Vapor Bag or Over Bag for Down Sleeping bags?

[Domestique]

Hello,

 

I just joined this site (a great wealth of knowledge here).

 

Anyways, I am looking at getting my first down bag for winter backpacking (have been a Synthetic user for years).

 

My question is, should I use a vapor bag like "Integral Design"

http://www.integraldesigns.com/product_detail.cfm?id=677&CFID=102569&CFTOKEN=82186501&mainproducttypeid=5

 

or use an over bag like MEC's

http://www.mec.ca/Products/product_listing.jsp?FOLDER%3C%3Efolder_id=2534374302865705&bmUID=1202356294240

 

Thanks in advance.

 

Edited February 7, 2008 by Domestique

[mattp]

I have not checked your links but I don't think you want something called a "vapor barrier" over your down bag. It will trap moisture that will reduce your down's effectiveness.

 

Temperatures and moisture determine what you want: if you are worried about serious moisture from outside (like rain), use a tent, tarp or a waterproof breathable bivvy bag. If you are worried about frost or dew, use a very breathable shell or overbag. If you are worried about moisture from your body, use nothing at all or an insulated overbag that absorbs moisture and keeps the dewpoint outside your down. The vapor barrier liner inside a down bag will help keep your bag drier on extended cold weather trips and allow you to carry a lighter bag than otherwise, but this system has its drawbacks like where then do you dry your wet cloting and many people complain that it is "clammy."

[Jon G]

Using down in the winter is tricky. You must guard the down from both moisture coming from your body in the form of sweat and vapor from your breath as well as moisture from the environment around you. Using a vapor barrier bag will work, but vapor barrier clothing worn over only a light baselayer will be more effective. A bivy bag can be used to prevent outside moisture from affecting the down.

[JayB]

Seems like on short trips in the Cascades, moisture from outside the bag would be the major concern, and something like this:

 

http://www.backcountry.com/store/BLD0253/Black-Diamond-Winter-Bivy-Sack.html

 

Would be the way to go. I've got one and it seemed to do keep the moisture at bay inside tents and snowcaves, and breathes pretty well too.

 

It sounds like VBLs and/or overbags might be the ticket for longer trips in colder/drier climates. Hopefully some folks with experiences from that sort of outing will chime in if that's what you've got in mind.

[markwebster]

I'm fairly sold on the stevenson brand of sleeping bag, though many people are now copying his designs. He's been around since the late fifties but is a small company and doesn't advertise much:

http://www.warmlite.com/bags.htm

His main concept is that much of the moisture in a bag comes from your own body's humidity. He builds bags with an inner vapor barrier against your skin. I think his new material is soft, and not the plastic-ee stuff he used to use. With the inner vapor barrier, you can use something quite waterproof on the outside of the bag to keep moisture from the tent walls off the bag. That way the down stays dry. I've had one of his triple bags for 30 years of climbing, it's amazingly well built, haven't even had to replace a zipper.

 

Many people only know his company as "that weird company that uses nude models", and that's true, but he also makes great gear, lightweight, innovative and well built. I've not bought anything from him in 25 years, and don't use his tent anymore as it kind of wore out...but I assume he still builds good stuff.

[mattp]

I have friends who swear by the use of vapor barriers, not only in their sleeping bag but in boots as well. These climbers are all using them on more extended expeditionary type climbing trips. Do you, Webster, use that Stevenson bag on "regular" trips around here?

 

By the way, some will recognize this comment and I'm sorry if I sound like a broken record but I have rarely found need for any kind of bivvy bag to keep moisture from the tent or even a snowcave out of my down.

 

I've used snowcaves quite a bit and, yes, you have to arch the roof so it won't drip, a ground cloth is a good idea, and I avoid snuggling up against the wall, but I have not needed the additional shell. I used to camp under tarps a lot, on extended trips in the winter and spring in the Sierra and Cascades, and there too I never used a bivy shell. I learned to pay attention to drips and take advantage of opportunities to dry the bag, but my down never got diasastrously wet.

[Ade]

In the past I've experimented with a Marmot Helium (-1C) bag and an MEC Penguin overbag (which adds 5-10C). This seemed to work pretty well although for the Cascades in winter you might want a thicker inner bag - I was trying to save weight. The Penguin isn't waterproof but it does give you an outer snow shedding layer that's more tollerant of moisture.

 

Andy Kirkpatrick uses a similar system

http://www.psychovertical.com/?modularsleepingbag

 

I've used vapor barrier socks before and really don't want to think what a whole body vapor barrier would be like. Similarly with a "breathable" bivi bag the key is to try and make sure as much moisture as possible doesn't get trapped inside the bag, i.e. keep your head outside if at all possible. I only ever take a bivi bag if a tent really isn't an option because there don't look like there are any ledges.

 

 

[G-spotter]

VBLs suck. Overbags are way better.

 

Analogy: when you put on your insulated, synthetic belay parka over your wet clothing the heat of your body pushes the wet out from your clothing and into the parka, and your clothing dries.

 

Same process with overbag over sleeping bag.

 

A VBL comes into its own if it is both really cold and really wet outside - somewhere like South Georgia Island or Baffin - and the bag+overbag system can't generate a moisture gradient.

[markwebster]

I used to snow camp with the stevenson tent and stevenson bag, but that was before kids, who are 23 and 20 now. Ever since they were born, I just use the stevenson bag on rock climbing trips (yosemite, smith, Josh, etc) where I sleep in tents without an outer bivy shell. It stays quite dry because my humidity doesn't ever get past the inner vapor barrier. I don't mountain climb anymore, so I'm probably not a good source of information from that perspective.

 

In the summer I use beater bags, as I don't need the warmth, and the stevenson is too valuable to risk losing it.

[G-spotter]

I just use the stevenson bag on rock climbing trips (yosemite, smith, Josh, etc) where I sleep in tents without an outer bivy shell. It stays quite dry because my humidity doesn't ever get past the inner vapor barrier.

 

ya, and you turn into a prune inside. no thanks.

[fishstick]

Both have their places.

 

The primary function of over bags such as the MEC Penguins is to move the dew point beyond the outer shell of the primary bag. I think of the temperature gains of using an over bag as increasing over the duration of the trip, because otherwise the primary bag would be getting damper and damper. Highly water resistant shells such as DryLoft (now known as Windstopper) may appear to be dry, but often condensation builds on the inside of the shell in cool weather (out of sight, out of mind, or at least for a while).

 

One of the more interesting experiences I've had with an over bag went as follows: I was testing a microfibre-shelled bag and was avoiding the use of the over bag because it would bias the test. At approximately 3:00am I woke up and the entire shell of the down bag was absolutely soaking wet. Facing another couple of weeks in cold conditions, I quickly pulled my basic (non-DryLoft)

over bag over top. At 7:00am the primary down bag was bone dry and lofting fully. The synthetic over bag dried quickly in the sun.

 

VBLs add more warmth per gram than overbags, or at least in the short term. They're well suited to trips where you might need something, but you really don't want to carry 700 or 800g of extra bag. One of the nicest thing about VBLs is that the sleeping bag system heats up much more quickly (it takes a while to warm up big winter bags). I find they seem much less bothersome if you start our by pulling it up only to your arm pits (keep your arms out). As the bag heats further, push it down to your waist and eventually to your feet.

 

The downfall of VBLs is they encourage sleeping with only minimal clothing, which is less than convenient in very cold temperatures.

 

A nice aspect is that should you get up at night to pee etc and return to the tent dusted with snow, the VBL will protect the inside of the bag.

 

The primary use of VBLs of course is REALLY cold weather. I think they're also well suited (mandatory) for use in bivisacks in the winter (the VBL will help, but the bag will still die). For big, cold trips, I'd probably carry both an over bag and VBL.

 

As an aside, if you're carrying the VBL just in case, use it as your pack liner. If you think you won't need it that night, put your entire pack in the VBL.

 

Cheers,

 

GB

[Don_Serl]

fishstick and others have covered this topic well, but i'll just add that i've sworn by and had great success with overbags over the past 30 years, including spring/winter use in the coast mtns and cascades, plus more exotic loctions such as alaska, kluane, peru, and the himalaya. the overbag system has never let me down (which is to say, i've never suffered a damp down bag with this syetem).

 

i've used VBLs a bit too, cuz they are way lighter than an overbag, and they're useful as an emergency bivy bag too. i find them tolerably comfortable for one night (esp if u do as fishstick suggests and kick the VBL down later in the night), and they certainly do make the whole system warm up faster.

 

one of the problems with the overbag system is lack of availability of an ideal bag - the MEC penguin has gotten quite 'tubby' over the years as MEC chases the mass market and compromises specialist products to lower retail prices. with more specialist insulation batting, a short single zip, a lighter shell fabric, and no hood, my 20-year old overbag weighs 620grams (long); the current long is cataloged at 850gm. and occupies 3/4 of the bulk as well.

 

i suppose there's no much point complaining about 'what might have been' - i've not been paying much attention to the bag market in the past few years, so i'm not knowledgable about what alternatives (if any) are available. you'll probably either have to go with the penguin or do without...

 

cheers,

Edited February 8, 2008 by Don_Serl

[jordop]

Just before they died, Serratus made a Pertex VBL which is a way better idea that the full-on rubberized plastic death by sweating job I bought when I first thought of uncomfortable ways to get the most bang out a sleeping bag. I have also used it successfully as a quick bivy sack to at least keep the dew off the bag.

 

 

[Jon G]

Vapor barrier clothing is more effective than a vapor barrier bag. It establishes 100% humidity closer to the skin, which stops perspiration faster. The less you sweat, the less energy used in evaporative cooling, and the warmer you will be. Of course this is the entire idea behind vapor barriers, it just works better in vapor barrier clothing. One can also wear clothing over the vapor barrier liner, allowing maximum versatility. I do not sweat much so i find vapor barriers work great for me. however, comfort is largely subjective to the user.

[Domestique]

Wow, Thanks for all the help.

 

I think for my needs (North-East winter Backpacking and eventually some mountaineering)I will go with an overbag and a 0 or -10 down sleeping bag.

 

Other then MEC's overbags, any other companies to look at? I live in the States and would like to avoid the 18.00+ shipping from Canada.

 

Also, Most of my trips are a week or less long (backpacking), do I need to even worry about bringing an overbag? My concern is the extra space my down and then an overbag will take up.

 

 

Edited February 8, 2008 by Domestique

[letsroll]

Anything eVENT. I have the Bugaboo and love it.

 

Integral Desings

 

Can get it in the states here.

 

Pro Mountain Sports

 

BackCountry Gear

[Domestique]

Anything eVENT. I have the Bugaboo and love it.

 

Integral Desings

 

 

I thought bivys didn't work as well for overbags as synthetic bags did? I thought the poit of the over bag was to draw the moisutre into the fast drying synthetic instead of the down.

 

Wouldn't a bivy just create more condensation on the outside of the down bag?

[mattp]

Yes, a bivvy bag is likely to create condensation and, if you are backpacking in the Northeast, you'll likely be sleeping in shelters or huts or maybe a tent and not subject to lots of miosture from above other than frost.

 

In these conditions an overbag is the clear choice of the two, but I bet you could do OK with nothing but a down bag. The synthetic overbag, though, will also serve as a nice summer-camping bag and you can get a slightly lighter down bag (not warm enough for real cold winter trips) that will be less to carry spring and fall.

 

A zero or ten degree down bag is a very versatile item for general mountaineering. You could get more specialized for a trip to McKinley or summer backpacking in California but it will serve you well for most trips you are likely to make.

[Coldfinger]

Good move on the down, I've found they are way warmer per rating.

 

I wouldn't get too hung up on the tech stuff until you master the art of how to sleep warm. IMHO it's best to avoid bringing moisture into the bag in the first place. So I usually get a good amount of body heat going (stamping out a tent platform and setting camp), jump in the tent, fire up the stove, strip off my shell and the layer closest to the shell (these have most of the moisture I build up during the day), put on a dry layer over the base, and spend a few hours melting snow, brewing, eating etc. BEFORE I ever get in the bag.

 

I would get a good eVent bivy, it'll protect you from condensation, but it also provides a backup if you get caught away from camp, etc. etc. Don't count on it breathing much, if the ambient temp is below freezing, which is why it's best to change out of whatever you wore during the day and give your base time to dry.

 

What you do is far more important than what you buy!

[Coldfinger]

I'd also recommend NOT getting a dryloft, etc. shell as you can get the bag and a bivy for about the same price and regular fabrics these days are pretty darn good for water resistance and will dry much faster.

 

Seems like all the clunk of carrying a down bag and a synthetic overbag defeats the purpose of a down bag: warmth, light weight and superior compressibility.

[mattp]

Coldfinger offers a reasonable perspective but, in my past experience with extended trips in the frequently wet Cascades and spring-time Sierras the ONLY way I could ever dry out wet socks or mittens or tee shirts was to take them to bed with me and place them on my chest overnight. And with a fully breathable shell fabric on my 0 to 10 degree down bag the moisture passed right through the down and never soiled the bag. Your mileage may vary.

[Domestique]

Thanks a lot guys,

 

Right now I am leaning towards a Mountain Hardwer Banshee SL (0 degree 800 fill down bag). It uses MH's conduit material for a water resistant shell.

 

As I mentioned earlier I will be using this for winter backpacking (2-4 days) with a 4-season tent. For now I am going to try to get away with not using an overbag or bivy and see how I make out. When I decide to ditch the tent for a hut or get into some mountaineering that invoves colder nights I will get a bivy and synthetic overbag.

 

 

[Coldfinger]

I have the spectre--great bag--as well as a Marmot Couloir--most excellent.

 

If you could use a bivy for the other three seasons try to find the cheapest 800 fill bag w/o a spendy shell fabric. You'd be surprised what deals are out there.

 

BTW make sure it has plenty of room, i.e. many winter bags only hit the zero rating because they are very tight (or have a gore or similar shell), perhaps good for those who want to save 5 or 6 ounces but not so good if you want to keep stuff in there or even--GASP--use a pee bottle.

 

Make sure you compare dimensions AND fill weights. Go to Mountain Gear--they provide fill weights for all the bags they sell unlike most other online stores.

Edited February 9, 2008 by Coldfinger

[Domestique]

I have the spectre--great bag--as well as a Marmot Couloir--most excellent.

 

 

How do you like your spectre, I was also looking at that and couldn't decide. Do you stil use a bivy with the spectre, and how roomy is the spectre?

 

MH also makes the phantom which is a 800 fill 0 degree W/O the shell. But it isn't that much cheaper.

 

Thanks again.

[mccallboater]

No one has mentioned an additional benefit of VBL's, which through experiment I have found to be even more useful than the extra 10 degrees or so of warmth I get from my down bag.

 

I DON'T HAVE TO PEE AS MUCH at night with the VBL (caps added purposely). My persperation rate decreases, due to the higher humidity inside the VBL. I lose less water through my skin overnight, and apparently process less water through my bladder, for reasons I do not understand.

 

I define happy winter camping as not having to melt as much snow, sleeping warmly throughout the long night, and not having to wake up from a - can't find a place to pee - dream and fumble around for the pee bottle in the dark.

 

If that's not a good reason to use a VBL, I don't know what is.

 

Caviats:

 

• If the tent or cave temp is above freezing, I don't bother with a VBL
• I don't sweat much. Your milage may vary
  
• I use a Marmot Lithium, but I don't think the down bag matters. I've used VBL's with synthetic bags with the same effect