Flaw in my TQ Logic?

[weaver2469]

I agree with all of this.......

It's not a lot of intentional product testing, more in field use and I wasn't really referring to a Syn/Down layering system as per say.

The Down Syn layering is interesting but difficult to achieve due to compression of any down inner layer. Problematic, but not an impossible.

I was more referring to the ability that good quality synthetics have of being able to dry out damp items of clothing, and themselves, while wearing or sleeping in them. You don't plan on sleeping in wet cloths, and you don't plan on getting your insulation damp or wet either, but it can happen. With down you are done.

That said, I'm not knocking down. Still the warmest, lightest, packable, by all means.

However, I'm staying with a Synthetic for an UQ as my goto for now, when I can afford another trip to AHE.

Presently, with a tarp with a 12' RL, I'm more wary of spray and splatter underneath, than anything coming down from above. I'm sure when finances allow, I'll get a good down UQ, for the fair weather weekenders and short week or less, hikes and it WILL probably get the most calls, due to the weight factor alone. Longer hikes, Thru or Section, if the weather is suspect at all, I'd want the Syn UQ again.

More importantly, I'll also stay Syn with my insulated jacket. Here is where layering, wicking and drying really come into play for me.

Worst case situation? You can wear them in the pouring rain, and you will be wet as a dog...but warm. Wear them long enough after the rain stops and whatever your wearing underneath will begin to dry pretty quickly.

Often I feel that when we get into the Down vs Synthetics discussions, it's always the weight vs warmth vs bulk vs cost equation. I'm just not yet convinced that formula considers all viable factors, or that the superior insulation qualities of down completely nix the warm when wet and drying abilities of high quality Syns.

[dirtwheels]

I like your idea, seems very logical. I know it would add weight but what do you think about sewing up a bag/slip cover for them? It could have an opening for access to the footbox. Maybe sil ripstop on the bottom and and regular ripstop on the top. Seems like it would for bottom quilts as well. Modular quilt system.

[SilvrSurfr]

The layering system seems logical to me. However, the drawback will always be additional weight. In deep winter weather, I might not even care about weight though - I just want to stay warm.

If I were to layer my topquilts, I would probably go synthetic inside, down outside. That would avoid compression of the down.

[K0m4]

I've got a sleeping bag setup along the same logic. Got the idea from reading about how Swedish military deals with the colds of winter up north - a double sleeping bag system (I think made by Carinthia), when combined rated to an extreme of -40 c or so. Individually, hte bags are summer and 3-season rated respectively. So it's definitely a viable idea with lots of versatility, the trick is that one of the bags should be larger and roomier, to minimise the compression loss. I'm defiitely willing to take the weight penalty, bags rated similarly will weigh that much anyway (well, almost). And as you point out, it saves a bunch of money as well.

I like the idea floated about a synthetic outer actually, makes a lot of sense to me. What's a roomy synthetic summer-rated bag that I could look into?

[Rolloff]

Well, if you can get even a thin layer of lofted down, that doesn't get compressed, on the inside layer, then theoretically the wicking and drying qualities of a high quality synthetic, could come into play.

It also might make for a dandy way to turn summer and 3 season insulation into serious cold weather gear.

Dry Down, mentioned in a couple other threads, might hold an important key toward this.

[Just Jeff]

I stack TQs and UQs all the time. I have a couple of 0F setups, but sometimes it gets well below 0F here in the Colorado mountains...just not often enough to actually make a -20F hammock kit (and no one makes one for sale b/c there's not a big enough market). So I just stack some extra stuff on there. Last time I used a 0F Yeti, 30F No Sniveler on top, and a PeaPod layered around all of it. (IIRC)

The military has been using overbags for a long time...same concept. Wiggys makes a good kit, though it's a bit heavy for lightweight backpacking.

Re: the drying, it doesn't actually "dry" the inner layer but it does keep so much moisture from building up in the lower layer in the first place. Basically, your warm body is producing moisture, which moves up towards the cool outer layer of your TQ. At some point, that moisture reaches the dewpoint and condenses into water. If that point is inside your TQ, the water stays there. By having two layers of TQ, you're (hopefully) pushing that dewpoint into the top layer...and it's easier to dry one thinner layer than a big thick TQ.

There have been some commercial attempts to create a hybrid down/synthetic sleeping bag based on this principle, but none have been very successful. Part of it is trying to capitalize on the "hype of technology," b/c the concept is sound but the execution is flawed. Generally, synthetic insulation is heavy enough to compress the down layer to the point that any gains in maintaining loft by removing moisture are lost by compressing the down in the first place.

FWIW, the original JRB winter kit (in ~2005 or so) had a NS+Nest stacked as UQs and an Old Rag Mountain as a TQ.

So the principle works, and it's a very flexible and cost-effective approach for people who don't need a dedicated cold-weather kit...or just don't want to spend the money on one.

[dakotaross]

I will bring my Golite Ultra along to supplement my Dreamwalker bag. Ratings don't stack as a result, but never been cold down to the teens. I'd say it truly adds 10 degrees temp rating to the 20 degree rated DW bag - as opposed to the very questionable liners that supposedly add 10 degrees.

I have the JRB liner which is very warm for what it is and about the same weight as the Golite, but the Ultra packs down a lot better, besides being warmer.