Polycro Tarp Tested!
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Kevin Beeden
(captain_paranoia) - F

Locale: UK
washer as stress concentrator on 04/19/2012 11:01:28 MDT Print View

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.

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: condensation on 04/19/2012 17:29:42 MDT Print View

> 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.
LDPE and polycryo tarps

Kevin Beeden
(captain_paranoia) - F

Locale: UK
re: tape loops on 04/20/2012 07:09:50 MDT Print View

> 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...

Matthew Eng
(DigitalLunatik) - F
Ideal tie-outs? on 10/16/2012 15:14:16 MDT Print View

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?

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: Ideal tie-outs? on 10/16/2012 15:49:46 MDT Print View

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).

Will Webster
(WillWeb) - M
Space blanket on 10/16/2012 16:55:53 MDT Print View

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.

Alex W
(AlexW89) - F
he did on 10/16/2012 17:03:10 MDT Print View

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

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: Space blanket on 10/16/2012 18:40:23 MDT Print View

> 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.

Jim Colten
(jcolten) - M

Locale: MN
Re: Space blanket on 10/16/2012 18:47:03 MDT Print View

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.

Matthew Eng
(DigitalLunatik) - F
Re: Re: Ideal tie-outs? on 10/17/2012 10:46:15 MDT Print View

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!

Angus A.
(mangus7175) - F

Locale: http://theshadedtrail.blogspot.com
Re: he did on 10/17/2012 10:48:55 MDT Print View

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

http://youtu.be/IZ-l2Dx4QLs

Douglas Frick
(Otter) - MLife

Locale: Wyoming
Re: Ideal tie-outs? on 10/29/2012 17:42:00 MDT Print View

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.

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: Re: Ideal tie-outs? on 10/29/2012 19:05:11 MDT Print View

> 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?

Douglas Frick
(Otter) - MLife

Locale: Wyoming
Re: Re: Ideal tie-outs? on 10/31/2012 13:37:49 MDT Print View

>> 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.

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: Ideal tie-outs? on 10/31/2012 13:54:33 MDT Print View

> 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.

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: another tape option on 11/26/2012 21:13:34 MST Print View

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

Michael McMillan
(mikegrok)
technique to fold guyline attachment points on 11/29/2012 10:58:11 MST Print View

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

David Gardner
(GardnerOutdoorLD) - M

Locale: Northern California
Re: Re: another tape option on 01/05/2013 22:15:04 MST Print View

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.

Solo tarp pitched high

Solo tarp pitched low

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.

Corner tie-out

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:
Solo tarp with prototype end flaps

Nick Gatel
(ngatel) - MLife

Locale: Southern California
ROFLMAO! on 01/05/2013 23:15:53 MST Print View

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.

Visklamp

Visklamp 2


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.

David Gardner
(GardnerOutdoorLD) - M

Locale: Northern California
Polycryo on 01/06/2013 00:25:15 MST Print View

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.