Underquilt Temperature Rating Question

[goober]

When someone writes about a "20 degree UQ", what is assumed to be above the UQ? Long johns, top quilt, what?
I have a zero degree down sleeping bag that functions pretty well up top. The "pad in the hammock" thing isn't ideal, so I'm thinking about an underquilt. But if I combine it with my zero bag, what do I need, in terms of a rating, for the UQ? Could I get away with something minimal? With which kind of UQ would I not need to bother with the top bag? Is a UQ supposed to make top covering unnecessary?

For now, I'd say that, overall, I'd like to be able to handle 25 degrees in the hammock.

Thanks in advance.

[dkurfiss]

Depends on you and how cold hot you sleep. 20 degree is normally a rating the vendors give them depend on the amount of material and loft in a quilt but that is an average not an exact number. I sleep cold so my 20 UQ will only get me to 20 with smart wool top/bottom, hat, and wool socks on. Others will be in a much lighter layer and be just fine.

Current wisdom says to put your warmer layer under you because of the chill from the ground and the air movement under you.

Me? I have The Nest from JRB and wish I had purchased the Winter Nest just for the additional warmth at 20F temps.

[Passinthru]

In the world of commercial sleeping bags temp ratings seem very inflated. It seems to me that a 30* bag means you may not die at 30* but you will only be comfortable at 45*-50*.
It seems that most of the private vendors we see mentioned here rate their products much more conservatively. For me, a 20* UQ will keep me warm wearing the underclothes I would normally wear at that temp (maybe light long sleeved shirt and long johns).
Your 0* bag won't do much for keeping your bottom side warm so I would match your UQ to the expected low temp - the TQ can probably be rated somewhat warmer than the under quilt if you decide to replace the bag with a top quilt.

[gnar]

In the world of commercial sleeping bags temp ratings seem very inflated. It seems to me that a 30* bag means you may not die at 30* but you will only be comfortable at 45*-50*.
It seems that most of the private vendors we see mentioned here rate their products much more conservatively. For me, a 20* UQ will keep me warm wearing the underclothes I would normally wear at that temp (maybe light long sleeved shirt and long johns).
Your 0* bag won't do much for keeping your bottom side warm so I would match your UQ to the expected low temp - the TQ can probably be rated somewhat warmer than the under quilt if you decide to replace the bag with a top quilt.
very well said! I used an eureka silver city mummy bag rated at 30f last winter. 1 night it was 38-45 and I was not so warm, keep in mind I had long johns and pajama pants 2 sweat shirts and tee shirt. tried again at around 30f with more clothes on and froze my butt off! that bag I would give a 40f rating to at best. also I did have a winter rated UQ on my back side...............

[hutzelbein]

Ratings are just a ballpark number since everybody is different. I know that a (high quality) 20° underquilt or sleeping bag will only work for me down to roughly 32° before I start getting cold. That said, as a rule of thumb I think that you need to pair a 20° underquilt with a 20° top quilt or sleeping bag to get down to 20° without being cold. Hot sleepers might be fine with a 30° top quilt or can sleep in underwear without being cold. Normal sleepers would probably wear a bit more. It's all very personal.

I found that the insulation from below is way more important than from the top. If I use my 0° underquilt indoors (temperatures are probably between 50° and 65°), I get away with using a summer sleeping bag that is rated to a comfort temperature of 70° and which I would only be able to use in 80° summer nights. I also find it more comfortable to be warmer from below than from above. It's easier to vent when you're hot or cinch the bag tight when you're cold.

Most underquilt makers offer underquilts for 3 temperature ranges: 40°, 20° and 0°. Some also offer 30° and 10°. With a 20° underquilt you would be on the save side, and it is one of the most versatile underquilts. A lot of people use it year round. If you don't sleep cold, you might be fine with a 30° underquilt. If you sleep very hot, maybe even 40° will work.

A note of caution: if you underquilt is not up for the task, more clothes won't help a lot in all likelihood. If you are using a net-less hammock, you might be able to use your 0° sleeping bag as a peapod. You'd have to try if this set-up would work with your sleeping bag and hammock model. The bigger/roomier the bag and the shorter and narrower the hammock, the better it works.

[dakotaross]

An UQ only replaces a pad. You'll want TQ, or at least a blanket, in all but the warmest temps. I wouldn't want to carry the bulk and weight of a zero bag just for a TQ. I think the Peapod idea makes sense if it will work for you. Otherwise, sell the bag and get a set of 20 degree quilts.

p.s. I assume measurement of temp ratings for an UQ is similar to that of a bag... most info for bag ratings will reference "sufficient insulation underneath" or "sufficient pad". The temp rating is mainly a calculation of the insulating material loft, not an actual test. So if loft is calculated to be sufficient for 20 degrees, it requires a pad that will keep you warm at 20.

Reverse for the UQ, but essentially the same. A 20 degree UQ requires the use of something on top that will keep you warm down to 20.

[HillbillyHanger]

You may have had on too much inside the bag. Your body has to radiate heat to warm the space. If you wear too much insulation on your torso then your hands, arms can get cold because you limit the flow of heat inside the bag. Experiment with it. I'm a cold sleeper, but I sleep comfortably in the 20s only wearing boxers inside a 20 degree bag. You have to have the right rated sleeping pad under you though. Body weight will compress the insulation under you and its almost useless. I use a Big Agnes bag for that reason when I use a tent in the winter.

[OneClick]

For 25°, I would personally trust my 20° UQ every time. But as mentioned, everyone is differnet. Lots of variables going on.

- Block the wind as much as possible (tarp, UQ protector, site selection)
- Try not to move around a lot. When you do, you will probably notive a cool spot since you "pumped" out some heat
- Try to reduce pressure points. Sleeping on your side, or even an angle, your knee can push the UQ away causing a gap. You basically want the UQ and hammock to "spoon" with your entire body
- A little extra insulation such as lying on clothing or wearing a base layer DOES help. It's just not something to rely on to get you down to a specific temp. I once got cold and tucked a fleece jacket under my back, cozy all night. It was impossible for any cold to penetrate that thick layer of fleece.
- Don't wait too long to get out and adjust. I know it sucks getting out in 20°, putting boots on, getting a headlamp and tightening UQ but it's just something you have to do sometimes.

[Moose85]

I just got my first underquilt and it's rated for around 20F. I did a test hang in my garage a couple nights ago and I kept waking up with a cold back. It never dropped below 40F in the garage and I adjust the under quilt several times throughout the night. I was using a sleeping bag (rated 32F) as a top quilt but I ended up putting it under me to try and get a little more insulation. Finally I gave up and went to my bed around 4 am. I think I had it set up right, is it normal for a rating to be so far out?
If not can anyone give me any ideas why my back kept getting so cold? I'm starting to wonder if I was sent a 1 season underquilt instead of the 3 season.

[Wraith6761]

Odds are, there's a small gap that you didn't notice that was allowing cold air to come in between the quilt and your back. The primary suspension of your UQ should be tight enough to lift the hammock (when it's empty) a few inches, while the secondary suspension (assuming your quilt has one) should be tight enough to seal the quilt around the hammock. I know some vendors, like Underground Quilts, use a draft collar to assist with this. If you're worried that you were sent the wrong quilt, check the tags, some if not most vendors put a tag with the rating on their quilts.

Also, get a second person to go down to the garage with you and either check for gaps while you get in OR get in while you check for gaps...sometimes it's easier to spot gaps when somebody's in the hammock that would otherwise be hard to see.

To the OP: a 20* quilt should be enough to get you down to 25 pretty easily, assuming you're about an average sleeper. If you sleep cold, you might have to go to a different rating, but I would think a 20* would work year-round in AZ. It almost does here in VA, and our winters tend to be a bit harsher than yours are (though nothing like the craziness of Minnesota or that area)