Sleep System Critique

I think you will be cold with that jacket/vest/bag combo. I see it good down to maybe mid 30's at best.

I don't remember the 'Daks getting down to mid 20's in Sept. Is that correct? Will you be sleeping up high? Seems like with judicious campsite selection you could stay in the 30 F temp range.

Richard, I don't have that much experience with synthetic bags, but it's similar to my down system. However, to make it work in cold weather I also add a vapor barrier liner to the bag whenever it's below freezing to prevent the down from absorbing insensate persperation (body humidity), which would destroy the loft. You probably give off about a pint of moisture during the night, both through the pores and respiration. In your case this wouldn't be feasable because you'ld be wearing your down inside the VB. To use a VB I'd ditch the down, since you're worried about a wet trip anyway, and go with synthetic pants and top, say, like the coccoon series from BPL or Smartwool/fleece layers. Alternatively, you could stick with what you have but add a bivy bag to your system (like the Equinox, ~7 oz), which would extend the lower range of your bag about 5-10 degrees. It's all an adventure, so try it, learn something, and then fine tune it. Happy trails!

Another option branching off Monty's would be to use the VBL with your existing system–but layer your clothing over you blanket style inside the bag. It's worked reasonably well for me in the past. But I haven't tried extending the range of a bag quite that much, either. I would try a VBL–Western's is 4 ounces, aluminized, pretty great addition to a kit.

Richard, if I'm reading you right, you're saying that your Marmot sleeping bag is only really good for you down to 50 degrees? For extra core insulation, you're adding the ultralight down vest and a synthetic jacket. I've never heard of the Micro-D-Luxe, but the Micropuff currently uses 3 ounce Climashield. Well, you're the only one that knows for sure if you'll be warm enough, since I'm not familiar with all this clothing. I would tend to doubt that it would be possible to push a 50 degree bag down to 25 with just those jackets, though. Also, I would bring a Prolite 4 rather than the 3. It's much warmer. Overall, the biggest weakness of your clothing/sleeping bag set up is the fact that the weight is inefficient. If you just traded all that stuff out for a good 20 degree down bag and just used your synthetic hoody for around-camp insulation, you wouldn't need to carry the excessive weight of insulated pants, socks, or a vest, and you'd still probably have enough around-camp insulation for nighttime lows in the mid to upper 20s with that synthetic jacket, although you would know that better than me.

I can't speak to the actual temperature rating but I like the concept of down inside a synthetic bag or quilt. Down provides broad comfort range similar to other absorbant natural fibers- but with the achilles heel of loft collapse once it's saturated. By using a synthetic outer layer, even in very humid conditions the dew point will be in the synthetic insulation, not the down. You get the advantages of light weight, compressibility, "drape, and thermoregulation from down combined with higher moisture tolerance from the synthetic.

That said, I see two weaknesses:
1. A 20 degree bag- even synthetic- can be lighter than the combination of bag + down insulated clothes for the same sleeping comfort. Of course the insulated clothes can serve double duty as clothes. This brings us to:
2. Down clothing is probably the worst choice to wear outdoors in temperatures around freezing due to problems with moisture. Woolen and/or synthetic insulation are best for cold with damp.

Also the system has a lot of components. Good for flexibility but might be a hassle.

I like the concept for winter, arctic, or expedition use.

For cool/wet conditions I think a woolen base layer and synthetic insulation layer make the most sense for comfort, warmth, and safety margin.

Certainly do not use a vapor barrier over down. In my experience a vapor barrier sleeping bag liner works well over fairly thin synthetic insulation such as polypro and pile. With too much insulation you will get condensation inside the vbl and that is very uncomfortable (unless you're accoustomed to vinyl or latex clothing). Also at temperatures around freezing or higher your thermoregulation might be difficult. I feel that a VBL has a comfortable range starting about the point that the bag without it was starting to feel chilly, then it gives you another 10 degrees of comfort.

As has been said already, do not put a vapor barrier over any insulation, or you will end up with wet insulation. So a VB liner will prove difficult to use with (over) your down clothing. It will probably make things worse. But have you considered VB clothing over a thin base layer? This would keep all insensible perspiration and or sweat out of all of your insulation, down and synthetic, as well as giving you a warmth boost by stopping evaporative cooling. But, it would still be additional weight, and things might be better served with simply a warmer bag if available.