Winter bivvy mat

[isotonic cake]

Hello,

I've got an alpkit numo sleeping mat which for the most part has been grand. However I was using it at the Strathpuffer at the weekend and found it pretty cold, even with a thin foam yoga mat underneath for added insulation.

I'd like to do a winter bike packing bivvy and would like to know either how to make the mat warmer or what the best mat would be?

As I already have what is in essence a good mat for the vast majority of the times id need to use it, so don't want to spend £100 on something id realistically use once or twice.

Would a thicker foam mat provide cost effective warmth or is there something else I should look at?

For note I have a decent down bag which was warm enough, bar feeling like the heat sucked out to ground via mat.

Thanks,

[whitestone]

I've an Exped Synmat Winterlite 7 http://www.exped.com/uk-ireland/en/prod ... nterlite-m which is the tapered or mummy shaped version of the standard Synmat. The tag on it states an R-value of 6.0 (no idea what the Numo is since it isn't mentioned on their web site). I used it last weekend in the snow and that part of my system was fine. However at £85 it might be more than you are willing to pay.

Edit: Reading the blurb about the Numo, it seems that it's little more than a Lilo. Hardly lightweight either - the Winterlight is just 70g heavier for considerably better insulation.

[johnnystorm]

I've got a numo. Pretty sure the r-value is rated at SFA.

Thermarest Xtherm for cold use here but again might be a bit spendy.

[jam bo]

Another xtherm here. Don't sleep well if I'm cold so worth every penny. Probably means you can get away with a lighter bag too.

[Justchris]

A thicker foam mat probably won't do much extra, but wearing an insulated jacket and a pair of leggings would. Or a synthetic fleese liner. Down on the base of bags are not much use when the ground is pretty much frozen.

[AlasdairMc]

What was your bag rated to? Mine is good to -7 and I was fine with an XTherm at the Puffer.

[Moder-dye]

Do you usually carry some sort of an emergency blanket? I usually have a sol escape bivy with me that I've just put my blow up zero r rated mat inside ( klymit static v). I've also just put a zip in the sol escape so I can have it pretty much wrapped around my summer bag without condensation issues but zip up if I feel the need. That way I have an emergency solution for me or others plus improve the sleeping warmth without having to buy another mat.

[Bearbonesnorm]

Heat loss occurs differently in different situations, in this case the culprit is conduction ... the cold ground is trying to reach the same temp as your warm body and it won't stop trying until it succeeds.

You need a barrier and you need a barrier that can trap air and hold it still, so:

Extra clothing layer - not much good as it'll squash just the same as the insulation under a sleeping bag.

Foil blanket / bag - not much good either. They're designed to prevent heat loss via radiation and to a lesser degree convection. The only one with true insulation properties is a Blizzard bag.

Additional foam mat - this will do something, however the mat really needs to be on top of the Numo not below it. If you place the foam below, the Numo will do its best to strip you of your body heat (you'll be heating the free moving air in the mat up and due to convection, that air will continue to lose heat through the night).

If you don't want to spend much (exped, neoair, etc) and can handle a little weight and bulk, a self inflating mat would probably be the best option. You can buy a full length Gelert one for £6. Nice thing about a self inflating mat, is that it'll still offer some insulation if it punctures

http://www.fieldandtrek.com/gelert-camp ... e=78217190

[benp1]

Agree with Stuart.

Foam mat underneath an inflatable mat just protects it, does little for heat. Stick the foam mat on top, will make a huge difference.

Cheapest fix for you is a 2nd foam mat, or a thicker one, so that the layer of foam is nice and thick. Will be lovely and warm, and will be cheap

[HaYWiRe]

If you go the foam mat route, what I find works well is cutting a CCF mat to size of the mat its on TOP of (or torso/feet/wherevers essential) and using elastic webbing to strap it inplace, no slipping and makes turning in the night much easier, it'll be very light, if not bulky. But for cold weather we all except a certain level of bulk for warmth anyway.

I've always found CCF very warm, if not my warmest mat, cheap too. You just need to find somewhere to put that massive (but ultralight) roll

[ootini]

With the above in mind, when taking a secondary self inflating mat to go on top of something like the Numo, would it work best between the Numo and the sleeping bag, or better inside the sleeping bag?
Curious.

[Bearbonesnorm]

With the above in mind, when taking a secondary self inflating mat to go on top of something like the Numo, would it work best between the Numo and the sleeping bag, or better inside the sleeping bag?
Curious.

I would put it outside the sleeping bag ... inside and it might pull the bag preventing it from fully lofting.

A little care's required when stacking mats, don't go mad or you'll end up like this poor lass.

[isotonic cake]

Thank you all for your responses. I'll have a look for for a suitable ccf mat and let you know how I get on.

Thanks