Confused or TQ+UQ temperature ratings... Please help.

[Grumpy Squatch]

So the poster (and myself) wants to know, how can you get by with a 20deg difference between the uq and tq? Is there some actual science to this differential working? do you tend to get cold on the top and not the bottom once the temps drop in to the delta? According to other posts above, you must have similar temp ratings for both in order to stay warm, but you seem to think different (and i'd like to believe so, too).

Think of an example from almost every night of your life ... in a normal bed you have inches (8" or more usually) of mattress below you, which is a pretty good insulator, and normally just a couple inches (or less) of blanket/comforter/whatever on top. And yet you're warm.

Whenever we outdoors people debate this subject we tend to mix two seperate concepts. There is the absolute insulation value of a system and its ability to trap enough heat to keep someone alive (if it's sufficiently cold outside). Then there is the perception or feeling of cold which is due mostly to the thermal flux or the rate that your body loses heat, along with other perception issues, including how much heat you're producing and your metabolism. We had a pretty thorough discussion of this earlier this year: https://www.hammockforums.net/forum/...al-Equilibrium!.

So a member private messaged me this... I asked if it was ok for me to publish... Any thoughts or opinions???

I find it hard to believe that the warmth of one doesn’t supplement warmth for the other, as the two repliers imply. I feel like a uq that goes all the way up past your sides has to create an ecosystem. I disagree that a 20* uq is good only to 70*. I just really feel that there is some science to show that once you’ve created warmth in a space, the external temp isn’t as important as the temp on the external of the top quilt. If you put a space heater in your tent (or even your body temp if sealed, to a lesser degree) and create a warmer ecosystem inside, then your sleeping bag only needs to be warm enough to battle the temp within that ecosystem, not outside of the tent. Shouldn’t that theory apply to the hammock as well? Perhaps it is possible that the uq creates no warmer ecosystem itself? A pad certainly doesn’t. because the pad doesn’t envelope you. perhaps the sock is the barrier that needs to exist in order to trap the heat and create the warmer ecosystem?

What about a down jacket that isn’t zipped in the front (leaving a 10inch gap top to bottom)? If you have ample down to battle frigid temps on your back, arms, neck, but a fleece in the front (that wouldn’t withstand those temps by itself) wouldn’t you be warm enough at that point (providing no wind factor, which wouldn’t exist with a tarp and uq)? I think so.

There HAS to be some science.

This is the point about perception - the old wive's tale about losing 90% (or whatever) of body heat through your head is largely based on the body's perception of comfort when the back of the head and neck is exposed to cold.

Regarding the micro-climate, I measured my overcover's ability to create an air pocket some 20° warmer than ambient outside temperature (see https://www.hammockforums.net/forum/...-Overcover-Add). It definitely made my insulation system way too hot: https://hammockforums.net/forum/show...=1#post1587240.

[AngryDaddyBird]

So from what I read wind also has a big effect on how well the UQ works. Is this correct?
2qZq make a quilt protector. Would it be a good idea to pick one up as I read it actually helps tral in more warmth.?

[Grumpy Squatch]

It's one component of an insulation system (and favored by some lightweight hikers to allow for smaller tarps). Its effect depends on the wind as you say. On a perfectly still night it won'd add more than a degree or two. On a windy night, it can make a quilt feel 10 or more degrees warmer. I repurposed on old Hennessy SuperShelter undercover and on some nights it's an excellent addition to the system. But you can accomplish most of what a UQ protector does with a large (winter) tarp pitched well. And the tarp is more versitile.

For me, an undercover/UQ protector is a tool I use to compensate for an imperfect hang and undersized tarp. IMHO, you will be far warmer pitched out of the wind and under a good tarp pitched low with the end doors closed than hanging in the breeze with an underquilt protector.

[AngryDaddyBird]

It's one component of an insulation system (and favored by some lightweight hikers to allow for smaller tarps). Its effect depends on the wind as you say. On a perfectly still night it won'd add more than a degree or two. On a windy night, it can make a quilt feel 10 or more degrees warmer. I repurposed on old Hennessy SuperShelter undercover and on some nights it's an excellent addition to the system. But you can accomplish most of what a UQ protector does with a large (winter) tarp pitched well. And the tarp is more versitile.

For me, an undercover/UQ protector is a tool I use to compensate for an imperfect hang and undersized tarp. IMHO, you will be far warmer pitched out of the wind and under a good tarp pitched low with the end doors closed than hanging in the breeze with an underquilt protector.

That makes sense. I bought a SLD winter haven focused on winter hangs. Glad I went for a tarp with doors.
Thanks for the info.

[goobie]

One-line answer:

You'll stay warm to the rating of your thinnest insulation.

I would amend this statement to say BOTTOM, not thinnest, insulation.

[kitsapcowboy]

I would amend this statement to say BOTTOM, not thinnest, insulation.

With respect, I might question such an amendment, because it would suggest that you'd stay WARM at 0 degrees F with a 0-degree UQ and a 50-degree top quilt. I'm not sure I agree with you on that... (Yes, a 50 TQ/0 UQ combo at 0 degrees F s probably better than a 0 TQ/50 UQ at that temperature (i.e., CBS), but I'd wager you'd still be cold in either underinsulated situation...)

[goobie]

Lay in your hammock with NO insulation and tell me what gets cold first. Of course going to one extreme or the other may change this somewhat, but, I think we can all agree we need more insulation UNDER us than on top. No one with even the tinniest bit of common sense would attempt what you're suggesting......

[kitsapcowboy]

Lay in your hammock with NO insulation and tell me what gets cold first. Of course going to one extreme or the other may change this somewhat, but, I think we can all agree we need more insulation UNDER us than on top. No one with even the tinniest bit of common sense would attempt what you're suggesting......

We agree on that. My example was a relatively extreme one in an attempt to illustrate better one simple, limited point. I am not suggesting that anyone try such a thing. In fact, my original post was to suggest the opposite -- trying not to have any cold spots in one's insulation, top or bottom.

I tried to offer one humble opinion, which I thought was well reasoned and stated in a manner that tried not to overreach. I respect that you feel that I didn't succeed in these regards. I defer to your experience, which anyone can see is greater than my own, I don't think anyone hear is going to fail to heed your advice or your amendment to my post, even if I made the mistake of questioning it.

I will withdraw from this discussion and try to learn more from the rest of you. Better for me to remain silent and be though a fool than to speak and remove all doubt...

[tstark]

It seems the most important point gathered from this discussion is that a lower rated UQ paired with a higher rated TQ will help to bring the TQ rating lower. In example, a 20* UQ and a 40* TQ will help to achieve 30* or 35* rating. Which could be useful if you're looking to cut ounces and you don't have a 30* setup.

[goobie]

We agree on that. My example was a relatively extreme one in an attempt to illustrate better one simple, limited point. I am not suggesting that anyone try such a thing. In fact, my original post was to suggest the opposite -- trying not to have any cold spots in one's insulation, top or bottom.

I tried to offer one humble opinion, which I thought was well reasoned and stated in a manner that tried not to overreach. I respect that you feel that I didn't succeed in these regards. I defer to your experience, which anyone can see is greater than my own, I don't think anyone hear is going to fail to heed your advice or your amendment to my post, even if I made the mistake of questioning it.

I will withdraw from this discussion and try to learn more from the rest of you. Better for me to remain silent and be though a fool than to speak and remove all doubt...

No need to withdraw from the discussion. If my post came across as overly harsh, that was never my intention. I guess we took two different approaches to get our point across, to varying degrees of success. There's plenty that BOTH of us, along with everyone else, can learn from this thread