Polycro Tarp Tested!

[David Gardner]

I really like the reinforcement tape pattern, adding strength in all the directions of stress.

To the extent that packing tape has exposure/UV issues, you could slice a roll of the 3M 2120 transparent duct tape to the same width as the packing tape and use that instead. That's what I do with all my tarps now to reinforce the hems.

Mount a utility blade with a couple of screws to a piece of wood of the appropriate thickness, then turn the roll against it to slice.

[Ryan “Rudy” Oury]

David – love the knife setup :) Use that basic idea often, though to fine tune height, I used an old book a lot of the time. Too high or low? flip a couple pages and retry.

This would certainly be an option and probably plenty strong along the hems/ridge, but I did find a substantial difference in tensile/tear-through strength between the 3M 2120 and the fiber packing tape. I can rip the 3M tape w/ my fingers fairly easily, and even folded over/layered a couple times, could pull through a tie-out loop made of it w/ my guy-line. Took some force, but not a ton.
*

In comparison, even this small loop w/ about a 1" double layer (just to create the loop so tape didn't stick to itself) was strong enough that I had to pull as hard as I could and SNAPPED THE GUY LINE before the tie-out even showed signs of cutting through or letting go. I'm not the strongest guy in the world, but I'm sure I put over 100 lbs of tension on it.
*

[Michael Ray]

LOL. I use the razor blade screwed to a board method as well, David. :)

Ryan, yes, the 2120 is not that strong but holds quite well IME. I think the polycryo would give before the tape would. Only failure I've had was when also using a washer, which then caused me to run some tests you can read about many pages up this thread. The nylon tape David was using was great but doesn't seem to stick as well so you need to use more of it.

[Ryan “Rudy” Oury]

I bet you're probably right since the polycro really is somewhat fragile, and the amount of tension it took to cut thru the tape was probably more than the polycro would have withstood anyway. If I get around to making another anytime soon, I'd like to try doing the same tape design I did, but using either 1/4-3/8" wide fiber reinforced tape that extends properly into tie-outs OR the 2120 tape ripped to 1/2-3/4" and tie-outs that incorporate both the 2120 and fiber tape. Might be the sweet spot of strong enough but not over-built :) We'll see.

Also want to try doing this basic setup w/ a space blanket for comparison! I know a couple have tried that as well so would be interesting.

[Michael Ray]

> Also want to try doing this basic setup w/ a space blanket for comparison! I know a couple have tried that as well so would be interesting.

My first one was aluminum coated LDPE (specifically what runners drape around them after a race) and it has worked quite well. Mylar works, too, but also has catastrophic failure modes (similar to polycryo but worse). You can check out the Homemade Tents thread in the Scouting section.

[Aaron Sorensen]

I'm doing a 2 hiking pole diamond shape Poly Tarp with only two stakes.
Simple easy and effective.

I'll have it at the GGG.

[Aaron Sorensen]

I finally have my scale back.
The tarp came out at 7.8oz.

I still need to add some no-see-um in the open area and few velco closers, but will still be under 9 ounces when done.
I'm actually going to start from the beginning because it did not come out tight enough after my dog jumped on it.

[todd]

Hi Aaron,

I'm very interested in learning more of your design!

Can't wait for more …. don't make us wait too long!

[David Gardner]

Aaron,

Your design has inspired me to try a 4 stake design, with a bit more foot and shoulder room.

Do you know what mil thickness the material is?

Also, if I recall correctly from GGG 6.0, your weight includes the stakes. What kind of stakes are you using?

Thanks,

David

[Aaron Sorensen]

David

This thing is 12 foot long, 44 inches wide and 44 inches high.
I made it so I can put a pack on one end.
I can do that and stretch my arms over my head without touching.

I also have enough room to stay dry in the rain with the opening on the exit side.
The opening only utilizes about 6 inches of space from the 44 inch width.

I used 2 large Gossamer Gear polycryo clothes. They are 1.0 mil.
With a weight of 3.65 ounces, 84" x 72" makes them .068 ounces per square yard.

On my next one I'll use some glow in the dark tape as the guy-line on the inside.
Amazon sells a 1 inch tape that is bright enough to cast a shadow (built in night light).

I am using a lightweight aluminum curved tent stake. I just need to use a washer the same width next time because you can get the tarp so taunt, it will tear the gorilla glue tape.
I am confident enough to try the set-up in 30mph winds. It doesn't budge when set up nice and tight. I also realy like that this is a fully enclosed tarp.
You can not beat it's 9 ounce weight (or so, with bug netting) for a fully enclosed shelter. I guess that really makes it more of a shelter than a tarp.
It also came out to 7.8 ounces (not 8.7).
It was my homemade jacket that was 8.7.

[Bob Gross]

"With a weight of 3.65 ounces, 84" x 72" makes them .068 ounces per square yard."

Your math is all wrong.

–B.G.–

[Aaron Sorensen]

Yes

That's becasuse it's 72" X 96" = .68 ounces per square yard.

[Michael Ray]

Did you put some kind of vent at the top? I'd think it would get pretty clammy being fully enclosed and non-breathable material.

And is that David's set up behind your's?

[Aaron Sorensen]

It's Dave's set up and it blows my away in terms of looks.
There is an opening with netting in the shelter that's comes from the ground up to 2 feet over a 3 foot distance and it's floorless.
Saying fully enclosed meaning full coverage.
Condensation is zero in the 4 nights I've slept in it and wouldn't even consider it to be an issue in an area with a high condensation level.

[Glenn S]

2 cents from a newbie:

*Don't use cheap-o film, go 3m all the way.
*3m also makes an "outdoor" window insulator kit, this tape might hold better in the cold.
*I use 3m on every window, every winter, it's currently 7 below zero outside now. Brrr.
*It's the warmest Tuesday in 3 weeks. Double, no, triple Brrr.
*I don't sleep on this film, but I make pack liners out of it.
*After kids and/or cats have torn my window film, clear box-tape seams to mend it well enough.
*When removing the film, even after many months, it separates from the tape easily; it's designed to be "easily removable".

Here's my thoughts on your tarp idea:
*The ridge-line is the right idea. The tie outs are not.
*Run both sidelines and both A-lines with cord, just like the ridge-line.
*Tie them together; make a self-supporting frame from cordage (1.25mm Z-line? Aka: titanium twine)
*Hem the poly over the cordage as a covering.
*Poly is meant to have a frame to fasten to, not be load bearing.
*Poly will never bond well enough to any tape to bear loads.
*If using a cordage frame, any bonding failure won't be catastrophic.

If you can build an A frame from cord alone, and then hem poly to it, even a charging canine won't tear down the supports, but you still might have a hole in the middle.

Again, just some newbie opinions, so judge me with care lol.

[robert van putten]

Well I'll be darned!

While developing my polycryo tarps I emailed several manufactures asking questions about their window insulation kits and I guess I got on a mailing list or something, because I eventually got an email asking me to enter into a " I Need Frost King" photo contest.

Well OK, I entered one of the photos I posted earlier in this thread – And won a 25 dollar gift card to Home depot!

So not only is polycryo a cutting edge tarp material, it can also be profitable….

Anyway, my big polycryo lean too is still set up in the woods and in fine shape. I was gonna take it down last fall but some wild turkeys had taken up residence in the trees above it and the tarp was covered in poo. So I left the thing in place.

Winter has cleaned it off, it still has no punctures and the tape tie outs still haven't pulled out, amazing!

[Aaron Sorensen]

I am switching to a single 84" X 120" from Ace hardware.

I can still make it as a simple 2 stake tarp with poles and it would suit my needs better than a fully enclosed version since I'll be using a bivy anyway.

You can't beat it for being stronger, lighter and easier to make.

[Brian Olson]

I'm a new member and this is my first post. I used a Duck brand 84" x 120" indoor kit to make a 7'x10' tarp ($6.79 at http://www.amazon.com/gp/product/B000NHW2Z6/ref=oh_details_o03_s00_i00?ie=UTF8&psc=1). I hemmed the edges with the supplied tape and put in 8 tie outs. Instead of grommets, I taped in 3" loops of shock cord by folding a piece of Scotch 2120 transparent duct tape over the edge of the tarp and then bunching the tape together to disperse the load as seen in the picture. I reinforced it with two extra pieces of tape on each side of the tarp making a total of 5 equal sized pieces of tape per tie out, except for the ridge-line tie outs. I only reinforced the top side of those because I used a single piece of tape to make both tie outs and the full length ridge-line reinforcement on the bottom side of the tarp. It's very strong and I may remove some of the reinforcement pieces on the side tie outs to see how many are actually necessary. I could have cut the tape down to 1" wide, but I'm trying to keep the build process as simple as possible so that Boy Scouts can potentially make them during a troop meeting. My only worry is that half of the tape for each tie out is on the top side of the tarp and is exposed to rain.

The tarp weighs exactly 9oz including 34 feet of 1.5 mm guyline and 8 mini line locs which I leave attached to it.

Now here are some questions for those who are more experienced than me:
1. Is the Scotch 2120 transparent duct tape water resistant enough for my tieout design with part of the tape exposed to rain?
2. Has anyone had success pitching one of these up in a side entry half pyramid even though the ridgeline tape would be going the wrong way? I am trying to decide if a stronger design like what Ryan made in January is necessary if I want to use both A-frame and half-pyramid pitches.
3. Has anyone tried slightly heat shrinking the tarp while it was pitched taught? I thought it might give it a slight catenary curve, but I could also be completely wrong.

[Delmar O’Donnell]

I'm interested in question (1) also, but the answer is empirical. Tape a piece of shrink film and leave it in a bowl of water. Test it every few hours for adhesion and tell us what happens!

[David Gardner]

3M makes an "all weather" duct tape, which is supposedly more durable than their own "tough" transparent tape:

http://www.amazon.com/Scotch-Heavy-All-Weather-1-88-Inch-45-Yard/dp/B0013AX62K/ref=sr_1_3?ie=UTF8&qid=1394087577&sr=8-3&keywords=weatherproof+duct+tape

Their blurb on Amazon says "Scotch Heavy Duty All Weather Duct Tape is ideal for outdoor repairs and will last longer than other heavy duty duct tapes, even in extreme temperatures and intense sunlight."

It's not transparent so it doesn't look nearly as cool, but the objective is durability.

[Brian Olson]

I'd prefer to stick with transparent or translucent tape if it holds up to the test so I don't have a big dark line blocking my night sky view.

I'll start the water test tomorrow. I don't have any measuring tools so it will be subjective. I also have some unknown brand ripstop nylon sail tape that I'll test with it.

[Adam Kilpatrick]

I'd love to see this done in a light cuben Aaron. Its like a simplified Gatewood crossed with a tarptent moment in some respects. Would be even more amazing with the cape option. With four identical triangular panels, much easier to MYOG too.

How long are your poles?
-Edit: Just answered my own question with Math. Your poles are about 49 inches or 125cm, right? :-)

Cheers!

[Jerry Adams]

I've had tape creep on me over a number of days. Maybe was affected by rain.

Make a test piece and hang a weight with it, like a jug of water, with the same amount of weight you'de expect on tarp. Leave it up for a number of days, hopefully including some rain events.

You could just set up your tarp, but it might have limited lieftime, and you probably don't want to use it all up testing.

[Ryan “Rudy” Oury]

Brian,
glad to have you onboard!

1) not sure how the tie-out water testing is going but for the question of whether the 2120 has good enough water resistance, my simply answer is pitch the tarp so the tape is on the underside, and thus is basically only exposed to condensation. At that point, it should last plenty long.

2) The question of if my design is "necessary" would really be up for debate. I think you could get away w/o all the reinforcement and pitch any style you like, but the tarp just might not last as long. I haven't pitched as a true half-mid style, but I've been close. The tarp was plenty strong setup in the partial mid-style (and would be fine in a true half-mid pitch) but the bigger issue is getting the pitch tight w/o tearing anything because you're going across the reinforcement lines instead of with them. But if one were so inclined, you could just modify which tie-outs you connect w/ the reinforcing tape to create the design you want. instead of going corner to corner and straight across sides in X's as I did, go corner to side in a more V or W shape, if that makes sense. The tarp would have to be pitched w/ the same side as the peak of the half-mid each time, but that's no biggie. And frankly, each run of tape probably only adds ~.25oz so you could do extra and give yourself flexibility in pitch style w/o much weight penalty.

3) I'd be pretty wary of shrinking the tarp… don't know for sure but I would suspect it degrades the strength a little, would create higher tensions points that would likely fail quickly, and could make it more stiff and less able to absorb tension changes. Granted, they're cheap so play around and accept you may be tossing $10, but I wouldn't expect much success.

[Aaron Sorensen]

Brian,
I've used shrink wrap on boats. Even the thicker material you use for them takes a careful touch to get it right.
After shrinkage, the material will weaken in spots (way to much for such a delicate material and not rip) and become harder in others.

For a half mid, I have 120" of length to play with and will put the top of the poles about 1 foot in from the top end.
This will allow for a small beak, but more importantly the ability to keep things taunt while still using a 2 stake design.
I'll cut the with of the material in the area of the pole enough to have a line-lock on each side in order to pull the sides tight.
This is key in getting a nice tight pitch.
I just use gorilla glue duct tape on all the areas that require a pull and will use a 3/4" width glow in the dark tape for the guy-line.
It doesn't need to be a super strong tape tape to keep it tight across the top bend.

My poles are 120cm so 47 1/4".
I still plan on making a few of the pictured dual pyramid fully enclosed shelters (pictured).
I will just be able to come up with better dimensions with the 2 larger pieces.
Instead of using two 8' X 6' pieces one way and the other, it can be one 6' X 6 ' and the other 8' X 7" giving you more head room.
I would be nice to have it just a little stronger as well.

It will nice to see how a hot knife will work, maybe lessing the ability start a tear?
I just hope the 1.2mm is stronger than the 1mm of the GG polycryo.
The GG really is about 80% of the strength you want to make it worth doing.

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