Originally Posted by NickJ
Thanks Billy. The science makes sense, but the practicality doesn't. In your final paragraph re getting another 20f, why not just wear slightly thicker thermals? (for example) Rather than run the risk of high moisture inside the hammock?
You are welcome Nick! And yes, another way to increase the warmth is to wear thicker LJs or just spend more money, weight and bulk on thicker insulation. Though frankly, I doubt that just having slightly thicker thermals would get me another 20*F, though who knows maybe for some. Also, when I use VBs, I end up with less moisture in both my hammock and my insulation, but it's true YMMV.
Note post 26 and 32 in this thread for example: http://www.hammockforums.net/forum/s...zzy#post387077
Also note the posts here- even on a short trip- comparing much less water weight even though the VB protected MW4 was NOT dried in the Sun for 4 hours:
Also, post #6 in this thread is interesting:
So, I could skip the $3, ~ 2 oz space blanket in my HHSS ( which I think gets me at least 15F, maybe more) and just use a second HH pad. Instead I would then have ~ 8 oz added and 30 plus $ and way more bulk.
But, that still would do nothing for the condensation issues. Most of us do great most of the time with our breathable systems. We get away with it just fine. But there are still folks who on week long cold trips report loss of loft in their down gear- and/or loss of warmth in synthetic gear- due to condensation inside their breathable insulation. I have heard about it many times over the years, and I have seen it happen with a friend of mine's PeaPod on 2 different week long trips. Though it didn't happen with my PeaPod, protected with a VB. Apparently 100% loft after one very wet week with no sunshine. It has worked well for me and others.
But don't get me wrong, I'm not trying to talk any one into VBs. Matters not to me. HYOH and all like that! And except for a space blanket (VB) under me in an HHSS or sometimes in my PeaPod, I mostly use breathable systems any way. But questions were asked, and it seemed there was some confusion on what a VB was meant to do, so I tried to explain to best of my limited ability. I hope it was of some help.
Although, I have never forgotten my 1st VB observation, over 20 years ago. I had a friend whose feet were freezing. One pair of wool socks, then another, still freezing. I loaned him my Patagonia VB socks which I had never even used. He put them on with one layer of wool socks over them. It didn't take very long until he told me " Oh Yeah, my feet are toasty!". Lesson learned.
Edit: Oh, and I forgot: If you choose to use a truly water and wind proof outer layer, like a 2Q sil-nylon UQ protector or the HHSS Undercover, you had better use an inside VB right under or pretty close to your hammock or you are going to have some serious condensation issues.
Originally Posted by MacEntyre
Originally Posted by BillyBob58
...it halts a major form of heat loss...
An adiabatic system would be appropriate for cold blooded animals, but not for us. We cannot survive if we keep accumulate heat.
Mac, I might be missing your point. Can you elaborate? Are you saying it might not be good to block evaporative cooling during a cold nights sleep, that it might be a problem? Or something else?