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The cold world of skimo & alpine climbing

The cold world of skimo & alpine climbing

Tuesday, December 11, 2012

The Belay Jacket Tutorial

Ryan Johnson bundled under a Fisson SL and a Dually layered over an "action suit" base, photo courtesy of Clint Helander
I write about, study, worry about, buy and use a lot of belay jackets.  It hasn't always been so.  And until relatively recently (only the last 10 years) in my own climbing career never actually used a "belay jacket".   While at the same time for the last 30 years I have been intentionally trying to climb "light and fast", all while not freezing my ass off. With varying amounts of success.
Sure, on the rare occasion I have carried what some would refer to now as a  "belay jacket".  But they were really just part of my sleeping system that allowed me to carry a lighter bag.  Not anything I intentionally wanted to climb in.  And even then it would have to be pretty darn cold for me to be able to climb in those same jackets without over heating.
With out a belay jacket, and more importantly, without the knowledge of how to properly use a belay jacket, the idea of "light and fast", generally will mean something other than: light, fast and no sleep till you were off the hill.
At  some point your endurance and your gear  will limited what you do in the mountains.  The limit (which seems pretty well proven @ this point) for us was 40 hrs of continuous climbing.  Better plan on a nap by hour 40.   Or even better, a good bit of sleep to recover and better rehydrate from the effort.   
It is the decision that you will likely go over 40 hrs that will determine what additional gear you'll need for the required nap.  And how much you'll likely suffer for the decision.  
From the email the blog generates and the typical Internet traffic on "belay jackets" I see, it is obvious to me that there is some confusion on how a "belay jacket" is best used. 
If you have any doubts the first thing you should do is read Mark Twight's EXTREME ALPINISM.  The current crop of belay jackets were specifically designed around the idea on a "action suit" for climbing and easily added over layers of insulation ( the "belay jacket" )  when stopped, to maintain body heat.   
But here is the rub.  Like many great ideas, it is how that idea is applied that counts.
Cool muscles work more efficiently than over heated muscles.
If you don't believe that or don't understand it try a simple test.  With the same clothes and effort run a 10K in the rain @ 50F degrees and run the same 10K @ 95F degrees
Now apply that lesson to your own climbing.  Sure you need to survive.  So you'll want to take the amount of insulation required to do so.   But you also want to be efficient in your own climbing.  Which will mean cool muscles are much better than over heated ones.  Take the least amount of weight that enables you to succeed.  What you need and nothing more.
A jacket designed for a 60hr ascent of Denali's Solvak route is not likely the same jacket you will need for your local 6 pitch mixed line in the lower 48.  
The belay jacket is part of your belay system.  It is not, by defnition, a part of your "action" suit.
One is for climbing.  The other is an addition to your climbing suit, to retain the body heat you have just generated by climbing, to limit the effects of no movement while belaying.
It is important to differentiate between the two.  A 60g Atom LT or a Gamma MX shell  that are the major part of your upper body "action suit" are not part of your "belay jacket" system.  In the opening picture for this blog Ryan is using a Fisson SL (76g)  and a Duelly (152g) as his "belay jacket" system.  That is a full 200+ g of Arcteryx's Therma Tek insulation!   Early Spring can be pretty cold in the shade on the Kahiltna.
The Atom LT Ryan climbs in or the soft shell you climb in as a the main upper layer of your "action suit" is not a "belay layer".    My guess where climbers get into trouble is by thinking that a 60g Atom LT and a 100g good as the combo is to climb in...will then be as warm as a Atom LT and Duelly combo.  The 60/100 g combo is not going to be as warm.  You are talking 160g verses 230g combos. Seems obvious doesn't it?  But I have seen others suggesting exactly that. 
It is bad math to add your action suit insulation to your "belay jacket" insulation.  In other words take the insulation required in your belay jacket....just don't take any more than required. 
It should be obvious by now that could be 60g or 260g depending on your objective.
I can't tell you how many times I have regretted not taking my own advice.  Freezing my ass off at a belay, and then because I was chilled, leaving my belay jacket on to follow the pitch.  Then almost immediately over heating mid pitch because of that mistake.  That is with just 100g insulation for my Belay Jacket, even @ -30C!   I would have been better off to start off cold and warm up on the pitch by climbing.  My clothes would have stayed drier.  I would have stayed better hydrated.  And most importantly I would have been stronger over all on route.  I am a slow learner.  But I do eventually learn from my mistakes.
Here is a list of what is available from Arcteryx and Patagonia as an example of insulation in their  various models.  Depending on the temperatures any one of them, or any combination of them, could be used as the perfect "belay jacket".

60g coreloft                   Atom LT
100g corloft                   Atom SV
140g Coreloft                Kappa SV
153g  of Therma Tek    Duelly
153g  of Therma Tek    Fission SL with GTX Pro Shell


60g of Primaloft 1          Nano Puff Series   
100g Primaloft Sport      Micro Puff Series
170g Primaloft 1             DAS (2011/2012 version)


Wyatt said...

Again a very timely article for me. A few questions:

I know temperatures vs amount of insulation required is based on the person so maybe just speak for yourself, but do you have a rule of thumb for how many grams of PL1 you need in your belay system for a given temperature?

What do you think about combining lighter jackets (60g or 100g PL1) versus one big jacket (170g+) like the DAS etc for a belay system (not action suit)?

Daniel Harro said...


Any reason other than price point to purchase the Dually over the Fission SL? Seems like the same weight of Thermatek insulation and minimal weight difference. I have used my Dually in some pretty nasty weather and it was the only piece of clothing to stay dry, don't know if the goretex is needed?

Dane said...

Hey Daniel, no reason I can see. Duelly has it pretty much covered. And I think is a little more climbing specific. I'll have a review on the two of them shortly. Your version of the DAS and the current Fission SL. I suspect from what I have been told the new DAS will simply be a slightly smaller cut..combination of the two. But who knows till you actually see one in person. I actually like the current cut for the Duelly. It is big but I want it big enough (seems perfect to me now) to go over everything I had in the pack.

Wyatt, I have intentionally layered 60 and 100g many times depending of the temps. But I think 100g jackets pretty much cover any need in the CON. US.
60 is not enough. 160+ too much for most I think.

100g is all I use in Canada, the Alps and and here in winter unless I plan a night out. Then I bump it up. But I like to just carry a thicker jacket if I need more than 100g. I'll use a Duelly, DAS or more likely something thicker in Down. But in general 100g of PI will do the trick I think. Much easier to carry than anything thicker as well. Just hope it is enough :)

MTN_NUT said...

what might make everything interesting is the new belay parka that black diamond is going to be producing soon. i saw a few of their sales guys wearing them in bozeman, and they say they will be warmer, better fitting, and cost the same as a DAS. From the look that i got, i think it'll be true.

Dane said...

BD?...another one to jump in on clothing and attempt to reap those higher profit margins with soft goods.

Can't be any worse than the Patagonia fit. But I suspect they will be hard pressed to better the old DAS. New DAS should be unvieled at the same time the new BD line is. And if they are going to match the DAS price point (the most expensive production synthetic belay jacket) they'll have a lot to live up to.

Dane said...

Forgot this part Daniel. I think...iirc anyway. Both the inside liner and the outside shell have the same Arcteryx super DWR water restistant finish and the Thermatex insulation being hit with the same DWR. From the explanation I got the insulation and both layers are hydrophobic and basically water proof. My guess is the the Fission SL isn't as weather proof inside and out and weighs more. But I'll have the details and differences on the two up shortly. I'm curious as well.

marcello said...

Don't they not even sell the duelly anymore? I tried looking pretty hard for it and couldn't find it.

Dane said...

Duelly will be back Fall of 13.

Daniel Harro said...

Looks like the Fission is an "Althletic fit" maybe more slim then the cut of the Dually? Dually is cut perfectly for me as a belay parka! Das... not so much.

I know BD is coming out with a whole clothing line up in the near future. Word on the stree is Arcteryx is coming out with a few down products in the near future as well...

Kevin Senefeld said...

BD will have clothing in the spring. Expect Arc'teryx's down (proprietary DWR stuff) in the Fall, along with the Duelly.

Anonymous said...

Hi Dane,

Great article, Do you ever pack Synthetic Belay pants on your trips?



Dane said...

Hi Stephan. Good question. But let me first clarify the description. They really aren't "belay" pants. No one I know of actually using them that way on hard climbs, where they do use "belay jackets". You could of course...just a lot of time to get them on and off. So depends on the cimbing how you would use them. Long time on lead? Might be a perfect place for them.

The synthetic over pants are better decribed as "break or bivy pants" I think. Pants to be added if required while you take a break to rehydrate and rest. I carry them (but have yet to find a pair I like) if the climb is long enough. But I like a lwt bag better I can use it without shredding the bag with my crampons better.

Brad said...


Great article - thanks. Still a it confused though, with all this talk about synthetic jackets, about your comparative take on jackets like the First Ascent BC Microtherm jacket -- which you suggested earlier on might be an ideal belay jacket?


Dane said...

Down is limited imo for belay jackets. Great for bivy jackets were it is easier to manage the moisture. But pulling a jacket on and off at every belay gets them wet from what I have seen. BC is a rare exception for the most part. BC is warmer than a Atom SV but same over all weight. But then it is down. Lots of options @ any price and the warmth you might require. Hard decision isn't it :)

Neil Newton Taylor said...

Hi Dane,

I liked your comment in the post

"I can't tell you how many times I have regretted not taking my own advice. Freezing my ass off at a belay, and then because I was chilled, leaving my belay jacket on to follow the pitch. Then almost immediately over heating mid pitch because of that mistake."

I have spent more than enough time being cold at belays and would rather not have to again, so that I can enjoy the climbing more. Like you say leaving the Bealy jacket on is always bad news when you are start climbing again.

For this winter I have some new gear to wear in the mountains so I am planning on using a Primaloft vest as well as a puff jacket together as a Belay Jacket to be more flexable, with not much more faff than one item.

Each climber has their own vest (think nano-puff vest style) and we share the jacket (think micro-puff hoodie warm).

At the belay I will wear both items so I stay as warm as possible. Then if I'm cold starting from the belay I can leave the vest on, but take the jacket off and put it in the pack. Then nicely warmed up at the belay, I can take the vest off before I start with my lead so I don't over heat.

At the same time I hand the jacket (and pack) over to my partner so he can use it and I put the vest away in it's pocket so I can clip it to my harness.

When I get to the end of my pitch I have the vest to put on so I don't get too cold waiting for my second with the belay jacket (as they always seem to take longer when I'm cold).

Hope that all makes sense. Have you tried a system like this before Dane?



Dane said...

Additional Duelly and Fission SL info? Duelly has twice the insulation as the Fission SL..hence the name Duelly.

2.7oz or 76g weight on the Thermatek used in both jackets. Fission SL gets one layer 76g, the Duelly gets two, 152g.

But with the addition of the Fission's Goretx shell, they weight almost exactly the same over all @ 1# 10 oz or 748g.

Anonymous said...

Coming March 2013. Supposedly the down waterproofing is significantly better than any other (Dridown, Downtek). 1000 fill power and the highest fill to weight ratio of any jacket ever. $699 retail!