WM Ultralite vs. Nunatak Arc Alpinist

I've been comfortable in mine with a down mat down to 10-15 F, in a tent. Mine has two ounces of overfill and a differential cut, and is slightly larger than an Arc Alpinist, more like an Arc Alpinist – Arc Expedition hybrid.

Evan
First let me just say that i own two Nunatak highly customized bags (10F alpinist and 30F sub alpinist see my review
here so I guess it means I really like Tom’s work
However his ratings are quite spartan…

what I suggest is you use WM/FF as a golden conservative standard (ppl claim Katabatic is conservative as well) and work from there. What i did is look at WM fill weights and then get some effective fill per unit of area number using length and shoulder/hip/foot girth data. I then extrapolated to my own bags (or quilt) by compensating for differing girth and taking something like 15% off to transform from mummy to quilt. If you do that trick you will see that the Kata quits are pretty much on the money.

In short – just have Tom overstuff a bit to meet the temp rating and you should be fine.

also depending on your usage of balaclava style – if you use a full down balaclava its prob fine…but if you are using something like sleece balaclava and BRR down hat etc – would consider adding a draft collar

another design point I would look at is what kind of pad you use – if you are like me and use short pads with significant drop off and augment your pad with your rucksac – you need to make sure that the closed part of the footbox is long enough to bridge over that area between your rucksac and pad otherwise you will have a “hole” there beneath you

RE down – I opted to upgrade to 950FP with Tom….$$$ but I figured it could help (I know some people dont subscribe to high FP stuff….but I trusted tom’s statement that this down was superior in his real world outdoor testing

Mike

I just tested out some WM bags at a local retailer, and I have to tell you their standard bags seemed incredibly constricting to me- to the point that as a practical matter I doubted that I could wear much high-loft clothing while in the bag. I'm a moderately acrobatic side-sleeper, so this was an issue for me and I ordered their "high girth" bag instead, the MegaLite. It's hard to tell from your avatar but you look about my size, and I suspect that the non-high-girth WM bags might feel tight to you, too. On the other hand if you're a satisfied quilt user maybe you're ok with that. (I have used a Rocky Mountain Sniveller for a few years now, but I use it with the omnitaped pad, so that sucker is ROOMY.)

That said, I agree that the WM bags seem to be stuffed better than their claimed ratings. Clearly, though, I haven't used one yet to really know.

Thanks for all the information! It still leave me scratching my head. In the end, I don't think I can go wrong. I'm thinking of asking for an over-stuffed Arc Alpinist . . . or just going with the Ultralite.

Relative to most able-bodied American males I'm on the small side: 5'9" 145 lbs. I usually don't have a problem with slimmer, tighter gear or clothing.

Ah, then yes you are smaller (i.e. less obese) than me so perhaps the WM bags will work well for you, though shoulder girth might still be a problem. I'm 5'10" on a good day.

(edited for typo)

I agree with Dean. The Ultra series is really narrow, such that for me, I can't relax my shoulders compressing down in the processes. Of course, they look super lofty in that series helped by the width and overall cut. I much prefer their wider series at the expense of weight. In fact, I ended up going with a custom Feathered Friends primarily because of the ability to get the cut I wanted.

I have a WM Ultralite and a Nunatak Arc Spcialist. Both are good to their rated spec. I expect the Nunatak you are looking at to be the same.

Thoughts…

At lower temps drafts can be an issue with quilts, so user skill is a factor. Many people use a bivy at lower temps.

The WM has a hood and fill/material on the bottom. You will need some sort of head gear with a quilt.

Dean made a good point about sizing. I am skinny so the UL works for me. I bought and tested mine in a store. It seemed pretty narrow. Took me an hour and testing of many bags to make my decision. After leaving the store with my UL I wasn't 100 certain about my purchase (I am a side sleeper).

I've had both my UL bag and Arc Specialist for several years and am happy with both. They do what the specs say they should.

My friend's WM 30º bag is a dream, down to 10º it's still comfortable for him. Just saying.

There was a quilt around earlier this month on the forums that won top honors on a reputable website. I wish I could find it. It used a bungee cord system that allowed it to tuck underneath side-sleepers. It looked really good- perhaps someone else knows the name.

You had to pay for it, I remember that…. something like $400

I FOUND IT!

http://www.outdoorgearlab.com/Backpacking-Sleeping-Bag-Reviews/Katabatic-Gear-Palisade

Enjoy.

Sweet. Thanks, Max.

Happy to help!

I'm just shy of 6' and was 145lbs when I got my WM UL. It was still plenty big for me to wear light insulating clothing inside. Even though i've put on almost 20lbs (too much climbing and hiking apparently) I still don't have much concern with fit.

As for warmth I used to be a cold sleeper until I fixed my sleeping pad warmth, now the WM UL is almost too hot for me in the low 30s, hasn't been cold enough to try 20s now that my pad is different. It should be warm enough for you with a lot less fiddle factor than a quilt in sub-freezing temps.

Not to throw another wrench in the wheel but if I were in Europe I'd look strongly at the offerings of Valandre. In my experience they are every bit as finely constructed as WM, FF, and Nunatak.

If only I were in Europe . . . but wait, I am! Thanks for the reference. I'll take a look at Valandre.

Hi, I’m searching for a 20F quilt right now. For that purpose I’ve prepared table that lists some options available. It is shared on my google docs here: link

Evan, do check out Valandre. First rate bags.

Richard

Evan
You would be just fine inside an Ultralite and still have some room to layer…
I am 1" shorter than you and about 10 lbs heavier (at the moment).
You need to get the 6' version of course…

For years I used my WM Highlite and WM Ultralite as quilts. If it got cold I zipped them up for extra warmth. Last year I purchased a 20 degree Zpacks quilt. I can zip it up when it gets cold but it does not have an attached hood and that makes a big difference for me since I am a very cold sleeper. Wearing a hat/hood is not the same as a bag with a hood and a neck draft collar. The quilt is my spring-summer bag and a WM Alpinelite is my fall-winter bag. The Ultralight is a skinny bag and I enjoy the extra room in the girth from the Alpinelite.

I have to agree with the hood part, I don't consider a hoodless bag anything but a 2-3 season bag. Having a hood and draft collar adds like 10º-20º in the temperature I can take a bag down to. Cinching it up so I've got 3 inches to breathe out of makes a warm cocoon.