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How do you accurately rate a sleeping bag/quilt?

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How do you accurately rate a sleeping bag/quilt?

Postby rlown » Tue May 20, 2014 8:45 pm

OK. this has been coming up a lot. How do you do it?

I spent the winter in the 90's in Minnesota with a -20 degree bag and slept out on the ice on Lake Minnetonka in the bag. I bought it in San Rafael. Polarguard fill. I was on a thermarest full. Slept fine and was warm but was awakend every time the ice shifted. It was a solid -20 according to the thermometer. Nice bag.

Now we get questions here about bag quality.

My answer is you pick a good bag manufacturer. WM, NF, REI stuff. If you go cheap, you're probably going to be disappointed. It really depends on intended use and weather.

I don't do quilts but there are several that have: viewtopic.php?f=15&t=10209&hilit=quilt

How do you actually test your bag/quilt?


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How do you accurately rate a sleeping bag/quilt?

Postby AlmostThere » Tue May 20, 2014 9:26 pm

Used to be a chart on the Jacks R Better website that showed how much loft a down quilt needed for the various temp ratings. Now there is this article:

2.5 inches of loft in a down item seems to be a standard for the quilts I've looked at. My 0 degree Warbonnet has 4 inches of loft, consistent with the Jacks' estimation. My Hammock Gear Burrow 0 also has 4 lovely inches of down in the baffles.

Zpacks also has an idea that's pretty close - tho they think my 4 inch loft quilts should be good to -20. I shall not be testing that theory - not really into that kind of cold temps...

This topic comes up a lot at Backpacking Light and Hammock Forums (HF tends to have a higher rate of DIY types, I've noticed). ... ch-of-loft

Personally, I use the quilts I have and stay warm - after the first sub freezing night with a quilt that freaked me out because it was so light and insubstantial, I was sold.
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Re: How do you accurately rate a sleeping bag/quilt?

Postby Rockchucker » Wed May 21, 2014 5:15 am

I test all my sleep setups car camping in the winter with a thermometer. When I wake up a bit cold I look at the temperature and see if it's close to the rating or not. My 20* quilt will go significantly colder than the rating while my 30* quilt is right on the mark.
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Re: How do you accurately rate a sleeping bag/quilt?

Postby Wandering Daisy » Wed May 21, 2014 8:08 am

There is so much more to sleeping warm than a bag rating! I can be cold one night and then warm another, at the same temperature, in the same bag. I prefer to see objective criteria - loft thickness, temperature loss rate inside a bag relative to outside temperature (without a human inside the bag). Then you must consider how the bag fits, how the down is distributed in the tubes- did you shake the down to the top side? I also think humidity plays a role. Dry cold is different from wet cold. Two days out in humid conditions, vs two weeks out in continuous humid conditions make a difference since built up moisture can reduce loft. Also, women sleep colder - about 10 degrees worth!

The bag is just one part of an entire "sleep system" - bag, pad, clothing, tent, and then your pre-sleep condition (food eaten before bed, your body temperature when you enter the sleeping bag). You need to rate your whole system. Add to that how a bag retains loft as it ages. Does the loft regenerate after washing the bag?

So, I do not think you can accurately rate any sleeping bag.

An aside question. I have been looking at buying a summer bag, and see that a lot of "down" bags are now made of duck down, not goose down. Are these duck down bags as good? I am avoiding duck down mainly because of my allergies, maybe not a valid reason either. The adds say "700-duck down". What does that mean? I thought a 700 rating meant 70% goose down and the remaining other down such as duck down.
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Re: How do you accurately rate a sleeping bag/quilt?

Postby markskor » Wed May 21, 2014 8:35 am

Wandering Daisy wrote: Are these duck down bags as good? I am avoiding duck down mainly because of my allergies, maybe not a valid reason either.

Maybe improvements have been made in the last 5 years, but IMHO, duck down is slightly different than goose in that it stinks.
I have only tried one but there was a distinct gamy-type smell with duck when wet. I prefer goose (like the guy in Top Gun?)

RE 700...Same system of rating down as in other down bags - 850 has more volume/weighs less than 700.
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Re: How do you accurately rate a sleeping bag/quilt?

Postby maverick » Wed May 21, 2014 8:58 am

Put simply, a sleeping bag seals in the heat that is generated by our body, and
as previously mention there are many variables beyond the bag rating itself that
will have an effect on how warm, or well, we will sleep. Insulation material, shell,
construction, quality, sleeping matt, whether we are sleeping in or out of a tent,
hydration, meals, how tired our body is, male or female, weather, all will have a
bearing. We should take that number as an approximate rating and learn the
variables including how our own personal bodies react when under certain duress
and get a sleeping bag accordingly (those of us who go out in more than one season
will have 2-3 bags to deal with these variables).

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Re: How do you accurately rate a sleeping bag/quilt?

Postby oldranger » Wed May 21, 2014 9:38 am

When in our 30's and 40's my wife slept cooler than me. Now in our late 60's I need one blanket more than Kathy when at home. When back packing i am comfortable in my 20 degree wm bag when she is too warm in her 25 degree wm bag. When she is comfortable in her bag I am a bit cool. Point is that we all are different and we can change, too. And as Daisy mentioned I can feel different from day to day in same conditions (temp., wind, humidity) depending on the amount of exertion and calorie intake. If I have dinner too early I frequently sleep cold.


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