I'll say this much: I have a get a great deal on Marmot Sleeping bags.
For my 2013 PCT thru-hike I am therefore only really considering their bags.

The problem is this: The standard bag I read about PCT thru-hikers carrying is 20 degrees. Marmot makes 30 and 15 degree bags (plasma model) that are super light!
I don't really know what temperature bag to get. I've honestly never been aware of my bags rating before and I guess I've been lucky enough that it's worked. Will I cook in a 15 degree bag? How do I tell if I'm a cold or warm sleeper (I tend to get cold)
Will my long underwear be the key...

Thanks for the help, I don't want to carry the extra weight of a 15 degree bag because I'm afraid that a 30 won't fit my needs.

Setting aside your metabolism and how it changes during the course of a multi-month hike (a dissertation in its own right) the environmental reality is the bag you're using mid-summer isn't the bag you want early and late in the trip, and vice versa. If one bag has to serve the entire hike then yes, a 20-degree bag is a safe choice and in that case, probably the gold standard is the Western Mountaineering Ultralite.

Brian Robinson, who was first to do the "calendar triple-crown" of all three major N-S trails carried a Feathered Friends Hummingbird. I'd have no hesitation recommending either.

Cheers,

Look on the bright side....A cold bag virtually guarantees that you will get an early start on cold mornings.

If you're relatively sure you will be cold in a 30*,you could get a 15* and just use it open as a quilt when it's warmer. I agree with the others that FF or WM are exceptional bags, Katabatic also makes great quilts. I own a WM Summerlite, and a Marmot Helium...got a great price on it :-)I also have a hammock and use a 20* top quilt and underquilt. When in a tent though, I find I take the Marmot more often than not because I'm a very cold sleeper. I also do most of my backpacking trips in cool to cold weather (live in the south)or in summer at elev. that tend to be cool at night. YMMV. Good luck.

I, too, have both the Summerlite and the Helium. I mostly use the Helium because I am a cold sleeper. On my scales, the Summerlite weighs 19 oz and the Helium weighs 28 oz. For me, the nine ounce difference is less important than is sleeping warm.
I recently talked with the people at WM about having a few ounces of down added to my Summerlite. They recommended adding 2-3 oz to provide extra loft and to keep the down from shifting. The cost would be about $50. After the addition of more down, the Summerlite would weigh about 22 oz and would probably keep me warm to 32°F. Getting a 32°F bag and adding a bit of down might be worth considering; I'm planning to do it.

What temperature the manufacturer labels the bag for often has little to do with what temperature the bag will take you to. The only laboratory standards for sleeping bags are the European Union's EN 13537 ratings. These tests use a dummy wearing long underwear and a knit cap and "sleeping" on a 1" closed cell foam pad.

There are three sets of EN 13537 ratings. "Comfort" is for the "average" woman (whatever that is) and cold sleepers. The "Lower Limit" is the lowest temperature at which the supposedly "average" man (warm sleeper) can be comfortable. "Extreme" is the lowest temperature at which you hopefully will not be dead of hypothermia in the morning. Of course, manufacturers who don't sell their bags in Europe don't have to use any standards at all. Even these tests are very approximate and have been subject to criticism. However, they are definitely more accurate than the fictional ratings of manufacturers' marketing departments and do provide a fairly objective basis for comparison between different sleeping bags.

Be sure you know which EN ratings the manufacturer or retailer is using! Some (especially retailers who don't understand the ratings) use only the "extreme" rating in their advertising. Also note that the sleeping pad you use makes a great deal of difference, especially on cold ground! The 1" closed cell foam pad used for the tests has an approximate R value of 5, warmer than most common sleeping pads.

The best place to find the EN 13537 ratings is the manufacturer's website. Looking at the Marmot website, the Helium is EN 13537 rated at Comfort, 27.7*F and Lower Limit, 16.3*F.

For some reason, Western Mountaineering doesn't list EN 13537 ratings on their website, even though they do sell their bags in Europe. You'll have to look on a European website, such as this one.. It shows the EN 13537 rating for the WM Alpinlite and Ultralite as Comfort, 28.4*F and Lower Limit, 15.8*F (converted from the degrees C listed).

In other words, the Marmot Helium is quite comparable to Western Mountaineering's 20* bags. One difference is the absence of a draft collar in the Helium, which is why I spent the extra $$ for Western Mountaineering. To me, a cold sleeper, that draft collar adds at least 5*F extra sleeping comfort (very subjective!) and allows me to ventilate the hood so it doesn't get wet or frozen from my breath. The weight difference is minimal (3 oz.) when you compare the Helium with the comparably sized WM Alpenlite. The WM Ultralite (which I have) is lighter, but it's a narrower bag and may be too snug for bigger folks.

Be sure you get a bag with full-length zipper so you can ventilate the bag on warm nights. At higher altitudes it gets pretty cool most nights. In hot spells in summer in the Oregon and Washington Cascades, I've often started out with my sleeping bag unzipped as a quilt, or sometimes with me on top of the bag, but by morning I'm usually inside my WM Ultralite and most or all of the way zippered up.

If you can afford only one bag and need to take advantage of sale prices, the Marmot Helium (with full-length zipper) should be fine. Take good care of it and be sure you keep it dry!

Thanks for the replies.
I am aware of the EN rating system, and how it is often an overestimate of warmth.
I am actually most interested in the Marmot Plasma 15 degree bag, which has a draft collar ( I believe) and is also substantially lighter than the helium.

I think I want to take the extra weight of the 15 degree bag, even if it dashes my hopes of an under 10 lbs base weight. I'm a big guy, so I can take a litte extra weight, right?!


Edit:

What is the viability of a quilt, bivy combo saving weight and increasing warmth? What do people think about this?

I have never looked at the Plasma, which is relatively new. I personally am a bit dubious about those vertical (as opposed to horizontal) baffles, which IMHO would potentially allow for more down migration. However, that's a very subjective opinion, probably also influenced by my age....

I hope you can find someone who has actually used this bag in a variety of conditions, preferably long-term, before you invest. Watch for reviews on Backpackgeartest.org and on various forums. Outside Magazine seems to like it, but I doubt they tested it on a thru-hike. It might be worth checking a bunch of 2012 online journals at postholer and trailjournals to see if anyone has this bag listed in their gear lists. (This might take quite a while as not everyone publishes a gear list!)

If you can get this bag from REI or backcountry.com, both of which have lifetime "satisfaction guaranteed" warranties, be sure to try out the bag on several preliminary trips to make sure that the down isn't going to migrate away from pressure points like shoulders, hips, knees. Actually, I suggest preliminary trial trips to test all your gear!

Again, the EN 13537 ratings are just about the same as for the Western Mountaineering 20* bags. The draft collar on the Plasma is, IMHO, a definite plus in below-freezing weather.

The Marmot Plasma 15 looks quite pricey. Unless you can get a really steep discount, it may cost more than the Western Mountaineering Ultralite--check prices first! If that's the case, I recommend the Ultralite, IF it's not too narrow for you (check your girth measurements while wearing your puffy insulated clothing).

My experience with quilts is limited to warm-weather use of my unzipped sleeping bag, so I really can't help you there. I personally prefer being enclosed snugly in a full sleeping bag--no drafts when I turn over, which I do frequently. This is definitely a "Your Mileage May Vary" situation. If you have a sleeping bag currently, try using it as a quilt (fully unzipped) on a cold night or two, perhaps with a blanket over it if it's not warm enough for winter weather conditions.

"I am aware of the EN rating system, and how it is often an overestimate of warmth."

I have a EN rated bag and it is spot on as far as I am concerned. If there is any abuse of the rating system, it is by manufacturers who deliberately mislead customers by only posting the extreme rating. Here is how ratings should be presented-
Temp rating Comfort -11ºC / Limit -19ºC / Extreme -40ºC
This is from a bag on the MacPac website. I have one of their bags (not this one).

If you don't see the complete rating, I wouldn't trust what I read.

Valandre, a lesser known but very high quality French bag maker publishes a complete report on its website for each of its bags.
www.valandre.com
Here's an example, click on the PDF link to see the report.
http://www.valandre.com/eng/Sleeping_Bags_and_Outerwear/sleeping_bags/shockingblue.html

EN rating for my Marmot 0 degree Never Winter is right on. It says 17F comfort rating for women, and hey, I got cold right about that temperature.

You'll want something good to 20F for the Sierra in summer, and the clothing you are taking should in addition to the bag take you lower than that. I've seen the weather turn - one trip the forecast when we started was a full 20 degrees warmer than what we got.

I have a quilt and never use it with a bivy. It's a Jacks R Better Hudson River. It's warm to about 25F quite reliably (I had it out with me a couple weeks ago when the water turned crunchy and we woke to a hard frost, the low had to be a sustained mid20F to get the water that way, and I was warm all night). However, you have to be sure your quilt can fit all the way around you so you can tuck in around the edges. I always take care to use it with an adequately warm pad - in my case either the NeoAir (original, not the current all season ones) or a Big Agnes Q Core rated to 15F. And you need a hat. But I'm generally warm in a base layer with just the quilt and a wool beanie.

Would you know, by any chance how the U.S. Military determines their rating system? My "coldest" commercial bag is a Marmot 20 degree bag.

I'm planning a trip in Jan where the temp could range from 30F to 5 or 10 F at night, on average, plus or minus 10 degree's.

I have my modular sleep system from the military which uses a bag for down to 30F, then add another bag for down to -40, or use second bag alone for 30F to -10F. Both bags together weigh 6lbs., so I'll probably just take the -10 bag.

I'm going on a couple of winter trips in December to test gear out for winter use, including some that I've just recently acquired.

I'll be using a NeoAir pad, but have never really used the ECWS bags, having been primarily desert warfare specialist.

So, other than taking a chance on freezing my butt off, I'm curious as to how the military comes up with their figures.?

Thanks,
J.

I have to agree with TomD here too. My Kelty bag is a low end down bag but the comfort rating of 32º is about spot on, and I am not a warm sleeper.

The generally advertised rating of 20º for that bag is misleading though. You have to dig past that to find the comfort rating. I'm really glad I learned that here before I bought another bag, and very happy with the Kelty.

Here is another good example of proper use of the EN rating-Marmot
http://marmot.com/products/helium_reg?p=117

If all you see is one number, you have no idea what it is based on. EN isn't perfect, but it does enable you to make comparisions between bags both from different makers as well as within one maker's range of bags. As you can see from the Marmot chart for the Helium, the range, at least for this bag is more than 40 degrees F, which is ridiculous if the manufacturer was claiming this to be a -16F bag.

As a woman and a cold sleeper, I've found the EN 13537 "comfort" ratings to be right on. In both my WM Ultralite and the Marmot Hydrogen I once had, the "comfort" temperature is the approximate point at which I have to start adding warm clothing inside my bag. The "lower limit" rating, for me, is the approximate point I start to shiver even when wearing all my insulating clothing plus a vapor barrier. (That assumes an adequate sleeping pad, not the regular NeoAir!) I still don't know why they have the "extreme" rating; I'd be dead long before it got that cold!

TomD is right, Marmot uses the EN ratings properly, showing all three ratings.

What is individual is each person's true comfort level within these ratings! A warm sleeper (regardless of sex) may be just fine with "lower limit." A cold sleeper (regardless of sex) is better off with "comfort."

The plasma has gates within the vertical baffles that stop down from migrating too far. You just aren't going to have down moving from your head to your feet since the baffles aren't as continuous as they appear.

With that said I'm very glad to hear people feel that they can rely on the EN rating system. It gives me a better idea of what I want, and I think a 15 degree bag is for me. I think I roll around too much for a quilt, and sleep too cold for a 30 degree bag.

TomD,

"the range, at least for this bag is more than 40 degrees F"

Doesn't the chart show a range of 11.4 degrees F (16.3-27.7)?

dj2

O.P. said:

Quote:

"The problem is this: The standard bag I read about PCT thru-hikers carrying is 20 degrees. ...
I don't really know what temperature bag to get...
Will I cook in a 15 degree bag? How do I tell if I'm a cold or warm sleeper (I tend to get cold)
Will my long underwear be the key..."

And later asked
As I think has been mentioned, metabolisms vary a lot, and your needs might even change as you lose potentially a lot of body fat on a thru-hike. What worked well for me was to start the hike with a 20F rated bag, and switch after I got through the Sierras to a 32F rated bag. I finished early enough that it wasn't getting really cold yet in northern WA; a 32F bag might be skimpy for the last couple of weeks depending on the particular year and how late you finish but was fine for me (good thing, as my wife hiked the last stretch with me and she definitely wanted the 20F bag!).
And of course as has been said here already, bag ratings vary a lot. I used WM bags, an Ultralite to start and then a Summerlite. And btw, relating to another post, I've had both of these refilled, and I did ask for them to be overstuffed at that time; I think this is probably the most effective payback for weight carried --- a little more down in the bag, as much as the manufacturer feels will still loft well.

I'm not saying that a 15F bag would be wrong for you. I don't know, and neither does anyone else here; insufficient data. If you have access to a decent 20F bag you can borrow, find somewhere this winter that likely gets down to lower 30's, upper 20's. For my part (my experience, my year), the coldest I think it got might have been mid-20's and almost always warmer than that. I had (always have) some puffy clothing that I can wear inside a bag that is large enough to allow that clothing to loft, i.e., I can augment bag warmth that way as needed. It wasn't often needed on the PCT for me.

In terms of whether you might be too warm, I do suggest that you select a bag with a full-length zipper, so that you can open it up fully to act as a blanket.

Quilt, bivy combo: I've never used a quilt (other than, again, opening up a bag) but I'm not much of a fan of bivy's. Bivy is for what exactly? If rainproof, it's pretty heavy. If not, then you need some other sort of shelter. If it's to keep bugs off of you, it can be too warm to want to be in the bivy yet the bugs are still swarming. It can get you and your bag wet from sweat. I carried a very light (not water *proof*) bivy for the first 700 miles to combine with a poncho. I used that bivy maybe twice, the only times that bugs were any sort of issue. I'd go with a light tent, unless you're not bothered much by tons of bugs, in which case a tarp and headnet. Or the hybrid approach I used (poncho as rain gear and shelter for first 700 miles, skip the bivy, switch to a single-walled or other light tent at Kennedy Meadows).

I'd also point out that some tents will add a bit of warmth (if you get a good light one, however, don't count on much of that). The selection of a bag is thus dependent not just on your metabolism and personal sense of what's too cold, but also based on clothing you can (and are willing) to wear inside the bag and on your shelter choice. And, heck, your experience at site selection. And probably other things I'm not thinking of.

Go out and do some relatively cold weather hiking and find out for yourself; if you don't already have some, it would be good for you to get some experience at hiking and camping in snow anyway! To be clear, I don't think I ever camped right on snow on that trip, though came close a couple of times (in the Sierras only). But you'll likely hike through a lot of it, and being comfortable/safe in cold/wet/snow is a pretty helpful skill before going into the Sierras.

I roll a lot. It's why i use a quilt. Easier to rearrange than a bag you've gotten twisted up in and then got the zipper stuck. First change i made to the three season pack and IMO the best choice i made....

DJ, No, you have the numbers in the wrong order. The chart shows a range from +27.6 to -16.7F, which is a difference of 44.3 degrees. In Celsius, the difference is 24.6C (-2.4 to -27) which is 44.28 degrees F difference, basically the same calculation.

1C = 1.8F for purposes of figuring the difference between two temps.
Example:
50 - 40F = 10F difference;
10 - 4.4C = 5.6C difference;
5.6 x 1.8 = 10.08.

Tom,

OK, now I get it.

dj2

jbylake

There is a test and evaluation unit in New England that does the rating for Army equipment. I can't find it's site, but it may have been reorganized somehow.

Sincerely
Steadman

DJ, what that range shows is that a bag rated without showing the full EN range could be almost useless at its claimed rating. I saw comments on a Wal-Mart bag rated at 20F in which users claimed it didn't keep them warm at 50F, but then again they only paid about $20 for it, so I wonder what they expected.

Steadman - I think you mean the lab at Natick - here is the link.
http://nsrdec.natick.army.mil/about/index.htm
This link goes to a page about the military sleeping bag system. Note that the contractor for the pad is Cascade Designs, which is Therm-a-Rest
https://peosoldier.army.mil/portfolio/index.asp?id=6f5ad3a8&pagenumber=94
The next page shows the system; scroll through this portfolio to see your tax dollars at work. It has pictures of just about everything a soldier uses, from base layers, to helmets, guns, pack, sunglasses, all kinds of stuff.

If I was making the choice, I would take the 15 degree bag. But, I am an engineer, and we like big safety factors.