Crazy idea: inside-out shelter?

[matt kirk]

Question: if one were to build a shelter with noseeum on top of a lightweight "waterproof" material with marginal HH, could the mesh possibly help boost the water repellency of the material by absorbing some of the energy from the raindrops? Why would someone want to do this: such a design could allow occupant the luxury to open and close the "windows" from bed. With 0.5 osy mesh and aforementioned 0.7 osy "waterproof" ripstop now available, combined weight could amount to as little as 1.2 osy. Such a versatile yet fully enclosed shelter could possibly weigh as a little as a sil nylon tarp. How dumb is this idea?

[Jerry Adams]

if the noseeum was suspended above it. it might work, good idea if the noseeum was against the tent fabric, maybe the raindrop would hit it and the high pressure of the impact would still be applied to the tent fabric maybe for an extra 0.5 osy, you could get fabric that was waterproof? crazy ideas are good, even if not directly useful. Can inspire another idea that's more practical.

[matt kirk]

Thanks for the feedback. Hmm, makes sense that there would need to be a space between the mesh and tarp material like you say. How much would suffice? In a deluge, it seems the mesh would be pushed into the tarp no matter what. Why not use heavier fabric? Well, of course the answer is the weight penalty. I drafted a simple hypothetical design (below) in which case, the extra weight would amount to about 3 oz. More info on rough sketch: tapered a-frame front triangle/panel peak height 36 inches, width 48; rear 18" height, 32" width, body length ~116". Panels are nylon with front zipper door. The body is both mesh and nylon with internal zipper running along both sides on inside of mesh. Zipped open, the nylon can be rolled back on either side. Here's a rather crude drawing. Materials: 7 yards 0.5 nanoseeum; 5 yards 0.7 ripstop; 3 yards silpoly pu4000 (for 90" x30" floor); 25(!)ft #3 zipper with pulls + thread, cordage, grosgrain etc. Estimated cost $150 sans shipping; estimated weight 16 oz. sans stakes and poles ($130/14oz respectively if pu4000 floor omitted and mesh is used with insertable plastic/poncho floor… Thoughts?

[Dale Wambaugh]

Points for thinking outside the box– or the tarp in this case. I think most would sew the mesh to the edges of the fabric to save the weight and live with the rest. Complete separate bug inners allow you to leave them at home when not needed, as well as breaking up the cost to ease sticker shock, as most are sold separately.

[Jerry Adams]

the waterproof coating weighs an extra 0.3 osy? which is less than the 0.5 osy mesh I would guess just about any gap would work – 1/4 inch?

[Franco Darioli]

A couple of problems that spring to mind are : 1) wear and tear on the mesh. It isn't tear resistant, easy to damage brushing against it or from debris falling on it. I suspect not all that UV resistant either. 2) it will be difficult to have enough tension not to sag into the fly, particularly when it is raining. Also Possibly much easier to damage in wind driven rain because of the extra weight from water trapped in the mesh. Thinking about that, it would also be harder and heavier to pack up when wet

[BlackHatGuy]

Joe Valesko once made me a cuben hammock tarp that had a large mesh area on each side on top, and the cuben 'panels' were zippered, so from under the tarp I could unzip the cuben panels on each side and roll them up so that only the mesh was above me. As far as I know that tarp is still in use today, but as a ground tarp instead of a hammock tarp.

[matt kirk]

More good feedback, thanks. Jerry, that calculation of 3+ oz. May be a bit off if that's what you're questioning, but there again that 0.3 osy number sounds about right if one were to beef up the material to the Membrane silpoly. Materials would be $27.50 cheaper, which is nice, but there is something magical about that 16 oz. Number… Dale, given my locale and projected hiking plans bug protection will always be an integral component. Having the stramlined set up is a plus too. On the AT the separate bug bivy under the tarp worked well due to abundance of lean-tos. But not where I'm headed… Franco, being below treeline should help mitigate most of the issues you raise. Interesting point about the mesh holding water. I feel a gentle shake, tap before pack up should shed most water, no? So is there much durability difference between 0.5 and 0.67 osy varieties? Doug, that sounds like a cool set-up from Joe. Would love to see pictures if you had them to share. Thanks again.

[Dale Wambaugh]

"Dale, given my locale and projected hiking plans bug protection will always be an integral component. Having the stramlined set up is a plus too. On the AT the separate bug bivy under the tarp worked well due to abundance of lean-tos. But not where I'm headed…" Then your shelter would be lighter by the weight of the top panel of the bug insert if the sides are sewn to the tarp top, like a Tarpent Pro Trail and others. http://www.tarptent.com/protrail.html I get your idea, but I would stick to simple. It will catch fir needles and other debris that would slide off the silnlyon. It may actually work against you to "capture" moisture in the mesh and I'm pretty sure it will slow the drying process. Don't feel bad: in a corner of one of Da Vinci's folios is a doodle that is instantly recognizable as a modern chain driven bicycle. It took 475 years for the rest of us to catch up :) Keep wondering!

[Anonymous]

"I suspect not all that UV resistant either." If made out of polyester, it would be fine. But nylon or polypropylene, not so much. Matt, i've thought of combing two different, UL materials for different "speciality" or niche purposes. Not exactly what you're thinking of though. For example, i've thought of combining polycryo with one of the UL, tightly woven nylon fabrics. The nylon provides most of the tensile strength, greater durability, and "structure", and the polycryo provides the waterproofness. If you space them apart just right, you would get a bit more insulation and less condensation for say, winter or cold weather camping. Or switch out the polycryo for mylar or similar IR reflective material for the inner, and bring some candles for winter backpacking–you'd get night light (very cool looking too) and even more thermal efficiency for winter camping. However, i wouldn't do this until they make a IR reflective material light and durable enough. Heat sheet material is definitely more durable in some ways than mylar space blanket material, but the aluminium coating on both, both rubs off and oxidizes–making it an essentially throw away material (which i'm trying to get away from). I'm not partial to the mesh outside idea, mostly for the reasons Dale mentioned. The stuff is almost like debris magnet. I'm a big fan of outside the box "crazy" type thinking though, so i would encourage you in this area–helps to keep the mind flexible and agile–it's what stretching/warm up for the body is to the mind. And generally it seems the older people get, the more they generally lose it–unless they take steps to maintain it. This is why in science, almost all the bright, novel, pioneering, and/or break through ideas come from the youngin's, and most of the resistance etc comes from the older or been "doing it for awhile" folks. Heck, even happened with Einstein and the youngin's of Quantum physics. Not only is it hard to teach an old dog a new trick–it's a pain to even get it to pay attention in the first place! Old dog speaking, "Bloody stupid new trick, why would i want to learn that, pfff, go away idiot." :0 For every good and practical idea i have had, i probably have had on average two that falls short in some way. But the try, the creative process, the search, the questioning, and openness/flexibility is important to engage in nonetheless. It's easy to be conservative and to not take chances and to always go with the "safe" or mainstream ideas. It's the path of least resistance for the ego (fear based) and social image part of us. But to dare to question, to dream, to go against the mainstream, to tap into creative wells–much more challenging, but also much more rewarding. Imagine on.

[matt kirk]

Thanks for the kind words of encouragement. The only limiting factor in my endeavors to reinvent the bicycle: an ultralight wallet. Good news is by transferring the horizontal zippers to run along the hypotenuse seam of door panel, eliminating pu4000 floor in favor of mesh a'la hexamid and switching to Membrane silpoly from questionable mysterious 7d ripstop as tarp material, projected weight stays below 16 oz. While material cost dips below $100 sans shipping. Not sure on dimensions though… Need to do mock up for sure. Thanks to Doug for link to aforementioned hammock tarp with zipper skylight. http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/50566/index.html?mb_sort= interested to hear any reports on durability and structural integrity. Also, still curious any feedback on 0.5 vs. 0.67 osy nanoseeum. Thanks again!

[Jerry Adams]

I don't think UV resistance is an issue I put a piece of silnylon fully exposed to sun for 5 months of summer. Didn't notice any degradation, just trying to pull on it and rip it. For any normal use, I would set the tent up at end of day and it wouldn't actually get much sun. Plus, I try to put it in at least some shade. Occasionally I'll leave it set up for a few days. It would take many years before I got 5 months worth of exposure. Or decades. If I was going to spend several summers camping out somewhere in full sun, then maybe nylon wouldn't be so good. Or if I had a boat cover or patio shade or whatever, for several years, then nylon would not be good.

[Anonymous]

Jerry, perhaps silicone coating helps significantly with the UV properties of nylon? I know that silicone is pretty UV resistant. If the fabric or whatever doesn't have a silicone coating, it might not do so well if nylon. But at the same time, i agree that unless it's being exposed to a lot of direct sun, it would probably take longer to degrade by UV than it might even be used for anyways.

[Jerry Adams]

uh, oh, another experiment, will have to wait for next year : )

[Anonymous]

Matt, as far as your mesh idea goes, barring UV issues, have you thought of inexpensive, easy to find in person (if you have a Joanne's or the like nearby), nylon tulle? It weighs in the neighborhood of 3 oz per square yd, and with coupons or sales can get it as cheaply as a few dollars a yard for 72 inch wide rolls. It's surprisingly durable for the weight. I don't know if it would damp down the force of the rain enough though.

[matt kirk]

Thanks for the recommendation on tulle. I have indeed looked at it at Joanne's and at Wally world. Though intrigued by its purported weight (I've read circa 0.3 osy) extremely skeptical on its durability. I admit to doing a few tiny buyer beware rip tests in store. Fail. Never used 0.5 osy nanoseeum, but have experience with the 0.67 variety and can say that the tulle seemed WAY more fragile to me. I ended up purchasing much more durable white mesh (probably used as bridal veil stuff, nice and pretty) for prototype 2 air bivy https://sub60.wikispaces.com/page/diff/Lab/555170733 Not sure on the weight, but heavier than half an oz. Definitely a tighter weave nylon mesh the white not as transparent from inside as I'd prefer (the point being here to have a room with a nice view), but that could also be advantageous: reflects a good bit of light from outside for a little privacy as you can see in photo. Hmmm, I guess this material could be paired nicely with cheap 0.54 osy zero-privacy "polycro" as tarp material for a poor man's rendition of aforementioned inside-out shelter. Will have to crunch the numbers to see how light and cheap. Could make for a good functional mock-up. One final thought: the tighter weace of this mesh offered at Joanne's makes is much smoother so it does not pick up debris like nanoseeum. Could also do a better job at absorbing rain drop energy though that would be of no importance if using super high HH of plastic… Will have to weigh a remnant of this "bridal veil" mesh, if in the 0.7-0.9 range, this may be a worthwhile side-excursion… As always thanks for the fodder…

[Dale Wambaugh]

You can buy sheer curtain liners in thrift stores— lots of colors too. Ikea has them too. Finer mesh than tulle.

[James Marco]

"As far as I know that tarp is still in use today, but as a ground tarp instead of a hammock tarp." Doug, Yes, we just went out with it a month ago. But, it leaked a bit. I think it needs to be sealed.

[Anonymous]

Tulle is definitely fragile overall and relatively speaking, but it will stretch some before ripping and breaking. I've bought and used polyester noseeum mesh, which is at least twice the weight of tulle. The initial tensile strength of the latter does definitely seem higher, but i would say for ounce per ounce, the tulle is actually more durable. Partly because it's nylon, which has a higher tensile strength for lighter weight than polyester, and it has more stretch than polyester, thus it will give/elongate some before completely ripping/breaking. So for example, if two branches of same size and shape drop similarity on two meshes of same weight per sq/yd, but one which is polyester and one nylon, the polyester one is likely to puncture easier. So, a nylon mesh that is a bit beefier and more tightly woven than tulle would be better than both the nylon tulle and similar weighted polyester meshes. My experience with nylon tulle is mostly for use in bug netting on a bivy. However, while i did use the bivy some, can't say that i used it even close to extensively. It was one of my earliest projects (when both first starting out, and having less spending money), and involved tyvek homewrap and tulle. If i knew then, what i know now, i definitely wouldn't have used the homewrap and probably wouldn't have used the tulle. It's ok though. The more tightly woven the mesh, the more water it will tend to hold. Plus nylon is somewhat absorptive to begin with. So it will definitely gain weight when wet.

[matt kirk]

Weighed a scrap of the "bridal veil" white mesh/tulle and it came out right at 1.0 osy, a bit too heavy. I think 0.5 nanoseeum is still the preferred choice at $5 per yard right now unless the heavier, but cheaper 0.67 has superior durability. Good point about finer mesh holding more water. As for the cuben tarp leakage, I assume the zippers are waterproof? Even so, thats got to be a difficult seam to keep sealed with the lateral tension. Will want to keep the zippers on the periphery! Cool concept though.

[Bob Moulder]

Just an idea… Polycryo over mesh with a tyvek floor. David Gardner (Gold Gear) and a couple of other folks did some fairly long-term tests (several months) and polycryo can be quite durable and resilient if the tie-out points and edges are designed correctly. Zero privacy of course! I'm using a tyvek housewrap bathtub floor with my Duomid and it's pretty durable. Testing with some lighter stuff this winter.

[Adam Kilpatrick]

TL;DR: from a science standpoint, the mesh would likely reduce rainfall intensity enough to help borderline HH fabrics. Just deleted a whole slab of dribble here as no one will read it. But (I've been involved briefly in rainfall energy-erosion research in the past) I'd be pretty confident that any of the meshes mentioned would reduce rainfall energy enough to make a "borderline HH" fabric workable. I think as long as the mesh isn't touching (it could be extremely close, eg sub mm) the main fabric it will work fine. Whether you'd want to or not is another story. My thoughts though on water absorption in mesh; why not just measure it? Get a bunch of samples, soak them, hold them up to drain for a set time (eg 1 minute), then weigh to determine water absorption. Do some WP fabrics while you are at it. I think empiracle data on water adsorption by them is useful around here. I hypothesize cuben has weight benefits beyond its base weight… I find light meshes pretty durable. Zpacks mesh groundsheets anyone? Mesh does pretty well… The math may well prove that its a negative sum weight gain over an ever so slightly heavier waterproof fabric, in combination with a much smaller area of mesh required for a bug free shelter. However if you require more space, ie a bug bivy you can sit up in, you will use it sans tarp for maximum breathability on dry nights, etc, maybe if you could pitch the super minimal tarp inside the bug bivy, it could work. There would have to be enough volume in the bug bivy so that the run of the tarp would drain outside of your (it'd wanna be) tub floor. Also of course, the bug bivy would need to be designed to accept the tarp's guy out points, etc. Another thought for you Matt; you are a poncho guy (clearly :-)), and this whole idea is about saving grams to the bone. I think having the roof as a detachable piece is better here. As I mentioned you can put it in when you need it. Nothing stopping you peeling it back too-that's just some clever guying. Still full bug shelter and good installation. But it means that you don't have to stress about destroying the mesh on the trail. I know you've built mesh and tents and hammocks and stuff into ponchos before, but this one is putting a lot of mesh in harm's way. I think you could build in permanent guys to the mesh bug bivy. These are then always used to pitch it. Then you would just need some loops off them in order to hook on (dutchware titanium dutch hooks) your poncho from the inside when needed. Another thought again…will this light silnylon have enough tear strength for you as a poncho? Would using 0.5oz cuben be a better idea? Probably better tear strength. Similar "marginal" HH. But same idea, go inside the mesh, maybe.

[Monte Masterson]

The .50 noseeum is very hard to work with, and as Franco said, it's prone to run or shred with the slightest snag. Very soft material. Holds more water than the .67. Stretches a lot too. Of course the .67 stretches a lot when compared to the .90. For just another .17 oz/yd sq it's amazing how much more substance the .67 has over the .50.

[Franco Darioli]

Matt, looks to me that you are somewhat focused on the cost of this project. If that is the case, before you start ordering stuff you need to work out how you are going to hold the mesh away from the nylon fabric at the apex. Specifically, given that the poles need to protrude through the nylon fabric to get to the mesh, how is the area around the pole opening going to remain waterproof. Don't underestimate the distance you need from fabric apex to mesh apex to keep the mesh from sitting over the fly in the middle of the tent ridge and sides (particularly when wet). Same for where you will attach the mesh at the bottom. I did a couple of quick tests. This is a mesh inner set up dry and taut : and this is after a minute of 'rain" : I must have watered more one side then the other, hence the difference in sagging. Note that the distance between the support/tie out points is about half as it would be in your tent. Then I wetted a 10g piece of that mesh. fully wet was 40g after several shakes it went down to 20g . With a bit of wind or sun it will fully dry pretty fast. All those weights are +/- 3g (1 ounce/yd2 mesh)

[matt kirk]

Franco, thanks for taking the time with this, appreciate the info! I'm moving away from my interest in using the more expensive marginal HH 0.7 osy ripstop in favor of something heavier (right now, Membrane silpoly). With that said, the need to space out the mesh from the tarp material seems to me to be less important (not as dependent on enhancing performance of tarp's water repellency). With that said, Adam hit the nail on the head (we've exchanged some PMs so he understands my erring on the side of simple and multi-functional gear), I'm going to direct my focus on designing a structurally sound "plus size bug bivy" and explore the option of a removable internal tarp. I imagine that the design will remain a-frame. Possibly run a ridgeline on the inside of the apex (for tarp to drape over. Grosgrain ribbon extending from corners and midpoints of waterproof floor to (and sewn thru) corners and midpoints of bug bivy. The ribbon/webbing providing some structure and attachment points for the corners/midpoints of tarp. I'm still not entirely sure I want tarp to double as a poncho, but having the ability to remove/replace may be a nice trick… As long as it doesn't add too much weight or complication in set up. Another weight/cost saving idea is to shrink this shelter idea down a bit further approaching normal bug bivy size, in which case I would begin to explore side entry options (the zipper ribbon providing a nice static lateral platform for tarp attachment. Will explore. Thanks to Monte for the cautionary note on 0.5 osy netting. That's honestly the first negative thing I've heard about it. Seems like 0.67 might be worth the weight…

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