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Sleeping_Bag_Ratings_-_A_New_Idea Powered By Docstoc
Sleeping Bag Ratings - A New Idea

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Sleeping bag temperature ratings are determined by the manufacturer, but
there is a better way.

sleeping bag ratings, sleeping bags, backpacking

Article Body:
It seems that sleeping bag ratings have no consistency. Temperature
ratings are still determined entirely by the manufacturers of the bags.
My 3-pound Sierra Designs bag, for example, was rated to 20 degrees.
Honestly, it never kept me as warm as my 17-ounce Western Mountaineering
sleeping bag, which is only rated down to 40 degrees. Isn't this a
problem when you buy a bag? Maybe a 45-degree bag will keep you warmer
than a 30-degree bag.

<b>Consistent Sleeping Bag Ratings</b>

No matter what temperature a bag is rated for, under any system of
testing, it won't necessarily keep you warm to that temperature. We can't
solve the problem of people having different metabolisms and bodies. A
particular bag might be good for one person down to 20 degrees, while for
another it is only good to 40 degrees. You generally can figure out if
you are a cold or a warm sleeper, but that doesn't help if you don't know
whether a bag is rated too high or too low.

You need to know that if a bag says 30 degrees it will keep you warmer
than one that says 40 degrees. With that, even if you add or subtract 10
or 20 degrees for your personal tastes, you can still figure out which
bag is the warmer one. How do we get this consistency?

Begin testing with any sleeping bag, by putting a bag of water in it that
is human-sized, weighing perhaps 160 pounds. Have three standard sizes
for small, regular and large sleeping bags. Always start with the water
temperature at 100 degrees Fahrenheit, and measure how long before it
drops to 90 degrees. External air temperature has to always be the same
too, whther it is 60 degrees or 40.

The numbers are not crucial. What's important   here is that once the
standards are chosen, every bag is tested the   same way, with the same
conditions (even the temperature and material   of the testing platform
would have to be the same). This is what will   give consistency to the
sleeping bag ratings for warmth.

Now, if a bag rated to 40 degrees keeps the water above 90 for two hours,
a bag rated for 30 would obviously have to keep it above 90 degrees for a
longer time. Pegging heat-retention times to specific temperature ratings
would be a bit tricky at first. However, once done, each new bag on the
market could be submitted to the testing and quickly given a consistent
rating. We would know that a lower rating would always mean a warmer bag,
degree-by-degree. We could even have old bags tested to see if it is time
to replace them.

<b>Manufacturer Acceptance?</b>

Would manufacturers pay a private testing company to have their bags
rated? Some, at first, because it would be a an advantage for those
companies who are already conservative in their temperature ratings. They
would have "proof" that the bags are even warmer than they were claiming.
Then, eventually, all bag makers would feel some motivation to have their
sleeping bags tested, because consumers would be wary about buying ones
that weren't tested.

I hope someone will take this idea and run with it. An existing consumer
rating company, like Consumer Reports, could do this on their own and
report the results. Even if they listed the bags without temperature
ratings, but in absolute order by which held the heat in the best, it
would be very useful. One could look at the list and if their current bag
kept them warm to 25 degrees, ythey would know that any bag higher on the
list would be warmer. Isn't it time for consistent sleeping bag ratings?

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