Summer without a sleeping bag or tent?

[Allchin09]

Hey all,

What are your thoughts on bushwalking in the summer without a sleeping bag or tent, but instead using one of those emergency space blanket survival bags as a tent + warmth replacement? I would still use a foam roll mat to protect the bag and to provide some insulation from the ground.

I'm sure it wouldn't be the most comfortable or quiet setup, but it sure would be light and pocket sized!

[Strider]

What you are describing is known as "stupid light".

http://andrewskurka.com/2012/stupid-lig ... or-better/

[GPSGuided]

Only if you really want to I guess. The night won't be too comfortable and it may affect your spirit and physique the next day. But it's all a choice, there's nothing to stop you.

[icefest]

Have you tried in the backyard to see how it works?

[Allchin09]

Strider - Very interesting article, makes you think about your decisions.

GPSGuided and icefest - Trying it out beforehand sounds like a good idea, I will definitely do that when I get the chance.

[forest]

In summer you will end up waking in a pool of body moisture as the bag just will not breath at all other than the hole at the top you climbed in.
Ever worn latex gloves, your hands get a bit sweaty and that's even with the minimal gap around the gloves.
Increase the gap size and use a whole body, man you would sweat heaps.
Australia is just to humid most of the time.
What you are effectivly looking into is using a "vapor barrier". Have a google on those. They do use it in the very cold snow etc. I've used bread bags on my feet as a VB effectively in the cold. But they do get damp, esspecially if you do the bread bag over thick socks.
It will work, I mean they are a "survival blanket", That doesn't mean it will be comfortable in any way though.
You would be warm and that's the idea, you will be damp warm........ Not the most happy place to be but better than damp/frozen cold.

If you give it a go report how it works.

[Nuts]

ACR make a breathable 'emergency' bivy? Relatively cheap and light.

[madmacca]

Forest,

My understanding of vapour barrier techniques is that they are primarily for cold conditions, where the dew point for body moisture is likely to be within the sleeping bag, so over several days the 'wetting out' can seriously degrade bag performance. Obviously VB has some insulative value in itself, but the intended function is to stop moisture entering the real insulative layer in the first place. True VB technique would be wearing bread bags UNDER your thick socks.

In summer conditions, where vapour can escape easily if it is allowed to, going for something that is breathable is probably the better option.

For the OP, perhaps sleeping in an inner sheet might be an option?

[icefest]

madmacca, you forgot the second component of VBL, they stop evaporation.

In effect they simulate 100% humidity, and prevent heat loss due to the enthalpy of evaporation.

This the the same principle that makes humid tropical heat feel warmer than dry desert heat.

[forest]

Forest,True VB technique would be wearing bread bags UNDER your thick socks.

100% correct and it's what I do now (Okay I wear super thin silk socks if I plan to use a VB as plastic bags on your feet aint the most comfortabel feeling I've experienced).
I just mentioned it as I found out the hard way the VB needs to be against the skin to work best . I guess my example was not great so thanks for clearing that up.

[icefest]

Andrew Skurka (IMHO one of the top users of VBL's) wrote the following blog: http://andrewskurka.com/2011/vapor-barr ... plication/


He suggests a thin polyester baselayer under the VBL.

[madmacca]

madmacca, you forgot the second component of VBL, they stop evaporation.

In effect they simulate 100% humidity, and prevent heat loss due to the enthalpy of evaporation.

This the the same principle that makes humid tropical heat feel warmer than dry desert heat.

If having evaporated, the vapour was to recondense within your insulative layers (the dewpoint problem), wouldn't this release heat energy within your insulative system, leading to a net zero? My understanding of thermodynamics is a bit vague, so I'm not sure if this actually holds true.

But you are right - where vapor can escape outside the bag, then reducing evaporation would reduce heat loss.

Yeah - Skurka's writings on VBL are good.

[icefest]

If having evaporated, the vapour was to recondense within your insulative layers (the dewpoint problem), wouldn't this release heat energy within your insulative system, leading to a net zero? My understanding of thermodynamics is a bit vague, so I'm not sure if this actually holds true.

Yes, theoretically you would gain some heat, but that all becomes moot when you have a soggy, wet down sleeping bag due to the condensation.
More so if you are spending multiple nights out.

[wayno]

if you want to save space and weight that much, use a bivy bag, at least they breathe and will cover your head if you need it, some will keep insects out.
space blankets are really last resort emergency items, designed to keep you alive but not comfortable when you have nothing else... medics use them but not for using all night...

[oyster_07]

I complete agree that attempting to save weight by neglecting a sleeping bag or quilt in favour of an emergency thermal blanket is well within the realm of 'stupid-light'.

A thermal blanket will offer minimal wind protection and is very vulnerable to tears that will further reduce its effectiveness.

A bag/bivy combination will be much more effective, or even just the bivy if weather permits.

A less comfortable sleep-system will result in added fatigue through loss of sleep, and a colder system will result in higher energy expenditure on producing body heat thus increasing the amount of food that needs to be carried.

In the effort to trim weight, look for other areas that you can reduce carriage. There are many options, but here are a few:

* Consider the caloric density of food and maximise food value while reducing weight. This can shave quite a lot of weight from what is probably the heaviest thing carried (bar water).

* Consider rotational weight that effectively weights three times as much as its static weight. As such, consider weight reductions in shoes and socks.

* How much static weight is there? This is the weight potentially carried as body-fat.

[Scottyk]

Could go naked?, that would be light weight.
Seriously this UL thing gets a bit silly sometimes

[Strider]

Could go naked?, that would be light weight.
Seriously this UL thing gets a bit silly sometimes

Be careful. He might just be stupid enough to try it...

[Allchin09]

Could go naked?, that would be light weight.
Seriously this UL thing gets a bit silly sometimes

Be careful. He might just be stupid enough to try it...

Well last night we headed out into the Royal National Park to try out the space blanket survival bag. I slept in a sleeping bag that I had just bought, but my friend used only the survival bag. The bag was apparently warm enough for practical use, but within an hour of sleeping in it, holes soon formed through the bag. Once this occurred the bag lost all it's warmth and became very cold. He decided to call it quits at 4am, and we packed up and walked back to the cars.

[GPSGuided]

Experiment well done!

[wayno]

Experiment well done!

AND with a lab rat!.. extra well done!

[Franco]

I posted this several times before but here I go again...
The word EMERGENCY should, by definition, explain that it isn't something you want to do if and when you have a choice , in other words when it isn't an EMERGENCY.
All too often folk mistake what can be done and what should be done.
I can go for several days without eating so should I ?

(actualy I could lose a few KG right now so maybe I should)

[wayno]

yup and some gram counters just look at the weight saving they can make from using an item like a space blanket and think, this item could be good...

[icefest]

What caused the homes to appear? Can the be prevented?

[GPSGuided]

What concerns me here is the lack of basic durability (for one night) of said emergency equipment. That does not an emergency backup make.

What's the exact model used? How did it develop holes? Through fair use or abused?

[Allchin09]

I posted this several times before but here I go again...
The word EMERGENCY should, by definition, explain that it isn't something you want to do if and when you have a choice , in other words when it isn't an EMERGENCY.
All too often folk mistake what can be done and what should be done.
I can go for several days without eating so should I ?

(actualy I could lose a few KG right now so maybe I should)

Franco - I realise that it is an emergency blanket and is designed for that purpose (I have always carried one in my first aid kits). The point of my exercise was to see if that could be used for a one off, not as a regular standard part of my kit, on an upcoming walk that I am planning on doing that involves large distances and big climbs in a short amount of time where any reduction in weight is a great benefit.

I wanted to know how effective the blanket would be in use, whether in an emergency, or in general use (but for one off general use). I would have expected it to work in both cases, keeping a person warm to a suitable level. If I was in an emergency, this item definitely would have failed to serve it's purpose which I found quite alarming! GPSGuided and icefest have also raised this issue.

The bag was made by Elemental which sell a host of generic products like matches and firelighters. I'm not sure if there are any brand name survival bags as I have never seen one before. The bag developed holes as the user turned and rolled during the night, all reasonable things that someone who would use a bag should expect to be able to do. As for fair use / abused - I think it was definitely fair use. It wasn't ripped by any sticks or branches, it was only through the bag material being weak and unable to support the movements of someone using the bag.

The problem with the type of material that these space blankets are made out of is that they tear easily, and any small hole easily become much larger as the rip can grow without much resistance. If the reflective material had a plastic backing, similar to that of a garbage bag that can deform slightly before a hole forms, any small tears that form in the reflective material will not cause any major issues as the plastic backing that has stretched to accommodate the hole, prevents the movement of air through the bag.

[Strider]

I wonder if they exist with a ripstop style construction.

[Scottyk]

There are reasons people use tents, hammocks, bivy bags etc. Because they work, they keep you conformable and alive
The space blanket should keep you ALIVE until someone comes to rescue you. Hence the term "Emergency"
No need to re-invent the wheel here I think.
I carry one of these http://www.adventuremedicalkits.com/pro ... roduct=263 for some walks, either for extra warmth over my sleeping bag or as an emergency shelter when pitching a tent can't be done. It might be worth trying
Good on you for going out to do a field test before using to on a long trip.

[wayno]

emergency blankets are a highly disposabble piece of kit,
really for throwing on people for short periods of time they arent made to be layed on, thats why they are so cheap light and compact
. good when needed in bulk for short periods since first aid services can carry a lot off them.
they certainly werent designed for situations like bushwalking where they come into contact with rough objects which will hole them quite easily if theres any weight put on htem or if they cet caught in foliage.

[Supertramp]

What about using some of the new breathable cuben fiber instead of a space blanket?

Might be a much better option instead?

[Strider]

What about using some of the new breathable cuben fiber instead of a space blanket?

Might be a much better option instead?

Does Cuben reflect body heat?