Alright! This is good, this is good. I've always wondered what a good way of carrying around some extra duct tape would be. In my recent So Cal creek rattler thread, I noted that the latest bottled water bottles are so chintzy you can crinkle a crack in one just holding the bottle between your knees while you shoot a picture of a rattler on the trail in front of you. So, I'll wrap some duct tape around it next time. Thanks.

Richlacal: This creates a very comical image in my mind. But hey, survival is survival right? ;-)

I have a couple of these cheap survival blankets. Each comes in a package that's about the size of a deck of cards. The next step smaller is literally nothing. So, are they better than nothing?

Well, I suppose thrashing around and cursing at the crappy cheap blanket would help keep you warm. So yes, in that sense, they are probably better than nothing.

+1 on heetsheets. Here's a review I posted a few years back:

"I used a Heetsheets single under my sleeping bag for the week. I paid no attention to the various twigs, stickers, pebbles, etc. on the ground before laying it down. There were numerous pinholes by the end of the week, but no other problems resulted. I did not rig it as a fly, though.

On the first night I managed to tear a hole in it by grinding my boot heel into it while putting on boots and gaiters. I intentionally ignored it, though, and left it unpatched. It did not tear or spread a bit.

It was also rather breezy at night and I saw the edges flap and move about quite a bit, but there was no noise from it. I'm extremely pleased with how well the HeetSheet held up to a full week's rough use."
Gear review

It is Extremely Comical,at the Very Least!,& Noisy as All Get out!I have AMK Heatsheets & Bivvy bags,They are fabulous,but noisy also!I carry/use a Space Blanket-Ripstop Nylon,They are Much larger than the cheap blankies,But Give back a Whole lot more,should the need arise,That in Unison with a Military Poncho,or even a Cheaper Poncho,Would do someone Very Well!Remember,Make use of Available Ground Trash,Whenever Possible,It doesn't have to be a Debris Hut,It could be a Big pile of Leaves/Branches! Insulation is The key!Make sure you know what Poison oak/Ivy/Sumac,& Nettles look like,Before gathering debris! The Cheapy Blankets WILL work,But you will be Miserable!

I hope you've tried that before. A poncho liner isn't the be-all and end-all. I've had lots of nights I'd wake up shivering when I was sleeping in the fire station (thermometer at 68, me in my shorts and Tshirt). I can't imagine using it when it was cooler than that, you're on cold ground, and it's wet.

Anything much warmer than 68F then I might be inclined to switch on a fan to keep cool enough to get some sleep.

Does anyone know the Tog rating for a Poncho liner compared to a mylar space blanket. Knowing this should give a guide to usability temperature ratings. Comparing the rating to real world data shown here will give some indication of the poncho liners ability to keep someone warm.

http://www.mammut.ch/images/Mammut_Sleep_well_pt1_E.pdf

For example you would need around 9 Tog for comfort at 32F.

I suspect that the Poncho liner doesn't have more than 2-3 Tog i.e the limit of comfort would be around 65-68F, just as you have described. It certainly puts the thermal abilities of the Mylar blanket in to perspective. i.e. virtual no capability.

Even using some Bivi Jacket ( approx 800 grams) and trousers (400grams) with a Tog Rating around 5-6 I probably wouldn't want to sleep in them in temperatures less than 8-10C (46-50F) and an extreme temperature (just high enough not to get hypothermic) just above freezing.

The foil survival blankets have no insulation value at all. If you have down or wool, they'll hold heat and feel warm after you've been in them awhile. The actually insulate you from the cold.

Foil blankets, though, have no insulation value at all. They do reflect your heat back at you, and they have their place, but they should not be expected to substitute for good ol' wool or down to keep you warm.

after reading about the Heatsheet here i dumped the foil blanket in my PFD ditch kit.i think the foil ones were seen used by marathon runners wrapping up in them at the finish line and the idea hit,or was pushed by there makers,that they would be a good survival item.