MY 3 piece military bag doesn't keep me warm at about 30 degrees??

[DaleW]

Sorry...........
Forgot to mention i was sleeping on a air-mattress on the ground, haven't received my Black bird yet.

Also i noticed when the bivy cover gets damp during the early morning
and my head is under the flap, it doesn't allow enough oxygen to pass.


@REV
Sierra Nevada mountain range, still snow around... but it only drops low in the early morning

An uninsulated air mattress can be very cold. The air next to your body picks up heat and it gets transferred to the cold ground--- little convection currents going on inside the mattress. That is why you see the expensive down or polyester filled air mattresses--- the fill does nothing for cushioning, it stops the air from moving around inside. Dead air space needs to be *dead.* Same thing with the self-inflating air mattresses. All that foam is to keep the air from moving heat.

I wouldn't try to sleep in an enclosed bivy. When they are talking breathable and Gore-Tex, they mean water vapor, not air for breathing. Some designs can prop the head opening up with a cord to a branch or trekking pole.

[dejoha]

+1 on the under quilt or closed-cell foam pads.

A lot of first-timers (myself included) experienced Cold Back Syndrome when trying to sleep in just a sleeping bag in a hammock, and wondered, "why is my n°-rated sleeping bag not working!"

On the ground, you've got conductive heat loss: the ground sucking heat away from your body. Often a small bit of insulation can prevent this, but you still need something to keep the ground from pulling the heat away. A pad works wonders on the ground, mostly for warmth.

An air-filled mattress has a similar problem to a hammock: convective heat loss. Convective heat loss is where the wind/air blows the heat off you. A bonus for hammocks when it's hot out. A horrible realization in a hammock when it's cold out. A pad works to prevent this, but under quilts work a bit better in terms of full shoulder protection, no pad slippage, and more "natural" comfort from the hammock (a pad can prevent some of the form-fitting properties of a hammock to work).

[FLRider]

+1 on the under quilt or closed-cell foam pads.

A lot of first-timers (myself included) experienced Cold Back Syndrome when trying to sleep in just a sleeping bag in a hammock, and wondered, "why is my n°-rated sleeping bag not working!"

On the ground, you've got conductive heat loss: the ground sucking heat away from your body. Often a small bit of insulation can prevent this, but you still need something to keep the ground from pulling the heat away. A pad works wonders on the ground, mostly for warmth.

An air-filled mattress has a similar problem to a hammock: convective heat loss. Convective heat loss is where the wind/air blows the heat off you. A bonus for hammocks when it's hot out. A horrible realization in a hammock when it's cold out. A pad works to prevent this, but under quilts work a bit better in terms of full shoulder protection, no pad slippage, and more "natural" comfort from the hammock (a pad can prevent some of the form-fitting properties of a hammock to work).

+1 on the wonders of convective heat loss in summertime. It's the greatest thing since sliced bread.

Also, underquilts--at least down ones--tend to pack down into a smaller volume than most pads (z-rest style ones excepted). At least in the limited experience that I have.

[dkperdue]

I converted the gore-tex bivy cover and patrol bag into an UnderQuilt and was toasty warm at 19 degrees .
Sleeping in long pants and lighweight polypro.
TopQuilt was a Snugpak Jungle bag opened up all down the side.

Also had an old poncho liner draped over the structural ridgeline , tentlike for some dead air space above me.

DKPerdue

[TRAVELER]

i have been into the 20s with the 3 pc. system and a pad in my skeeter beater just gym shorts never cold..when it goes to the teens..i slip the bivy over the hammock and use it as a pod works for me but i am a warm sleeper...i have pictures in my album..i do not know how it will work for winds at 20mph or more haven.t been in that situation yet but i will try it for a night at home this winter to find out.. you just have to try different things to see what works for you ..

[DAVISDESIGNS]

Thank you all so much for your responses and the lesson on convection in air-mattresses.

Could you please recommend some good sleeping bags that I would be warmer in than the 3 piece military bag. I'm always cold anything below 78 is chilly to me.

I'll put the new bag in the bivy and turn the rest into a under quilt or something.

[dejoha]

If you can get warm on your back, your military bag may very well suit you fine. I find that if I am warm below, I'll be fine above. Cold Back Syndrome is really the saving grace of hammocks and also its Achilles Heel. Above all else, get warm underneath.

[Fiddleback]

What one sleeps in is important...not only what bag but also what clothes. Sleepware is a big part of a sleep system and an easy, cheap and effective way to boost the low temperature rating.

A new/different bag may not be needed, just clean, dry sleepware.

For Rev: It's been in the high 30's here (half-hour east of Missoula, @3600') two nights this week, low 40's the rest of the week. I imagine it's been well below freezing in the mountains. Mountain snows are probably four weeks away.

FB

[AaronAlso]

I have that same 3 piece sleeping system. I used if for many many years before I became a hanger. They are very good the quality of the manufacturing is really top F'n notch, at the expense of weight however. It is heavy & bulky but when used as directed I've had comfortable nights below 0Fdeg on the ground. The catch to the-20Fdeg rating the Military puts on those bags is they expect you to be wearing a polypro base layer and any other dry clothing you have available, they expect that you are using the
issued foam sleeping pad (ridge rest or similar), and finally the expect that you have had some level of wilderness survival training and will attempt to lay down a base of misc. debris to sleep on, and build a fire whenever possible. Using these guidlines I have had comfortable nights in extremely colder conditions (natural insulation helps too)

Keeping all that in mind I must add. Those bags are often sold as surplus items (they are being decommissioned) and sometimesyou get a bad one. I've seen ones where the green bag was so thin you'd think it was a liner bag and the black bag had massive clumps of insulation all threw it. I assume once they go to surplus they are
kept stored in a compressed state, usually until someone buys them. This can damage the insulation irrepairably as I undertand it. When I first got mine many years ago, I washed it in a top loader with some liquid hand soap and tumble dried twice (once no heat) with half dozen tennis balls. That seemed to revive mine. Perhaps you should give it a try.

-A.A

P.s. Sorry for any formatting errors I'm sending this from my notso-smart phone.

[AaronAlso]

Thank you all so much for your responses and the lesson on convection in air-mattresses.

Could you please recommend some good sleeping bags that I would be warmer in than the 3 piece military bag. I'm always cold anything below 78 is chilly to me.

I'll put the new bag in the bivy and turn the rest into a under quilt or something.

Today I use a JRB sierra snivler & AMK Thermoflect Bivy 2.0 (whatever it's called) with a Shamu underquilt from TTTG. Unfortunately, I've not had cold enough weather to fully test the effectiveness of this set-up, or time enough off work, yet! Though, from years of use with the ECWSS I think this will suit me fine down to 20Fdeg maybe even the mid teens. Of course that's with good base layers and my natural insulation, YMMV.

-A.A.