Down
Facts and Performance Sleeping Bags
MAXIMIZING YOUR BAG'S WARMTH
Fuelling the fire
In November of last year I spent a cold week waiting in the Hornli
Hut for the weather to improve on the Matterhorn. Although my bag
was rated to -18°C and I had plenty of clothes on, I froze my
ass off even though the hut temperature could only have been just
below zero. We'd only had our hill food to eat, which comprised
of small portions of couscous and after two nights of poor food
and sleep we decided to walk down to Zermatt and get some better
'soul' food. That night after slogging back up to the hut again
(why doesn't the téléphérique go all the way
to the hut?), we ate a mountain of pasta, cheese and tomatoes and
then crawled into bed. Wow! What a difference. My sleeping bag turned
into an inferno and very soon I had all my clothes off and my feet
sticking out of the bottom.
The lesson is that scrimping on fuel is a false economy if you
want to stay warm. Fuel the fire and you can get away with a lighter
bag. Fats are what you're after as they produce heat due to inefficiency
in digestion. On cold routes I now carry a small Nalgene bottle
full of olive oil and also take nuts (pine nuts are great things
to add to any meal) and cheese.
Let the down do its job
If you are cold and jump into a cold bag it's a bit like jumping
into a flask, you'll remain cold. Down is not warm in itself, it's
simply an insulator. I've woken up on the top of El Cap in scorching
heat totally oblivious because the bag was keeping the heat out.
Firstly, you have to heat up the bag. Getting in hot is the best
way. Wearing tons of clothes stops the heat getting into the down.
You may not be cold as your clothes will provide some insulation,
but you're not making the most of the potential warmth of the down.
Heat will seep out into the down slowly if you are wearing all your
clothes and you may wake up warm in the night, but it's better to
get warm from the start.
One trick is to do sit-ups in the bag, or jog around before you
jump in. Take off clothes inside the bag so you don't lose any of
the precious heat you already have, allowing the warmth to pass
from your clothing to the down. Insulation that allows convection
like thermal base layers or open fleece can be worn as the heat
is able to pass through it into the down.
Following these rules will allow you to sleep warmer if your bag
is up to the job, if it is not then you take appropriate action
in order to increase your bag's insulation or else spend a long
cold night.
Boosting bag performance
The snow is lying thick outside your tent, you've eaten all your
cheese and drank all your olive oil, you've taken off all your clothes,
yet your 200g bag just isn't doing it for you.
Firstly, make use of any other insulation you have. Down is the
best insulation to hand so this should remain your first insulation
layer. Anything else should be placed on the outside of this. Are
you losing heat through the ground? If so lay on your side to reduce
surface contact and try to increase your under insulation. You can
do this by laying on your pack, or by laying your clothing underneath
you. I often suffer from a cold backside and knees so I often slip
my gloves into my trousers to increase their insulation. If the
top of the bag isn't keeping you warm then drape clothing over the
top of the bag. I cannot overstate how effective this can be, even
if it's just a shell jacket. Of course, the down side is that you
can't move around.
Make good use of your partner, as they may well be as cold as you.
Spooning together is a great way to gain heat that would otherwise
be lost and a good way of getting to know your partner better.
Make sure the clothes you're wearing are dry, especially your socks
and hat. Cold feet will cool you as they won't be able to warm the
down in the bottom of the bag. If you don't have dry socks wrap
them in a spare thermal or pop your mitts on the end once you've
warmed them up by hand. Down boots are a good investment if you
suffer from cold feet. Because you lose 6% of your heat from your
noggin it's a good idea to insulate your head well. If you've got
a down jacket with a removable hood, or can buy a down hood, you
can use this to improve the rating of your bag with very little
bulk or weight.
A bag may not perform due to many factors, with the two most common
being either a fill weight too low to insulate the user and, secondarily,
a fill that has lost some of its performance. The first one is easy
to remedy before the event if experience is applied and an over
optimistic attitude is kept in check when planning your nights sitting
in a warm room. The second factor can be limited by a good understanding
of what can go wrong and using this to care for the bag.
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Facts and Performance Sleeping Bags
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