daveg
Trail Wise!
Michigan
Posts: 565 
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Post by daveg on Jan 1, 2017 22:03:14 GMT -8
 This past summer I picked up a 7' x 11.5' remnant of a polycryo window insulation kit at the Habitat Restore for $2.00. My original intent was to use it for groundcloths. Instead, after making one groundcloth I decided to make a tarp out of the remaining 7' x 9' piece. I essentially followed these instructions but, except for buying a roll of Scotch Tough Transparent Duct Tape, made do with materials I had on hand. Rather than purchase nylon washers for the tie-outs, I used a one inch hole saw to cut washers out of a scrap of ABS plastic. The double sided tape used to hem the edges was from another window insulation kit. I gather it doesn’t hold up that well to outside use. The ridge line is a length of Coghlan’s guy line. I had enough scrap lengths of 1/8" shock cord for the edge tie-outs. The A-frame pitch in the photo gave me a peak height of 37" and the width at the base was 59". As near as I can tell with my micrometer, the polycryo is the thin stuff (0.75 mil). The weight of the 7' x 9' piece of polycryo was 5.2 ounces. The completed tarp, including the guy lines (but not stakes), is 8.2 ounces. It’s pretty bulky – I still haven’t figured out how to roll/fold/stuff it into a compact bundle. And I have no idea how durable it will be. But it’s a new toy to play with. |
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Post by topshot on Jan 2, 2017 4:44:47 GMT -8
I make mine for a half pyramid pitch and used my latest version for 6 days in the Wind Rivers this summer. Make sure you put a flat side on your washers toward the tieout so it resists tearing through the tape much better.
Not sure how compact you are trying to make it. I've never used any other type of tarp, but it's MUCH smaller than my Lunar Duo. I fold it on the short side and then roll it.
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Post by rachelsdad on Jan 2, 2017 7:24:21 GMT -8
I can't believe that will hold up to weather.
Topshot: how durable is it??? This looks like a ball to build with my daughter
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Post by topshot on Jan 2, 2017 8:07:59 GMT -8
It is surprisingly strong. Some of the older posts on BPL had people doing strength tests on it. The hardest part is the tieouts since the material is naturally somewhat resistant to adhesives and you want to spread the load over greater surface area.
The modes of failure for the polycryo itself are tearing and punctures. "Hemming" the edges generally takes care of the former. Being careful takes care of the latter. Which reminds me that I should test the latter with rocks to simulate hail. I did that with the heatsheets version I made first years ago and used in the Wind Rivers in 2010 and Maroon Bells in 2011. It took about a quarter size rock before you'd get any real damage. I'd expect polycryo wouldn't be quite as stout since it doesn't really stretch.
It is fun to build though doing it well takes some patience. I had some Scouts build heatsheet versions.
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Deleted
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Post by Deleted on Jan 2, 2017 8:34:16 GMT -8
I can't imagine using a tarp in the Winds; wouldn't the skeeters eat you alive?
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daveg
Trail Wise!
Michigan
Posts: 565
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Post by daveg on Jan 2, 2017 8:46:01 GMT -8
I make mine for a half pyramid pitch and used my latest version for 6 days in the Wind Rivers this summer. Make sure you put a flat side on your washers toward the tieout so it resists tearing through the tape much better. Not sure how compact you are trying to make it. I've never used any other type of tarp, but it's MUCH smaller than my Lunar Duo. I fold it on the short side and then roll it. I did put a flat side on the washers I used for the edge tie-outs. But not on the ones for the ridge tie-outs. This was new to me so I was blindly following the instructions. I don't understand why the instructions say a flat side is not needed on the ridge tie-out washers. It seems the ridge tie-outs would be subject to at least as much loading as the edge tie-outs. Can you help me out?
I'm not sure why I was having problems folding up the tarp. Perhaps I was somehow trapping air or folding it "against the grain" so to speak. But after trying some different ways I finally got a compact bundle just a bit larger than my silnylon tarp of about the same size.
Have you had any failures of your tarps? If yes, what happened and what was the fix? What, if anything, do you carry in case you need to make repairs in the field? Any other advice for using a polycryo tarp?
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Post by topshot on Jan 2, 2017 10:29:27 GMT -8
I can't imagine using a tarp in the Winds; wouldn't the skeeters eat you alive? My Heetsheets version I actually sewed on netting as well complete with a zipper so no trouble there aside from sewing through tape (see link below if you want to see it). It was fun taunting the skeeters.  This past summer I was there in mid-Aug so was past the bug season. There were a couple spots I passed through that had a few but never really where I camped. I would have worn my headnet if there were any "bugging" me in my bag. How do those things survive the freezing nights anyway? Had one night of 18*F. But, yes, if you tarp in the Winds you'd normally have a bivy as well to deal with bugs. I'll sew on netting again if I go during bug season. I did put a flat side on the washers I used for the edge tie-outs. But not on the ones for the ridge tie-outs. This was new to me so I was blindly following the instructions. I don't understand why the instructions say a flat side is not needed on the ridge tie-out washers. It seems the ridge tie-outs would be subject to at least as much loading as the edge tie-outs. Can you help me out?
Have you had any failures of your tarps? If yes, what happened and what was the fix? What, if anything, do you carry in case you need to make repairs in the field? Any other advice for using a polycryo tarp?
My guess on the ridgeline is that you have line going between the washers as well so the forces are more on the line than the tape. I've never done an A frame pitch but I've often read people have a line stretching across the entire length so assume that is the same here. Only one "failure" in the field so far. I had a "storm door" for my original one and one of the corner tieouts for it came undone during the one time I used it. I used more tape to keep it in place for the remainder of the storm. Ironically, both tarps I've taken to the Winds have had issues. My original heetsheets one was torn up when my dog got tangled up in my guylines while on her cord. I had to tape up a decent size tear (and stitch up the netting where it had torn) and several spots her claws punctured through. She had even significantly bent my trekking pole! I was amazed the tent wasn't in worse shape. I think it was in Part 2 of my video where I noted some of the damage she had done. The one I took this summer got compromised when my son had taken it down this summer to mow the lawn. It laid out in the sun all wadded up for a day and was permanently deformed as a result so I could never get the edges taut. Having the material shrink has never been an issue. My theory is that being wadded up trapped too much heat (think of your car in summer) so certain areas were able to get hot enough to shrink some. While I don't believe I ever had more than 20 mph on this trip, it would rattle a lot in certain conditions and I taped down the worst edge which helped a lot. I've had tieout failures while at home/testing. Fixed with more tape. The only thing I carry for repair is maybe 6' of the transparent duct tape (3M 2120) which is wrapped around my trekking poles. It is cut half the width (~15/16") since that is what I normally use anyway. As for other advice, if you're with a group, hopefully you aren't shy since there is 0 privacy.  Similarly, it's not good for shade or if you have trouble sleeping with lights (i.e., moon). I prefer the latter since it's neat to watch all the satellites and meteors at night. Lastly, know the limitations of a tarp setup depending on your other gear and how you will handle inclement weather or some kind of failure. Like nearly all shelters I'm aware of, the weak link is the tieouts. If those hold you should be fine barring major hail or gale force winds perhaps. So far I've only had small hail and maybe 30 mph while in use. |
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Post by topshot on Jan 3, 2017 11:43:55 GMT -8
After several years I finally loaded an avatar, which is a 2010 view of Elephant Head from my original heetsheets version with the netting. You can't see much (nor really any damage my dog had done) in that pic but gives an idea. My original was a little small when pitched low, being just a hair under 6x8. Thus, my latest tarp went up to almost 7x9. The main reason for the original size is the material I had was 4x6 so I taped 2 pieces together. I actually do have some real heatsheets that are larger so I might do another version from it, especially if my "hail" test on the polycryo indicates it would not hold up nearly as well. The main disadvantage to heetsheets is the material will permanently stretch/deform so you need to tape along all edges and directions that will be under tension. I sort of do that anyway with the polycryo so it's not that much of a hit. Here is my latest version at about 11,000' below Klondike Pass (head of Tourist Creek), and you can see how the edges are not taut (and if you know what to look for some of the wrinkles where it shrank a bit).  |
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daveg
Trail Wise!
Michigan
Posts: 565
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Post by daveg on Jan 4, 2017 20:42:53 GMT -8
topshot -- Is that a 7' x 9' flat tarp in a half-pyramid pitch? It looks like you have strips of tape on the back center and corners. For reinforcement? And a different positioning of the tie-outs for that pitch?
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Post by topshot on Jan 5, 2017 4:03:11 GMT -8
Precisely on all counts. And a larger real metal washer for my pole since that is what I had.
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trinity
Trail Wise!
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Post by trinity on Jan 5, 2017 6:57:38 GMT -8
I'm impressed. Those are great looking tarps.
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This past summer I was there in mid-Aug so was past the bug season. There were a couple spots I passed through that had a few but never really where I camped. I would have worn my headnet if there were any "bugging" me in my bag. How do those things survive the freezing nights anyway? Had one night of 18*F. But, yes, if you tarp in the Winds you'd normally have a bivy as well to deal with bugs. I'll sew on netting again if I go during bug season.
Similarly, it's not good for shade or if you have trouble sleeping with lights (i.e., moon). I prefer the latter since it's neat to watch all the satellites and meteors at night. Lastly, know the limitations of a tarp setup depending on your other gear and how you will handle inclement weather or some kind of failure. Like nearly all shelters I'm aware of, the weak link is the tieouts. If those hold you should be fine barring major hail or gale force winds perhaps. So far I've only had small hail and maybe 30 mph while in use.