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Polycro Tarp Tested!
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robert van putten

Locale: Planet Bob
Dennis brand on 03/07/2014 12:14:04 MST Print View

My first tarp which was made out of a 1.2 mil Dennis brand exterior kit is still going strong after a full year outside - Two winters!

I did have to re-build it once when my original tape gave up the ghost. Now I'm simply using Gorilla tape and it has held up fine.

The tarp is now set up lean-to fashion which puts rather more stress on the tie outs than an A setup.

By contrast my Frost King .75 mil tarp died late last winter.

I think the thin interior patio kits are great for a cheap and fast to make A setup that is entirely suitable for most three season use, at least down low. And they certainly are lightweight.

For more ambitious projects, try the Dennis exterior stuff!
It seems quite stout. I didn't even hem that tarp.

Aaron Sorensen
(awsorensen) - MLife

Locale: South of Forester Pass
New Half Pyramid Poly-cryo Tarp on 03/09/2014 22:49:42 MDT Print View

New Half Pyramid done.

This is from a single piece of the 1.2mm from Ace Hardware.
Came out to 7.9 ounces with 4 stakes.

This is a tight fit at the feet. There is still plenty of room to throw your pack below your feet and with about a 57" width at the poles, it works out just fine.

I'm more than happy going from 7.8 ounces to 7.9 but having a much stronger tarp and with 4 stakes, it is actually a lighter tarp. After adding in the ground cloth, this shelter came out to 10.0 ounces.
I am not sure if I want to add no-see-um at the opening.

I have a velcro piece added for better storm and wind protection. The picture shows this configuration. You can also open the door up a little more without it and you can even stake the 2 door ends together for a complete seal, but probably with a lot of condinsation.
I used glow in the dark tape as the ridgeline. With this desing, you do not need any string going down the ridge and actually works better with the tape.
I also cut thin plastic cutting board pieces for the tie outs, (works great).

The excess material on the front of the beak is just left uncut and forms a little vent in the top. The only material that needed to be cut was off the bottom. This is a very simple tarp to make.





The 1.2mm poly is easily twice as strong as Gossamer Gears large poly-cryo.
I would highly recomend this as a ground cloth. I am hard on gear and the GG will barley last 1 trip without a rip or tear. The Ace Hardware (item #5604277) will hold up for seasons of abuse.

Edited by awsorensen on 04/02/2014 13:38:15 MDT.

Benjamin Evison
Re: New Half Pyramid Poly-cryo Tarp on 03/10/2014 17:11:31 MDT Print View

Aaron, thanks for your photos, looks very promising...
I do have some questions. It's a little hard to see the proportions in you photos.

1. When you call it a half pyramid, is it a symmetrical footprint with five corners (i.e. long diamond truncated at head end - it looks like this) or a half-mid with one (entry) side more vertical than others?

2. Where is the entry point? Any chance of a diagram??

3. Have you "folded" the sheet of film around the pitch in a single uncut piece or did you cut it into panels and join with tape?

5. GLOW TAPE: Do you find the glow tape sheds enough light to be useful? If so, which brand of glow tape are you using? Does it have a structural function here?

Thanks again!

Aaron Sorensen
(awsorensen) - MLife

Locale: South of Forester Pass
Re: Re: New Half Pyramid Poly-cryo Tarp on 03/10/2014 19:27:14 MDT Print View


It was a half pyramid but I realized that if I brought the poles in about 18" it would allow the sides and front corners to come together and be more wind/ water resistant. Also makes the top height where your head is.

Entrance is in front of 1st picture, it's just closed off with the velcro strip. You can see where the front beak ends where the silver tape ends. When you release the velcro, you can open up the entrance all the way up (then get in and close off the velcro).

No cuts just cut the excess off the bottom.

Glow in the dark tape is a nice touch but don't think it will be bright enough to act as a night-light???

David Gardner
(GearMaker) - M

Locale: Northern California
Re: New Half Pyramid Poly-cryo Tarp on 03/10/2014 21:03:15 MDT Print View

Cool design Aaron.

Where are you using the 4th stake? It looks in the pictures like there's one at the foot and 2 at the head?

Would love to see a detail picture of your tie-outs and the cut nylon sheets. I've been pondering ways to spread the load on the tape better/more evenly than a round nylon washer does.

Aaron Sorensen
(awsorensen) - MLife

Locale: South of Forester Pass
Re: Re: New Half Pyramid Poly-cryo Tarp on 03/10/2014 22:52:33 MDT Print View

The 4th stake goes to the top, (thin orange line you can see).
You can set it up with 2. I'm going to put a small piece of velcro on the doors to be able to keep them open all the way.

I have a stove set up that takes 2 stakes, so they can work both jobs.

I used thin flexible cutting board pieces for the tie-outs. I just used a hole punch for the center holes for the stakes.
Each tie out only needs to be pulled in the direction they do, so the tie out pieces are pretty much the same thing you use but you can cut them into whatever shape you want.

Edited by awsorensen on 03/10/2014 22:58:12 MDT.

Aaron Sorensen
(awsorensen) - MLife

Locale: South of Forester Pass
New Half Pyramid Poly-cryo Tarp on 03/12/2014 22:09:09 MDT Print View

Here's a few more pictures for some better understanding.

Showing the un-cut excess that should also act as a vent.

I didn't have any cord-locks, so this pulls the sides down keeping it tight.

The pull from the front beak

Area for poles.

Keeping the poles together.

The foot corner stake.

Keeps poles tight across the bottom.

Material used for the stakes and tie-offs and ridge line.

Edited by awsorensen on 03/12/2014 22:33:24 MDT.

Adam Kilpatrick
(oysters) - MLife

Locale: South Australia
Re: New Half Pyramid Poly-cryo Tarp on 03/12/2014 22:28:01 MDT Print View

I likey Aaron.

I've been playing around with a spreadsheet making a pyramid like one of your earlier ones, with the door lined up on the side with one of the poles. But I think it makes a bit more sense if the door is at the front. Means that you aren't zipping/closing/velcroing the door under tension over a pole-which could get annoying/tricky.

Aaron Sorensen
(awsorensen) - MLife

Locale: South of Forester Pass
Re: Re: New Half Pyramid Poly-cryo Tarp on 03/12/2014 22:40:41 MDT Print View

The only thing that was hard with the pyramid was having to tape the 2 halves together where it tensions.
I like the layout much better thou.

This new design is a much tighter fit and the opening on the pyramid was easier to get in and out and has better ventilation with your head being right at the opening.

The new half with the single piece is much easier to make and I really like taking something weighing 8 ounces if I'm expecting rain.

Benjamin Evison
anyone tried a polycro trailstar? on 03/16/2014 18:13:43 MDT Print View

I'm contemplating making a 5 sided mid tarp with these materials in the style of an MLD Littlestar. I realise this will use quite a lot more material but would be a more versatile item for my purposes.
If the angles of the apex panels are closer to a right-angle than equilateral I can get 4 panels from one 7'x10' sheet and then the fifth from a second sheet.
I'm thinking of using strips of cuben reinforcement radiating from tie-outs like Steve B (aka Geokite) has done with his magnificent cuben tarp here:

The problem of course is figuring out the geometry. Can anyone here describe the relative proportions/dimensions of those trailstar triangles?

Edited by benevision on 03/16/2014 19:49:36 MDT.

Aaron Sorensen
(awsorensen) - MLife

Locale: South of Forester Pass
Re: anyone tried a polycro trailstar? on 03/20/2014 15:24:44 MDT Print View

Check out George Tate's "Poor Mans Tarp"

Maybe he can give you some detailed specs?
It is just what you are looking for.

Jeffrey Wong
(kayak4water) - MLife

Locale: Pacific NW
Cross linked Polyolefin tarps on 03/30/2014 00:58:34 MDT Print View

@Dan Johnson
I just noticed this thread. Your incarnation of this shelter enthralls me. The possibility of starry nights looms large for new moon camping during dead-bug-season (I'd probably go nuts using this in open country during any time within a week of a full moon)

@ Brian Olsen, I like your method of attaching pull-outs, Brian. So long as the temperature doesn't rise enough to "thaw out" the adhesive, I'd bet the Scotch 2120 duct tape holds--I just don't know if it fails a bit at a time or all at once.

@Michael Ray
In addition to all the time you've spent with this cross linked polyolefin thanks for the informative testing on pull-outs. I like knowing of 2120's UV resistance and 8959's power (I hope to find these locally). I just had a mini-rainstorm brainstorm to make the pullouts more "elegant": use short lengths of carbon fiber or aluminum arrow shaft in the 2120--it may keep the tape from bunching up & may more evenly distribute the stress on the tape.

@everyone else: Thank you!

Jason Webb
(nikeman240) - MLife
carbon fiber tie outs on 06/03/2014 14:09:09 MDT Print View

Jeff.. I read through this entire thread to see if anybody else recommended this before I posted. I should have just skipped to the very last post! haha. If you are worried about the strength of your tie outs (although I believe in most cases, the adhesive will fail prior to tie out failure), go so and buy a section of carbon fiber pole. Wrap the tape around it and run your line through the hollow carbon fiber pole. This will evenly distribute the tension across the entire width of the tape. It is also extremely lightweight (.216 oz. for a 32 inch section of .075" (1.91mm) inside diameter tubing. So you could do six 2 inch wide tie outs for less than a tenth of an ounce! I'm currently working on a polycryo tent/tarp similar in design to Six Moons Design lunar duo. I have all the plans drawn up in CAD, just waiting for supplies to get here. I will post back as soon as I get it done. Thanks to everyone for their info and testing. It has been a huge help to me in creating an ultralight liveable shelter without breaking the bank!

Edited by nikeman240 on 06/03/2014 15:04:23 MDT.

Jeffrey Wong
(kayak4water) - MLife

Locale: Pacific NW
dreaming on the trail under poly cryo on 06/04/2014 08:10:35 MDT Print View

Hi Jason,

I made my tarp of the the duck brand 7x10. with several of the pullouts using the carbon fiber shafts. I used them for pullouts at the peak as well, running the ridgeline under the tarp ridge, and linking the pullout to the ridgeline with prusiks. Works quite nicely, though I have a low opinion of twisted mason line for for anything beyond tying my tomato plants to their supports (even then, I prefer cotton twine) I camped three nights on the Olympic National Park Coast under this thing and found it wonderful for letting in light in and for seeing stars at night. I even wore my specs and slept mostly on my back to enjoy the show. The last night it rained, but not enough for water to collect and start dripping into the dry area. I think I had some drip lines tied to the ridgeline, to forestall that in heavier weather.

I remember wishing I'd pitched the 7x10 higher, though that would have made it more difficult to reduce cold drafts from under the tarp edges. I began thinking about a larger tarp, maybe 9x10. Since then, I've found hammocks and hung once outside in my yard with the tarp pitched above my 10.5'x 60" DIY hammock.

If I remember, when I get back home in ten days, I'll take some pictures and post them.

Paiolo Montanel
(Paiolo) - F
Some dubt on 06/06/2014 06:40:25 MDT Print View

Hi all!

Just bought my first piece of Polycryo, and I'm nearly ready to play with it! ;-)

After reading this POST, I have a bit of confusion about 2 things:

- in this test:
there were two tie-out that worked: the 2nd and the 6th from left; it seems to me that the 2nd is easier to make (no need to buy or build the plastic reinforcement) but it also seems that most of you built tie-out of the 6th type: why?

- I have a little confusion about which tape to use for tie-outs: there are too much types! Can someone make a summary of good tie-outs tapes? (possibly reasonably cheap and easy-to-find tapes, and not super-specific tapes). Is 1-inch-large "gorilla tape" a good choice?

Aaron Sorensen
(awsorensen) - MLife

Locale: South of Forester Pass
Re: Some dubt on 06/06/2014 10:42:19 MDT Print View

Do a combo of both and you cannot fail.
I use 1" gorilla glue tape with a nylon washer.
There no possible way that the tie-out will break.

Just In Time
(ArcturusBear1) - F
Re: Some dubt on 06/06/2014 11:18:13 MDT Print View

I have had some success with Tyvek tape, which is a bit on the expensive side. Polycryo as is called here, is a mix between polyethelyene and polypropylene (olefin).

These two plastics share certain similarities, both are very slippery, chemically stable, and very hydrophobic. It's hard to bond anything with them, except for a rare couple of ways.

Since Tyvek tape was designed specifically for Tyvek which is made out of polyethylene (the high density kind), and since i've used Tyvek tape with good success on Dri Ducks and Frogg Togs material, i figured it would work decently with cross linked poly olefin material, and it seems to work well. I did not do tests like some others here did though.

I had made a tarp out of a sheet of "polycryo" with a polyethylene reflective heat sheet bonded to same.

It's a decent tarp, but since i do most of my backpacking during late fall, winter, early spring when it's colder (like the cold, not so much the heat), i have since realized that a more wind resistant shelter is for me, so i went with a used cuben solomid i got from here. I'm giving it to a friend for their bugout bag.

I've had ideas of reinforcing polycryo with one of the super light woven nylons (which have much higher tensile strength) and creating a more true two walled shelter material, but since i have a good shelter now the motivation to spend money on an experiment i'll likely not use isn't really there. But the idea is to over lap say Titanium Goat's Nobul fabric with polycryo, roll/fold over the edges a few times, and sew that with a semi long stitch. Obviously the polycryo would face outwards for water protection and the nylon would go inside. The edges (which would be exposed nylon) could be sprayed with silicone so they don't absorb as much moisture.

While this could be both a bit lighter and more condensation free than silnylon, it will be a bit more expensive and definitely less durable than cheaper silnylon.

So, not too sure it's worth it, unless you want a little extra warmth or no misting and less condensation. Part of me is tempted to try it anyways, just to see how well it works or doesn't.

David Gardner
(GearMaker) - M

Locale: Northern California
Re: Re: Some dubt on 02/24/2015 09:52:39 MST Print View

I should have figured this out from Aaron Sorensen's earlier posts, but I didn't really think about glow in the dark tape until I noticed it in my local hardware store when looking for other tape(s) to use for a tarp. If it can hold up, it would be ideal for tie-outs so you can see them in the dark and not trip over your stakes. Testing for strength and adhesion now.

Matt Swider
(sbslider) - F

Locale: Santa Barbara
any plans? on 11/08/2015 10:16:39 MST Print View

I will admit I have not yet read through all 11 pages of this thread. I am very interested in making a half pyramid type version of this, but am not really sure of how to guess at the dimensions. The materials are sprinkled throughout, so I think I could likely get that. Ace Hardware (item #5604277) for the poly cryo. 1" gorilla tape and nylon washers for the tie outs. I would guess there is some velcro in here as well. Not sure if I saw netting or not for ventilation? Anyway, I like making things but the design of this would definitely be more than I could handle. any help is appreciated.

thanks, Matt

Edited by sbslider on 11/08/2015 10:17:50 MST.

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: any plans? on 11/08/2015 11:02:06 MST Print View

If you mean overall dimensions, I wouldn't go smaller than 8x5 if you expect to experience any kind of weather. I had an 8x6 for my first try and decided I wanted a bit larger so went 9x7 on the next one. All mine have been half pyramid. You can find my videos through my profile (once on my YT channel search for MYOG)