Companion forum thread to:

Ultralight in the Icebox

Andrew you’re the Man!

Great article... Well written and insightful!

Good luck! (PS: Tortillas can be used in freezing weather, you just need to put a liner between each disc. Parchment paper would work, and it is burnable!)

I really enjoyed reading this. When it gets really cold I hear that Minnesotans button the top button of their shirts while the rest of us layer on the down. Not sure if that's true or not but I lived in Fargo, North Dakota as a child and I can tell you that the local definition of "cold" was very different from mine!

I must be crazy. I lived in Fargo for ten years, moved out to the mountains for a few and now I live in Northern Minnesota. I've been talking to Andy about this hike over the course of the past few weeks and as odd as it sounds he's been disappointed at the unseasonable warmth and lack of snow the local climate is currently offering.

I don't think the below sentence is accurate. Human skin does not sweat in response to "sensing" humidity differentials between "outside" and "inside".


"For VBLs to work, they must be next to (or very close to) the skin - otherwise, the skin keeps sweating (because it senses that the outside humidity is still lower than on the inside) and the layers inside the VBL get soaked because the perspiration is trapped."

I can relate to the disappointment of unseasonably warm weather. I keep waiting (and waiting) for winter to start. I sit here and stare at my snowshoes and skis patiently. I hope we get hit with a vengeance! At least that's my perspective from the Midwest...

I'm 30 minutes east of Missoula and at about 200' higher elevation. It was over 48° yesterday and today it's been to 37° with rain all day. Yecch!

Nice idea but it's pretty warm...I find it irritating to have to always put snowshoes on then take them off but, that's just me...I'd rather do this trip when there's LOTS of snow to get you over all the rocks and fallen trees...still, it will be very interesting to follow your trip...the scenery is great...the grouse will get your heart beating and you should have a blast no matter what the weather...after all, you're OUT THERE! LOL...

Snot doesn't freeze when you're wearing a nose cozy!

Edited by Mataharihiker on 01/03/2007 16:58:02 MST.

Re: "For VBLs to work, they must be next to (or very close to) the skin..." Although not stated clearly, I believe Andrew was referring to the Vapor Barrier theory pushed by Stephenson and others: if skin gets wet enough, it sweats less than it otherwise would, so it's good to put a barrier real close to the skin to quickly saturate it, and persuade it to stop sweating. I'm not certain, but I believe that is part of the theory. I'm not sure what, if any, scientific evidence supports this theory. Another thing that bothers me, isn't moisture going to escape into Andrew's bag from the ankles, waist, neck, wrists, and the un-taped seams? Or will the body have slowed or shut down the amount that it sweats due to the above body reaction?

Linda, Patent that Nose Cozy quick! LOL

Hi Andrew

Yes, the Simmerlite is a nice stove, but one of these days I must get you to try out either a Coleman Xtreme or a Coleman Fyrestorm Ti. You will never look back.

Good luck!
Cheers
Roger Caffin

Hi Andrew - i hope the lithium batteries don't burn out your Tikka!

All the best!

This trip is fascinating! I've read it several times now. Thanks Andy- I can't wait to read more!

A couple of comments:
1) I've used the RBH vapor barrier socks for a few years now. It's amazing how well VB works and also how comfortable the RBH material is against the skin. I can't wait to learn more about VB for longer duration winter trips.
2) I agree with Roger- the Coleman Xtreme seems superior to the Simmerlite. I have one and have loved using it as a snow melter. One advantage to the Simmerlite- Unleaded is very easy to fine.
3) In that snow melting system, I've just started using an Outback Oven cover to increase effeciency in melting snow. I wonder if the weight of the cover is worth the increase in effeciency (and the lighter fuel load required).

Keep it up Crazy Man Skurka!

Doug

> isn't moisture going to escape into Andrew's
> bag from the ankles, waist, neck, wrists, and
> the un-taped seams? Or will the body have
> slowed or shut down the amount that it sweats
> due to the above body reaction?

There will probably be that effect, but in theory the amount of perspiration will be less than if wearing no VB at all. If one was to wear a VB on their feet and hands, et al throughout the night their skin would never be given the chance to breathe nor dry and I think this would lead to more blistering.

Another vote for the Extreme stove...I've
used it at -11 and 11,000 feet (not at the same time, mind you) and it worked equally well both times...I think I've had mine since they first came out...learned to try a new canister before commiting it to a trip after one canister valve failure...I've used the cover of the Outback oven winter camping when melting snow or boiling water...many of us do...it's another way to avoid heat loss while cooking...I don't use any other part of the Outback but that's cuz I can't eat starches easily...

You know, I just thought of something...I always bury my Dromedary in snow when winter camping...I won't be able to do that next week-end at Pix Rox if there's no snow...bummer...

Is anyone planning to meet up with Andrew anywhere, I wonder? I am interested in how his VBL gear will work....

Edited by Mataharihiker on 01/04/2007 16:15:03 MST.

To clear a bit up on the theory of VBLs, saying that your body stops sweating in response to a highly humid area is not true. NOR does this have anything to do with the potential benefits of a good VBL system.

A couple of facts to get out of the way...
1) Your body ALWAYS sweats or perspires, ALWAYS (except when your are severely dehydrated, which is no way to stay warm)
2) You body controls the RATE of perspiration in an attempt to regulate body temperature (specifically in an attempt to cool the body because... da.. da... da... SEE #3)
3) Evaporation takes a LOT of energy ([url=http://en.wikipedia.org/wiki/Latent_heat]Latent Heat[/url]), which the perspiration molecules steal from the body in order to waft out into the surrounding air.

VBL technique relies on the little known (or maybe I should say little paid attention to) fact that
4) Evaporation also requires a non-saturated (aka "dry") vapor medium (aka "air") for the perspiration molecules evaporate into. The more unsaturated (or "dry") the vapor layer, the more it enables the perspiration molecules to steal energy from the body in order to evaporate. (Think about how dry winter air is... regardless of it being cold, the air is very unsaturated with moisture this enable evaporation (or heat stealing) to occur at a rapid rate).

A VBL, therefor, doesn't cause perspiration to stop. What it does is create a layer around the body that is saturated. When you have a saturated envelope around the body, perspiration molecules (yes, that would be mostly water) evaporate from (steal energy) and condense on (give energy back to) the body, resulting in a net-zero latent heat loss.

I'm not sure if that helps those of you not familiar with VBL, but I tried to simplify it to make it easier to comprehend.

Linda,


RBH Designs has several new VB items on their web site.

Joshua: thanks for the help. Since we're talking cold weather hiking, as long as the body feels too cold, is the rate of perspiration at some minimum, until the body feels too warm?
Does a vapor barrier result in a significantly smaller total loss of water over a night? Or does it just save energy when it "condense(s) on (give(s) energy back to) the body, resulting in a net-zero latent heat loss."? Since Andrew chose not to use a VB bag, but used separate items of clothing, is a lot of the water going to leak out and condense in his bag, and not give the energy back to the body instantly?

Robert, yes active sweating will be minimized in cold weather until the exercise raises your body temperature slightly to induce active sweating.

A vapor barrier does not, in my opinion, result in a significant smaller water loss overnight. The passive perspiration occurs no matter what even though a VBL may slow it somewhat with high humidity around the skin. Remember that passive perspiration (insensible sweating/perspiration) is greatest in a dry environment and is lessened by a more humid one. There are also regional differences in passive perspiration with more coming from the palms, soles and neck, IIRC. Much of the passive heat loss (and water loss) is going to come from respiration which will usually be at a higher rate (of respiration) due to altitude. The VBL stops evaporative heat loss from the skin surface yes.

Andy's setup should work nearly the same as a bag VBL. Some water vapor may escape but it will be minimal as long as the pieces are closed up fairly well.

Edited by jshann on 01/04/2007 22:09:11 MST.