Tarp as a bivvy.

[BigMonster]

Hi guys.
I have recently upgraded my tarps to silnylon and I love the stuff. But I have one question.
"Back in the days" when I was hiking with what you call here: Polish Lavvu, I also used it as a poncho (each half is a rain coat used in polish army). One of the things I liked about it is it was made from impregnated canvas so it was fully breathable, as a result I have spend many warm nights simply wrapped in one of them sitting under a tree.
How bag you think it would be to wrapp or simply cover yourself and maybe a sleeping bag in silnylon? One I have is 30D nylon IMPREGNATED with silicone so it's not 100% waterproof, it's more hydrofobic than water tight. When I roll the tarp in to the bag I can actually slowly squeeze the trapped air through the material.

What you think?

 

[lannyman8]

it would work ok for for a night maybe but your problem would be condensation, think about the 2.99 waterproofs that make you sweat more than they keep you dry????

think this is correct??????

 

[Scots_Charles_River]

http://www.raymears.com/Bushcraft_Product/962-The-Jerven-Bag-Thermo-Extreme/

Maybe you need a Jerven bag ?

 

[lannyman8]

why not have a look at some pertex and make some thing with that?????

 

[BigMonster]

That was purely theoretical question how bad the condensation would be. Have anyone tried it maybe. Also you are not really sealed but wrapped in it so there are gaps between layers. I gues I have to spend one night on the floor in my living room ij a tarp

 

[Wayland]

I recently tried a Jervens bag as a bivi and had a lot of problems with condensation.

First try I admit but not impressed at the moment.

 

[ged]

...What you think?

The cotton ponchos are great, they're warm and they breathe out moisture. Obviously they're heavy, which I guess is why you've moved over to silnylon. I don't have any silnylon but I do use a Dutch issue ripstop nylon poncho. Of course your mileage may vary, but I've had a lot of success wearing the poncho over a good quality breathable waterproof. Last autumn I spent several months walking and sleeping out in that combination, sometimes in some pretty wet weather, and I never had any problem at all. I would expect silnylon to perform in a similar way to the nylon poncho.

Jerven bags are great and I take mine almost everywhere, but it's not necessarily my first choice for sleeping. Mine's an older one and the 200g/m2 lining can't be removed so in the UK it's too hot most of the time. You need to be able to air them well at least every couple of days as they don't breathe at all.