tent questions

Jerry Adams has an article here:

http://www.backpackinglight.com/cgi-bin/backpackinglight/myog_silnylon_floorless_2-person_tent.html

It describes a somewhat smaller version of what you're planning, and covers all the detailing. Subscription required to read the whole article, however.

Several people have made tents using that article as reference so might be worth reading

Do vertical seams with flat felled seam. thru-hiker.com has a good description of flat felled seam – "projects", "basic seams…" – other info

I dcn't do anything to seams and don't find that they leak. I do a lot of camping in rainy Pacific Northwest. Most people use silicone caulk diluted with mineral spirits (1:10) or Permatex Flowable Sealant or McNett silicone seam sealer.

I've been using #3 coil zippers for almost everything and they work pretty good. For main door, since it takes quite a bit of stress across it I'd maybe use #5. No reason to use waterproof zipper because you can't put anything directly under the zipper anyway because you have to open door to go in and out. Regular zippers on steep wall of pyramid don't leak anyway.

I reinforce the peak with a circle of heavier fabric. Set up tent. Put circle over peak and make a hand stitch at each of your vertical seams, making gathers in the circle piece so it conforms to the pyramid tent shape.

It was recommended to me by someone that knows their gear that I consider PU coated Polyester instead of silnylon due to stretch issues- the polyester, once stretched, will not rebound like Silnylon. However, I'm having a heck of a time finding light weight pu coated polyester. Does anyone have any comments on using this fabric, or were I might look to find lighter weight fabric of this type?

Seattle Fabrics has polyester Spinaker Fabric, but it's just DWR

I've used it successfully, until my sleeping bag touched it on the inside and water wicked through profusely

I think it was called 0.7 ounce per yard, but it weighed more like 1.1 ounce/square yard.

Ray,
Thru-Hiker used to sell a highly water resistant sail fabric, comparable to the material used on the GG One tent. At one point, there was a note on the T-H site about the difficulty of finding sail fabric with a reliably waterproof treatment.

In any event, like other sail fabrics, it was very stiff. Possibly OK for a tarp, but not so good for tailoring a tent.

Then there was the polyester Epic Malibu formerly used by Black Diamond for its small single wall tents. Very supple, but with no sagging like nylon. Around 1.8-1.9 oz. per sq. yd. Tests to around 1500mm HH, but leaks a lot above that, and may be subject to leakage at much lower HH if exposed to oil and dirt, so definitely not for clothing. Last place to sell it was OWF, in a darker color. Not sure you can still find it.

You can order a large Chinook tarp in green or sand, do some cutting, and end up with a fair amount of PU coated polyester yard goods, around 2.1 oz per sq. yd. If I recall correctly, their site claims its HH is 2000mm. The Diamond-shaped Kelty tarps are a little heavier yet, and also seem to remember that they are polyester.

Luxe tents make a number of shelters using polyester shaped in many innovative shapes.

Except for the stiff sail cloth, none of the above rival good quality silnylon for weight. I'm always looking, though, and watch the UK sites and the German site, Extrem Textil. Lighter weight polyester coated with PU and silicone is out there. Wilderness Equipment uses it. It should show up in the consumer market eventually.

> polyester Epic Malibu
I tested that. Yes, it withstands a bit of pressure when clean, but when it starts to leak the flow rockets up suddenly. Definitely not suitable for rainwear.
However, it makes a good outer shell or windshell for sub-zero conditions – for ski touring.

Cheers

I've seen lightweight uncoated ripstop polyester, would it be possible to do a DIY silicon coating and get an even coating?

Ray,
You can search and find a multitude of posts and some articles on this site about restoring sil coatings, usually on floors.
The problem is that the silicone needs to be diluted in order to coat well, and no one seems to have come up with anything outside a chemical factory that will really dissolve the silicone. So we try mineral spirits, camp stove fuel, and many other things. Haven't been able to find silicone sold in a highly diluted form.
The best I've seen on BPL is a mixture, referred to by some as a slurry, in which the silicone never really dissolves into the solvent. Add to that the fact that some of the solvents have some oil content that interferes with adhesion.
The result is eventual peeling, with some approaches lasting longer than others.

There are also silicone sprays, that are not so much waterproof as intended to provide a durable water resistant coating (DWR). I had an interesting experience with those. A much used silnylon fly from Wilderness Equipment was showing a lot of wear, so sprayed it with Atsko silicone. The result was not good. The fly fabric lost all its body and became flimsy and translucent; that is, you could see through it. Some months later, just for the heck of it, tried Kiwi CampDry silicone based spray(not the polymer based spray in the blue can), and all the body was restored to the fabric and it looked even better than when new.

So you have given me an idea. I have some "showerproof" polyester from one of the UK companies, that weighs a total of 1.3 ounces per sq. yd. It obviously has some kind of a DWR coating, but don't know if it is silicone or not. So will cut off some swatches and try both the silicone and polymer sprays from CampDry, Tectron and ScotchGaurd and see what happens. Don't have a Suter tester, but cruder tests will show if any one of the six swatches is markedly more water resistant than the others after spraying. Who knows, as with the WE fly, sometimes we can just stumble on to great results.

So what I am saying is that you may have to do some experimentation to try to arrive at a polyester that is nearer to the weight and water resistance of good quality silnylon.

P.S. Roger, I see you haven't changed your mind about Epic. But lots of folks have reported here of staying dry on long treks under tarps made of grades of Cuben fabric that Richard tested to around 500mm HH after not so much scrunching. The Epic treated Malibu polyester fabric goes to 1500mm HH, three times that. Assuming the Epic tent is not exposed to anything oily, like bug dope, and is well cared for and carefully stored to prevent mildew, might you be a bit less averse to its use? If you see something on the BBC news about some crazy yankee driving across the US with an Epic Malibu tent pitched on top of an Outback, it will be just me drying it out, and at the same time demonstrating that it is also just as wind resistant as a tunnel tent. The speed limit on I-80 in Nebraska is mostly 75 mph.

"I've seen lightweight uncoated ripstop polyester, would it be possible to do a DIY silicon coating and get an even coating?"

I've taken silicone:mineral spirits, maybe 1:10. It takes a while to get the silicone to disolve, maybe 10 minutes, stir occasionally. I coated silnylon that wasn't completely waterproof.

Top and bottom of bivy floor – the bottom didn't work very well, started peeling off after a while, too much abrasion on ground. the top of the floor worked fairly well, made it waterproof for maybe 50 nights.

Pack – inside and outside – made it waterproof for maybe 50 days of backpacking and it was still waterproof on recent trip.

Might work less well on uncoated polyester.

Hi Sam

> lots of folks have reported here of staying dry on long treks under tarps made of
> grades of Cuben fabric that Richard tested to around 500mm HH after not so much
> scrunching

Two very different situations imho.

In the case of the Cuban, what you get (as far as I know) is a few leaks at the worst crease points. The amount of water coming through increases slowly with increasing pressure. OK, unfortunate, but not life-ending.

What I found with EPIC was very different from this. When the pressure reached the threshold, the fabric started to leak everywhere: the water came through in a flood. When the pressure reached the threshold the water was breaking through at every little gap between every thread, because the surface tension effect was breaking down everywhere at once.

Mind you, I don't mind what anyone uses. I was just reporting what I have found happening myself. I did check the facts with a representative of the company, and he agreed with my assessment of the situation.

Cheers

Thanks, Roger. Not that your earlier reports were anything but clear, but even clearer now. Richard's video did show a fairly good flow through the Cuben at high HH, but nothing like what you just described for the Epic. I tried sealing the Epic Malibu with Atsko spray, but it made no difference in WP. Really wish I could find a light supple coated polyester to make a tent with no sag factor, so am in the same hunt with the OP. Maybe I'll try sealing the Epic with the Kiwi silicone Camp Dry that worked better on the Wilderness Experience silnylon.

Thought about making a .5 oz. Cuben cover for the Epic in the event of failure, but that would put the total fabric weight well over 2 oz. per sq. yd., more than the Chinook PU coated polyester, and goes strongly against the 'keep it simple' concept. Unfortunately, as you may know, the tent design I'm using requires the main canopy fabric to have a fair of amount of stretch on the bias, so cuben won't work. Even tried the Cuben WPB, because it is more supple, but no luck. Appear to have designed my way out of using the Cuben.

Hi.
I've just completed my mid and "planning" on making a write up on it, just need to book some time with the type-writer.
I also used the mentioned myog pyramid article, but also these:
http://trailsandtracks.blogspot.com/2011/07/myog-pyramid-tent.html
http://chrisroane.blogspot.com/2011/02/myog-10×10-pyramid.html
http://chrisroane.blogspot.com/2011/03/pyramid-version-20.html

A few short points. I made cut mine as MLD does, i.e. a short horizontal seam. Flat felled all the way. Bottom just hemmed + 5mm velcro for mosquito perimeter netting. On the top reinforcement, I did it like others have described. Cut a circle piece of sturdier fabric with a suitable radius (~200mm I'd say). However, I was sweating and biting my tongue with fear of ruining it all at such a late stage. While planning the whole thing I was 50/50 on making it this traditional way, versus reinforcing the individual triangles top from the beginning. Then going business as usual, incorporating the reinforcement fabric in the flat felled seam. Did I explain it clear enough? :)
On the catenary curve, supposing you will make one. I had 100mm deflection at the center on the ~2.7m ridgeline, I'd say that's appropriate, no less.

Hit a reply if you need more help.

Edit.
Oh, and double sided tape (++) and amann rasant 75 thread, microtex 80 needles.

So far, I've mostly been struggling with fabric selection. Right now, top of the heap seems to be a couple ultra light nylon sail cloths. They have resin bonded threads to strengthen and reduce stretch, (stretch is suppose to be equal or just slightly more than polyester sailcloth) and PU coated. I ordered samples of 1/2 oz, 3/4 oz, and 1.1 oz (actual coated weight), so I'm waiting on that before I go further. besides looking at tear and puncture resistance, I also intend to build an HH tester and see just how waterproof they are.

Ray,
I don't think anybody sells sailcloth at actual coated weight.
Please post how that works out, and the results with the DIY tester.
Thanks.

Ray, as Samuel says, you will not recieve fabric with an actual weight of 1/2 or 3/4 oz per square yard OR per sailmaker's yard. The convention upheld by sailcloth mills and sail lofts is to market spinnaker fabrics in several nominal categories that are named according to tradition and not according to real weight. Contender, for example, sells an "Ultralite 0.4 oz" spinnaker that weighs 0.9oz per square yard and 0.75 oz per sailmaker's yard, before finishing. Most "1/2 ounce fabrics" weigh about 0.8 oz per sailmaker's yard (roughly 1 oz per square yard), and I've bought "3/4 ounce" sailcloth that weighed 1.8 ounces per square yard.

I don't know who assured you that 0.5 oz and 0.75 oz are the real finished weights, but they are almost certainly not correct. A nylon fabric that is 0.5 oz/yard after finishing would need to be woven with 2-3 denier fibers. Such fabrics don't exist.

Just something to bear in mind when you are shopping for fabrics.

> The convention upheld by sailcloth mills and sail lofts
This applies mainly in America.

In the rest of the world, in the general fabric industry, fabric is specified by finished weight per square metre. The abbreviation is gsm, for Grams per Square Metre.

The sailmaking industry in other countries seems a bit variable as many of them have American head offices, and they sometimes get a bit confused as well. Retailers on the other hand generally wouldn't have a clue.

Cheers

I called the retailer with some questions, and when the woman that answered the phone didn't have any idea what I was talking about, they transferred me to someone else in the company, who did seem to know his stuff. According to him, the 1.1 oz fabric is a higher end stronger fabric, and the weight is definitely 1.1oz total weight. He said that the 3/4oz fabric is a 1/2oz fabric that comes to 3/4oz with treatment. We didn't talk about the one listed as 1/2oz, but I saw it when I was ordering the samples, and figured I'd get it since samples were a buck. I'll just have to see what they feel like when I get the samples.