So with today's forecast being predicted all day rain I figured it would be a good time to set up my new tarp and see how it does for a couple hours of constent. I've included lots of photos because I know I like looking at photos so I'm assuming so does everyone else :) Please bear with me as I still haven't weighed it (I know shame on me...) During setup I got some quick glances from my neighbors. They must have thought I was either a hobo or my wife kicked me out. Funny thing is my wife took a photo of me thru the kitchen window laying under it and posted it on Facebook before I even knew.











I set it up and guyed it all out and found it to be pretty stable. Far more stable then I had thought originaly. After my last post about what I would do differently, I said I would have only had 3 tie-outs on the long side rather than my 4 that I have currently. I will say now after further testing that I will stick with the 4 from now on. It really makes it a more stable shelter. Setup time isn't very quick yet, as I'm still learning with tarps but I was happy overall with my speed.

Edited by Seattle on 02/09/2012 20:16:46 MST.

Looks good - nice and tight pitch. I'll be interested to hear the weight. Did you use Gorilla Tape instead of Duct Tape ?

L E Gant!

I love the simplicity of this.

Daryl

&

Edited by JasonG on 04/06/2013 16:28:52 MDT.

May I ask your inspiration for this MYOG project? Maybe just to test the shape? I really can't wait to hear more about how long you plan to use it and how it does after more use. You may have just given me an idea. I had a brief thought a while back to use polycro to make a front for my cuben poncho tarp in half pyramid pitch. I was just going to try using styrofoam twisted around the corners and tied to my tarp but maybe taping tie outs would be better.

Hmmmmmmmmm...

Polycryo

Nice looking tarp

Are there grommets in the middle of the duct/Gorilla tape?

My neighbors make odd comments to me about setting up tarps in the front yard too...

@Phillip

I really wanted a tarp that was light weight and just really simple. That was my thought behind this tarp. I've played around with my big blue 8x10 poly tarp but the bulkiness of it is a huge turn off. I chose polycryo because I heard everyone saying that they use it for their ground cloth and I thought, "Hell, if people are lying on it, why not just try to make a tarp from it". Then I saw Matt Kirk's (Fool on the Hill) youtube video he did on his polycryo shelter with the cuben doors. I figured I would take some of his ideas and use them. Living in the PNW I know it can rain or more or less drizzle for hours so I wanted lots of coverage to spread out wet items. I didn't want to stress the thin plastic so I ran a ridge line under it to take the pressure off the main ridge tie-outs. I figured this alone would really lengthen the life span of the tarp.
The tarp came in a basic 7x9'ish dimension and I thought about cutting it down to something smaller but I figured I would see how this goes and adjust later. I thought I could always cut it down to size if i wanted and just retape the perimeter. I also heard that polycryo has a tendency to rip if it get a hole in it so I used the truely awesome double sided tape that came with it to line the perimeter and then fold over the plastic to basically "hem" it. I found this really strengthened it. The tape provided has very little "give" to it when pulled just like the polycryo so I knew they would work well together. As for the Gorilla Glue tape I used, I'm still on the fence about how much to use. I figure once this tarp is useless I will do some super non-scientific testing and see how small of tie-outs I can get away with.

edited for spelling

Edited by Seattle on 02/09/2012 20:18:50 MST.

@ Jerry

The center tie-outs are also Gorilla Glue. I ran the ridge line under the tarp and thru the tie-out hole so that the line's force would always stay on the tape. I didn't use any grommets but rather just made a hole for the line to go thru. I saw this as a way of increasing the life span of the tarp and it more importantly kept my ridge line in the same place and not faaling over to one side or the other.

Edited by Seattle on 02/09/2012 20:23:31 MST.

Nice job! Good ideas on the side tie-outs--- I like the "V" with one stake. Good thinking with the continuous ridge line too. Did you just punch holes to run the guy lines?

So how do you think it will do in the wind?

Perfect! I never thought of the "hem" idea. I bet that alone would make this idea work for me. Any idea where some of this double sided tape can be found? Is it like scotch double sided tape or like thicker foam 3M double sided tape, or maybe something in between?

EDIT: After watching a video on this I see the kind of tape used that comes with the window film. In the video the maker also used velcro to stick to the polycro and then was able to sew grosgrain tieouts onto it. Great idea. I'll definitely be making something with this and I'll be sure to write a post on it.

Edited by pdcolelli42 on 02/09/2012 20:46:10 MST.

So how much does this wonderful little contraption weigh? Looks great! Been debating on something like this for my hammock setup.

I am curious about the weight as well. I have been thinking of delving into the hammock/ tarp camping in a effort to reduce my shelter weight. This would fit the bill. Curious how it would compare to a silnylon on weight. I also wonder if it could be dyed to at least opaque it a little. That way it could provide some shade from the sun. I suspect no though with it being waterproof by design. This is good stuff though.

Great work! I want to see a Polycro Poncho/ground sheet like the zpacks cuben one. Any takers?

Hey Johnson, when you say running a ridge line under it, what does that mean?

Edited by gregpphoto on 02/15/2012 23:36:45 MST.

Sorry, I somehow missed this thread.

> After my last post about what I would do differently, I said I would have only had 3 tie-outs on the long side rather than my 4 that I have currently. I will say now after further testing that I will stick with the 4 from now on. It really makes it a more stable shelter.

Yep. More = stability. I would have done at least 3 (not incl corners) per side. I'll admit it's rare that I use them though - only if it's windy or I expect a storm. Though I pitch in a half pyramid so it's inherently more stable than an A frame IMHO. Since I don't use a bivy, I want more protection.

> I figure once this tarp is useless I will do some super non-scientific testing and see how small of tie-outs I can get away with.

I wouldn't wait that long as it should last for years, but as I said before you can get away with much smaller tieouts. By smaller I mean where the guyline actually ties on. You do want to distribute the forces along as much edge as possible. I did that buy just overlapping a 15/16" piece of tape perpendicular (i.e., along the edge or across the corner) to the 15/32" guy tape.

> After watching a video on this I see the kind of tape used that comes with the window film. In the video the maker also used velcro to stick to the polycro and then was able to sew grosgrain tieouts onto it.

Which video was that, Phillip? I know Bill Fornshell has said it was pretty tricky to sew it.

> So how much does this wonderful little contraption weigh?

Should be on the order of 6 oz, maybe 7 if the double-sided tape is heavy. My 7x10 piece weighs 4.4 oz. I know tape added at least several ounces to my original shelter, but D has used less than I needed for seams, edges and ridgelines.

> when you say running a ridge line under it, what does that mean?

He ran cord under the entire length of the shelter.

What was the cord for? When I put up an A frame tarp between two trees or hiking poles, I run a line between the two objects, and simple drape my tarp over it A frame style.. is this all the ridge line means?

It just refers to that section of a tarp, just like the ridgelines of your house.

Yes, D did just what you are saying. Many users will just tie guylines to the ridgeline tieouts, relying on the tarp material to maintain its integrity and shape. With this material it would likely stretch a bit and cause premature failure perhaps if you did that and it wasn't reinforced with tape. Cuben and other fabrics don't have that problem.

I've never measured it, but I bet I put at least 30 pounds of force on my ridgelines. Being made from LDPE (think 1 mil trashbag), they would definitely fail if they didn't have tape on them.

Easy way to remember the spelling :
POLY as in polymer and CRYO as in Cryogenic
(a polymer film used for window insulation . Cryo =icy cold..)
Franco

> POLY as in polymer and CRYO as in Cryogenic

Ah, is that where they get cryo from? I've seen it written both cryo and cro and couldn't figure out what cryogenics would have to do with it. That would be ironic since it is heat that makes it shrink. I thought "cro" was short for "cross" since it's cross-linked polyolefin (CLP).

Interestingly, I just searched and it seems that polycryo is slang for CLP solely within the BPing community (originating from Gossamer Gear, of course). I found no other references. Ironically, the URL for the GG webpage uses polycro.

So use whichever you please. Or use CLP - I won't charge any royalties. :)

D,

Just curious if the cord down the center of the ridge line is necessary.

Do you think that it might do just as well pulling on the tie outs directly and stressing the polycryo material itself verses supporting the material with the ridge line cord?

Party On,

Newton

I wouldn't do that long-term with this material unless it was reinforced with tape.

John:

I'm sure you could just use the tie-outs and omit the ridge line cord but I wouldn't want to rely on the material for too much. I feel much better knowing that the stress isn't put on the tarp for that long of a section. I'm sure it would work to just use the tie-outs but the structure feels much more sound with the ridge line. I've had it sent up in my yard for a while and even with the breeze doesn't seem to phase it.

My wife said I can make another one and this time I'll be using the bear minimum tape needed as to not go overboard and increase the weight for little to no gain.

"Ah, is that where they get cryo from?'
Well I just assumed that ....
The original function of that film was to coat window glass to protect it from cold weather, hence the cryo bit.
Cryo , usually a suffix, comes from the Greek word kruos meaning very cold/frosty.
But you are correct, it is possibly the most misspelled name of a product
(along with Thermo Rest and variants)
Franco

I'm fairly certain that Polycryo is the same wrap used to package meat in American supermarkets where it is a very large continuous sheet on a long roll. Handles freezing well.

"Interestingly, I just searched and it seems that polycryo is slang for CLP solely within the BPing community (originating from Gossamer Gear, of course). I found no other references. Ironically, the URL for the GG webpage uses polycro."

What does CLP stand for? I too could not find Polycryo outside of Gossamer Gear, whats it called if you went to a hardware store?

http://www.acehardware.com/family/index.jsp?categoryId=1259828

CLP is my abbreviation for cross-linked polyolefin, which is what this stuff is though there are MANY varieties of that as well. That makes me wonder how different it may be between brands.

Polycryo seems to be a word Gossamer Gear made up.

Window shrink film or window insulation kits are what you would commonly find it as. So the southerners will need to order it most likely.

Some of you materials scientists out there ought to give us a list of these modern materials with chemical name, common name, and relative advantages or disadvantages of each, maybe something like "tougher than generic polyethylene," other names.

Start with:
Cross-linked polyolefin, Polycryo, ...
... Dyneema...


Thanks.

--B.G.--

Yep, I couldn't find it at my local hardware super store.

Yeah, I can't imagine window insulation would be high demand in SoCal. :) There are a variety of kits in a variety of sizes that you can order - 3M, Ace, Frost King, Duck, ... (5000+ hits in Google Shopping)

Hi Dan,

I'm making a very similar tarp (nearly identical) and I'm wondering how you attached the ridgeline to the tarp at the edges (or if you did at all). I am planning on tying on a very small loop to the tarp and then using a friction knot on the loop to grab the ridgeline cord. Also, a big thanks for all the testing you have done, it has been a huge help with my project.

Will

I'm stoked that you're building a tarp too! For my ridge line I simply ran the cord under the tarp. For the ridge line tieouts I made a small hole (just like the rest) so that I could run the cord thru it. This I thought was definitely needed since I was affraid that the isolated stress from the cord would tear the Polycryo fairly easily. Because the cord had to go thru the hole in the tieout it rested the cord stress on the burly Gorilla tape. After building it and setting it up I wish I would have added ridge line tensioners to tighten the material along the ridge.

And of course we'd all like to see pics! Plus if you could weigh your tarp for us that'd be sweet. I can't find time to find a scale to use or else I'd weigh mine :(

Also what size is yours?

I think the tensioners will help a lot, I have it set up inside to test (strung between two posts of a bed), and with a bit of tension across the tarp there is little stress between tarp and guyline, except at the reinforced edges.

I used a 84" by 110" sheet, is was labeled for 'outdoor use' and cost a dollar extra. It also did not include the hairdryer shrinking in the instructions. Either they expect UV from the sun to shrink it on windows, or this might be a non-shrinking version. I 'hemmed' all the edges with the included double sided tape and used gorilla tape for the guyline attachments (total of 12: ridgeline, four corners, three on each long side).

any updates on the research or photos of newly made poly tarps?

@Dennis

So far mine is holding up nicely so nicely I haven't needed to make another. My site selection techniques have improved drastically since using this material but it's paid back more so in it's low cost and low weight. I have been thinking of making a 6x8 for more "emergency" situations though.

Did this yesterday as my first MYOG project. Hemming the edges was very finicky; toward the end I found that it's much easier if you tape down the whole tarp taut first.

My tie-outs are gorilla tape wrapped around heat shrink tubing. I didn't read the thread recommending nylon washers until later. Fortunately, the $7 window insulation kit included enough polycryo for me to make another one!

Lookin' good Chris! What size did you make?

The kit came with a 62" by 210" sheet, so I cut that in half to make a 62" by 105" tarp. I'm considering the first one just as practice. Now that I know how to make neater hems, and found the thread suggesting nylon washers as grommets, I plan to use the other half to make a better tarp with more tie-outs.

The hardest part is just keeping the cat away while I work with crinkly plastic and string, essentially her two favorite toys.

So after over a year of waiting, I finally decided to pull out one of my large pieces of polycryo/cross-linked polyolefin (aka window shrink film) and make "Prototype 2" of my half pyramid. I wasn't able to pull it off in time for my recent trip with my boys, but I have Scout training this weekend with some good storms and winds in the forecast.

I had already had in mind a few design changes and I incorporated others from Dan's research and threads the past couple months - using the supplied double-sided tape to "hem" the edges and nylon washers instead of loops of tape for my tieouts. So here is the first pitch as barebones as it gets.

I bought a pack of 50 nylon washers at Fastenal for $2. They were too small for my trekking pole tip at the peak so I just used a metal washer I had. Detail of the pole connection.

Cross-linked polyolefin is known for being tricky to adhere to and I can tell the weatherproof adhesive on the 3M 2120 tape does not stick as well to it as it did to the LDPE so I used more tape than I would have otherwise. That may also make adding netting without sewing a challenge if I do that again. Here is a view with a full-size pad in it, where I'm playing around with differing peak heights and how far out the sides are pulled.
It took about 3 hours, which included cutting the size down to 6' x 9', taping all edges, taping the 2 ridges, adding all the tieouts and running to the store for washers.

There are a few things I'm still not decided on yet.
1. Adding shockcord loops to some or all 4 corners as I did on #1. This material isn't as stretchy as LDPE so it takes much more force to deform (though I had reinforced the LDPE with tape pretty well). My gut tells me it should be fine without them.
2. Adding tape down the center. I was forced to on #1 since that was a seam, but it did seem to keep the pitch tauter. The LDPE would deflect a fair bit in the wind. I may compromise and add a tieout a couple feet up from the edge.
3. I may add a bit more tape on some tieouts as I get a better feel for how the forces act on the material. For now I distribute the load perpendicular to the "ideal" force, but I've already seen where I don't always pull the front corners from close to 45 degrees. I may also need to change to the Gorilla Glue tape if 2120 does not hold long term.
4. Put the pole washer just a wee bit farther out from the edge so it's not on as much an angle.

Specs: 6' x 9' (finished size about 1" shorter because of the "hem"), total weight with the tieouts and washers but without guylines - 150 g (5.3 oz). FYI, the tieout tape and washers (9 plastic and 1 metal) added 22 g.

Thoughts on improvements?

I think that's a pretty impressive weight for such an inexpensive shelter.

Have any of you guys tested these shelters in any kind of significant wind? Could they stand up to some 30mph gusts? How long could it hold up to strong winds w/o failing?

BM

My LDPE version has seen 30-35 mph gusts. I'd expect it to be noisy but last indefinitely. I'd assume the same performance from this material. We were supposed to have 35 mph gusts at training but they just say winds up to 20 mph and not as much rain now. Bummer.

Cool shelter Michael!

I'm gonna build mine soon. These are awesome.

Could you add a photo on how you taped the tie outs along the sides? (I guess this request would apply to all of you who have made a poly tarp.) I'm trying to figure out if the washer has to be taped off of the poly as in the photos from the poly testing thread or can the washer be placed on the poly and then taped into place. Thanks.

@ Dennis:

You might be able to get away with putting the washer on the Material itself and then taping it down. The biggest worry I see is that the material is not very tear resistant (non at all really) so once it has a hole it is so much more susceptible to complete failure.


I recently got a new job (yay for me!) and i now have access to a scale. Today at work I weighed my Polycryo tarp and it came to 10.8oz. And that is with a crap load of heavy cordage and excessive tape used on all the tieouts. Also it is 7'x9 in size. I have no doubt that my next one (which will be smaller in size) will be sub 6oz if not less.

Very nice! Keep us posted on your next model. Close ups of the key points and weights are always appreciated.

Dennis,
I think you could do it either way. It would be a little cleaner putting them within the hem, but I would still add tape in both directions. I don't think the material would continue to tear because of the tape but that would be a good test for you to do. :)

FYI, I have one long piece of tape, containing the washer, that runs parallel to the ideal force direction, looping from the top of the material to the bottom of it. The "loop" is either an 8" piece for corners or 5" piece for secondary points. Then I added 2 perpendicular pieces on the top and 1 on the bottom. I used only 1 on the top in general for the LDPE version but the 2120 doesn't stick as well to this material so I thought the 2 extra pieces were good measure.

I just went out and took these before the sun rose. I found it interesting that ALL the places where there was tape had a film of condensation. You can see where I wiped the hem in this pic. You can also see I'm not pulling at exactly 45 so I made add a couple other pieces of tape to distribute the force better.

Here is a side tieout. It's also the only place on my "hem" I had a major wrinkle. This was the last side I had done so it wasn't taped down at all (I removed the tape holding the corners down tot he floor as I went). I was also going too fast. :) It's a bit easier if you can keep the material taut.

And here is the only other condensation. Granted it didn't have my respiration to deal with but it also had no groundcloth and the back is essentially pitched to the ground.


Dan,
I'm surprised your's is that heavy. You must be including guylines and stakes?

@ Michael

Being this was my first tarp I experimented with I used a "butt load" of tape. And it doesn't help any that the Gorilla Tape that I used is insanely heavy. Not to mention that because of all the "over engineered" guy-outs I made it doesn't pack up very small due to the tape not folding very well. My packed size for the tarp and guy lines is the size of a nalgene. And my 10.8 finished weight does include the guylines. I'm using cheap cordage from REI that is pretty thick/bulky/heavy so I'm sure that's not helping me.

My overall weight for my 7x9 tarp, guylines, stakes, and ground cloth come in at 20oz. Keep in mind I'm not useing the lightest stakes either.

It didn't look like you had used more than 1 large piece per tieout. As long as your guys are, I bet they're at least as heavy as the tape. Anyway, for reference, my Prototype 1 (LDPE) weighed 21.8 oz with everything, incl netting W/ zipper, ground cloth and stuff sack. That was a 6' x 8'.

I'm not sure I'll like trying to sleep with a headnet (or just a hat for that matter). I really liked taunting the skeeters in Wind Rivers through my netting. :) Keeping the annoying buzz away from the ears may be worth the weight penalty to me, but I'll give it a go without for a while.

I actually had a failure point this morning. One of the washers ripped out of the tape (the very corner I took the picture of earlier). I did get pretty small washers (3/8 OD I think) but this tape has worked well for me in the past. Now I know I must add another layer of 2120 tape around the washer. You might not have this issue with GG - just something to watch.

Edited by topshot on 04/13/2012 10:35:38 MDT.

I wonder if Tyvek Homewrap strips would be better for mounting the washers than the tape .

Frankly, if it doesn't hold now, I'll just go back to my loops of tape. They don't look as elegant, but they worked. I will theorize it failed because I folded the tape right against the washer rather than leaving some space on the side where the force is applied. When I added my reinforcement layer, I did it that way, leaving maybe 1/8". I think I may try a subjective test of tieout design. I wish I had a fish scale.

As it turns out, the training I drove over 90 minutes to attend was canceled and they failed to notify me. Grrr. So I pitched in the backyard again, purposely the wrong direction so it should pop open like a parachute. Supposed to have some decent winds and gusts Sunday.

I wish I had a fish scale or similar to make this more objective, but I played around with some different tape combinations to see how much force it would take for them to fail.



You can see that only 2 had not failed at the point I decided the pain in my hand of pulling on the Triptease (didn't use a glove or wrap it around a rod) was likely more force than it would normally take. I'm sure it was over 40 pounds. Interestingly the one I judge the best was just the tape loop (2nd from L) I'd been using all along. I normally use half that width (far L) so it doesn't bunch as much, but I also normally make it with 8959, which is stronger than 2120, and then cover it with 2120 for UV protection. The far left was just a single layer of 2120. The loops are technically double layer to prevent sticking, but only a single layer contacts the material.

The second best (6th from L) was what I have on my tarp now after the failure from the other day - one loop butted against the washer and a second layer that leaves 3/16-1/4" on the force side of the washer.

The worst one was how I started - one loop butted against the washer (3rd from L). It was pretty much tied with a single loop that left 3/16-1/4" on the force side (5th from L). Next came 2 loops butted against the washer (4th from L). Finally, the GG tape took a bit more force (maybe another 10 pounds?) to compromise. Both were pretty similar on whether the loop was butted against the washer or left a gap.

Edited by topshot on 04/14/2012 15:18:04 MDT.

Video added
Notice my comment, too. :)

Thanks for the video. Now I see what you are (were?) doing with the washers. I made a tarp of this material for hanging over my hammock. I only had it out for testing once and there was very little wind. I will try to get it out for more testing soon.

I saw your comments about the failure and am wondering just how much stress this will take. I'll let you know if I learn anything in my testing.

I'm pretty sure the corner that had originally failed before the video (see further up this thread) went first. I discovered I'd repaired it with only a single layer with a gap (5th from L in the pic) so it was one of the weakest designs. Even so, it took some pretty serious gusts before it went.

Once that went, I bet the peak went since I'd butted the washer against those pieces of tape and it had also been pulling out from the backside as you could see in the video.

If you look at the short followup video, you can see I fixed the angle issue at the peak with a larger ID. At this point I've decided to stick with the washers rather than replace all the tieouts with loops of tape. I may go back to loops with Prototype #3 if I have any more issues, but I think I've learned enough now to know how to make the washers work. I definitely like a washer for the pole connection (similar to the grommets on my Lunar Duo).

Others have suggested placing the washers within the hem itself for a cleaner look like a generic blue tarp with grommets. I believe the reinforcing tape would need to be different in that case. For one, the washer would only be captured by it on one side (sandwiched against the polycryo). Knowing tape doesn't stick as well to it, I think it would be easier for the washer to slide under force. Thus, I'd be wrapping at least a couple layers of tape around the edge of the hem to stop the washer once it made it that far. I'd likely put it very near the edge to start though since if it does slide the polycryo would then have a small tear in it. That's just my expectation though. I haven't tested it and don't plan to as I prefer my method.

Michael,

Thanks for all your experimenting and sharing. Very helpful.

Daryl

I've been thinking about this and maybe round washers are not the hot ticket. Your tape folds over the washer, and the edge of the washer concentrates the load at that middle point of the folded over tape- a point load, if you will. What might work better would be a rectangular washer. Take some kind of semi rigid plastic, maybe a section from a milk jug or something similar, cut out a square the that matches the width of your tape, and sandwich that in your loop of tape. Maybe fold the plastic piece in half, doubling its thickness... I dunno- just thinking out loud. But either way, the straight edge of the plastic reinforcement would spread the load across the whole width of the tape, and you'd have more area of adhesion between the tape of the reinforcement increase the amount of load carried in shear.

I'm better at coming up with ideas than I am at explaining them, but I hope that makes some sense.

BM

You are correct that that would help. Perhaps buying some larger OD washers and grinding off one side would be a simple solution. I don't think a milk jug even doubled over would be stout enough. The plastic should be harder.

I have a little data to share now on the tieout failure tests since I was able to borrow a cheap fish scale.

The worst case started deforming around 10 pounds and busted in the 15 range. The best of the ones I had done previously managed about 40 before breaking on a single attempt but repeated pulls to 30-35 would eventually cause it to go.

I did a few other combinations. I doubled up some GG and it held to the 50 lb max of the scale. I doubled up the loop and it held repeatedly at 40-45 but gave out at 50.

Then I made a single loop of the 3M 8959 that I had used on my previous tarp and it held 50 repeatedly. I suspect it would also fair better using washers since it's essentially high-grade strapping tape.

So what would I do different knowing this? Prototype #3 will likely go back to using 8959 for the actual connection point of the tieouts. However, it must be covered with 2120 to provide UV protection or it will disintegrate like normal strapping tape. GG could be used but it is not as strong as 8959, is heavier and it just doesn't look as nice. :) Maybe I shouldn't be so vain. LOL

While it's difficult to determine just how well the forces are distributed via the tieouts, you can at least guess that if you can accommodate at least a 3" section that it would take at least 25 lbs to break the tarp material based on the thread we had a couple months ago. So if my tieouts don't break until 50+ lbs, I shouldn't have to worry. Ryan's Storm Resistance article (when will Part 2 ever come out???) says, "Generally, moderately stormy conditions (snowfall equivalents of several inches through a night, or wind loads induced by 30-40 mph / 48-64 kph winds) can transfer up to about 40 pounds (18 kg) of tension force to guylines and stake-out points for most solo shelters." So I should be good to go there, but the article also states, "a significant mode of failure of ultralight shelters, especially those that employ low-stretch fabrics such as Cuben Fiber, is the shelter’s inability to be staked out tightly at high enough loads that induce a good distribution of tension evenly across all fabric panels. (emphasis added)" I think the saving grace here will be that the material does have a little give.

As an aside, one other point that I noted in the video but not here - the "catfish dropline" I got at Walmart held repeatedly at 50 so it would be suitable for some guylines. I don't know if it would work with linelocs or hitches though as I just tie a bowline on each end. But it's cheap, lightweight, braided nylon twine.

As UM suggests, a round washer will tend to concentrate stress at the radial edge.

I considered making a simple reinforcement by taking a piece of PET bottle wall, folding it in half, and then punching a hole in the centre. You might even use a hot tool to melt the edges of this hole to soften & thicken the edges. PET bottle wall is pretty strong (I made some nice mudguards for my MTB that lasted until it got stolen...).

If the sharp edge of the PET is an issue, you could fold the PET around a round washer, allowing the straight, folded edge of the PET to act as a load spreader for the washer.

Since we've put a piece of folded PET inside a loop of tape, we have the choice of using the punched hole, or simply threading the guy through this PET loop. Again, the sharp edges might prove a problem, but some careful manipulation of the PET with a heat source might allow us to add a curved shape to it.

> you could fold the PET around a round washer, allowing the straight, folded edge of the PET to act as a load spreader for the washer.

That would help.

> Since we've put a piece of folded PET inside a loop of tape, we have the choice of using the punched hole, or simply threading the guy through this PET loop.

Actually if using simply a loop of tape like I've done in the past, it doesn't give right where the guyline passes through as you might expect so the PET would be pointless in that case.

Yesterday morning I was concerned this material was going to condense really badly because it was soaked on the inside. I thought that was odd since the previous days I hadn't noticed hardly any. So I put up my LDPE shelter next to it since I'd rarely had a condensation issue with it. This morning there was still significant condensation but not as bad and it was fairly similar in both shelters so I was happy to see that. Here's a shot of my original shelter and it's slightly larger younger sibling.

> Actually if using simply a loop of tape like I've done in the past, it doesn't give right where the guyline passes through as you might expect so the PET would be pointless in that case.

Yes, I'd expect the tape to simply bunch together, spreading the load over the entire width of the tape, even if the loading at the contact with the tarp body becomes a little non-uniform as a result.

My comment assumed that the PET had been put on the loop anyway. So, if it's there...

So, what's the best way to construct tie-outs on a tarp like this? I'm making one out of 3-mil Polyethylene. I like the idea of grommets on tape-reinforced areas, but would making loops be better for side tie-outs in case you wanted to stake it all the way to the ground?

You could run a stake through the grommets to take it to the ground (assuming you're using nail/hook stakes). I normally use bowline knots so have a smaller loop of line around the grommet that I use with my Y-stakes if I want it close to the ground.

As for the best way, read through all the above and note the ones that clearly didn't work as well as others. :) I haven't tested every way either, of course (like embedding the "grommets" in the hem).

BTW, since polyethylene stretches so much you'll need to reinforce any ridgelines with 3M 2120 Transparent Duct Tape (also known as L520 I think it is). I did it with the polycryo as well, but it's not as necessary there (I'd still recommend it though unless you're going for not as long life and light as possible). You can see exactly what I mean if you watch my videos on my tarps (search the channel for myog).

Has anyone tried doing this with space blanket material? I'm thInking about putting together an emergency bivouac kit for winter dayhiking, and if can stand up to the service the reflectivity might be worth the noise.

a shelter with a space blanket http://www.youtube.com/watch?v=QatcuLnqnhQ&feature=plcp

> Has anyone tried doing this with space blanket material?

Technically, my first one (shown in my avatar as well) was since it's aluminized, but it's LDPE rather than mylar. The original designer I got the idea from did use mylar but was concerned it wouldn't hold up to hail at Philmont so switched to LDPE for that trip. Mylar will catastrophically fail whereas LDPE will not. LDPE is also not as noisy.

Has anyone tried doing this with space blanket material?

Hi Will,

Checkout this thread

Edited by jcolten on 10/16/2012 18:47:49 MDT.

Home Depot didn't have the 2120, I ended up using what turns out to be non-UV resistant packing tape :( We'll see how long it lasts, and if it's worth repairing. I think I see silnylon in my future...

I'm a newbie to tarp camping, and just made my own hammock and bug net to boot. Thanks for all the great info on this site!

Here's a straight to the point video of a space blanket tarp.

http://youtu.be/IZ-l2Dx4QLs

I've been using a fairly big (10ft x 12ft) 3-mil poly tarp with the kids this summer, and it has worked well. Not exactly UL, though. I have an extra GG Polycryo ground sheet, so I think I'll do a bit of experimentation.

There are two things I'd like to try, and if anybody has already, I'd appreciate your input. The first is to attach the corner guys with a sheet bend, Ray Jardine-style. This has worked well with my poly tarp.

The second is to use Dow WeatherMate Construction Tape (like DuPont Tyvek Tape) for the hem and tape loops. It's UL, waterproof, strong, and very sticky.

> The first is to attach the corner guys with a sheet bend, Ray Jardine-style.

I'm surprised it distributes the force better but if it works for you, go for it. I'd think it would cause more flapping in the wind, too. Personally, when I do corners I add tape that goes perpendicular across my tieout to spread the force over the whole corner (and hold the tieout better).

> The second is to use Dow WeatherMate Construction Tape (like DuPont Tyvek Tape) for the hem and tape loops. It's UL, waterproof, strong, and very sticky.

This sounds like an intriguing alternative to the Transparent Duct Tape. Can you typically find it in big box stores and how much is it?

>> The second is to use Dow WeatherMate Construction Tape (like DuPont Tyvek Tape) for the hem and tape loops. It's UL, waterproof, strong, and very sticky.

>This sounds like an intriguing alternative to the Transparent Duct Tape. Can you typically find it in big box stores and how much is it?


I can't find where I bought it, now, but it's available on Amazon for $15 (1 7/8 in x 55 yd); it's a special order item at Home Depot. I bought it for making a bivy out of #14 Tyvek (6.8 oz; oversized). The entire roll weighs about 7 oz.

For this application, Scotch-brand clear packaging tape might work as well; it's certainly cheaper.

> Scotch-brand clear packaging tape might work as well; it's certainly cheaper.

Maybe to hold the tieout, but not for the loop. It's also not UV resistant.

Please report here your findings on how well the Dow tape does in your tests.

David Gardner shared another tape option - nylon sail repair tape. Not too expensive and he says it's lighter than duct tape.

I found this a few months ago and I think that it addresses the problems people in this group are having with your guy lines.

It basically says that after the tape leaves the edge of the tarp, you fold the tape inwards in thirds so that no sticky is exposed to the rope, yet you also don't weaken the tape.

http://www.youtube.com/watch?v=PktX1SxDTQs


-Michael

Much lighter, and has great adhesion even when cold and wet.

Just made my third polycryo tarp using the ripstop nylon sail repair tape. Uploading photos of it pitched "high" for headroom and "low" for weather protection.





Didn't see the thread on using nylon washers but stumbled upon the same idea while wandering the aisle at the local hardware store. I used 1" O.D. washers on the side tie-outs and 1.125" O.D. washers on the ridge ends, which distribute the forces well.

My tie-outs are taped to both sides of the tarp membrane. I cut 8" pieces of the sail tape and fold them in half, tape to the underside of the membrane with the fold 1" outside the hem, stick the washer down, and then fold the tape on top of the washer and membrane. Corner tie-outs are at 45 degree angle to edges; side tie-outs are perpendicular. The wide tape spreads the forces very well.



You can see in the photo that I also use a small loop of shock cord at the side and corner tie-outs, both to keep a nice taught pitch and also to provide some give when subjected to high winds.

The big washers at the ridge line tie-outs are connected to each other by a ridge line cord running between them. Separate tie-out lines are knotted to the outside edge of the washers. This way all of the ridge line tension is maintained by the cord and not the membrane, and the membrane stays in place instead of being free to move on the cord.

7' x 9' tarp with 10 tie-outs (4 on each side, 2 at the ridge ends) weighs 5.4 oz.

With 40' of cordage (200 lb. kevlar bow cord), 2 graphite poles, 2 Nano stakes for the ridge line cords and 8 titanium shepherd's hook stakes for the side tie-outs, total weight is 12.3 oz.

I favor the A-frame style because it's roomy, but I'm trying to figure out a good way to enclose the ends with flaps and/or vestibule. The trick is accommodating different pitch angles for the sides. Here is a prototype with overlapping flaps that velcro to each other:

You guys are about 40 years late to the party. I used polyethelene tarps quite a long time ago. Surprisingly durable. My experiments yielded that anything thinner than 4 mil did not hold up long. Having used polycro a lot as ground sheets, I wouldn't expect much out of that material as a tarp if under 4 mil too.

Did a lot of experimenting with adhesive tie-outs too. A real weak point. What does work are visklamps.






By the time you reinforce those polycro tarps with tape and use extra cords you might find that a spinnaker tarp is lighter. Cuben will definitely be lighter.

But, BRAVO for your experiments.

I remember using polyethylene "tube tents" with the same ball and hoop rig back when I was in Boy Scouts. For sure, it works.

The polycryo weighs about 0.57 oz/yd, so there are a couple of grades of cuben fiber that are lighter I believe, 0.51 sq/yd and 0.34 oz/yd. They're also $30/yd, so $210 for a 7' x 9' tarp versus $10 for the whole polycryo sheet.

The polycryo sheet by itself weighs 4.0 oz and with tie-outs it weighs 5.4 oz, so all the tape tie-outs and nylon washers only add 1.4 oz.

The polycryo is designed and intended for extended extreme weather exposure. It's pretty durable. The first tarp I made from it has been set up outside since September and it's hanging tough. The sail repair tape remains intact as well. The conditions here in Northern California are not extreme by any means, but it's had plenty of sun and rain exposure, and now we'll see how it does with freezing temperatures at night.

No question cuben fiber is stronger and more tear-resistant, but based on my experience the polycryo should be fine for careful 3-season use.

I have a lot of experience with "minimalist" shelters. We need to make sure we can stay warm and dry in poor weather. With wind and rain one can die from hypothermia in 50F temps. I would never trust my life on a polyethylene or polycro tarp less than 4 mil. Plus using a smallish tarp requires skill and experience. Just be careful. Often in deserts and mountains the weatherman can be wrong and predicted good weather doesn't happen. My opinion.

With that thin polycro I can just envision it collapsing without the hiker waking up. It could probably suffocate someone like a dry cleaning bag can. Again, IMO.

Polycryo is much better than polyethylene as a shelter material. The only thing that should have any serious chance of damaging it is having a stick fall on it where it would puncture. It will stand up in 50 mph winds. If you're going to go out in more extreme weather, then , yes, I'd take a more orthodox tent.

FWIW, I've been through a couple hailstorms in my 1 mil polyethylene tarp (space blanket grade, not the cheaper stuff they make dropcloths with - would definitely want 3 mil or better with that).

Here is a picture of tarp prototype #1 that's been set up in my yard since September. Basically, I'm torture testing it to death. Going to see how long it takes for some part to fail, whether the membrane loses integrity or tape stops adhering or ??? So far, so good, even on the un-hemmed sides (later versions are hemmed all the way around). The only thing I've had to do is re-set the stakes a couple of times when the ground was soaked and they started to pull out.

The only failure mode that seems likely to me is high winds, which might tear the membrane or blow the whole thing down. So I don't think there is any real danger of it settling onto a sleeping hiker and suffocating him or her.

Nice, David. In my experience the tape was the weakest point. I found the 3M 2120 did a fair job of adhering to the membrane even after 2 months of constant exposure to summer sun. I'd guess your nylon sail tape would fare even better. That is why I didn't bother using the 3M 8959 tape on my second prototype even though it was significantly stronger. I didn't need the extra strength but did need the long-term integrity. I didn't test the shockcord, but I'd guess it would weaken over time and UV exposure as well.

What are the worst winds you've had so far?

We've had some blustery storms here with gusts to 30 mph. Worst weather is yet to come, so this should be interesting.

FWIW, I'm still using my first tarp I made with this stuff. I'm very cautious about my camp spot. I try to always be in the trees or at least behind a good wind break. I'm not sure how everyone else is doing their ridge line but since I run the cordage under the middle of the tarp I've been able to get a real tight pitch every time. Doing it this way also really helps with any deflection from wind since it puts most of the pressure on the cordage.

My only concern at this point is the repeated folding/rolling on the material after unpacking/packing it. But it's still going strong :)

Came up with a good idea for tarp ends/flaps for weather perfection. Tested it in the rain yesterday and last night. Taking it to the Gathering of Gear Geeks this weekend.

Weight of the Solo Tarp with vestibules, including two 8' ridge line tie-out cords and eight shock cord side tie-outs is 169.7 grams/6.06 oz.

Nice job, David. I'd be interested on hearing more details on the door attachments and how you deal with varying pitch widths.

The doors are attached on the outside edge with the double-sided tape that comes with the polycryo package and on the inside edge with sail repair tape. As the pitch becomes wider the vestibules become shallower and don't stick out as far. At the widest pitch they are almost vertical.

I can see the lines of sail tape for what you're calling the inside edge. A pic would help me understand what you mean by outside edge. It appears they are inset from the end a couple inches, which is what I would have done as well. It sounds (and looks) like you aren't connecting the flaps in any way (or is that what you meant by outside edge?), just putting a guyout on the corners and staking to the same point?

Michael,

The "outside" edge of the end flaps is the side opposite the sail tape. Tried to take a picture, but the tape is so transparent you can't see it. If this explanation doesn't do it, I can make a sketch and send it to you as a PDF attachment to an email.

The flaps are velcroed to each other at the bottom where they meet. One flap is staked to the ground, the other is the "door". May extend the velcro all the way from ground to peak. Working on a new refinement of the flaps based on this weekend's experience at the Gathering of Gear Geeks.

So I picked up some window film to play with last weekend –
I got what I could find, some exterior stuff by Dennis and some interior stuff from Frost King.

I see that Dennis lists their interior film as .6 mil, and their exterior stuff as 1.2 mil thicknesses. Frost King does not apparently list the thickness of their stuff, anybody know what it is?

I made a rather huge tarp out of the Dennis material. It is about 120 inches long by 105 inches wide, with one seem in the middle tapped with two runs of the supplied double sided tape. I used ordinary silver duct tape and steel washers as that is what I had on hand. I used Atwood 3/32 “tactical” cord for the tie outs ( four per side ) and ridge line.
I did not tape-hem the tarp. Probably a mistake?
I set it up in the deep snow in my yard, and my wife helped by throwing snowballs at it while I was working on it. The tarp does seem to deflect snowballs well enough.
She thinks it might do well for a night or two but is betting the tape tie outs will rip the material in short order. We will see!
Total weight ( not counting my high tech 2x4 snow stakes I set it up with ) is 12.5 ounces.

I’ll post a picture or two of the setup when I get the time.

I am curious, has anyone used the thin interior material successfully, either for ground cloths or tarps?

I reckon I might as well go ahead and make a tarp out of the interior kit I have and hang it in the yard and see how well it lasts. The stuff sure is light, but it may well prove to delicate for use as a shelter?

Edited by Bawana on 02/18/2013 14:06:07 MST.

OK, here are some pics. You ever notice how hard it is to get decent photos of something transparent?







I'll leave the tarp up and sooner or later we'll see how it does in some serious snow.

Robert,

Don't know the thickness of the Frost King interior or exterior, but I assume it is similar to the Dennis.

Interested to see how your tarp does under a snow load. It has a pretty flat pitch; steeper sides would probably help it shed the snow. Also, are you running a ridge line cord, or just the double-sided tape? A ridge cord would definitely help with loads. Hemming too. Can't beat the stakes though.

Look forward to pictures after a good blizzard.

David

Oh yeah, it has a ridge line. The seam is perpendicular to the ridgeline in the middle of the tarp, not running down the ridge line.

The weather has been unusually nice latley, might have to wait till next week but I'm sure the tarp will get to see some snow before long. I bet it slides off the slick polycro pretty easily.

So I gather you use the exterior kits then.

Edited by Bawana on 02/18/2013 17:57:15 MST.

Yes, I use the Frost King exterior kits. Trying to source some thicker polycryo, but no luck yet. If I can get a hold of some I will post it here.

I'm using indoor kits. Duck brand doesn't list a thickness. The Scotch one someone gave me says 0.75 mil.

The Duck brand I purchased at Walmart last spring appears to be .75 mil. Here's what I got when I measured four thicknesses of Duck brand:





Hope this helps.

Inspired by Lance, I got .048" when I measured four thicknesses of Frost King exterior polycryo. So it seems to be 1.2 mil, like the Dennis exterior product.

But, isn’t .048 inch 48 mils? Divide that by four and you get 12 mils.
If you were measuring 40 thicknesses, got a reading of .048, then divided by 40 you’d get 1.2 mils. I think.

The reading Lance got checks out, .003 inch, or three mils, for four layers, or .75 mil per layer.
Feel free to check my math guys!

- Isn’t math fun?

David, I have what looks to be the very same El Cheapo harbor freight digital calipers, which I got for ammo reloading. I was trying to read the thickness of my Frost King interior kit with it last night and I repeatedly got .002 inch, or 2 mils for one thickness of the material. I’m quite sure that is very wrong.

I gotta say that after checking this calipers I do not trust them one bit, especially for such small measurements. It's fine for overall cartridge length, maybe even bullet and bore diameter, but I don’t think that instrument is up to the Polycryo challenge!

By the by, the plastic sheeting alone from my Frost King interior 84” by 110” kit weighs exactly four ounces on an El Cheapo on-sale-at-wal-mart digital kitchen scale ( Not exactly NIST traceable ). I’d be curious to know the weight of the same size exterior kit.

Anyway, we can conclude that some folk use the thinner interior kits and some folk use the stouter exterior kits, and they all seem to work well enough?

Edited to add - I had two inches of fresh snow on my tarp this morning. It was sagging, but holding...
It will be interesting to see if it is still staying up tonight when I get home.
Also, I see the silver duct tape isn't recomended?
Why? It seems to be holding well enough on my tarp, so far anyway.

Edited by Bawana on 02/19/2013 12:43:29 MST.

Yeah, my math sucked on that one. Apparently, so do my calipers.

My experience with duct tape is that it dries out and comes loose from whatever it is stuck to over time.

Doing a little research and have identified the following brands and thicknesses.

Ace Hardware - Most kits are .6 mil, but they do have 1.2 mil outdoor kits available, item number 5604277. I have yet to find one in store.

Scotch - 3M - Indoor and outdoor kits are .75 mil

Dennis - interior are .6, exterior are 1.2

Duck - Exterior kits are .7 mil

Frost King – They replied to my email and say the exterior kits are .75 mil

Am I missing any brands?

My tarp in the above photos is made of Dennis 1.2 mil stuff, and is holding up well to four inches of fresh snow so far.

Edited to update thickness info -

Edited by Bawana on 02/21/2013 12:45:50 MST.

http://www.homehardware.ca/en/rec/index.htm/Hardware/Builders/Weatherstrip/Window-Kits/64-x-10-1-2-Outdoor-Insulation-Window-Kit/_/N-2pqfZ67l/Ne-67n/Ntk-All_EN/R-I2396507?Ntt=Window+Kit

It's available in various sizes, and in a roll... 1.4 mil stuff is available, that's what I've got set aside as a groundsheet.

http://www.homedepot.ca/product/bulk-film-84-in-x-25-tape-195/975246

pretty good deal on a roll here.

I'm thinking a huge T-P would be the best application for Polycryo.
Although it would not be something you would want to have a bunch of drunk friends in.

I couldn't for the life of me figure out what a "huge T-P" was untill I was actually typing this out. Duh.

I've made Tipis from heavy duty poly tarps and contact cement. They last for years.
They are fun and easy to make.

Lay out a big tarp –



In the center of one edge hammer a stake and tie a line to it. This line is used to mark out the circular bottom hem, and while yer at it draw a sharp W up at the top.
This gets cut out and the center V gets folded over and glues down with the top suspension line tied to it.



Mark out the big semicircle and draw out some smoke flaps in the unused corners
Cut everything out, and glue and fold over the bottom circular hem with a cord in the seam.
Cut holes in the hem when dry and tie stake down loops.




Select and trim poles



Set up the tripod and tie yer lifting pole to the top suspension line. You can see the stake down loops on the bottom hem.



Warming up in a partially erected tipi



Quite comfortable in there. I’ve lived for weeks in a tipi and know someone that spent a Canadian winter in one.
Sorry about the thread drift, I couldn’t resist.
I’m not sure heat shrink material is best for a tipi because the best feature of a tipi is the ability to build a fire inside it!

Edited by Bawana on 02/21/2013 13:31:54 MST.

We have gotten about six inches of snow this week, and will probably get six more by Monday.

The load on the tarp is tremendous and this 3/32 Atwood cord stretches quite a bit!
But knock the snow off and the tarp snaps back up. I’ve knocked the snow off only once because I want to see the tarp flattened with snow to load test it!






I've also made a second tarp out of a Frost King interior kit.
I did hem this much lighter material with the included double sided tape, and I used some big faucet washers for grommets. I used six inches of tape per tie out and as there are eight tie outs on the side and two in the center, that's a total of five feet of tape. It turns out this isn't duct tape but rather an old roll of "canoe repair tape" if there is any difference -



I used the same Atwood 3/32 cord and the ridge line is 29 feet long, because I like to be able to easily tie off to trees.

Total weight of finished shelter, 7.2 ounces!
Not bad for such a big tarp. I used a patio door sized kit, 84 inches wide and 110 inches long, so this is an 7 foot by 9 foot tarp.

Edited by Bawana on 02/22/2013 18:02:44 MST.

Robert,

Very cool. Any plans to spend the night under your shelter?

The polycryo is pretty durable stuff. Sure wish I could find a source for 1.5 - 2 mil sheets. Anyone out there have any ideas?

Did you use the 84" x 110" Frost King interior kit for the new tarp? Do you plan to pitch it in the snow also?

Yep, The new one was made from a frost king interior kit. I'll be setting it up in the snow tomorow!

I intend to use the big one I made on trips with my nephews and the smaller and lighter tarp as a solo shelter. No real plans to sleep outside right now, it's hard to do when I have a perfectly warm and dry bed not very far away, and with a wife in there to boot...

I guess I'm getting lazy in my old age?!?

The 1.4 mil Comfort Plus stuff Peter found seems to be about the stoutest, and I bet it's pretty durn good stuff. I'm impressed with the 1.2 Dennis stuff I used in my first tarp, I didn't even hem that one.

I have no idea how thick the Frost King interior kits are and am guessing the same 7.5 mil as their exterior kits? I'll ask 'em in another email.

This Frost King kit film weighed 4 ounces alone. The tape hem added another 1/2 ounce.
The rest is the tape, washers and cord.

Edited by Bawana on 02/22/2013 18:12:55 MST.

Peter, I can't figure out if the 1.4 mil polycryo comes in the 84" x 25' roll or the window kits, or maybe both. Where is your groundsheet piece from?

Thanks,
David

Last night we had a big storm with high winds, and after almost 6 months of constant outdoor exposure part of my prototype polycryo tarp finally failed. The tape tie-out at the ridge line on one end separated from the other tape it was attached to. None of the tape-to-tarp connections failed, only the one tape-to-tape connection. It is a construction detail that I only used on this prototype; the tarps in production have only tape-to-tarp connections. Still, 180 days/26 weeks of exposure isn't too bad, and is probably equivalent to many years of regular use. Now I will torture test to death one of my production tarps, and see how that goes.

"Peter, I can't figure out if the 1.4 mil polycryo comes in the 84" x 25' roll or the window kits, or maybe both. Where is your groundsheet piece from?

Thanks,
David"

David, It is available here (Canada) in both forms at "home hardware" stores... I'll check soon if I get a chance and get a pic and use my QRcode reader.

Cool! Was there a reason you had done tape-to-tape on this one? I assume this is the nylon sail repair tape? I have 2 rolls on their way here.

Do you have an estimate of wind speed and direction in relation to the tarp?

I'm thinking of making a big A-frame like your's for my son and I to use as an alternate shelter for our summer trip when there aren't any skeeters.

Yes, it is the nylon sail repair tape. I did tape-to-tape for two reasons:

1. To make the triple tarp I joined two 84" x 110" pieces of polycryo at the ridgeline using the sail repair tape, then added the tie-out. There was no un-taped tarp to attach the ridge line tie-out to.

2. Lack of experience building and testing tarps. My technique has evolved so that now the tie outs are made from the same pieces of nylon tape (one on top, one underneath) that I use to join the polycryo sheets.

Gusts were up to 45 mph, blowing at 45* to 90* directly across the ridge line of the tarp. That's lot of surface area and the wind loads really add up.

Have fun making your big A-frame. The basic tarp is pretty simple and straight forward, but the end flaps are tricky. Let me know if you want construction details and I'll send photos and/or sketches in a PM.

For me this whole thread has been a lot of fun. I ordered some polycryo and hope to join in.

Thanks for all the input. I've read every post.

The seam in the big tarp I had set up in the snow ( pictured above ) failed when my wife was knocking the snow off it. She got under it and was vigorously whacking it to knock the snow off it because the snow had built up along the sides so that it couldn’t just slide off anymore, but has to be propelled some distance away. She didn’t know there was a seam in the middle, and it parted. It was made with two runs of the double sided tape that came with the plastic.

The plastic had stretched a little along that edge, but after it was dried out and warmed up we were able to put it back together with more tape. This time I also reinforced the seam with bits of the duct tape I used to make the tie-outs.

I am convinced these tarps are sturdy enough for most conditions but of course they probably would not be my first choice for winter trips, at least up here!

I think my preference is for a simple flat 7 x 9 foot tarp made from a patio door kit with no seams. I think long term freezing weather may affect how well the tape holds?
I don’t think I’d want a shaped tarp made this way, but end flaps are probably OK.

I’ve had my smaller tarp made from the indoor patio kit set up out in the snow for some time now and despite the fact it is half as thick as my big tarp it is holding up well to heavy snow loads with no sign of failure. At under half a pound and under twenty bucks, I think this tarp is just the thing for day hikes where I don’t intend to stay out overnight but think some shelter might be wise just in case, for three season trips where bugs don’t present much of a problem and the like.

Edited by Bawana on 03/07/2013 16:42:22 MST.

Thanks for the info. It's nice to know they'll hold a fair amount of snow load.

I'd also guess the adhesive on the provided tape isn't superior to some of the other tapes we're using (especially if from an indoor kit like mine is). It seemed fine for "hems" on the edge. Just personal observation and opinion, nothing scientific to back that up.

My door kit is 7x10 and I plan to make just a simple flat tarp instead of my normal half pyramid for my son and I to use as an alternate shelter this summer when there aren't skeeters wreaking havoc.

I've considered a shaped design but my engineering mind leans toward the KISS side of things. Maybe if I ever get to use a shaped tarp some day that seems superior for my needs I may give it a try. No reason it shouldn't work though the taping could become challenging (more so than sewing I'd guess).

I'm having a hard time finding a source of thicker 1.2 or heavier shrink film in the US besides the Dennis outdoor kits. Anyone able to secure a source in the US? A 25' roll would be perfect.

I wonder if the heat shrink stuff they use for winterizing boats will work?

Interesting thought. Did a quick search and I'd say it wouldn't be practical.

"This film is a heavy duty shrink polyethylene available stock in BLUE, WHITE, or CLEAR in 6 MIL and 7 MIL, from 12 feet wide to 36 feet wide."

Quite thick so it will be heavy, polyethylene based so I'd bet it stretches more than polyolefin and it would be hard to find small quantities when rolls are 12' wide min. Not too expensive really. I saw a 14' x 150' roll for $147.

Are there any problems with Polycro shrinking in the hot sun? Do you need to preshrink it or anything??

Edited by staehpj1 on 05/18/2013 10:06:46 MDT.

preshrink....

hmmm...

Make a tarp and then use hair dryer to shrink it. It would form catenary curve. Actually, maybe better than a catenary because it would take into account the reality of your particular tarp.

somebody try this : )

No need to preshrink. It needs much hotter temp than sunlight to shrink.

I see from this post that most people have run a ridge line through the entire length of the tarp, rather than using ridge pull outs. Is there any concern of abrasion on the film from running an full ridgeline?

Hoping to get one of these made.

Nathan,

I have not had any problems with abrasion of the film from a ridge line cord.

David Gardner

>>"I have not had any problems with abrasion of the film from a ridge line cord."

I'd be curious if anyone had problems due to NOT using a ridge line? Not saying that is the case here, but I like to avoid weight added to avoid a problem that has never occurred.

Edited by staehpj1 on 05/20/2013 13:34:34 MDT.

> I'd be curious if anyone had problems due to NOT using a ridge line?

Not yet, but I have always reinforced any ridgelines with tape as a precaution as I expect it would stretch some over time. I don't know if that would really be a problem or not.

> I'd be curious if anyone had problems due to NOT using a ridge line?

Pete, I would personally not use the tarp without a ridge line cord. The ridge line is subject to significant forces, especially tension. The one thing polycryo is vulnerable to is tearing, and for just a couple of grams (I use 1 mm 150 lb. dyneema cord) you can virtually eliminate that danger. Also, the ridge line cord, when properly constructed, takes all the stress off the tape-to-tarp connection at the ridge line. Plus, the ridge line cord holds the A-frame shape of the pitched tarp and keeps a nice taut pitch in side winds.

David, in your experience are tarp-tape connections at the ridgeline necessary, in addition to a ridge line cord? Don't they fulfill redundant purposes?

Nathan,

They are not redundant. If you just run a ridge line cord the tarp tends to move on the ridge line in winds and sag in the middle all the time. You can see this in the first picture in this thread. I actually run three cords for the ridge line. One between the tarp-tape connections at each end to nylon washers folded into the tape, then two separate cords at each end from the washers for tying out. Thus the center portion can be kept taught between the tarp-tape tie outs, and considerable tension can be put on the ridge line cord(s) without putting any significant tension on the tarp itself.

I just add washer-grommets right in the center of the tarp where I want the ridgeline to go, and pass a Loooong cord through 'em. The grommet goes through the tarp itself.

I use a long cord because I prefer to tie off to handy trees instead of stakes and sticks or poles. It is much faster, stronger and easier to pitch this way.

In use I tie off my ridgeline and sorta scoot the whole dang tarp back and forth to where I really want it, then stake out the edge cords to hold it in place.



One concern about doing it this way is water running down the ridgeline and dripping under the tarp in heavy rain. Short little bits of hanging string near the ridge grommet will catch and deflect these drips.

Edited by Bawana on 05/21/2013 12:50:35 MDT.

I still have one of my tarps set up in the woods near my home. It has suffered damage but not from the cords.
I've had trouble with both my duct tape tie-out and the double sided tape that comes with the window kits and used for hemming coming undone. Cold, snowy conditions take the "stick" right out of many adhesives.



Because I'm not going to blow three times as much coin on special tape as I did the plastic sheeting itself, I've started using gorilla tape which holds better and isn't to expensive.

Can't get away without another polycro tarp picture....

Polycro winter camp! Extra big tarp set up lean-too fashion.