Temperature

3:11 p.m. on May 14, 2002 (EDT)
(Guest)

This is an odd question, but I'll ask it the best I can. Let's say the outside temperature is 45 degrees. What would the temperature be inside your average decent tent? Does the tent provide an extra 10 degrees warmth, 20 degrees, or what? I do have a reason for asking this, even though it sounds a little strange. I would appreciate any input on my wierd question.

8:15 p.m. on May 14, 2002 (EDT)
37 reviewer rep
747 forum posts

Quote:

This is an odd question, but I'll ask it the best I can. Let's say the outside temperature is 45 degrees. What would the temperature be inside your average decent tent? Does the tent provide an extra 10 degrees warmth, 20 degrees, or what? I do have a reason for asking this, even though it sounds a little strange. I would appreciate any input on my wierd question.

Tough question Grace. It depends on a balance of ventilation, how many people are in the tent, other heat sources like a candle lantern or dog, and how the people are dressed and whether they are in sleeping bags and whether or not its screen tent - wind conditions.

Since you used the figure - outside 45 degrees and didn't mention wind - and I will assume two people in a small double walled nylon tent - not screen, no dog. I think you might expect to close-up your tent in windless conditions and take off your coats and have the tent warm up enough from your body heat to keep you as warm as with your coats on outside - maybe 20 degrees worth of effect? In bad windchill situations the effect is far more dramatic though.
With one person in a sleeping bag in a well ventilated tent - there is little warming of the interior except by your breath.
Jim S

6:49 p.m. on May 16, 2002 (EDT)
(Guest)

Me blowing hot air

Hi Grace,
I read your post when it first came out, and I have been wondering for 2 days on how I can answer your odd question by not answering it. You see, once a while, we get questions just like this one.

In short, it all depends on... Well, here is your answer, may be that is why backpacking is a key part of experiential education.

Bump up your milage and you'll get your answer, or... rephrase your odd question to something like... what should be the temp rating of my sleeping bag? Can I melt snow inside my tent? What is the greenhouse effect inside my tent on a 45F/sunny day vs. a 45F/cloudy day? What is radiation cooling? Can my tent gets wind-chilled? How many candles can I use inside my tent? Or how many men and cans of bean can I use to blow enough hot air for every 10F increase in temp?

You see, an odd question deserves a wierd answer. Good luck in your own experiential learning. :-))

4:33 a.m. on May 17, 2002 (EDT)
(Guest)

In *MY* experience with solo tents, I get 10 degrees out of the tent. Meaning if it's 45F outside, it'll be 55F inside my solo tent. NOW, how this translates to bag rating, I have no idea...does a 20F bag mean "good down to 20F sleeping outside with no pad", or "good down to 20F on a self-inflating pad inside a tent"? Also, does it mean "20F bare-ass naked", or 20F in boxers and a t-shirt"? NOW add to the equation whether you are a warm sleeper or cool sleeper..

For example, for *ME*, temps down to 45F, I don't bring my 20F bag- I bring my 55F fleece bag. Because not only do I get 10F out of the tent, but I could also wear a pair of thermals & get another 8-10 degrees of warmth. This is the sort of experimentation that is half the fun of backpacking!

Good luck,
ELi

8:40 a.m. on May 17, 2002 (EDT)
(Guest)

Thanks for your answers to my odd question. Or at least thanks to some of you. A couple of you made some sense. As I said, I did have a reason for asking the question. My 11 & 14 yo boys are going on a 50 mile bp trip on the AT this July. I have heard that the temps drop at night (possibly down to 45 degrees. There Slumberjack 15 degree mummy bags weigh just under 3 lbs. We have just ordered a liner/summer sleeping bag of the same brand which is only 1 lb 8 oz. These kids have never done this kind of hike before and I want them to be as light as possible. I don't want them to learn to hate bp. I am assuming this liner/sleeping bag is 55 degrees as I have noticed that is what most are. I will check to make sure. So I feel we are right on that fine line of "which one do we take?" I really don't want to send them with extra weight if it isn't necessary. I was thinking along the line of the warmth a two man tent would provide and yes, sleeping in thermal underware. The question made sense to me. Obviously it made sense to a couple of you also. Thanks again for the responses. I would still appreciate anyone wanting to provide further input.

8:57 a.m. on May 17, 2002 (EDT)
30 reviewer rep
1,240 forum posts
Grace's question is perfectly understandable to me!

you think wandering how warm it will get inside the tent and thus how to prepare her kids for cold weather is strange?

9:10 a.m. on May 17, 2002 (EDT)
(Guest)

Jumping the gun... hot air and powder smoke.

No strange. Just a bit smokey about the timing of the 2 postings. :-))

10:58 a.m. on May 17, 2002 (EDT)
30 reviewer rep
1,240 forum posts
Les, sorry man, I have absolutely no clue as to what you are talking about!

Perhaps thats a good thing.

1:12 p.m. on May 17, 2002 (EDT)
(Guest)

Grace,

I suggest that you ensure the boys each wear a toque (fleece skull cap for you south of the border folks) when they sleep at night. It will make a big difference in their comfort. Also, ensure they stay well hydrated and perhaps have an energy snack prior to turning in for the night.

D

1:54 p.m. on May 17, 2002 (EDT)
(Guest)

Just one question... any cotton?

In reference to your original question, it is so tempting to give you an equation and the coefficient of heatloss of an average decent tent... Some of us have correctly guessed that it is really a bag question and not a tent question, nor about dogs or candles. Enough said.

You are on the right track, and since I don't know anything about your experience, I like to ask this one question: is there any cotton blend in any of the sleeping bag material and in the thermal underwear? I'm sure other can pick up on this topic if needed. Cheers. :-))

2:48 p.m. on May 17, 2002 (EDT)
(Guest)

Grace:

45 F is a pretty mild temperature assuming:

1) your boys bring adequate insulation from the ground (thermarest, ridgerest or ensolite)
2) they have a quality tent (not a $25 special or a tarp)
3) they are able to camp in an area that is protected from the wind (not too hard below treeline)

If the liners are indeed rated to 55 F your boys should be able to get to the comfort zone by adding clothing and taking the advice of Diligence - hat, calories, hydration.
A small candle lantern will also help. If you are still not sure, here are some other options:

a) if the liners will open like a blanket, by 3 and have the older boy carry the extra. This way they can spread out the third on and lay it over the top of them if needed. Your younger son will be more likely to sleep cold because he will have more air circulating around him, in which case he could use two liners, one inside the other.

b) vapor barrier liners are very effective at maintaining body heat by preventing evaporative cooling. They are also lightweight and inexpensive. While normally used to get more performance out of very low temp bags and prevent the down from absorbing moisture, they could still be used in milder conditions as long as the boys are cautioned not to use them until they get cold inside their bags (stick the vbl in the bottom of the bag with feet inside and pull up if needed.) Avoid sweating.

If you are worried about them carrying too much weight, make sure that they are carrying adequate clothes for warmth, but not excessive clothing for "cleanliness." This is the mistake that most people make. What happens is they end up carrying a whole bunch of grungy clothing instead of just one set of grunged out clothes and end up in the same situation with a much heavier pack than is necessary.

Also remember, in the mountains, cotton is the enemy. Very good deals are available on fleece clothing for kids at Kmart, Wallmart, Target, etc. Leave North Face and Patagucci to sponsored expeditions and/or yuppies.

And don't worry, they'll have a blast.

6:02 p.m. on May 17, 2002 (EDT)
(Guest)

a.k.a. Markmc

Quote:

does a 20F bag mean "good down to 20F sleeping outside with no pad", or "good down to 20F on a self-inflating pad inside a tent"?

I wanted to know this just last March. One of the NOLS books inidicated that bag temp ratings are based on 'in a tent with a pad'. Made sense to me.

7:05 p.m. on May 17, 2002 (EDT)
(Guest)

Thanks guys. I think I know my answer now. I'm not sure exactly what it is yet, but I know my answer is within these posts somewhere. I'll put it all together and come up with the right answer in time. You have given me a lot of helpful info to consider. Maybe the next time I ask a question, it will have a simpler answer... like maybe YES or NO. But then you guys with all the knowledge and experience wouldn't have as much of a challenge answering it would you. Almost sounds boring!

12:41 p.m. on June 14, 2002 (EDT)
(Guest)

Quote:

This is an odd question, but I'll ask it the best I can. Let's say the outside temperature is 45 degrees. What would the temperature be inside your average decent tent? Does the tent provide an extra 10 degrees warmth, 20 degrees, or what? I do have a reason for asking this, even though it sounds a little strange. I would appreciate any input on my wierd question.

I wouldn't send my children out with minimal protection. One of the most enjoyable parts of camping is resting warm at night in your bag. If you are too cold you will not sleep well and you will hate the trip. I took a friend backpacking in the Sierras and he brought only a 40 degree bag. This isn't nearly enough in the high Sierra. About 2 in the morning he is sliding up under my bag trying to get warm. Meanwhile I am sleeping comfortably. He hated the trip.

I think the key is not to depend on the tent to keep you warm. If it is real windy the tent may provide little if any warmth. If your sons pick a good camping site that is free of wind then the tent will add some warmth. However, tent designs vary so much that it would be impossible to say how much warmth tents provide.

My rule of thumb is get a bag rated 5 degrees above the expected low temperature. For example if the lows are in the 30s then get at least a 25 degree bag. Don't expect the tent to do anything other than repel rain and/or snow and some wind.

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