Shelter Brain Storming Ideas ??

Kevin,

Why not a cuben AlphaMid or a full MegaMid since you are predisposed towards a pyramid to begin with? I would like to see either one of these tents made out Tyvek as in the type used in disposable clothing since it is not only lightweight but also breathable, i.e. very breathable. You wouldn’t be concerned with condensation and brushing up against the sides at night. Your profile strongly infers that it will be a three season tent. Tyvek is also inexpensive and the risk seems to be minimal. If you don’t like it, let me know, I would like to buy one unless I can persuade my wife to sew one or teach me to sew in the meantime. I look forward to hearing about your progress on this. John

One suggestion is to make the bug netting strip wider.

At 6" I think it may be too short and blow around and let the bugs in. I would say 12" is the min. And 16-18" would be closer to optimum so you can tuck it under and weight the edges with shoes, etc.

Skip the Silnylon for reinforcement. It stretches a lot more than the cuben and so the stress would really be mosty all on the cuben. Use multiple layers of the cuben and space the stitching out.

-Ron

John,
I have played with Tyvek and have sewn it into gound sheets in the past but I don't see it working well for something this large. Too heavy and I'm not sure how well the seams would hold up compared to Cuben. I hate cutting the Cuben Fiber but the sewing and taping come pretty easy. We have a million dollar ultrasonic cutting table at work that I cut some Cuben Fiber samples this morning and it cuts the material like butter so I will be working on some cad programs to make all the shapes for this project. If I get all the patterns programed and the design works well, I could probably run some Tyvek for you to sew up.

Ron,
THANKS for the suggestions !!! I will incorporate all of them into the design as they all make perfect sense.

Here is a thought, since we are brainstorming.

One of the problems with single-wall pyramids is the condensation running down the inside and onto the end of your bag, or onto you hair if it touches the wall. I wonder if you could avoid that, eg. with an inner wall just around the lower 2 feet, to act as a spacer between the bag and the outer wall. It could hang loose, and be pegged where you need it from the inside; or it might not need pegging at all. You might be able to keep the tent dimensions at 8-9 feet.

The alternative is to make at least one dimension much bigger, eg. 12 feet.

Steve,
Now you got me thinking about both of these ideas. Thanks!
I think I might have to sketch up a few concepts. I could make the lower inner wall start about 18 inches from the ground and run all the way to the ground and then hang loose for an extra 12 inches long like Ron suggested for the insect protection. Would also act as a mini gound protection to lay packs on. Two for one! The Cuben would be lighter than the noseeum as well. Then I would just use the noseeum to bridge the gap between the outter and inner wall for ventilation and bug protection. Hhmmmmm ???? Would add the the cost $$ and I'm not really sure I would have that much condensation ?? I guess I could always add it later if needed ??

Hi Kevin

> I'm not really sure I would have that much condensation ??
WRONG!!!!!!
As soon as it cools down a bit, you WILL have condensation in a Cuban Fiber shelter unless you have very good ventilation at the top. And don't even think about closing it down!
The one rule I would give aspiring shelter makers is to be paranoid about getting enough ventilation right at the top of the shelter, to let the humid air out. Sure, on a hot night in the desert it might not matter, but not all nights are hot.

Look very seriously at using sailmaker's seam-stick tapes for joining Cuban Fiber fabric, backed up by long stitches if you must – but the right tapes don't need sewing and make a much better (stronger, waterproof) join. The company can advise on the best tapes, but 3M 9485 is pretty good.

Use tapes for the reinforcing too. This stuff is NOT a woven fabric. Different thinking is needed.

Cheers

Roger,
I'm beginning to see the light. I guess I had assumed that condensation would not be all that bad based on previous history BUT my shelters were all pretty ventilated. I had planned on making a large mesh area right at the top of the crown and may make that mesh area even larger now based on your statements. I'm trying to determine if the condensation would really run down the walls almost to the ground. I think I might need to errect some Cuben at the designed angles to make sure the walls are steep enough to allow the moisture to run down the walls versus dripping. If it will run down than I can route it out away from the inside.
As far as using the tape I have that dialed in pretty well. I use the 3M tape but cut the width in half and then sew right down the middle of the tape. It appeared to work better than just using tape (not cut in half) from the one test I did. It has worked very well so far. I'm also looking at trying some Hysol urathane glue in the next few days to see if that works even better ? More testing for sure before I cut out 10 yards of material !!

10 more yards of the Cuben material just showed up at my door step today so the cutting should begin tomorrow. I think I have almost all the details figured out BUT we will see. The Mid will end up being 102.5" x 102.5" to minimize the scrap using the Cuben. The material needs to be trimmed on the edges to aproximately 52.0" width to remove the side flashing. I'm going with a 64.0" height and 4 upper vents that will be adjustable. I also plan on doing perimeter nanoseeum with cuben for insect protection. I don't see how I could make that any lighter. This is going to use a LOT of 3M tape and I still plan on sewing any seam that will be in stress. I will post some pictures as I progress. Thanks for everyone's input and really helping me think through a key few points. Thinking this might be a large undertaking for my second project but it really seems pretty simple in my head. If not, I may have lots of extra Cuben to make rain gear and bivy's !!!!!

Have you seen these? just asking, before you make the 1st incisions in that very spendy Cuben —-
http://www.ryanjordan.com/2006_arctic/2006/06/ultralight_shel.html

the photos in the blog entry are clickable. I think the dimensions of the Arctic 1000 ‘mid or of say the BD mega-light (around 90″ X 90″ seem right to me for a 2 person design. You go too big w/ the “mid design, you risk a weaker, more wind catching shelter. Gotta keep surface area down on a shelter supported by a single pole.

Kevin,
I have looked at Ryan's design in GREAT detail. I was actually going to build something much more simple until I saw the one on their web site! Great looking and it seems to make the most sense for me to build.
Ryan's claims to be 8' x 8' which would be 96" by 96". Very close to my dimensions of 102" x 102" I think my will be a little taller as well. Not sure what their height is but the zipper is 36" long for scale reference.
I need to make my shelter large enough for three people with some gear though. I'm also incorporating more guyouts and a few more features into my design. Time will tell.

Kevin, Is it possible that your fear of the heavy weight you associate w/ Tyvek is based on housewrap rather than the disposable clothing Tyvek? Will Rietveld says that the size large Tyvek pants weigh 2.2 ozs. Suppose you quadruple or quintuple that for the shelter you propose? You are still at or under 10 ozs and have a shelter that breathes. This stuff is very lightweight, is water proof and is more breathable than much of the gore-tex type materials out there. It is also very very inexpensive whereas cuben and event is super costly and fragil.

John,
I just built a pair of Cuben rain pants two night ago and they ended up weighing ONLY 29 grams !!! 1.1 oz. I have used the lighter weight Tyvek for ground sheets and it just appears that the Tyvek is heavier and not as strong. In fact, putting the Tyvek in the washing machine to krinkle and soften the material put a small hole in the ground sheet that I had to patch. I don't see the Cuben doing that as it seems tougher and lighter to me? I could be off base if there is some other type of Tyvek that I haven't seen yet ??? Others might be able to comment more on the comparison between the two materials. I'm guessing you really want to use the Tyvek as it breathes ?

Gosh Kevin, I had no idea that this small of weight could be achieved. That just blows away consideration of any other material. Yes, my whole focus is on breathability now. I have been attempting to find a solo shelter to serve me as well as the Hex does as a two man and purchased exactly what I had in mind only to find that condensation is a much bigger problem in a smaller more confining shelter. Therefore condensation is big issue. But it is hard to balance that against the weight you are achieving.

However, I wonder if we are talking about the same material? I have been wearing the disposable clothing as raingear for many years. The white pants that you see in the picture have been worn for at least 7 years with the bottom of the pant leg receiving heavy abuse from the abrasion from my foot gear rubbing against them with mud and gunk from whatever I am walking through. I just hose them off with a garden hose when I get home and they have not shown any wear except for the pair I ruined last January working through thorn bushes. I have heard of “kite t yvek” but I wonder if it is the same material that these disposable clothes are made from?

>…Suppose you quadruple or quintuple that for the shelter you propose? You are still at or under 10 ozs and have a shelter that breathes…<

Breathability in any breathable fabric can only be achieved if the relative humidity on the inside is higher than on the outside. Watervapour will than travel along the humidity differential. I wonder if it is possible to create a high enough relative humidity (pressure if you will) inside a three person pyramid shelter.

Anyone have more substatial comment on this than me wondering?

Eins

John,
I'm pretty sure the Tyvek I used was "Kite Tyvek". Maybe it is just a thinner version of the regular Tyvek. I know there is a pretty good web site that describes each type of Tyvek. Since I have been using the Cuben I just haven't thought about using any other types of materials. I'm really interested in seeing how well this design ventilates with the Mid shape and all the bottom perimeter netting and top vents I will be using. If condensation turns out to be a problem I can always look at replacing the top portion with Tyvek to see if that helps ?? Maybe joining the two fabrics together ?? I'm programming the large machine at work to cut the last few patterns today so I should be ready to start taping and sewing the shelter tonight!

Einstein – A high relative humidity is precisely what you want to avoid inside the tent.

A big factor that causes condensation is a warmed-up interior combined with cold tent walls. The warm air inside the tent can hold more moisture than the cold air outside, although the RH may be the same. When that moisture-laden warm air comes into contact with the cold tent wall, it immediately cools to a temperature which cannot hold that moisture. So the moisture precipitates out as condensation on the tent wall.

If the RH inside the tent gets too high it can form a mist. Breathable fabrics prevent that, and help prevent condensation. Good ventilation does two things: it prevents the inside warming up, and it helps carry the moisture out.

Steve,

Yep you're absolutely right that you want to avoid a high RH in your tent. However, the only way for water vapour to permeate through any fabric is along a relative humidity differntial. Ie from a high RH to a low RH.

If the air inside you tent is exactly the same as on the outside there is no differntial and there will be no water vapour permeating through the fabric so there is no need for a breathable fabric.

Eins