Underquilt Temperature Rating

[BillyBob58]

Set up is key. You can have a 10 degree quilt and if it isn't hung right, you'll freeze at 40.

You have to remember that any insulation system does not create heat, it keeps the heat your body generates from escaping (in our case) into the woods.

That for sure. Plus, individual user variation is significant. I think the vendors here are all generally quite conservative for their ratings when used by the so called average sleeper. (plus, even that sleeper can vary a lot one night to another depending on many condition variables like wind, moisture, fatigue, hunger etc) And you say/ask:
"Generally if I know the low for a weekend is around 10-30*F I take my 0* sleeping bag. Is this the same for an underquilt? "

It might be, for you! Impossible for us to know. Your bag may be way over rated, or you might have a quality bag with a conservative rating but you are a very cold sleeper. If the later, then a 20F rated quilt from these vendors may not keep you warm at 20.

Have you used any quality bags like Marmot or Western Mountaineering? If so, were you warm near the rated temps?

One final caveat: There can be a learning curve with either TQs or UQs. Any gap or draft will freeze you, and it is much easier for this to happen than when you are on the ground zipped up in a bag. Plus, often a part of the bags rating is an excellent hood and neck collar. You will need to compensate for that when switching to TQs if you expect the results to be as warm. With all of that said, I find the quilts like JRB and WB and PeaPods and others here to be easily as warm as rated. But that's just me!

[sargevining]

A addition question. Is the temp rating sleeping naked or clothed?

Its my understanding that most temp ratings are based on a 30 year old man in good health wearing a proper base layer.

[hutzelbein]

From what I have read here, it seems that most agree with the underquilt temp ratings, provided the underquilts are set up correctly. If you are a warm sleeper, chances are you can go lower without being cold. If you sleep cold, you probably won't be able to go as low as indicated by the manufacturer.

[OneClick]

My 40° HG Incubator is fine down to 30°, but I'll take my 20° if the temps are that low fore the whole trip just to be safe.

My 20° HG Incubator kept me toasty warm at 7° on my last trip with thin base layer. To be conservative, let's call it about 13° since it was actually warming up slowly throughout the night.

In general I would say these are rated with a 10° safety margin. And as already mentioned, a proper setup is key. Since wind can really screw things up, I also recommend not going cheap on a tarp.

[FLRider]

Its my understanding that most temp ratings are based on a 30 year old man in good health wearing a proper base layer.

Correct. It also assumes that he's well-hydrated, well-fed, and not totally exhausted before bed.

Note that this is simply personal experience, but I find that for every ~500 to ~750 calories that I'm in the hole for the day (that is, I burned ~500 to ~750 more calories than I ate), I sleep about five to ten degrees colder than I normally would (that is, my insulation is less effective by ~5º to ~10º). Hydration is a little harder to pin down, but I do remember being colder when I was dehydrated (despite not having to get up as often to water the bushes during the evening). This is especially noticeable after very long days where my body is already very tired--which, coincidentally, often intersects with those days where I'm calorically deficient and mildly dehydrated (when I'm truly exhausted, it's a struggle to care enough to eat and drink just for comfort down the road).

Just a thought for folks to ponder. YMMV, as always.

[phatt_millips]

Thanks this really helped!

[MK-9]

As others have said, proper setup is critical.

Did a few nights in the Chattahoochee Nat'l forest in November. First night there I woke up to 17 degrees and I froze my toes & buttcheeks off due to operator error. Next night after the adjustments to my UQ (20* HG incubator) & tarp, I was perfectly warm and had never had a better night in my hammock.

[TonyYarusso]

One thing that I've noticed over the years is how the temperature rating on a sleeping bag is often overrated.

Temp ratings are extremely subjective. A consensus of 100 people for a given bag rating doesn't tell me if I will be cold or not until I hit that temp.

That used to be the case, but the advent of EN 13537 testing has helped tremendously in that market. I'm not aware of any similar standardized testing for quilts, over or under.

[OneClick]

That used to be the case, but the advent of EN 13537 testing has helped tremendously in that market. I'm not aware of any similar standardized testing for quilts, over or under.

I really like this. Both of my Marmot bags had this rating and really helped when making a purchase.

[genixia]

That used to be the case, but the advent of EN 13537 testing has helped tremendously in that market. I'm not aware of any similar standardized testing for quilts, over or under.

EN13537 is the best thing to happen to sleeping bags since Noah packed waterfowl for his float trip.

It's not without its limitations though; Testing Sleeping Bags According to EN 13537:2002: Details That Make the Difference

An interesting read, and as you've observed, no one is even thinking about quilts yet.