first-time UL bag buyer—advice? (marmot plasma)

without a doubt … use the EN comfort rating, not the lower limit … most bag makers rate even the womens bags for the lower limit (men's) temperature

the plasma 15 is rated to 29F for women …

I think the 15 would be more versatile if its your only bag. Its also not much heavier than the 30 deg version. I had the helium for a long time and its a great bag. But if you have a really good discount I'd take advantage of it & get a plasma. I checked it out in a store and its a really nice bag.

OK, gonna say right off the bat that I don't know what qualifies a bag as an "ultralight" bag. But I'm pretty much a one-bag woman like you (and also 5'2") and did a pretty extensive search for THE bag last year. So, here's my experience for what it's worth.

My goal was a a sub-2lb down bag with an EN COMFORT rating of 25-30*. I found many bags, like your Plasma "15" where the EN comfort rating was significantly different than the (seemingly) arbitrary number in the bag name. I didn't blow off the non-EN rated bags (I don't know if WM is EN rated now but I don't think they were when I was looking); I did my best to extrapolate based on fill ct, weight and bag size (area).

I chose the 25-30* EN comfort range because my experience has been that a traditional "20-degree" bag has been the most versatile 3-season bag for me. Most 20* bags, however, aren't really rated to 20*, especially when you look at the comfort rating; they were actually mostly 30-35*.

Size is also important, especially if you're small since you can save quite a bit of weight with a properly sized bag and stay warmer to boot. I happen to really like the "women's cut" bags — sized to fit my shoulders but roomier (proportionally) at the hips/thighs. I never feel like I'm sleeping in a straight jacket.

In the end, I chose between Western Mountaineering and Feathered Friends. I ended up buying the Feathered Friends Grouse, which is a women's cut bag, in a 'small' sized for 5'3". I liked the feel of the Nano fabric better than the WM and the fit is perfect. My bag weighs 25oz. I had it down to the low 30's this past April in the Grand Canyon with no shelter on top of Whites Butte (i.e. windy) and I was cosy with midweight baselayers and a ProLite pad. I sleep pretty average (for a woman, anyway.)

I've found that I prefer bags to quilts but am in the process of making a quilt with about the same temperature specs for a second/backup kit and when saving a few ounces is critical. I expect the quilt to weigh less than a 16oz and provide about the same warmth as my Grouse. So, if you're open to quilts, you can save quite a bit of weight. Again, it helps to be small in terms of saving weight.

I'd get the Marmot Plasma 15F. Eric makes an important point about the EN rating. And, remember that the EN rating assumes your pad insulation is around R 5. I have a Marmot 0F bag for winter, and I like it.

Edit: It depends on what kind of a deal you're getting on the Plasma. I probably wouldn't want to pay more than $50 more for the Plasma over the Helium.

Have you considered a quilt instead of a bag? I love my quilt and will never go back to bags. I'm not sure what kind of deal you can get on the Plasma, but you can get a 20F quilt from Hammock Gear for $229 that weighs 21 oz (http://www.hammockgear.com/cart/index.php?main_page=product_info&cPath=2_10&products_id=2). And for an extra $50 you can order it in 7D and drop about 3 oz. There are other quilt manufacturers too – Nunatak, enLIGHTened Equipment, Te-Wa, GoLite,…

Thanks, all, for the advice! That was a really good point about the EN ratings, and I'm glad you pointed it out, as I probably wouldn't have realized that's what they mean (I know, I know…)

As for the commenter who recommended a quilt, I'll look into it. I'm probably a bag kind of woman, but I'll check them out!

There is no way that that quilt is a 20F comfort rated quilt. 12oz of down in a hooded sleeping bag would give you about a 32F to 34F EN rating. 3.5" loft is not going to cut it withough layering in clothing.

A 12 oz. fill in a bag has the down on the top and bottom = extra unused down. Quilt has it all on top. That is the weight difference, and how you get a higher temp rating at lower weight.

For reference, the Western Mountaineering Apache is listed at 6 in loft for a 20 degree rating. 3 in top 3 in bottom which is less than the hammock gear quilt that has 3.5 loft on top.

What Michael said is correct, more so, using "oz of down" as any sort of comparative is typically useless, unless comparing two bags/quilts/whatever with the *exact* same raw dimensions, and I've always wondered why it's so common. Simply put, two bags of different internal volumes, are going to require equally different amounts of down to reach the same target temp.

You've got to look at loft instead, although coverage is always a very important factor in determining warmth. To that, I'd point out, that while the hammock gear quilts are a great value, and Adam Hurst is a friend of mine, please bear in mind that they're sized for hammock use, which require much narrower dimensions to provide adequate coverage(read: warmth), and less complicated profiles, than ground sleeping.

@M. G. That's fine, some people prefer bags. I had never heard of quilts before BPL so I wanted to mention them to you.

As a side note, many people seem to think Hammock Gear quilt ratings are conservative. And yes, his quilts are narrower than what people normally use on the ground, but I figured that for the OP, "a small woman, 5'2, 120lbs", their width and length would probably be sufficient.

As for a "weight of down" comparison, it is not exact, but the GoLite UltraLite 3-Season Quilt (size Regular) is rated for 20F with 11.8 oz of 800 fill down. The HG 20F Burrow has 12 oz of 900 fill down.

Yes, by loft height, Adam's listed temps are very conservative. 3" of loft should be good to 15deg at least in an adequately sized quilt with appropriate bottom insulation. However, I'd suggest they're probably accurate for ground sleeping considering the dimensions.

I would go with the 15 degree bag if its your only bag. As mentioned, it doesn't weigh much more than the 30 degree bag, but is a lot warmer. Once you've built a bag and added some insulation, it doesn't take much weight to greatly increase the amount of warmth. Much of the weight is in the zipper and fabric holding the down.

Which leads me to my next point. All of the really good sleeping bags have top quality insulation and fabric. This means that the only real difference is how much insulation they have and the design of the bag. The design involves trade-offs. A slim bag will be warm for its weight, but it will be tight. Likewise, bags with half zippers are lighter, but don't have the flexibility. There is similar story with quilts. These are all reasonable trade-offs, but there is no magic formula. If you can get a good deal on a Marmot bag, I would go for it.

The only possible exception and innovation in bag design is Montbell, which uses elastic to keep the bag tight (to keep you warm) but allows you to stretch your legs. Whether than innovation is worth the cost is debatable.

Except that assumes a pad with an R-value of over 5 (as per EN testing). The fact that a quilt omits a hood, whereby most of one's heat loss is through the feet and head, a quilt with a 3.5" loft rating is not going to be sufficient at those temps without additional clothing.

And for those wondering, I use quilts exclusively (two actually).

richard actually showed that loft had less relevance than oz of down on his posts a while back …. too bad he is MIA

regardless …. en testing provides a MEASURED baseline for comparative "warmth" … whether you fit the euro norm is a different question …

but the days where a "reputable" bag maker can claim a 15F bag based on the survival ratings are basically over …. unless u are valandre ;)

Agreed, but the Marmot has less than 20oz of down so I am taking that into consideration. It is also cut extremely narrow so obviously there is some reliance on radiant heat but not for average sized humans who would compress the down sufficiently to make this a 'cool' bag.