UQP vs increasing warmth

**Halfed** · 05-13-2019, 15:17

I know all the benefits about using one, specially protecting your investment (UQ).
But as title says does it really increase the warmth? Has anybody knows of tried to measure it.

Sea to summit thermolite reactor sleeping bag liner says it adds up to 15°F of warmth to the sleeping bag, just for reference.

Thanks

PS: Mine is from Dutch produced by 2QZQ (Argon 90).

**cmc4free** · 05-13-2019, 15:26

I'd be a little skeptical about it actually increasing warmth, though I'm not saying it wouldn't. I'm more confident about it preventing loss of heat, by reducing the amount of convection (wind) transferring heat away from the quilt. Kind of 6 of one, half dozen of another...

It's a little bit like a winter tarp blocking wind. The tarp doesn't make the sleep system any warmer, but it does keep the occupant warmer by reducing convective heat loss. It's all in how literal an interpretation you're looking for.

To see if an UQP actually increases warmth, you'd have to test it on a day with no wind. It's obviously not adding any heat to the sleep system, so the question is does it allow the system to retain more of the heat your body generates in the absence of forced convection (wind).

Nope... I'm not a lot of fun at parties.

**SilvrSurfr** · 05-13-2019, 15:47

A UQP is not insulation, so it will insulate about as well as air. Mystery Oneal was working on an air UQ a few years ago. Can't believe they shut that thread down - it was cutting-edge!

https://hammockforums.net/forum/show...ill-for-and-UQ

**michigandave** · 05-13-2019, 16:43

That was a good thread SS. Ranks up there with hanging over a fire to keep warm.

I look at using a UQP as a way of increasing comfort, blocking the wind, and protecting my UQ from precipitation. On a hot summer trip last year, it was 80 all night long and I didn't need an underquilt, but I did use my UQP as an extra barrier from mosquitos that wanted to get to me through my hexon 1.0 hammock.

I do seem to recall there's been a lot of discussion about this in the forums.

**cmc4free** · 05-13-2019, 16:49

It's going to have some effect. I wouldn't call it insulation either, just like I wouldn't call a t-shirt insulation, but a t-shirt is going to keep you warmer than wearing nothing. The reason is two fold - some of your body heat is retained in the air space between the shirt and your body, and the shirt reduces heat loss from your body via convection.

I do enjoy the Mystery Oneal thread though.

**leiavoia** · 05-13-2019, 17:29

It's more of a windbreaker than insulation. If you are in a breezy situation, there will be some benefit. Otherwise, not much.

**cougarmeat** · 05-14-2019, 14:12

Halfed - you may think you are reading a tangle of words. Once I posted a tread about how down (TQ's, UQ's, pads, etc.) doesn't "create warmth". It's a misnomer (and marketing) to think, a particular bag/quilt is "this warm". You make the heat; you make the warm. The UQ's, etc. only allow you to keep the heat you create. So imagine yourself in a closet (small space) with nothing to take away or dissipate the heat your body normally gives off as part to of the energy conversion with food. You will get hotter and hotter and hotter. So there is nothing that is adding heat - in the normal world there are just circumstances that take heat away. Anything that can minimize your heat loss will result in you being warmer.

A UQP keeps your UQ clean (many of us have inadvertently had the suspension bungee slip out of our hands when setting up). It will keep the UQ from rain drops that sneak their way under your tarp. But more importantly, it will be an additional barrier against the convection heat loss because of wind currents under the hammock. Yes, that's what the tarp is for. But the tarp is usually set up in one orientation and the wind is free to swish around anyway it wants. Some claim it lies in wait to see the orientation of your tarp, then it picks the direction parallel with the ridge line. A UQP helps there. Also, getting the end closures correct on the UQ is important to enable it to do its job. That can be difficult if you are by yourself because it is hard to see what is going on at the ends when you are in the hammock. In that case, a UQP covers the UQ ends and makes that fit less critical.

As to any measure of "added heat", remember, it is "kept heat". and you can imagine how much that would vary given wind speed/direction.

For me, the UQP is worth the weight. For others it is not. I suppose I won't need one if I had a tarp with doors. But I am just trading the weight from the UQP to the tarp.

So you know, tomato/potato.

**cmc4free** · 05-14-2019, 14:25

Cougar, your points are correct.

Heat is a quantifiable form of energy. The user is the only element in a hammock/quilt/tarp/etc system that generates heat (assuming no electrical heating elements, chemical hand warmers, hot water bottles...)

Warmth is a user perception. All the elements of a hammock/pad/quilt/UQP/tarp system contribute to the perception of warmth, i.e. preservation of heat generated by the user.

I think the OP's actual intended question was "does using a UQP help keep you warmer?" The answer is yes. It will have the greatest effect in windy conditions, but even in still conditions, I'm sure it retains at least a small amount more heat than the quilt alone would (t-shirt example).