Vapor barriers -what is your opinion?

[BillyBob58]

I have previously written about a time 34 years when I was shivering all night, and though I knew about VB theory then, it never occured to me(or any one else on that trip) to use my rain gear close to skin for sleeping on that 24º June night. I'm sure if I had thought of that I would have been nice and warm instead of miserable.

I just remembered another time when I wish I had thought of this. This time only maybe 10 years ago. In the same high mountains as the first shivering night, but Sept instead of June. And in a hammock rather than on the ground. I took my Speer 20F Pea Pod. Plenty warm on bottom for expected temps, plus easily augmented with clothing or quilts if needed. But the "TQ" part was always tricky, because of the tendency of the hammock's edges to raise the top section of the pod, leaving a gap on top. But if you fill that gap with a light quilt, or even clothing, it is a lot warmer than the 20F rating.

But I didn't want to take the weight and bulk of even a 40F TQ, and didn't have one anyway. So on 2 high Rocky's trips(one to the Wind River Mountains of WY, the other the Sawtooths of ID) with hammocks and Pea Pod, I have managed to get by just layering my camp/hiking clothing on top of myself, with the pod closed over that. On the first night of that 1st trip, in the mid 20s, I was just barely OK on top(plenty warm on bottom). I realized that if it had been any colder- and it easily could have been- I would have had a cold sleep. But now I'm wondering where my head was? By this time, I had plenty of experience using VBs and radiant blockers under me in my HHSS. And I had plenty of stuff with me that would have worked fine as a VB: my rain gear, or the space blanket that I had under me some nights, not because it was needed for warmth, but just to keep the pod drier. I could have put that over me like a blanket- or wrapped up in it- and still layered my clothing over that, laying on top between me and the pod. Or just worn my rain gear. I have no doubt that if I had done that, I would have gone from just barely OK and nervous about it getting colder(it didn't), to being toasty warm. It would seem that sometimes I am just slow to catch on, and make use of well known facts regarding evaporative cooling.

[cmoulder]

Another VB data point...

Last night I slept completely warm at 12°F (thermometer actual reading) with a 30°F rated EE Enigma TQ and 0°F Incubator UQ.

Head to toe VB was a Lightheart Gear (LHG) rain coat and rain pants with plastic grocery bags for my feet.

Top layers (in order) were: OR Echo T/OR Echo LS 1/4 Zip/LHG rain coat/approx 150wt fleece Eddie Bauer jacket. Bottom: REI lightweight polyester longjohns/REI Mistral pants (Schoeller-like material)/LHG rain pants/Montbell down pants. Head: 200wt fleece beanie, 100wt fleece buff/rain coat hood. I had my EB Ascent down parka at the ready but did not need it.

All dry this morning except for a very small area at the top of the quilt where it cinches around my neck. Lots of frost on the tarp but none on the hammock netting. VB jacket and pants had quite obvious moisture on the inside, but not a ton. Felt slightly clammy at times but not too bad, and always warm.

I was surprised I stayed warm with the 30°F quilt, so this is a new and very useful data point for me.

Last night's venue, about 150 yards south of Dutch Doctor shelter, Harriman SP:

[BillyBob58]

Another VB data point...

Last night I slept completely warm at 12°F (thermometer actual reading) with a 30°F rated EE Enigma TQ and 0°F Incubator UQ.

Head to toe VB was a Lightheart Gear (LHG) rain coat and rain pants with plastic grocery bags for my feet.

Top layers (in order) were: OR Echo T/OR Echo LS 1/4 Zip/LHG rain coat/approx 150wt fleece Eddie Bauer jacket. Bottom: REI lightweight polyester longjohns/REI Mistral pants (Schoeller-like material)/LHG rain pants/Montbell down pants. Head: 200wt fleece beanie, 100wt fleece buff/rain coat hood. I had my EB Ascent down parka at the ready but did not need it.

All dry this morning except for a very small area at the top of the quilt where it cinches around my neck. Lots of frost on the tarp but none on the hammock netting. VB jacket and pants had quite obvious moisture on the inside, but not a ton. Felt slightly clammy at times but not too bad, and always warm.

I was surprised I stayed warm with the 30°F quilt, so this is a new and very useful data point for me.

Last night's venue, about 150 yards south of Dutch Doctor shelter, Harriman SP:

Well, yet again, worked as predicted. Seems to qualify as proof of concept, more or less. May I also presume you have not been previously as warn with oherwise similar layers with this quilt way below it's rating? And that the insulation and quilts outside the VB felt dry and puffy? (assuming no outside moisture issues and except for the one spot you mentioned near your face). If so, excellent!

It seems the benefits would be even more noticeable on a multiday trip where you are packing up every morning, and where the sun was lacking. Some folks like to take quilts rated 10-20F lower than the lowest expected, or even record, temps. It would seem since you were plenty warm almost 20F below your TQs 30F rating, that a 10-20F rated TQ would not likely ever be needed if expecting no lower than 20-30F using a 30F TQ. It would also seem that bulk, weight and expense can be saved, especially if any dual use for the VB's can be found. Or, it can be justified simply for warmth insurance and keeping insulation drier for longer.

Thanks for testing, vry useful data!

[BillyBob58]

"VB jacket and pants had quite obvious moisture on the inside, but not a ton. Felt slightly clammy at times but not too bad, and always warm." I forgot to say: that seems to be the only sacrifice, and a very minor one. Depending on the fabric worn and it's thickness, in my experience they dry very quickly.

[cmoulder]

"VB jacket and pants had quite obvious moisture on the inside, but not a ton. Felt slightly clammy at times but not too bad, and always warm." I forgot to say: that seems to be the only sacrifice, and a very minor one. Depending on the fabric worn and it's thickness, in my experience they dry very quickly.

Yes, the LHG rain gear dried very quickly. Just turned them inside out and gave 'em a good shake and laid them on the gear pile. By the time I packed them, a few minutes later, they were dry.

If the rain coat/pants could function as my primary shells that would be fantastic, and I will experiment with that concept on some day hikes when it gets cold again. Together they weigh 303g (10.7oz). However, I'm guessing that completely non-breathable is going to be tough to manage in extreme cold.

I did forget to mention that re-configuring layers for VB is a royal PITA because I'm used to just hopping into the hammock with what I'm wearing. But the benefits are so stark that the hassle is well justified. As you point out, it is very much worth it (at least it would be for me!) for any multi-day outings in very cold and extreme cold conditions.

I'm going to experiment next time with frost bib or some alternative to collect that last bit of moisture around the top of the quilt.

By the way, I weighed the frosty HG Palace tarp when I got home and it was 540.9g, and then later when it was completely dry and it was 443.9g, so exactly 97g (3.42oz) of frost remained after giving it some good shakes before packing it up. The weight is the whole tarp system.... tarp, guy- and ridge lines, door closure rigging, stakes and stuff sack... so don't worry that my Palace has done too much holiday over-eating!

[cmoulder]

And yes, I think I would have fared well with the EB parka and MB Down pants without the VB. But the quilt would have been wet, no doubt.

[BillyBob58]

And yes, I think I would have fared well with the EB parka and MB Down pants without the VB. But the quilt would have been wet, no doubt.

Were you wearing the EB parka on this test, or the 150wt fleece Eddie Bauer jacket? Or both? And what do you usually wear with that TQ at these temps?

[cmoulder]

Were you wearing the EB parka on this test, or the 150wt fleece Eddie Bauer jacket? Or both? And what do you usually wear with that TQ at these temps?

I was wearing only the fleece, and I'm almost certain that without the VB I would have needed both fleece and parka. That certainty is approaching 100%, but because I didn't actually try it and I never before tried using this particular quilt that far below its rating, I will have to leave it at 99.44%.

However, being able to remain warm at 12°F with a 14oz quilt is a pretty neat trick.

BTW, at that point my campsite was an easy 1.7mi walk from my car so if I had been seriously uncomfortable, or worse, bail-out was handy.

There was one emergency, however... I forgot my coffee!! I discovered that fact the previous evening and darn near bailed out then.

[BillyBob58]

I was wearing only the fleece, and I'm almost certain that without the VB I would have needed both fleece and parka. That certainty is approaching 100%, but because I didn't actually try it and I never before tried using this particular quilt that far below its rating, I will have to leave it at 99.44%.

However, being able to remain warm at 12°F with a 14oz quilt is a pretty neat trick.

BTW, at that point my campsite was an easy 1.7mi walk from my car so if I had been seriously uncomfortable, or worse, bail-out was handy.

There was one emergency, however... I forgot my coffee!! I discovered that fact the previous evening and darn near bailed out then.

Yep, that(no coffee for the cold morning) is almost a disaster all right.

Warm at 12F with a 14 0z TQ could well men warm at 11F or 5F. That is still an unknown, seems to me. Add your parka, wow, who knows?

[OneClick]

The weather is not cooperating for more testing. I was possibly going out later this week, but I'm sure glad I'm not!!! 30-40s, rain, and warm lows as well. I'm sticking with my original plan of new years in the woods! Should be cooling down nicely and I look forward to testing since it will be either 4 or 5 nights in the cold.