jefnvk

Does anyone use the additional warmth varieties, and do they work?

Looking at sleeping temps two weeks out from my trip, they are averaging 10-15F colder than the low of what I am used to, and flirting with my 25F bag rating. Normally, this bag gets used down to the low 40s without issue, only wearing boxers, whereas night temps are hovering around freezing now. Even though I'll have long underwear and clothes that can be slept in, I'm wondering if any liner is worth picking up to help out?

Cyclist0108

It definitely will work, but I don't think they are any better than sleeping fully clothed and with a pair of sock on. They do have the advantage of keeping your sleeping bag cleaner, but it is one more item to transport.

jefnvk

FWIW, I also have a 0F bag, but the additional bulk is considerably more than my 25F bag and a liner

prathmann

One liner method I use only when it's expected to drop well below freezing is a vapor-barrier liner. I hit upon this by accident one night when the temperature dropped down to low single digits (F) and my bag was rated to about 25F. I also had one of those 2 oz. mylar emergency blankets, so I wrapped myself in that and then got back in the sleeping bag. The mylar was a little crinkly but it made a surprising difference in how warm I felt for the rest of the night and I slept well. Later learned that I had basically created a vapor-barrier liner - i.e. a fully waterproof layer right up against my skin. Therefore I was no longer losing any heat energy to evaporation which explains why I felt so much warmer. I've also found that I wake up less thirsty in the morning and there's less condensation in the tent. Note that this is only recommended when you'd otherwise be rather cold. Under warmer conditions your body would continue to perspire and the inside of the vapor-barrier would feel like a wet sauna. I've now bought and use a waterproof nylon liner which is a bit more comfortable and less noisy than the mylar version and still only weighs a few ounces. But again, only on below freezing nights when my sleeping bag alone would not be sufficient.

J.Higgins 

Hey @jefnvk check out the Sea to Summit extreme series of bag liners. I just ordered their regular liner, but they have several different liners, and they claim to add 20 degrees to your bag as well as feeling soft and comfy. Lightweight too!

fietsbob

Vapor barriers get used when it gets really cold

all your perspiration is contained so none evaporates to cool you..

think aluminized plastic bag. (but it will pack small..)

jefnvk

@NoControl - those were the ones I was looking at specifically, they caught my eye at a Gander Mountain closing sale. Since I can get them locally for the same price as online, I'll probably keep an eye on the weather situation over there, and if it isn't looking like I can expect the temps to be in the mid-40s or better, grab one right before I leave.

berner

I use a down bag from Western Mountaineering. The original rating was 30F but I asked the company to over stuff it slightly. I found the bag almost comfortable with snow on the ground so temps were in the 20sF. Of course, for a winter hike I had packed a warm fleece base layer and could further supplement by throwing my parka over the bag as necessary. These extra layers were part of a standard winter and shoulder season kit. I generally try to pack light but not ultra light and for a short week-end hike, I don't mind being a bit cold at night.

fietsbob

Patagonia Silk weight long underwear, was what I put on in the night, as PJs.. In My sleeping bag & in Hostels..

AYH had a hostel regulation to bring a liner, rectangular, with a pillow cover pouch,

rather than use your outdoor gear and release any bugs you may have brought in with you.



...

tspoon

I have the Reactor Extreme thermolite liner, but I'm not sure if my experience is typical. My sleeping bag has a supposed -1C (30F) rating, and the liner claims an up to 14C (57F) extension to that rating. The coldest I have used it is -3C (26F), I also had numerous layers of clothing on and was still cold (on a hammock, with a inflatable matress layer underneath). I tend to think my old bones just won't warm up like they used to, as I should have been snug as a bug in a rug. Either that or the -3 number I was given by another person was erroneous, although I would say it would not have been too much colder.
I have seen other peoples reports where they say the 14C claim is quite optimistic, so you'll be warmer, but not by that much. Like yourself, I like the idea of having a light bag, and in winter just adding the liner.

Tourist in MSN

I have never thought that a liner helps make a sleeping bag that much warmer, but a gal I used to work with always used a liner, she said she used it to keep her bag cleaner when she was grungy. It made so much sense to me that I always used a liner since then.

Iceland last summer, I used my 25 degree bag and a Sea to Summit Thermolite liner. I got that liner from REI at a scratch and dent sale for a lot less than full price. That combination was warm enough for me. But it never froze when I was there.

When I feel chilly in my sleeping bag, I often drape my down vest over the torso area of my sleeping bag for extra insulation above my bag. And wear a skull cap type stocking cap on my head. I think the stocking cap adds more to staying warm in my bag than a liner does.

I brought long underwear tops and bottoms to Iceland, never used them.

***

Different topic, I am not sure if I previously suggested that you put the weather service app on a smartphone to use there. I never had a sim card, but I could use it where I had wifi. It gave me great forecasts for wind (meters per second) and wind direction, temp (celsius), and likelyhood of precip. This is for android, maybe there is an equivalent for apple devices.
https://play.google.com/store/apps/d....android&hl=en

If not available for apple, it is available as a website. Or you could use it on a tablet if you have wifi.
Home-page - Icelandic Meteorological Office | Icelandic Meteorological office

BikeLite

I don't use liners but do use sleeping bag covers like the one from equinox.

fuzz2050

I've always thought those Sea To Summit Reactor liners are absurd. Insulation isn't magic, and the reactors claim to have the same warmth as an inch and a half of down loft. It just doesn't seem all that likely to me, and the fact that they aren't rated by any independent organization doesn't give me much hope.

Liners do help a bit, but I'd guess 5 degrees tops. If you're really cold, I'll second what's been said here before, put on your down jacket. It's not the most fun, but it beats being to cold to sleep.

pdlamb

IME, a silk liner adds about 10F warmth to an old bag. The extra dead air keeps me warmer than I'd frankly expected. Keeping the bag clean is a bonus, too!

dh024

Agreed. I also find that I sleep better using one because they do a surprisingly good job of reducing those annoying "drafts" you get if you don't zip up your bag all the way up like a cocoon, which can be too hot for me in warmer weather.

And if you want to extend the range of your existing bag, I also highly recommend the Survive Outdoors Longer Escape Bivvy (Survive Outdoors Longer® Escape? Bivvy | S.O.L.® | Survive Outdoors Longer®). Worn OUTSIDE your liner or your bag (YMMV), they really do add an appreciable amount of warmth to a bag, plus they are almost as lightweight and packable as a silk liner. But you definitely want this breathable one, not the other non-breathable bivvy bags they sell.

Using a big with these two liners, I find it pretty easy to dial-in a comfortable sleeping temperature for a wide range of overnight temperatures. It is a bit like the layering concept with clothing, I think. I have adopted this system over my warmer (but bulkier and heavier) three-season down bag - much more versatile and just as warm and comfy.

Tourist in MSN

For your iceland trip, I do not know if you might use a hostel or not. Some of the hostels have a lower charge if you use your own bedding. Where they have geothermal heat the hostels are quite warm too. I stayed in three different hostels while there and the liner is nice to have when the sleeping bag by itself is too warm.

fantom1 

I've used a silk liner and noticed a small difference. Liners and clothes are not nearly as effective as a good and appropriate bag for the temps though.

jefnvk

Valid point.

J.Higgins 

Hey @jefnvk I got my liner last night, and I was surprised to find it a little bigger - when stuffed in its bag, and a little heavier than I expected. Its not a problem, really, I just expected a little smaller. Still, it packs down to the size of a softball. I haven't tried it yet, but I'm impressed with the quality of the fabric, and I'm certain it'll make my bag a lot warmer.