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 SV...as 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)