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Keeping tent warm
- Thread starter OmegaA
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- Jun 16, 2003
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Brothers and Sisters,
1. "CLOTHING" vs "SLEEPING BAG."
Insulation is the result of "dead" (still) air trapped in the material used for insulation.
A sleeping bag is just a type of garment. All other things being equal, it does not matter whether the insulation that keeps you warm is called a "sleeping bag," a "blanket," or a "sweater." A layer of polyester fleece (for example) in a "sweater" keeps you warm just like as the same layer in a "sleeping bag" or "blanket." Keep this in mind when reading advice not to wear "clothing" inside a "sleeping bag." The trapped dead air does not know what name you are using.
(Of course, it is not helpful to wear garments made of the wrong materials (cotton) or to wear garments already damp.
2. MOISTURE MANAGEMENT
Water in insulation reduces it's insulative value. That is a problem with wool or polyester. It is a monster problem with cotton or down. Wool and polyester maintain 70-80% of their insulative value when damp. Down loses its insulative value - colapsing as it absorbs mositure. Cotton loses it's insulative value -- or if touching you has negative insulative value.
When sleeping, assuming the tent does not leak, water comes from three basic sources: a) water/snow you bring into the tent; b) water released when you exhale; and c) persperation. As to perspiration, you perspire to some extent all the time as your body tries to maintain 100% relative humidity next to your skin. If liquid does not form on your skin, the perspiration is called "insensate." You may perspire quite a bit in severe cold because the relative humidity goes down with the temperature.
To keep the inside of the tent relatively dry, you need to minimize "tracking" water/snow into the tent AND have ventilation from near the floor to a point as high as possible inside the tent. This allows warm, moist air to excape. Otherwise, you will get condensation --- even rain or snow -- inside the tent. "Breathable" tent walls are not a substitute for such ventilation. A tarp anchored to the ground and covering the entire tent will inevitably trap moisture.
To keep the sleeping garments relatively dry: a) use proper materials (polyester best; wool good); b) do not breath inside the garments; c) do not overinsulate. The warm, moist air resulting from persperation will reach dew point, becoming liquid water, somewhere. The colder it is, the more likely dew point will be reached inside the sleeping garments. Branded polyester filling is silicon-treated to facilitate mositure transport driven by body heat. In severe cold, ice can form inside the sleeping garments. (A North Pole expedition was forced to abandon its bags for sustitutes due to the weight of ice trapped in the bags.)
WEIGHT OF BAGS
I have a -30 rated Slumberjack sleeping bag that weighs nine pounds. I have used it at -27 f (-47 c). It's weight is not unusual in bags constructed of nylon and poyester batting.
AIRING OUT GARMENTS
In our local climate, where daytime Winter temps are typically above 20 f and the days without sunshine, down collects moisture despite all measures to avoid it -- solely from perspiration from the sleeper. In thirty years of Winter camping here and in Michigan and Pa, there has been little success in drying damp garments except on unusually cold days when the mositure freezes and then subliminates into gas.
1. "CLOTHING" vs "SLEEPING BAG."
Insulation is the result of "dead" (still) air trapped in the material used for insulation.
A sleeping bag is just a type of garment. All other things being equal, it does not matter whether the insulation that keeps you warm is called a "sleeping bag," a "blanket," or a "sweater." A layer of polyester fleece (for example) in a "sweater" keeps you warm just like as the same layer in a "sleeping bag" or "blanket." Keep this in mind when reading advice not to wear "clothing" inside a "sleeping bag." The trapped dead air does not know what name you are using.
(Of course, it is not helpful to wear garments made of the wrong materials (cotton) or to wear garments already damp.
2. MOISTURE MANAGEMENT
Water in insulation reduces it's insulative value. That is a problem with wool or polyester. It is a monster problem with cotton or down. Wool and polyester maintain 70-80% of their insulative value when damp. Down loses its insulative value - colapsing as it absorbs mositure. Cotton loses it's insulative value -- or if touching you has negative insulative value.
When sleeping, assuming the tent does not leak, water comes from three basic sources: a) water/snow you bring into the tent; b) water released when you exhale; and c) persperation. As to perspiration, you perspire to some extent all the time as your body tries to maintain 100% relative humidity next to your skin. If liquid does not form on your skin, the perspiration is called "insensate." You may perspire quite a bit in severe cold because the relative humidity goes down with the temperature.
To keep the inside of the tent relatively dry, you need to minimize "tracking" water/snow into the tent AND have ventilation from near the floor to a point as high as possible inside the tent. This allows warm, moist air to excape. Otherwise, you will get condensation --- even rain or snow -- inside the tent. "Breathable" tent walls are not a substitute for such ventilation. A tarp anchored to the ground and covering the entire tent will inevitably trap moisture.
To keep the sleeping garments relatively dry: a) use proper materials (polyester best; wool good); b) do not breath inside the garments; c) do not overinsulate. The warm, moist air resulting from persperation will reach dew point, becoming liquid water, somewhere. The colder it is, the more likely dew point will be reached inside the sleeping garments. Branded polyester filling is silicon-treated to facilitate mositure transport driven by body heat. In severe cold, ice can form inside the sleeping garments. (A North Pole expedition was forced to abandon its bags for sustitutes due to the weight of ice trapped in the bags.)
WEIGHT OF BAGS
I have a -30 rated Slumberjack sleeping bag that weighs nine pounds. I have used it at -27 f (-47 c). It's weight is not unusual in bags constructed of nylon and poyester batting.
AIRING OUT GARMENTS
In our local climate, where daytime Winter temps are typically above 20 f and the days without sunshine, down collects moisture despite all measures to avoid it -- solely from perspiration from the sleeper. In thirty years of Winter camping here and in Michigan and Pa, there has been little success in drying damp garments except on unusually cold days when the mositure freezes and then subliminates into gas.
Ditto on getting a good bag & a good sleeping pad (I like to add a closed cell pad under my thermarest when it gets really cold out)
eat something prior to turning in - stoke your internal fire, so to speak (I usually eat a granola bar).
take a 1 liter nalgene bottle, fill it w/ hot water, stick it in a sock & put it in the foot of your sleeping bag.
eat something prior to turning in - stoke your internal fire, so to speak (I usually eat a granola bar).
take a 1 liter nalgene bottle, fill it w/ hot water, stick it in a sock & put it in the foot of your sleeping bag.
I second the candle lamp method. This is not an item that should be improvised due to safety factors. Buy a commercial one, and stick with the instructions.
A candle lamp will supply a surprising amount of warmth, particularly if you have a small hiker tent.
A candle lamp will supply a surprising amount of warmth, particularly if you have a small hiker tent.
Codger_64 said:
Yes. It can also introduce excess moisture and soil deposits if not wiped down during bad weather or in close proximity to bodies of water. Occasionally it produces low frequency snoring noises and twitching movements, but this is quickly ended by a sharp elbow. Deluxe model comes with an adjustable motion detector and audible alert feature.
- Joined
- Nov 29, 2001
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Definately go with the layered clothes and sleeping bags. We bought the SPEAR system and have great sleeping bags. With a good hat I'm toasty warm in the morning - snuggling helps but then you get overheated. 
Suzanne Settle
Owner
Bear Mountain Tomahawks
www.bmtomahawks.com
Suzanne Settle
Owner
Bear Mountain Tomahawks
www.bmtomahawks.com
I'm supprised no one has offered the Hot Rock or the fire Pit methods. Heat rocks in the fire and bury them under the tent, or just build a long bed fire in a pit and let it burn to coals. Bury it in several inches of dirt and pull the tent over it. Move the fire back and forth if you stay in the same site several nights.
I have slept a few nights in the snow with a small two man tent from Eureka and good bags. Woke up in the morning and suprised to see that it had snowed.
Badge54
I have slept a few nights in the snow with a small two man tent from Eureka and good bags. Woke up in the morning and suprised to see that it had snowed.
Badge54
- Joined
- Nov 29, 2001
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I tried that once, did it wrong and it was too smoky to sleep.
Suzanne Settle
Owner
Bear Mountain Tomahawks
www.bmtomahawks.com
Suzanne Settle
Owner
Bear Mountain Tomahawks
www.bmtomahawks.com
- Joined
- Dec 10, 2000
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- 554
20+ years in the Army taught me a little about staying warm. I spent some time on jump status where I learn all about "travel light freeze at night"! Some thoughts:
1. Always wear something inside your sleeping bag. It keeps it cleaner and allows it to breathe easier. I used to put on a set of clean dry thermals at night and then change back into my wet and dirty thermals and uniform in the morning.
2. Always wear a hat. You do loose a lot of heat through your head.
3. If your feet are cold put a vapor barrier over the foot end of your sleeping bag. We used to carry our sleeping bags in a waterproof bag and I would use that, just pull it over the foot end of my bag. Works like a charm. Just be sure to dry the bag out whenever you get a chance.
4. Use plenty of insulation under the bag. A thermarest or other foam mattress is worth its weight in gold.
5. Eat something with some fat in it before you go to bed. Hot cocoa with a table spoon or two of margarine works well.
6. Do a few isometric exercises in the bag to fire up the body temp.
7. A lantern, either propane or even a candle type helps and I used to brew up using a stove in the morning.
Hope this helps.
1. Always wear something inside your sleeping bag. It keeps it cleaner and allows it to breathe easier. I used to put on a set of clean dry thermals at night and then change back into my wet and dirty thermals and uniform in the morning.
2. Always wear a hat. You do loose a lot of heat through your head.
3. If your feet are cold put a vapor barrier over the foot end of your sleeping bag. We used to carry our sleeping bags in a waterproof bag and I would use that, just pull it over the foot end of my bag. Works like a charm. Just be sure to dry the bag out whenever you get a chance.
4. Use plenty of insulation under the bag. A thermarest or other foam mattress is worth its weight in gold.
5. Eat something with some fat in it before you go to bed. Hot cocoa with a table spoon or two of margarine works well.
6. Do a few isometric exercises in the bag to fire up the body temp.
7. A lantern, either propane or even a candle type helps and I used to brew up using a stove in the morning.
Hope this helps.
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Good thread and good tips, in this season I think it would be worth to keep it as a "sticky" in this forum category.
Is there some moderator already awake to do this if he deems it useful?
Is there some moderator already awake to do this if he deems it useful?
This is what we did in the British Army too. Great at night, not so fab on a Jan morning after when you have to put the wet (not to mention, monkeys cold) kit back on.
I also did this on a 3 month tour of Australia in 01. You have to have a warm, dry, clean place to go. The regimen of it helps too especially if you tend to sloppy.
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rnpollard said:
Vapor barriers add warmth and do not wet the insulation layer if placed over the body part and under the insulation. In my area, the bag once wet stays wet. That problem prohibits placing anything not "breathable" over the outside of any part of the sleeping bag -- or any part of your other garments for that matter. I have a pair of socks too thick to use as socks that are just the ticket for keeping the feet warm in the sleeping bag in Winter.
You might want to check out this product.
http://www.zodi.com/web-content/Consumer/zodihotvent.html
Zodi's Tent Heater. It allows the heating element to be outside your tent. I keep it in my rain fly, and it just vents the warm air into the tent. It works amazingly well.
http://www.zodi.com/web-content/Consumer/zodihotvent.html
Zodi's Tent Heater. It allows the heating element to be outside your tent. I keep it in my rain fly, and it just vents the warm air into the tent. It works amazingly well.
Cliff Stamp
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Thomas Linton said:
No it doesn't, there is a huge difference between a sweater and a sleeping bag made out of the exact same material just like there is a huge difference between gloves and mitts (no fingers in mitts). Ask anyone who is outside in decent cold temperatures if gloves or mitts are warmer. A sleeping bag and mitts don't insulate your body from itself, a sweater and gloves do.
-Cliff
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Cliff Stamp said:
This issue was whether or not wearing dry insulative clothing inside a sleeping bag would cause total insulative value to be reduced.
Please note "all other things being equal." If you are saying that design matters, sure. Gloves present greater surface area for heat loss than mittens so they are not as efficient at trapping body heat even if made of the same thickness of the same material. That is, all other things are NOT egual in a glove vs. mitten comparison.
If you are agreeing with the urban legend that wearing (dry) insulative clothing inside a sleeping bag reduces total insulative value, we must agree to disagree. Wearing dry insulative clothing inside a "sleeping bag" just adds the value of the "sleeping bag" garment to the value of the "clothing" garment(s) = more total dead air = "warmer."
Cliff Stamp
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Thomas Linton said:
The biggest issue is they prevent your body from warming itself, similar to two people sleeping in individual bags vs together. Your fingers will warm each other in a mitten, they can't in a glove.
Not unless it overheats and causes you to sweat, but the wrong bag can do that on its own
-Cliff
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Hiya Omega,
Some simple rules will help you no matter what kind of equipment you are using.
Increase your insulation versus the ground, it is a massive heat sink and will pull heat from you and your shelter.
A flame heat can be safely used, if you are careful with it. Candle lanterns, tea lights or a Nu-Wick Can Candle all can help warm and dry the air in the tent, but don't ever leave them on when you are sleeping. We are not talking about great big flame here, you don't need a stove or a bonfire.
Increase layering of your bag. This will be more effective than adding clothing and sleeping in your bag clothed. An alternative is to use a Space blanket type emergency sleeping bag as a bivy sack. The Thermolite Emergency bivy available from Camp-Mor is what I use. It weighs 7 ounces is wind and water proof and adds a lot of warmth, they also are available in double size, if you need to add a bit of cuddle factor. Double (two person) sleeping bags are the best bet for really cold weather. Doubled (two bags, one stuffed into the other) bags are best if you are sleeping single.
If you are car camping, carry whatever kind of catalytic contraption fits your budget and is safe. It ain't my style for camping, but if it gets you out of town, I'm all for it, even if it is car camping.
Conquer yourself first, all else will follow.
KJM
Some simple rules will help you no matter what kind of equipment you are using.
Increase your insulation versus the ground, it is a massive heat sink and will pull heat from you and your shelter.
A flame heat can be safely used, if you are careful with it. Candle lanterns, tea lights or a Nu-Wick Can Candle all can help warm and dry the air in the tent, but don't ever leave them on when you are sleeping. We are not talking about great big flame here, you don't need a stove or a bonfire.
Increase layering of your bag. This will be more effective than adding clothing and sleeping in your bag clothed. An alternative is to use a Space blanket type emergency sleeping bag as a bivy sack. The Thermolite Emergency bivy available from Camp-Mor is what I use. It weighs 7 ounces is wind and water proof and adds a lot of warmth, they also are available in double size, if you need to add a bit of cuddle factor. Double (two person) sleeping bags are the best bet for really cold weather. Doubled (two bags, one stuffed into the other) bags are best if you are sleeping single.
If you are car camping, carry whatever kind of catalytic contraption fits your budget and is safe. It ain't my style for camping, but if it gets you out of town, I'm all for it, even if it is car camping.
Conquer yourself first, all else will follow.
KJM