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Thermawrap warm enough?
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Aug 7, 2007 at 9:58 am #1397682
Doug – I would be comfortable with your system.
Brian – Yours is more borderline, but I think I could stay comfortable.
Richard – Please tell us more about how your watch works. This is exactly the sort of information I come here for.
Aug 7, 2007 at 11:31 am #1397691Brian, I wonder if you might be better off with stretch woven pants over spandex shorts rather than smartwool long johns under golite reed pants.
I don't know what precipitation is like in RMNP, but I imagine that it's the typical afternoon thunderstorms found in the mountain west. In those conditions, rain pants are not so versatile, and the stretch wovens really shine-they are warmer than the long john/ reed combo (in my unscientific opinion)yet breath better- more comfortable in a broader range of conditions, take a while to wet out, and dry quickly when they do.
pack those thermawrap pants and you are good into the twenties. this is my go-to summer layering system.
Aug 7, 2007 at 2:36 pm #1397724Joshua – Most, if not all, of the International thermal standards use the same theoretical male and female.
If you multiply the W/m2 times the surface area, you will get a resting wattage of 80.1 (1 MET). When sleeping they will only use .8 MET and so the sleeping wattage is 64.1 watts.
You are correct regarding your thermal insulation factoring procedure for a different BMR.
Aug 7, 2007 at 2:39 pm #1397727Perfect! That's exactly what I was looking for. If it was in the report, I simply couldn't find it.
Woohoo… time to go geek out…
hmm… that's not right… I can't have a 40% lower than… oh, okay that's 80.1 W not 80.1 W/m2… that makes more sense…
hmm… one more question. One does NOT need to adjust the BMR in these calcs for the whole, 'about 75% of the energy expended winds up in heat'… aka the calcs already take the 75% rule of thumb into effect, correct?
Aug 7, 2007 at 3:09 pm #1397730Joshua – Correct.
The definition of the standard male and female wasn't included in any public domain document that I am aware of. The first time I tried to understand it, I got stuck the same place you did.
Aug 13, 2007 at 3:26 pm #1398461I think you'll be fine. I use a system very similar to what you described. My system includes:
Base Layer
– Short Sleeve T (I like the terramar anti-odor series)
– Long Sleeve mid-weight shirt
– Campmor Microfleece tights for sleepingMid Layer
– Micropuff Vest
– Montbell UL Down Inner JacketShell Layer
– Marmott Chinook wind jacket with hood
– DriDucks Rain Gear with hood (may not be great choice if you anticipate lots of hail or snow)Extremities
– Two-layer gloves, fleece inserts and waterproof shell
– micro-fleece REI hat
– microfleece headband (great for 40's hiking, where full head coverage is too warm)
– Outdoor Research sun-capSleep
– MH Phantom 32
– Big Agnes Aircore matIf I am dry, and wear all of my layers, this will keep me warm into the 20's no problem. I've never camped in the teens, but I would think that the sleeping bag + all clothes will keep you warm.
I've used this system on several Rockies summer camping trips, with lows into the low 30's, and have never felt like I was under-dressed.
I do think there is some risk of being cold if you get soaked to the bone for some reason, and you encounter extreme cold temps. But that shouldn't happen, and it's never happened to me.
I think you'll be fine with your equipment setup. Enjoy the trip.
-G$
Aug 14, 2007 at 1:16 am #1398526Thanks for the good info. I do have a basic question about figuring values on sleeping systems – are the sleeping bag comfort ranges that are given by manufacturers based on using the sleeping bag in the open, in a single walled tent where you need a lot of ventilation, or a double walled tent (that could presumably slow heat loss from the surrounding air)?
I found that I tend to have more trouble predicting what will be neccessary to sleep comfortably than I do with figuring out what to bring to stay warm while awake, maybe because I get into my sleeping bag when it gets too cold.
I'll be in the high Sierras around Yosemite in late summer and I am having trouble figuring out whether i should get a 20 or 30 degree bag (Western Mountaineering). As these bags are pretty expensive I'd like get the lightest one that can keep me warm for summer camping conditions (down to freezing I figure) so i really need to know how these bags are rated. Then i can factor in the difference for keeping warm between sleeping on the open, or single walled, or double walled tent. Then factor in age and gender differences. I'd be wearing some midweight smartwool to sleep in.
I mostly camp at higher altitudes, but below 8k ft, and only in the summer thru September. I don;t really know how cold I can can expect it to get at night either. If anybody has this info I would really appreciate hearing about it.
I'll be getting a bag with a full zip so that i can use it in warmer conditions as well, which is another reason for not getting a bag that is warmer than I need.
Aug 14, 2007 at 7:27 am #1398543Terry – Most sleeping bag insulation values are measured in a temperature controlled rigid enclosure without any wind (forced convection). The rating is generally applicable to any enclosure which effectively blocks the wind (single wall tent, double wall tent, or tarp).
Effective tent venting, such as one high and one low vent, will allow natural convection to remove water vapor and prevent forced convection from reducing the sleeping bag's temperature rating.
If you purchase a bag accurately rated for the average low temperature you expect, you can augment it with your clothing insulation when required.
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