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#109383 - 01/15/09 07:50 AM Re: Clothing Science and Folklore - open discussion [Re: JAK]
JAK Offline

Registered: 03/19/04
Posts: 2569
How is this for a simple formula as a last minute
check to see if you have enough clothing insulation?

Tskin - Tmin [degF] = Clothing Insulation in Ounces

Tskin = average skin temperature ~ 85degF
e.g. for +30degF, 55oz = 3.4 pounds clothing
e.g. for -30degC, 115oz = 7.2 pounds clothing
The intent is enough clothing for prolonged periods of low activity, which might be twice the clothing required for fastpacking, but half the clothing needed to lay down and sleep in extreme conditions.

This is for top, bottom, hands, head, and socks, including 1 light shell, 2 if for puffy clothing, but not including heavy rain shells, or shoes and boots. Clothing must also be suitably lofty outdoor clothing, like non-cotton skin layers, wool and fleece layers, down or synthetic fill layers, all reasonably well fitting and evenly distributed. The idea is you could just get dressed in it all before you go and weigh yourself full loaded without shoes and rain gear, and subtract your naked weight. This would also be a good check to see if all the layers are fairly evenly distributed, and fit inside one another so as to be worn in any combination.

The real question is whether the formula is right. It depends mostly on what activity level could be sustained for prolonged periods of exposure to the extreme conditions. I figure this should be something in between a slow energy conserving trudge, and sitting down now and then. Perhaps 150-200 kcal/hr.

Of course people could adjust the formula to suit their needs.

An idea I had was that individuals could calibrate their formula by dressing some very cold night for a long slow walk, wearing what they felt was appropriate. Maybe after the first hour of settling in they could combine walk and rest to stay just warm enough, and then using some tables or heart rate monitor estimate their calorie consumption, so they could adjust the formula if they felt they were too active or inactive compared to what they felt they could sustain for prolonged periods in a survival situation.

#109385 - 01/15/09 08:57 AM Re: Clothing Science and Folklore - open discussion [Re: JAK]
JAK Offline

Registered: 03/19/04
Posts: 2569
Here is a typical winter layering system for myself...
(I don't normally wear this all at once, but I could)

Feet: (not reall sure of these weights)
thin wool socks 2oz
thick wool socks 4oz
felt insoles ( I won't count these but I would could felt liners if I was wearing my mukluks)
subtotal = 6oz

Skin Layer 5oz
Intermediate Skin Layer normally reserved for sleeping 7oz
200wt fleece 12oz
Flannel Boxers (I won't count these because their cotton)
Rain/Wind Pants 6oz
Hiking Shorts (I won't count this 2nd shell)
subtotal: 5+7+12+6=30oz

Skin Layer 6oz
Intermediate Skin Layer normally reserved for sleeping 9oz
light wool sweater 20oz
100wt fleece 10oz
Wind Shell 4oz
Rain Shell (I won't count this 2nd shell)
subtotal: 6+9+20oz+10+5=50oz

Hat/Mitts: (not reall sure of these weights)
Alpaca Wool Hat 2oz
Knit Lopi Wool Necky 2oz
Light Wool Gloves 2oz
Medium Wool Mitts 2oz
hood with rain shell, pockets used as overmitts
subtotal: 2+2+2+2=8oz

grand total = 6+30+50+8 = 94oz ~ 6 pounds

Using my forumula this might be good for down to -9F ???
Seems about right, as its been more or less what I've been wearing on walks to work, through some woods and across some ice and through some more woods, but I would really have to test it out for a more prolonged period, at a slower pace.

Its a bit top heavy, but I think that is ok, and some of those top layers are overlapping to the butt area. I'll have to test things out to see where the weak points in my armour. For -20F this weekend I will need to add about 11oz more, so I will swap some stuff in and out from my closet. Don't worry, I won't be testing this too far from home. wink

Normal conditions we can and probably should delayer unevenly, but for the extreme for that trip, we should dress more evenly, but still a little more body than legs and arms. In Fall, the extreme might be 20F, and we might be dressed evenly if we got hit with that. In midwinter if we have clothing for -20F, then at 20F, even 0F, we can delayer unevenly, and also risk being more active through the day as we have more clothing to fall back on. Anything below 0F gets very sketchy though, as routine things like going to the bathroom and getting dressed and making water and making meals gets more and more critical, with less and less margin for mishaps. Going through ice is never a good thing, especially with any current, but its not quite the same on a sunny 20F day as it would be on a windy -20F night. Alot of people are so afraid of going through ice they don't prepare for it. Its best prevented by most all means, but if we still go out on the ice, even if its really thick, we should give some thought to going through. That's somewhat of a different topic, but some clothing is better than others for falling in and getting out and getting warm and dry again.

Edited by JAK (01/15/09 09:00 AM)

#109449 - 01/16/09 04:53 AM Re: Clothing Science and Folklore - open discussion [Re: JAK]
danneskjold Offline

Registered: 01/16/09
Posts: 2
Loc: Seattle, WA
Recently the Army came out with a new multilayer (7 I think) system that was based on a slightly (2-3 years) older system developed by Mark Twight for special forces.
The manual for it is pretty interesting, towards the back it gives a list of scenarios and what items in the layering system should be worn during those scenarios. Its pretty heavy on the "warm and wet" concept; the goretex jacket is not supposed to be used unless you are in a static position.

I hope this link works:

#109457 - 01/16/09 09:34 AM Re: Clothing Science and Folklore - open discussion [Re: danneskjold]
JAK Offline

Registered: 03/19/04
Posts: 2569
Well I did a little testing last night, -18F down to -24F, no wind though. From 10pm to 6:30am it wasn't long enough to figure out what works, but it was long enough to learn some more and know what doesn't. It also occured to me that the clothing formula also depends on a persons size as well as sustainable activity levels. Anyhow it seems to work for me but I will now modify it so that only the insulation layers count, and the shells and boots and shelter are extra.

85F - Tmin [degF] = minimum clothing insulation weight, in ounces
e.g. 20F = 4 pounds, 5F = 5 pounds, -10F = 6 pounds

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