Space Blanket Rant
Space Blankets Suck!
If you take nothing else away from these gear pages, I hope that you will remember this fact.
Space blankets are worse than useless. They are marketed as an emergency blanket, and are touted as windproof, waterproof,
and capable of reflecting heat back to your body. This is marketing hype at its worst.
First off, a space blanket will not keep you warm. It has no insulating properties
at all. Although in theory the aluminized surface is supposed to reflect heat back and prevent radiative heat loss,
in practice it doesn't work. The reason is that the space bag has too many gaps and openings and it's very difficult
to get it to stay wrapped around you. If there is a wind, or even a breeze, it's pretty much impossible.
I know this from first hand experience. For years, I carried a space blanket as insurance
against an unplanned night out. When it came time to actually use the blanket, I soon found out that it was useless.
It wouldn't stay wrapped around me, the wind constantly blew it around, and I was no warmer with it than without it.
The material that a space blanket is made out of may be waterproof and windproof, but, again,
the space blanket will not keep you dry or protected from the wind. Trying to cover yourself with this blanket as a
shield from wind and rain is an exercise in futility and frustration. The material is just too lightweight, and it's
next to impossible to keep it in place.
So. Throw away your space blanket.
Then, go out and buy a space bag. For an extra ounce of weight
and a few extra dollars, you will have something that actually works.
Unlike its moronic sibling, the space blanket, a space bag is a very useful piece of gear.
The space blanket's downfall is that it is very difficult to get it wrapped around a person in a manner that will actually
allow the material to do its job of reflecting radiant heat and protecting you from wind and rain. A space bag, however, because you can crawl into it and it completely surrounds you, does these things very well.
It provides an excellent wind and rain barrier, and its heat reflective properties are also readily
apparent. You do actually feel noticably warmer inside a space bag. However, while better than nothing, a space
bag will not by itself keep you warm on a really cold night.
It has no insulative properties at all, so if it's cold out, that cold will eventually sink through
and chill you if you are not wearing adequate insulation. Likewise, a space bag will not protect you from the convective
heat loss of sitting or lying on snow, the cold ground or a cold rock. So, it won't take the place of a thick down jacket
to wear or a foam pad to sit on.
But, provided that you have a warm jacket and can insulate yourself from the ground with your
pack or some pine boughs or some other insulation, a space bag can provide a lot of protection from wind and precipitation,
and give you an extra margin of warmth that could keep you from hypothermia.
At under 3 ounces, a space bag is easy to take along, even on day hikes. It's a great
piece of gear to have along just in case things don't go as planned. If I'm out in the backcountry, I almost always
have a space bag in my daypack.
|Montbell UL Sleeping Bag Cover
Montbell U.L. Sleeping Bag Cover
(7 ounces) (including stuff sack)
This is the lightest and most compact waterproof/breathable bivi sack I know of.
It's made from Goretex fabric and is completely seam sealed. It's pretty basic, with a
simple drawstring closure. The fabric is very lightweight and somewhat fragile, so you have to be careful with it to
It's a great piece of gear for going fast and light, however. If you need a superlight
bivi sack to keep snow cave drips off of your down bag, this really is a great choice.
Integral Designs "Endurance" Pertex Bivi Sack
(10.8 ounces) (including stuff sack)
Before I found the Montbell bivi sack, I thought that this one was the lightest and most compact.
It's still pretty small and light, and the fabric is slightly more robust than the Montbell bag, so the Integral Designs bivi
is a good choice if you're going to put your bivi sack to regular use. The Integral Designs bivi also is a bit
roomier than the Montbell bivi, so there's room inside to for a loftier sleeping bag and also room for boot liners etc.
The Pertex fabric breathes well and the fabric is completely seam taped for waterproofness.
Overall, this is a very nice piece of gear.
This is an interesting piece of gear, however, I have no idea if it really works or not because
I haven't used it yet.
I read about it on the psycovertical website and decided that I should buy one.
It is, more or less, a space bag with insulation. It provides protection from wind and
rain, and supposedly, it has the insulative value of a 40 degree sleeping bag.
For 13.7 ounces total weight, that's pretty impressive, as it combines the weather resistance
of a bivi sack with the insulation of a lightweight sleeping bag.
So, why haven't I used it? Mainly because once it's opened, it becomes a lot more bulky
than it is when new. From the manufacturer, it's packed in a vacuum sealed plastic bag and is rather thin and compact.
However, once opened and the insulation expands, it can't really ever be packed down so small again.
At $40, it's not all that expensive, but it's not cheap enough that I want to experiment with
it either, so I haven't ever really tested it out.
I've carried it with me on a number of occasions. I find that I drop it in the bottom of
my climbing pack when I'm doing an alpine route that I'm "pretty sure" I can do in a day, but where there is a real possibility
that I could end up spending the night out due to routefinding issues (or general incompetence.)
Outdoor Research Advanced Bivi
(2 pounds, 0.9 ounces)
This is a two pole bivi sack with a gore-tex upper and a coated nylon floor.
The two poles form a sort of clam shell opening, which can be adjusted to open the sack all the way, or just a little. You
can open the sack up, but still leave a sort of awning over your head. With this configuration, you have a roof protecting
you from rain, but can still ventilate.
I used this bivi shelter for a week-long backpacking trip in the Wind River
range and was very happy with its performance. It kept me dry through a number of rainy nights, packed up small and light
weight, and didn't give me a claustrophobic feeling.
It is a good shelter for solo backpacking, although there isn't room to bring
a pack inside with you, so you will need to bring along a pack fly to cover your pack, or else park your pack underneath a
dense tree to protect it from rain at night.
Although this is a decent shelter, I've found that I prefer the versatility
and additional space of my Henry Shires/Tarptent "Contrail" (reviewed on the pyramid/tarp page.) For less weight, the
Contrail provides more comfort, more elbow room, more headroom, and a less claustrophobic living/sleeping experience.