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Polycro Tarp Tested!
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Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Polycryo on 01/06/2013 02:16:12 MST Print View

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.

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: Re: Polycryo on 01/06/2013 10:14:48 MST Print View

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).

David Gardner
(GearMaker) - M

Locale: Northern California
Re: Re: Polycryo on 01/06/2013 11:41:39 MST Print View

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.
Torture-testing Polycryo Tarp

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: long-term testing on 01/06/2013 12:10:43 MST Print View

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?

David Gardner
(GearMaker) - M

Locale: Northern California
Re: Re: long-term testing on 01/06/2013 12:30:50 MST Print View

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

Dan Johnson
(Seattle)

Locale: PNW
Mines still going strong on 01/06/2013 15:17:38 MST Print View

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 :)

David Gardner
(GearMaker) - M

Locale: Northern California
Re: Re: Re: another tape option on 01/24/2013 09:22:20 MST Print View

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.tarp with final design end flaps

David Gardner
(GearMaker) - M

Locale: Northern California
Weight of Solo Tarp with Vesibules on 01/24/2013 21:21:05 MST Print View

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.

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: Weight of Solo Tarp with Vesibules on 01/25/2013 06:12:24 MST Print View

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

David Gardner
(GearMaker) - M

Locale: Northern California
Re: Re: Weight of Solo Tarp with Vesibules on 01/25/2013 09:16:11 MST Print View

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.

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: Re: Re: Weight of Solo Tarp with Vesibules on 01/25/2013 09:36:56 MST Print View

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?

David Gardner
(GearMaker) - M

Locale: Northern California
Re: Weight of Solo Tarp with Vesibules on 01/27/2013 18:27:17 MST Print View

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.Polycryo tarp at GGG

robert van putten
(Bawana) - F

Locale: Planet Bob
.6 mil interior film? on 02/18/2013 14:05:19 MST Print View

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.

robert van putten
(Bawana) - F

Locale: Planet Bob
tarp pictures on 02/18/2013 17:05:00 MST Print View

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

12.5 ounce tarp

tarp 2

tarp 3

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

David Gardner
(GearMaker) - M

Locale: Northern California
Tarp Testing on 02/18/2013 17:27:42 MST Print View

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

robert van putten
(Bawana) - F

Locale: Planet Bob
ridge line on 02/18/2013 17:56:34 MST Print View

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.

David Gardner
(GearMaker) - M

Locale: Northern California
Re: ridge line on 02/18/2013 18:17:41 MST Print View

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.

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: .6 mil interior film? on 02/18/2013 18:52:55 MST Print View

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

Lance Marshall
(Lancem) - F - MLife

Locale: Oregon
Re: .6 mil interior film? on 02/18/2013 20:14:50 MST Print View

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:

Duck brand polycryo thickness measurement

Duck brand polycryo box

Hope this helps.

David Gardner
(GearMaker) - M

Locale: Northern California
1.2 mil Exterior Polycryo by Frost King on 02/18/2013 22:07:42 MST Print View

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..048"