Some temp rating questions

**Insaniac99** · 09-17-2013, 05:50

I am saving up for an underquilt (I like the idea of the Hammockgear Incubator; I'd do it DIY, but the price difference seems to be minimal -- almost the same price even-- and I suck at sewing neatly) and one question that I can't really find an answer to easily is this:

If it is, say ~40*, what difference would you feel if you had a 0* underquilt vs the three-season or summer; assuming you are using 40* top insulation with each set?

My thinking, and I can't find any clarification on this yet, is that as heat rises and the main purpose of the bottom insulation is to reduce the convective heat loss from wind you wouldn't notice a difference between the 3-season and 0* quilts because once you have cut the cold and gotten rid of the convective heat loss your primary loss is from the top insulation. I figure you WOULD notice a between the 3-season/0-degree and the summer quilt because you would be right at the temperature rating of the summer quilt.

My prime motivation for asking is because I figure I will only be able to afford 1 UQ for a long time, and I still haven't figured out if it is best to do the bigger bulk and weight of the 0-degree or the 3-season. While I'm at it I also wonder what the stuff size difference is as my only pack is 50L. If the difference is pretty inconsequential and my theory is correct then it clearly makes the most sense to buy a 0* UQ as my first quilt. If my theory is wrong or the size difference is significant then I have to noodle on this while I save up...

**Jayson** · 09-17-2013, 06:26

I use a 0° under quilt only. Slept many nights this summer with no overheating issues.

**kayak karl** · 09-17-2013, 06:37

i compare it to a mattress on bed. you change blankets with seasons. you could use a ) all the time, but if backpacking you may want a lighter option in summer.

**DuctTape** · 09-17-2013, 06:42

In general heat does rise, but it will escape a body from any higher temp source to a colder in any direction. While convection is often discussed it is mostly radiant heat loss that most experience. Both the tp and bottom quilt trap the radiant heat ( and some from conduction). To stop convective heat loss you need a wind barrier. A weathershield and/or a well pitched tarp will minimize the air mobement from stealing the trapped warm air in both your TQ and UQ. Dont underestimate the amount of heat lost from you UQ when the wind is blowing..

**rocketBoy** · 09-17-2013, 08:21

I was curious about the same thing. I had mostly been camping in cold weather with my three season Yeti. The past two trips only got down to about 70F and 50F overnight and I was still comfortable with just adjusting my top quilt. So IMHO a three season or winter underquilt would be a good fist choice. Keep in mind, though, that more is not necessarily better... for example, don't get a 0deg underquilt if you're really not going to be out much below freezing.

**Rolloff** · 09-17-2013, 08:38

Originally Posted by rocketBoy

I was curious about the same thing. I had mostly been camping in cold weather with my three season Yeti. The past two trips only got down to about 70F and 50F overnight and I was still comfortable with just adjusting my top quilt. So IMHO a three season or winter underquilt would be a good fist choice. Keep in mind, though, that more is not necessarily better... for example, don't get a 0deg underquilt if you're really not going to be out much below freezing.

Rocket's got it.

In theory makes sense, but only after asking yourself, what temps and conditions you intend on using the UQ. Is it going to be on your back? Will you be looking to make miles? Cold sleeper? Car camper?

DIY, for the most part you are right, very close on cost points, for most cottage made. If cost is a major concern, check out Undergroundquilts.com. Shell for a 30 degree or a 0 is the same. Only cost diff is the amount of down you decide upon. If you can sew at all, or wish to explore true injecting, tacking the baffles and sewing one side shut is a great place to start.

Rolloff

**DAdamEich** · 09-17-2013, 08:47

You also can't discount the amount of cold air trying to get IN. Lower degree UQ, TQ, or a bag, are going to have more loft/fill. The extra loft is going to give you a thicker barrier between your body heat and the outside air. I can use a 20* bag when it's 100* outside and be comfortable because my body heat is cooler than it is outside. It's about putting an appropriate barrier between you and the outside air. If 30* temps penetrate the loft of your UQ 1" and you have 2" of fill total, you're okay. If it gets down to 5*, it could penetrate all 2" that you have and you're cold.

Personally, I'm a cold sleeper and use way more insulation than most people need all year round. You know more about what you need than anyone. If you're going to do a DIY UQ, make it so that you can add or remove some fill to adjust it to exactly what you think you need.

**Insaniac99** · 09-17-2013, 15:06

I was pricing up the quilts last night, an argon shell from underquilts.com ($100) + 12 oz of 850 down ($168) = $268, and I'd still need to sew and do suspension. A stock incubator from Hammockgear.com with argon shell and 12 oz of 900 fill down = $249

How accurate are the temperature ratings? I don't do much winter camping in the pacific northwest --almost none in fact -- but I'll still go out when it gets down into the 30s and I have learned from experience of cold nights that most commercial sleeping bags are off by at least 10*

**Rolloff** · 09-17-2013, 16:48

Wasn't aware Argon was in the mix. Last I checked regular ripstop UQ shells were as low as 50 bucks. Suspensions are shock cord and cord locks.

HG makes some great stuff. Cast no doubt. My UQ is a 20 degree HG clone. Picked up here in the For Sale thread for 75 dollars, from another member, 2nd, 2nd hand.

With all the new fabrics, down treatments, and designs available, you can pay just about anything you wish, or have the time, patience, or funds to allow. You might not be able to afford multiple insulation sets, but are more than prepared to put the cash down for cutting edge shell materials, and top of the line(at present)down treatments.

Sure can't fault you for that

**Insaniac99** · 09-17-2013, 23:00

Well, one you decide to drop a couple Benjamins on a piece of gear, spending a little more seems like small change if you get some serious advantages for the increase. It is another thing to justify buying two pieces of gear that will perform the same function, especially to the nice lady asking what you spent your money on