Is Spinnaker waterproof?

Hi Mike

> Roger, if you don’t mind me asking, do you just use cuben for these items (rain
> gear, shelter, and groundsheet) because you feel Spinnaker and silnylon are inadequate?

Ah, there’s the rub. I have been trying to find a reliable source for the Chinese fabrics I mentioned, but there are problems:
* the words ‘reliable’ and ‘Chinese’ do not sit comfortably together.
* finding the source for the fabrics has been impossible: A got it from B who got it from C, but A won’t tell you a thing about B and C. No way!
* buying from A means we have absolutely no control over the quality. QC seems to be unknown, as are the words contract and specifications.
On which score, read our article Made in China for a longer rendition of the theme.

On the other hand, I don’t use Cuben fabric for my tents because it lacks elasticity, and my designs assume some degree of elasticity. Also, try persuading my wife to change clothing inside a clear Cuben tent…

So right now I am sitting here evaluating several fabrics for a new summer tent and not feeling happy about any of them. Sigh. Mumble.

That said, my new orange winter tent uses silnylon for the fly – the water pressure requirements for the fly in the snow are not as high as for rain. But the floor is made of older wet-look silnylon which has a 10 PSI rating.

Cheers

My own experience is that both coated spinnaker cloth and sylnylon are adequate to our needs. I've had them out in pretty hard rain with no soak-through. Condensation I've gotten, without a doubt.

One particular instance was instructive. After a long, overnight rain during which I remained dry, I lay in the tent during semi-darkness as the rain abated. As drops of water fell from the trees, I felt sprays of water on my face. "Oy," I thought. "This tent sucks." The rain is leaking through. I turned on the light and saw that the tent was coated on the inside with condensation. As the large (from the sound of their impact) tree drips hit, I could see the condensation dislodge from the inner walls. The drops weren't passing through. They were forcing the inner condensation off the wall.

In fact, the 2 PSI rating of spinnaker thus seems adequate to our needs. There's not much you can do about condensation in the supersaturated air of an Ohio rainstorm, after all.

I also talked with an acquaintance who frequents the public programs at the observatory where I work. About a year and a half ago, he finished his own scratch-built sailboat, on which he used spinnaker cloth for the sails.

ALERT to the original poster: He bought the fabric at a local boat supply store, where he was able to examine several grades of the stuff. He chose a version that was clearly coated, so maybe the best bet is to go to a boat-supply outlet rather than using Internet or hiking sources.

Now here's the deal: He said that rain "runs right off the stuff." Perhaps the key here is buying the right grade with the right coating. Sadly, he wasn't much paying attention to the details when he bought it. But the point is that the stuff he bought at the local outlet was clearly coated.

I will, however, agree with this much of what the anti-spinnaker/ silnylon folks are saying. Cuben really is a fine fabric. If cost is no object, there's no harm in going with it — and a lot of advantages.

However, silnylon and coated spinnaker, even at a measly 2 PSI, both seem adequate to our needs. They are relatively inexpensive and lightweight, and are apparently easy to work with.

If I were making my first tent from scratch, I'd work with the cheaper material just because it would be easier to recover from if I screwed up.

Stargazer

Roger,

Are you talking about PU one side and sil the other?
Or are you talking about the blends?
Occasionally I get Domestic (US) blends of pu/sil.
I believe Henry Shires was getting it for his products a
couple of years ago. Wouldn't be surprised if it is what
Jardine is calling mist proof as it appeared on the market
the same time the mill that made the "oily" look
sil went out of business. There were some air pollution
issues with sil manufacture which may be the reason
for availability problems.

I just got some 1.9 ripstop with a .5 oz (double thickness)
sil in. Coated just one side so would make very good, if
a bit heavy,floors. Not quite so slippery.

It is in a pretty red. Let me know if you
need some.

I think we are going to have to send the Chinese ambassador and the trade representative over to have afternoon tea with you, Roger.

–B.G.–

In trying to reach conclusions about tent/tarp fabrics, an article on the Wilderness Equipment website may be of interest:
http://www.wildequipment.com.au/article.php?article=lightweight_tent_fabrics
Or, just go to the site, select any tent, and click on
>lightweight tent fabrics.
If nothing else, the article illustrates why any conclusions about fabrics are so hard to reach.

Wilderness Equipment has changed its ultralight fabric for flies from "Sn240" silnylon (a 'dry-look' fabric that has withstood heavy rains for me without leaking or misting for over 5 years) to a polyester with a silicone coating on one side and either a polyurethane or "polyether" (discussed on their current home page and in their article) coating on the other side. Since one general statement that can be made about Spinnaker is that it is usually polyester (but not always-Goodwinds kites has sold a stiff nylon fabric made for sails), this suggests that most Spinnaker will provide polyester's stretch and UV resistance. But the quality of the coating can vary from product to product and batch to batch just as much for Spinnaker as for silnylon. So the answer to the question, "Is Spinnaker waterproof?" is that it depends on the quality of the coating.

Although the Spinnaker fabrics I've experimented with were all stiff and noisy, I can see no reason why a polyester tent fabric with good stretch and UV resistance can not be just as supple, and just as noise free as nylon. Since such a fabric is not easily to be had, I have looked to the two-sided coating on silnylon to make it less water absorbent, and therefore less likely to wrinkle and sag in the rain, but others may not agree. Again, the quality of the coating may be a factor.

So I think that we consumers are all at the mercies of a globalized economy, as suggested by Roger's rummagng through the weeds in China. We can only evaluate and rely on the judgment, ethics and experience of manufacturers (most posters on this site seem to favor the small ones, as do I). Or if we are DIY addicts, as I am, we can also develop a simple and fairly reliable means of testing for water resistance, and test every batch we order before incorporating it into a tent/tarp. That's about the size of it, isn't it?

Hi Dave

> Are you talking about PU one side and sil the other?
The particular (Chinese) fabric I was drooling over was PU one side and Si the other. Yes, the coating were different on the two sides, and so was the response to water pressure.

When pressurised from the PU side the fabric took up to 70 kPa without leaking. And it was about 40 gsm! But I could not find the mill which made it.

When pressurised from the Si side the fabric did not leak at 70 kPa, BUT I could see the water penetrating the fabric under the Si coating. I had it under magnification at this stage, and the result was very clear. This is consistent with the general feeling that Si coating are slightly porous compared to PU coatings.

The Contender Dynakote 75 has a PU coating with a Si gloss over the top to add water-shedding. This stuff, along with the Contender Superlite 50, is what passes for 'spinnaker fabric' among much of the outdoors industry today. Unfortunately these two fabrics have low pressure ratings as they are not made to a pressure rating specification.

The spinnaker fabric sold by other major sailmakers usually has a pressure rating even lower than the Contender stuff. Once again, those spinnaker fabrics are made for spinnakers, and the focus is on water-shedding, not on water-pressure.

> the same time the mill that made the "oily" look sil went out of
> business. There were some air pollution issues with sil
> manufacture which may be the reason for availability problems.
The original wet-look silnylon was coated by Duro. The EPA shut that particular production process down because of the emissions, and Duro (apparently) could not be bothered installing a new coating plant to meet the EPA requirements for that process. But Duro themselves are still in business, and still do silicone coatings with other processes.

> I just got some 1.9 ripstop with a .5 oz (double thickness) sil in.
>Coated just one side so would make very good, if a bit heavy,floors.
> Not quite so slippery.
> It is in a pretty red. Let me know if you need some.
Interesting! Yes indeed, I would love to see a sample. I have some Therm-a-Rest Prolite 3 mats which move across the silnylon floor of my current summer tent like an ice-skater! I'll PM my snail-mail address to you.

Cheers

> an article on the Wilderness Equipment website may be of interest:
The author Ian Maley is the founder of WE. I have known him (by correspondence) for a long time. He knows his stuff.

cheers