked" leech which is very bad for performance. 

I've noticed this kind of thing happening in photos of some sails made of Odyssey with plain barrel-cut horizontally cut panels, and wondered why. Now I think we have the answer - different amounts of stretch in each direction. 

And so, I will continue to advocate vertically laid cloths, parallel to the leech. 

To come back to your query, Jami, this ultralight cloth is not ruled out completely, so long as you pay careful attention to the way the cloth is laid. And don't mix up cloths that are laid in different directions. At 3.40 euros a metre, this is the least expensive material you're going to find, so it has to be worth considering, for a trailer sailer that is not going to cover huge distances. Perhaps longevity is going to depend more on good craftsmanship than on cloth weight?