4 season mummy bag

[Eric Blumensaadt]

I have a Western Mountaineering Megalite mummy.

> Last year I had WM overfill it with another 1 0z. (800 cu. in.) of down so I could use it down to at least 25 F. Works great if I wear a set of thin polyester long johns and a stocking cap.

> I have comfortably used it with synthetic insulated (Thermolite) pants and jacket to 15 F.

> I will soon be using an old down top (which formerly zipped on each side to a ripstop covered pad) to cover the Megalite's top, hopefully adding another 20 F. I used a few Velcro strips to hold it in place.

* Wearing insulated undergarments mainly in camp and while sleeping is certainly multiple use.
* using a 3 season bag year around also qualifies as multiple use.

BTW, I DO have 2 true winter bags but both are synthetic, heavy and bulky. The Mt'n. Hardware bag is a -20 F. bag, a true monster.

Anybody else stretch their 3 season bag into winter?

[Mark Verber]

I have sometimes pushed my 30F down quilt to the moderate conditions in the sierra, e.g. lows typically not below 0F. The first was a surprise cold front in early fall when we weren't that high. Dropped to 12F when we were expecting a low of 30F. i wasn't comfortable at the coldest part of the night, but was warm enough to be safe and to eventually get back to sleep. Since then I have occasional taken my quilt on winter trip when I someone needed to borrow my winter bag (WM Versalite which I am toasty in at 0F with no clothing).

For me it make sure enough padding, use my bivy to keep side drafts out, use a a warm hat + a down baklava, wear heavy base layer, and high loft (down and/or synthetic jacket and pants).

That said, while I tend to take less insulation that many people I know on 3-season trips, I really do enjoy a warm bag on my winter trips.

–Mark

[Kevin @ Seek Outside]

I have ran this system from 60F to -15F. I suspect it could go to about -30 F and perhaps lower.

20 degree down EE quilt
Lightly insulated Bivy
20 Degree down EE quilt

The bivy is 13 ounces. It has some insulation. In temp measurements the bivy seems to add from 10 F (sides) to close to 30 F (top). It is synthetic.

The 20 Degree quilt I use on it's own in milder temps. In cooler temps below 30 usually I add the bivy. In really cold I snap two quilts together giving a silly amount of loft and put them in the bivy. Total weight is a under 4 lbs 8 ounces. I have not tested it, but realistic sleeping rating is probably 5 " of down loft + 20 degrees of synthetic. The combination probably goes pretty low.

[Randy Martin]

I like that system Kevin. I have been debating the merits of investing in a dedicated winter bag and it seems it would be just as effective both from cost and function to invest in a second quilt that I could lay on top of my summer quilt.

I have a Katabatic Gear Chisos (40 degree quilt) for summer use and could probably add a 30 degree quilt to that and extend down to zero when included with my uninsulated bivy.

[Kevin @ Seek Outside]

As long as you can seal up your quilt very well you should be fine. One of the merits of the insulated bivy is that it helps keep condensation out of your down when you are below freezing all the time.

[Stephen M]

Hi Kevin,

Could you post some.info about the insulated bivy.

Thanks,

Stephen

[Kevin @ Seek Outside]

What kind of information are you looking for? We are planning on possibly producing it and are tweaking and testing. The basics though, is it is a pretty standard material UL bivy with a layer of apex on the top. There are a few things we are changing probably more from a function perspective than anything while trying to keep weight low.

[Stephen M]

Hi Kevin,

Would like to know the amount of insulation used as well as what material the bivy uses.

Thanks,

[Kevin @ Seek Outside]

2 oz apex, material is basic silnylon and lightweight ripstop.

I don't worry much about the ground moisture as I have a pad there, however I could see using something with a higher hydrostatic rating for the bottom.

[Stephen M]

Thanks Kevin,

[todd]

Bill Fornshell made & posted ( on this site) about the first insulated bivy that I ever saw:

http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/4262/index.html

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