Heat transference between layers (when camping)

General cycling advice ( NOT technical ! )
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horizon
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Re: Heat transference between layers (when camping)

Postby horizon » 1 Sep 2019, 9:23pm

PDQ Mobile wrote:Clothing is better used as insulation outside the bag.


Very, very interesting. I would really like to hear some more comments on this - it's very much at the heart of what I've been trying to work out.
I have two doctors, my left leg and my right leg. (G. M. Trevelyan)
PS I always wondered why the YHA HQ was called Trevelyan House. :)

PDQ Mobile
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Re: Heat transference between layers (when camping)

Postby PDQ Mobile » 1 Sep 2019, 10:02pm

^^
My understanding is that the sleeping bag is specifically designed to insulate. Therefore if you warm its inner layers it is the most efficient part at holding that heat.
Down actually lofts in response to heat so the effect in a down bag is even more pronounced.
Clothing (and/or layers of newspaper) for the most part is better underneath you.
My personal method is that i carry a double emergency bag- just a cheap plastic one- bright orange!
(2 man tent pitches fly sheet first)
I put that orange plastic under the ground sheet and usually put the Karrimats on that sandwiched and held by the groundsheet.
Sleeping bags then go direct onto the rather flimsy ground sheet.
In very cold ground conditions a fleece and newspaper can be added under the bag at the pressure points.

I have an old but quality (Mountain Equipment Lightline) 2season down bag. Always used with a silk liner to keep bag inner clean.
Wear just thin underwear.

Have slept pretty comfortably in minus 10c with an additional cover over everything (had vehicle) - nose gets cold! Inner needs to be pretty open to fly space or tiny ice crystals form and fall on you.

Just my way.

Other do it otherwise I am sure.

Barks
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Re: Heat transference between layers (when camping)

Postby Barks » 1 Sep 2019, 11:06pm

For best performance:

Use high quality air bed (like Therma Rest Neo Air series, they have various cold ratings and they are very durable and easily repaired if worst happens)
Use down quilt - down underneath is waste of time as it compresses to nothing - with sufficient rating for expected temperature range
Wear socks hat and merino woool thermals
Use a silk liner - adds warmth and keeps sweat and dirt away from very expensive down quilt
Do NOT breath inside the sleeping bag or quilt under any circumstances.

If gets so cold that you can’t stop shivering add extra clothes layers and have a hot drink. If that doesn’t work you are potentially at risk of hypothermia so commence emergency actions including considering requesting assistance.

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horizon
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Re: Heat transference between layers (when camping)

Postby horizon » 1 Sep 2019, 11:16pm

Barks wrote:
If gets so cold that you can’t stop shivering add extra clothes layers and have a hot drink. If that doesn’t work you are potentially at risk of hypothermia so commence emergency actions including considering requesting assistance.


One sleeping bag maker said that TOG ratings are all very well but sleeping bags can only keep heat in: they don't produce heat - they need a source of heat. This will vary from person to person. A hot water bottle/hot drink would at least be a source of heat.

add extra clothes layers
Or not? Or add them under or over the bag?
I have two doctors, my left leg and my right leg. (G. M. Trevelyan)
PS I always wondered why the YHA HQ was called Trevelyan House. :)

Tangled Metal
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Re: Heat transference between layers (when camping)

Postby Tangled Metal » 1 Sep 2019, 11:20pm

My experience is my own and I do not expect everyone to agree with what I outline below but I'll put my experience out there anyway.

Sleeping bags work best when free to loft to their fullest. So do not add clothing on top or wear inside. Doing so will offer less insulation than you lose from compressing the most efficient insulation you'll carry to your camp.

Extra clothes do not add much to your warmth, neither do liners of any commonly sold variety including silk. In fact there has been research I once read that said no clothes or only very thin clothes is warmer than thicker clothing inside the bag.

Warm, dry socks are nice.

Buy the sleeping bag that fits you. Size plays a part. Too long and you'll heat wasted volume. Too small and you'll get freezing cold feet. Trust me. I'm tall and for years used a warm synthetic sleeping bag that always left my feet cold. I figured it out and bought an American brand marmot bag in xl and warm feet from that night onwards. Being American xl also meant too much girth in the bag. This is not as big an issue though and would allow layering inside he bag since I'm relatively slim.

Hats dont help for mummy sleeping bags. Keep the hat in your bag so it's nice and warm for when you get up though.

Hats are essential for quilts.

Quilts are at least a warm as sleeping bags ime. However get a good one. Mine was made by the now defunct brand golite. It's got a sleeping bag foot with water resistant fabric at the foot and head opening to account for foot contact with the tent wall and your moist breath.

Mats? Ccf, insulated air mat or TAR? It's your choice. If the mat has good enough tog or similar rating then it's good enough. You always used to get warnings of leaking TAR mats and Ccf is best. Now those warnings are about air mats. IME I've never had a puncture in a TAR but have in a cheaper version from vango. Buy good quality you'll probably not have many issues. I've used exped UL synmats before. Very warm compared even to 4 season ccf from good makes.

Tent choice is important. Mesh inner walls and American tents with high gap flysheet tents have too much draft in wind. Avoid if you are planning on using in cold or windy conditions.

Above all my experience is that you buy the kit to suit the use you have for it. If your bag is too cold it's the wrong bag. If your tent is letting the storm in, potentially with wind carried rain, then it's the wrong choice of tent. If you feel cold from below your mat is wrong one. There is no good way around a bad choice of equipment.

One last point is based only on my understanding of PhD designs of sleeping bags and extras. Their system of layering sleeping bags is based on a larger outer bag. They account for giving the inner bag room within the outer bag. That works because its a designed system. You cannot bodge that level of design afterwards.

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NATURAL ANKLING
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Re: Heat transference between layers (when camping)

Postby NATURAL ANKLING » 2 Sep 2019, 1:18am

Hi,
On socks, probably not so important with cycling as opposed to walking, but if your feet get wet from rain or sweat, in bag make sure the socks are unused and dry, if your feet are wet etc, socks hold the moister in and feet will not be dry enough for next day, blisters will form quicker.

I find that I sweat quite a lot in sleeping bag, even if on the edge, so I expect sweats and come early in the morning chills even shakes too, sun up that normally subsides.
Most difficult to get comfort just right, if you have been exercising in the day, and tent is well vented over night (mesh 3 season), wind blows and inner space is colder.

Personal taste and some of us are colder, make sure inner clothing if you wear any is lightweight as possible to minimise moister retention and thus chills later on which can wake you.

Colder people need more insulation for sure.

Be careful against any tight spots in your bag, this will give cold spots which you may well feel.
A lightweight bivvy bag breathable is a good thing to have, I found that on my latest jaunt I got wet overnight in a downpour (long story) but wet and cold got into bag and bivvy and warmed up, cheap bivvy £23 waterproof and breathable suposidly, had zero condensation with a dry bag when I got up. 360 grams you could probably get lighter, a must if you intend to camp, makes a good emergency shelter if caught with no shelter in a downpour.

Things guaranteed to depress you, cold, cold and wet, cold and hungry. Wet and hungry I will take as a better than the formers.
Always carrying some emergency rations is mandatory for me.

When camping with another in same space, I could notice it was warmer, whether this is simply down to less air to heat per person or simply less air hard to say. So possibly less air in the inner is warmer?
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drossall
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Re: Heat transference between layers (when camping)

Postby drossall » 2 Sep 2019, 9:29pm

I'd agree that a mat, then a bag, and then a small tent are the things to look at - the small tent because your body has to heat the space. I've always understood that the main role of clothing etc. is to trap air layers; these layers do much of the insulation so, all other things being equal, extra layers are better than thicker ones. (Also you can fine-tune temperature with several thinner layers.)

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Re: Heat transference between layers (when camping)

Postby sizbut » 2 Sep 2019, 10:04pm

Best improvement in my sleeping gear in the last few years has been a longer, wider sleeping mat. As a 185cm bod, my feet were always over the end of the previous ones and that clearly compromised the effect. Now I have a mat that is 195cm in length and a lovely 65cm wide and its been a great couple of years camping.

Hat and then socks next if its really parky and a then a lightweight camping duvet (Alpkit) to go over the sleeping bag if it really is too cold. Easy to throw off, add back on without too much fuss, and useful too when just sitting around.

I can't do clothes as I just wake up with a damp t-shirt or whatever (never worked out why its not a damp sleeping bag, probably unconsciously stick my arms out if overheating.

Food is good too. Eat late. When I eat I get hot as the stomach gets to work. So use that free energy.

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Re: Heat transference between layers (when camping)

Postby Tangled Metal » 2 Sep 2019, 10:25pm

To think a double layer of think nylon or polyester is a great insulator! I'll wrap my house in it and watch my heating bills shrink this winter!

Sorry for the facetious comments above. The tent only cuts out the wind and rain. It offers no insulation in itself. You can find shelter without a tent or tarp and just using your sleeping bag and mat if you know a good location. Not to recommend it as a tent or tarp is kind of reassuring.

Mat and sleeping bag are the only real ways of getting your insulation right. You have to get the right ones for your intended conditions and your personal choices. The tent is just the windbreak.

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Re: Heat transference between layers (when camping)

Postby Tangled Metal » 2 Sep 2019, 10:34pm

185cm is the typical maximum length for sleeping bags for men. Do you find you have cold feet? Are your feet at the end of your bag and compressing the insulation at the foot end?

I'm 196cm and for years shoe horned myself into a standard length bag. Until I heard about a shop 40 minutes away from where I worked from a bargain thread online that was selling a bag that was reasonable weight, xl size, from a good brand and a bargain price. I left work at lunch (early finish Fridays) and bought it. Instant foot warmth. A year later the same website bargain thread had a tip for the same shop selling an even better quilt for even less money. No brainer. I now have a supposedly - 7C UL quilt in xl that only cost £100 is 600g on weight, 950 fillpower down and small pack size.

Buy well and you're warm. Buy poorly and you're cold. Simple case of working out your intended use and conditions.

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Re: Heat transference between layers (when camping)

Postby sizbut » 2 Sep 2019, 11:11pm

"The tent only cuts out the wind and rain. It offers no insulation in itself." - Sorry but it does. Stopping that air movement is a huge plus. Heat is moved around through the processes of radiation, conduction and convection. A tent wall might seem thin but it massively reduces the convection route for heat loss. Plus I like staying dry too.

But good to mention location. That spot down the slope of the field by the river is lovely in the evening, and a total frost, fog, mist magnet over night. Use the hedges and your neighbours big tents as wind breaks. There can be surprisingly large variations in temperature within the bounds of the same field.

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Re: Heat transference between layers (when camping)

Postby NATURAL ANKLING » 2 Sep 2019, 11:45pm

Hi,
Then it rains :?
Tent ticks all the boxes.

On my really cheap tent I pull the fly to the floor, then even when the wind blows not much effect on the inside.

In the past up on the Cheviot could still read a map overnight (you need to be up a hill away from town lights so your eyes are wide open) left the tent (Campari) door open, sheep pulled my sack out and socks too.
Door open all night even in my cheap milets bag
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Re: Heat transference between layers (when camping)

Postby drossall » 3 Sep 2019, 10:10am

sizbut wrote:"The tent only cuts out the wind and rain. It offers no insulation in itself." - Sorry but it does. Stopping that air movement is a huge plus. Heat is moved around through the processes of radiation, conduction and convection. A tent wall might seem thin but it massively reduces the convection route for heat loss.

Certainly I've found that, when I've been forced to go out of the tent on a cold night to pay a visit :D then, when I return, the tent is still noticeably warmer than the open air, even with no wind. I generally make a point of closing the tent when leaving it, to preserve that.

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Re: Heat transference between layers (when camping)

Postby sizbut » 3 Sep 2019, 6:28pm

Well that gets us to the other way of keeping warm, which is having a companion. You don't have to be intimate - its simply that N+1 bodies warms the space more than n - and gives your grief, sorry, reminds you, when you leave the entrance open.

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Re: Heat transference between layers (when camping)

Postby Vorpal » 3 Sep 2019, 6:51pm

What insulates is air trapped, either between layers, or in insulation, such as a sleeping bag.

Where the insulation is the most beneficial is close to the warmth that you want to keep in.

Theoretically, then, clothing, first, sleeping bag second, tent last.

That said, the ground is a heat sink, so insulation between a person and the ground is also important.

Also, it may somewhat depend on where it is easier for you to add insulation.

I recently camped in the the mountains in Norway, where I woke up to frost in the morning. I was comfortable. My layers were as follows
thick merino socks
merino long underwear (top & bottom)
thermal trousers
cycling top
wool jumper
3 season 'mummy' bag (done up around my head, but I had a buff in the bag with me, in case I needed it)
self-inflating / insulating matress (it's one of the more common brands: I don't remember which)
Helsport Nordmarka (3 season) tent

If I had had either a 4 season tent or a 4 season sleeping bag, I probably could have done without one layer of clothes. If I'd needed more, the easiest way to get it would (as above) be an insulating sack that my sleeping bag goes in.
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