OK, I realize most hammock users much prefer quilts vs bags, mainly for sheer comfort and ease of use. I can see all of the advantages. Some have actual quilts designed primarily for hammock use, others just try to make their bags function as a quilt.
The later describes me. But, in my case, I feel that my mummy style bags are no where near as warm when I use them as a quilt, and usually if I get cold, getting in the bag and zipping up with hood over my head and neck collar sealed will result in quick improvement. Usually by what seems like a 20* (or more ) improvement. I can go from uncomfortably cold to toasty warm by zipping up.
But sometimes when I get in the bag, it seemed to me I would also notice increased warmth on my back. But, I wasn't sure if this was because I was just warmer over all. But it did get me to wondering about the superior compressibility of down vs PG. and how this might work against you in a hammock.
So, at morning a couple of days ago it was 58* with a steady breeze, and my hammock was up, so I grabbed my old winter PG Delta bag and went out in just my PJs. First I hopped in quilt style, with the bag very lose over the top to avoid any overheating. It only took about 5 minutes to determine that I was definitely uncomfortably cool on my back, and that I wouldn't be able to make it very long like that without getting chilled. And the longer I lay there, the worse it was getting, especially when the wind would gust a little.
So, then I rolled the bag out and laid down on it, but not zipping up, leaving some pretty good ventilation on top. I went back in about 30 minutes later with the temp still at a very cloudy 58*. I was just fine the entire time, with no problems from a cold back at all. Not even when the wind would gust. In fact, sometimes I actually had just a slight warm sensation on my back. Both times, of course, there was no pad or quilt.
So, this raises the question: Is PGs relative lack of compressibility actually a slight advantage in a hammock, for those few who would actually use them as a sleeping bag, rather than a quilt? Would this possibly be an advantage for both quilt and bag users when dealing with hammocks compressing insulation on the sides? Possibly allowing the use of thinner or more narrow and lighter pads or lighter UQ? Or no pad or UQ at all at a temperature that would just barely require a pad or UQ with a down bag or top quilt of any kind?
I can't really quantify the results of my simple, quick test. Just quite uncomfortable at 58* with no bag layer under me, just fine with it. I do know that previously I did a test with just PJs ( tee shirt only on top) and no bag or quilt or pad, at 68*, and that seemed to be about my lower limit. Maybe closer to 70* when the wind would pick up. So, I'm guessing
that this PG bag might be good for 5 or possibly 10* worth of bottom insulation. Compared to zero degrees bottom layer insulation for quilt style and probably ( guessing) about zero degrees bottom layer help inside a highly compressible down bag.
Has any body else here noticed any similar results? It just has occurred to me that this might be an additional benefit to synthetic bags, at least for bag ( vs quilt) users in a hammock, compared to down. In addition to the possible "warmer when wet/quicker drying" advantages. This advantage would not seem as likely for a ground dweller who is already depending on a thick pad for both cushioning and insulation. At least, I use thick pads on the ground, as thick as I can stand to carry! Which is why I like being off the ground.