Arcteryx Atom AR as a belay jacket on Rainier Summit?

I'm having a hard time choosing between wearing the Arcteryx Atom AR or Patagonia DAS on summit of Rainier if wet cold conditions are possible. Would the Atom AR suffice? Which would you choose?

DAS.

Depends on how warm your "action suit" is and what else you are bringing (I run hot on the way up and need to bring a thin synthetic/active insulation piece for the way down). In full summer slog season I would likely bring the atom AR.

They would be used very differently.

DAS: Used while taking breaks, or, if god forbid an emergency situation came up. This will be too warm to really do any activity in.
Atom: You could potentially wear this as your main action layer. If you already have a good and warm action layer, you could throw this on during breaks.

This is what I find works well for me on Rainier:

0) Marino wool half zip
1) Very very lightly insulated jacket with a hood to protect from sun (OR Deviator Hoody)
2) Thin softshell hoody (Eddie Bauer Sandstone Hoody)
3) Insulation layer, which may go under layer #2 if conditions get weird, but will usually stay over it (Arcteryx Atom LT)
4) Another insulation layer to go over layer #3 (Arcteryx Atom LT one size bigger or Mountain Hardwear Ghost Whisperer)
5) A hardshell that can go over layer #4 easily and if necessary go over layer #5 (Arcteryx Alpha LT or SVX depending on forecast)
6) If I am leading the group, I'll take a parka like the DAS just in case something goes wrong (Mountain Hardwear Nilas)

This is my setup. Not worried about dry days, I think I got that nailed down. It's wet days that concern me

Dry days:

1. Smartwool 250nts longsleeve
2. Patagonia longsleeve zipneck capilene thermal weight {optional}
3. Patagonia R3 fleece hoody
4. Patagonia houdini wind shell hoody
5. Arcteryx alpha FL hardshell
6. Arcteryx cerium sv hoody

Wet days:

1. Smartwool 250nts longsleeve
2. Patagonia longsleeve zipneck capilene thermal weight {optional}
3. Patagonia R3 fleece hoody
4. Patagonia houdini wind shell hoody
5. Arcteryx alpha FL Hardshell
6. Arctery Atom AR Hoody or Patagonia DAS????

DAS.

It can be weather/season dependent, but usually my belay puffy is my safety margin in a worse case scenario. To me it is worth the ~6oz extra.

What I've been thinking of doing on a summit wet day is take off my hardshell exposing my wind-resisant/water-resisant shell, put on my down puff and put my hardshell on top. Down jacket would get a little wet when switching but nothing too major.

Sterling Falconer wrote:What I've been thinking of doing on a summit wet day is take off my hardshell exposing my wind-resisant/water-resisant shell, put on my down puff and put my hardshell on top. Down jacket would get a little wet when switching but nothing too major.

If you are going to keep your insulator under the hardshell, you are going to need to make sure you don't overheat. It sounds like a weird problem to think about, but once you get moving, things can get pretty damn hot. If you begin sweating it will result in dehydration and the soaking of your inner layers.

In summer months, if you are wearing the Atom AR under a hardshell, you probably dont want to be wearing anything more than a t-shirt under that. Even in bad weather.

You may want to check out RMI's recommended equipment list for layering. It's pretty solid and will keep you covered under pretty much all circumstances.
rmiguides.com/mt-rainier/4-…

I don't plan on climbing with a belay jacket on if that's what you're thinking. I'm talking about when you've already reached the summit and just hanging out taking pictures.

Sterling Falconer wrote:I don't plan on climbing with a belay jacket on if that's what you're thinking. I'm talking about when you've already reached the summit and just hanging out taking pictures.

Generally the summit of Rainier is not a fun place to hang, even on a good weather day. I've never spent more than 90 seconds up there. But in the event that you do decide to hang out up there, that wouldnt be a bad setup.

However, my mountain-sense tells me that if the weather is shitting on you, it's better to GTFO.

I was looking at RMI's equipment list and it look likes the down jacket as a belay jacket will be okay but I would need to replace my Patagonia Capilene Thermal Weight Shirt with something a little heavier like the Patagonia R1 Fleece Jacket. If I layer the R1 with a R3 Fleece Jacket and the Patagonia Houdini wind jacket it should create a flexible softshell without sacrificing mobility.

Liberty Ridge I did the entire 26 hour summit descent day without changing a layer and maintaining comfort:

1:) Merino T-shirt
2:) R1 Hoody
3:) Houdini
4:) Atom LT

I had in the pack:
Alpha FL Hardshell and Feathered Friends Hooded Helios but neither came out on summit day. Weather was decent enough, if we had hung out on liberty cap more I would have thrown on the big puffer. I'm glad I had both even though I didn't use them much.

So I'd say grab the DAS. It's not something you want to be moving in but if you need it you'll be glad for the warmth. Consider it your emergency bombproof layer.

Sterling Falconer wrote:I was looking at RMI's equipment list and it look likes the down jacket as a belay jacket will be okay but I would need to replace my Patagonia Capilene Thermal Weight Shirt with something a little heavier like the Patagonia R1 Fleece Jacket. If I layer the R1 with a R3 Fleece Jacket and the Patagonia Houdini wind jacket it should create a flexible softshell without sacrificing mobility.

Multiple layers of fleece under your windshirt is a bit of a pita to adjuster. I'd do the R1, houdini, and then an "active insulation" puffy. I hate dicking around trying to get a windshirt off/on when I'm actually out in the wind, not to mention the cold that gets through while you have it off. Keep in mind I run hot while active though, so I would likely be in thinner fleece than the R1 with a windshirt at lower elevations.

Personally for Rainier: Rab silk weight (120gr) merino t, BD coefficient hoody (same as R4), alpine start windshirt, and montbell thermawrap vest. I didn't put the vest on until around 12k. Now I would bring a nano air hybrid jacket instead of the vest.

Also for comparison, approaching and soloing some easy ice in the ghost recently it was around -8 to 0 degrees, occasional 20mph gusts. I wore a poly mesh t (for cyclists under gillets), BD compound hoody, nano air light hybrid jacket, alpine start windshirt, loose knit poly beanie. While rappelling and walking downhill I left my stance belay parka over it.
My partners had a mid weight base layer, dead bird photon, and nuclei. Other partner had on enough to look like the kid in a chirstmas story, think she had a down puffy UNDER her BD stance belay parka.

Kyle hit the important point. No one here can reliably answer your question without knowing when you'll be climbing, plus your personal temperature and thermal regulation.

That said, The system you have listed (wet version w/ DAS) is probably warmer than what I bring for winter on Rainier. I can't imagine wearing a 250g long sleeve baselayer plus a Cap4 plus an R3 while moving... that's like polar explorer level of insulation...either that or your own personal sauna. Being too warm up there is a legitimate problem, so I tend to prioritize a light weight and breathable action suit and pair it with a bomber puffy for stops/oh shit moments.

Personal system for summmer: 135g Merino or silkweight synth t shirt - BD Coefficient Hoody - OR Ferrosi Softshell
In pack: OR Chaos Parka (same as DAS), Montane Minimus Shell

Personal system for winter: 200g merino or Cap 3 LS - BD Coefficient Hoody - OR Ferrosi Softshell - Arc Atom LT Hoody
In pack: OR Chaos Parka, Montane Minimus Shell (unless weather sucks, then eVent shell)

Thanks guys. I also think it would depend on my body temperature when it comes to choosing the R1 vs Cap 4.