Polycro Tarp Tested!

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

&

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 8×10 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 7×9'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

@ 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.

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.

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?

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 7×10 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.