The Belay Jacket image

The Belay Jacket

November 9, 2008

Reading Time: 1305 minutes.

The wind is blowing hard, the temperature feels way below freezing, you’re wet, you’re cold, you feel the first signs of the onset of hypothermia. You could be belaying in a winter storm in the Cairngorms, benighted high on an Alpine peak, sitting waiting for the mountain rescue team, eating your packed lunch, or even sitting out a rainstorm on a multi-pitch Spanish sport climb. You’ve got on every stitch of clothing you have; shell, fleeces and base layers (or just your cotton vest and sun cream), but you know it’s just not enough to fight off the terrible cold that’s slowly creeping into your core. You feel far more exposed than you’ve ever felt before and you are suddenly fully aware of what it really feels like to be naked to the elements and, worst of all, you know you won’t last long unless you can do something about your predicament.

I’m sure almost all climbers have experienced this horrible feeling at some time or other, that feeling of becoming dangerously cold and knowing you don’t have anything else to put on or any reserves of heat to call on to stop it. My own experiences of this have generally not been winter climbing or on expeditions but in places like El Cap (twice), Mallorca or walking home from nightclubs (one of the few remaining urban killers). The common factor is usually that I’ve been caught without enough insulation (or my insulation has been overpowered by unexpectedly bad weather) and I was unable to put on any more clothes, or my body was unable to generate any heat because I was unable to move; stuck on a belay for example.

Another less serious but potentially terminal consequence of cold is its psychological effect. If you’re standing on a ledge freezing your butt off your morale will rapidly drop until the point you lose all interest in the route, your partner or life itself, often leading to a total loss of interest in the climb. Getting cold also makes you acutely aware of your own vulnerability - which isn’t always a good thing - especially if you are very vulnerable - and again is probably one of the prime causes of retreat. A deep-frozen body and mind also doesn’t operate properly, often leading to errors in judgment, like failing to navigate correctly, belay safely or thinking problems through properly.

Like most climbers, in the past, I would maybe carry a spare fleece (something like a Buffalo belay jacket) to wear if things got really bad but would rely primarily on having enough clothes to see me through the day. The problem is if you wear enough clothes to keep you warm no matter how cold it gets you’ll just end up suffering the flip side of hypothermia - heat exhaustion.

If you carry a second fleece then the problem is that to put it on you must first remove your outer shell, losing any stored heat if it’s stormy and potentially wetting everything below in the process. A fleece also doesn’t provide that much protection compared to its weight and bulk in your ‘sack, being designed to insulate when active.

A much higher, loftier layer is a down jacket and if it’s super cold then this was what I used to carry, but the problem with a down jacket in a maritime climate like ours is that it will rarely survive long, even with a high tech shell (a wet down jacket can still provide quite a bit of insulation mind you, although its warmth to weight ratio is seriously reversed). On a big mountain route, you are also often reluctant to put on your down jacket if it’s stormy, especially if you have many days ahead of you, as it will always eventually wet out.

Companies like Rab, Mountain Equipment, Marmot, Arcteryx and PHD all make fantastic hooded down jackets that provide huge levels of protection (the PHD Delta for example has a water-resistant outer and inner), but none will stand up to classic ‘Scottish’ conditions - even if you’re not in Scotland. The main gripe I have when using down jackets outside in anything but super cold conditions is that you know that the high degree of protection they provide is fragile and so fails to provide the psychological crutch one needs to face the worst the weather can throw at you - and most of all have the bottle to battle on.


If you were to sit down and write the spec for the perfect item to keep you comfortable then this is what you’d be looking for:


You may not necessarily need this jacket, but because you never know when it may come in handy it needs to be light enough so that it’s always in your ‘sack and should ideally weigh under one kilogram. This is also not just a winter item and can be used for adventurous cragging (multi-pitch, mountain, sea cliffs), so it must be light enough to be stuffed in a stuff sack and clipped to a harness (or simply tied around the waist).

Low bulk

You don’t want it to fill your rucksack up and needs to be easily portable (see above).

High loft

What you’re after is a piece of clothing that will double your insulation and thereby warm your core and give you a considerable physiological advantage as you know you can always rely on it when things get bad. Having a thin insulator is a false economy, as the difference in weight between the two is pretty minimal.

Robust insulation

You want the warmth to be robust enough to survive getting wet and to dry fast. The jacket needs to be idiot-proof, doing its job in the worst weather, even when worn over a soaking wet shell. It can be stuffed away wringing wet yet still keep you warm if you need it later. Robust insulation means that a heavy and expensive taped shell isn’t required making it lighter, lower bulk and cheap.


The shell should cut out wind in order to maintain the top’s loft and also resist snow and dissipate rain.


The jacket must have a hood, both to protect the head physically and psychologically - don’t underestimate a hood’s effect on one’s morale - and to keep the weather out of the jacket. It also needs insulated handwarmer pockets and zip that’s easy to operate with mitts on, or the ability to attach a stonking pull tab.


This doesn’t want to cost the same as a full spec shell or a down jacket as you won’t wear it all the time and being affordable means you are more likely to buy one.


The answer to this checklist is, of course, a synthetic, high loft, filled jacket. Warmer, more windproof and more compact than a fleece (for about the same weight), it will give almost as much insulation as a down jacket, but more cheaply and without any worries about the insulation dying - with the downside being it’s 20-30% bulkier and heavier than down. This type of jacket is best illustrated by Patagonia’s DAS Parka which was probably the first jacket that filled these criteria on the market (although there were some good synthetics around in the ‘70s and ‘80s also) and one which quickly became known as the ‘belay jacket’ (popularized by climbers like Mark Twight), although its usefulness goes far beyond technical climbing.

The word ‘belay jacket’ is now firmly in the climber’s lexicon, a sign that the concept really works, although saying that a lot of climbers haven’t yet turned on to the system, more due to a lack of suitable jackets on the market (and shops not stocking them) rather than a lack of interest. If you haven’t tried the concept then you’re more likely to go for a nice smart down jacket that you can wear around town.

Personally, I’ve found the use of the belay jacket has really extended my climbing (as in my survivability) as it has saved my ass countless times (and many others who’ve borrowed my jacket) and I don’t think I’m being melodramatic when I say I probably wouldn’t be writing this without it.

What I most like about this type of jacket is its resistance to the elements, meaning when the proverbial hits the fan you can still operate effectively (keep climbing, descend etc) far longer than a climber without one (both physically and more importantly mentally). Sure, a down jacket maybe a couple of hundred grams lighter, but once it gets wet it’s far heavier and isn’t as warm. Another factor is that if you rip your jacket, down won’t pour out, meaning it’s not a good idea to wear it when doing technical climbing.

For a team of two carrying two jackets means that on really long belays (standing at the bottom of The Vicar, or waiting for your mate to find a good belay on The Fly) you can wear both jackets, providing enough insulation for even the most arctic of temperatures. Also having this spare insulation can prove vital if an accident occurs, as combined with a bothy bag and modern survival bag (Blizzard Bag for example) can give a significant safety advantage. I’m told a lot of guides really like this concept as they can throw their belay jackets on their clients when they begin to flag in a storm (more inexperienced people are more prone to either ‘cold panic’ or failing to recognize the onset of mild hypothermia).

The belay jacket doesn’t last as long as a down jacket, both due to its synthetic fill’s tendency to slowly lose loft and, more importantly, the fact that you give it a lot more hammer. My current jacket has done about three months worth of major trips over two years in total and although I’ve been careful to look after its loft its shell now has more holes in it than Jeffery Archer’s life story and is far beyond repair (it’s done everything I could have asked of it).


Firstly, when I say fill what I mean is the type of insulation used, as it’s not actually a fill like down i.e. it’s not stuffed in the jacket as it’s sewn in. In the past synthetic fills were prone to being heavy, bulky and not that resilient to repeated compression, meaning their loft would quickly drop off. Modern synthetics are now encroaching on the lofty (get it) heights of down, being only a little heavier and having a much greater life span if looked after (avoid tumble drying or hot washes). Down is still the tops when it comes to warmth, drape and luxurious feel (and always will be), but the advantages of synthetics are now allowing them to do almost as good a job as down but in places where down would quickly die. Here’s a rundown of the main fills:


This is a continuous filament, meaning it is manufactured in a single strand that when spun together forms the loft (up to 8,000km long). The main feature of 3D is that it has a hollow cored fibre that has a triangular cross-section, making it both warmer than a straight solid fibre and more resistant to compression, meaning it will maintain its loft even with a lot of hard abuse. The fibres are very fine (14 microns) and slick, meaning it’s soft and very compressible - perhaps not as compressible as other fills but this translates into a longer loft life.


This is an ultra-fine short filament (15 microns) fibre, meaning that instead of having a single strand you’ve got something far more like down (seven microns) with a vast number of individual fibres being stabilized by a thermally bonded scrim. Primaloft was originally designed for the US army as a viable alternative to down, being very warm (warmer than it looks, in fact) and compressible and it is perhaps the nearest we’ve got to man-made down so far. The individual fibres have a special water-resistant coating giving the fill a very high water resistance, absorbing very little moisture and drying fast. The downside of the fill’s down-like qualities is that it is slightly more affected by repeated compression - although in clothing this isn’t as big a factor as in sleeping bags.