Insulation

Wind Chill and the Compression of Insulation

Normally convection and evaporation are the primary considerations when thinking about insulation. However, very high winds can compress your insulation and reduce its protection (thicker insulation traps more air). The more compressible and packable it is, the less it will insulate in the high winds that are sometimes capable of knocking you off your feet. Also, very lightweight down insulation may be compressed when worn beneath heavy waterproof clothing - one reason that lightweight shell fabrics are used in the construction of these types of garments.

Tests conducted at Manchester University show that FurTech fabrics maintain more than half their thickness under loads equivalent to windspeeds of 286 miles per hour (460km/h)!!!

Rope Work and Insulation

Whether you pitch it or move together should depend on the protection you require, but different styles may need different clothing strategies. Climbing long pitches may involve long periods of time belaying and often some sort of overshell insulated jacket will be very useful. Moving together is obviously very different, with a consistent heat output and no stops.

On easier climbs and scrambles I often find myself short pitching and moving together. This reduces the amount of time spent on belay and means there's less time to get cold, so donning an Overshell isn't necessary. However, it may be useful to carry one in case short stops become longer ones. The leader may be best positioned to make that judgement call and shout down his advice. A shortish rope also makes communication so much easier.

Layering with the ShellTA

The ShellTA can be used for emergency or planned bivis as a tarp, bivi bag or storm shelter, but is also useful as a mountain changing room, solving the problem of how to add layers in wet weather. It's a simple concept, pulling the ShellTA over your head and changing inside, but the clever bit is that its waterproof breathable fabric, sucks water off wet clothing while at the same time protecting you from the weather. This means that less water is trapped between inner layers and you stay warmer and drier. It's even useful when adding an Overshell over waterproofs in wet weather.

For more information please click here.

The ShellTA can be bought here.

Layering in the Wet

If you need to add insulation in the rain, remove as much of the wetness as possible. Shaking the fabric can help. This reduces the reverse breath ability effect which can dampen under layers as the rain evaporates inwards and it improves the effectiveness of the insulation. This post shows just how much insulation you lose when it gets wet.

It's useful to have a clan tent, bothy bag or shelter so that you can get out of the weather. The ShellTA design uses a hydrophilic waterproof breathable material which absorbs water and helps to remove wetness from your layers as you change, which can help enormously.

Blizzard Jacket Photos

Here are a few pictures of the Blizzard Vest. The jacket has transparent PU sleeves which add waterproofing and help to seal out drafts. Despite its 1950s sci-fi appearance they work surprisingly well. (Please click to enlarge.)

Hypothermia Without Shivering!

I'd over done it. I hadn't been out running for months, I was feeling the effects of the Christmas festivities, I'd set off too quick and climbed Clough Edge too fast. Now I was struggling across the frozen peat of Bleaklow following the Pennine Way. I can't quite put my finger on how I felt, but it wasn't good and somewhere near Hern Clough my run became a walk.

My memory of most of this isn't very vivid but a few things stay with me very clearly. The second is a grassy pit near Mossy Lea Farm, lined with dry grass that looked as inviting as fur and I had the strongest desire to curl up in it and go to sleep. But by then I already new things were bad. I have a vivid memory of my hand, gloved in thin fleece and covered in rivulets of ice where water had dribbled from my bladder hose, yet I was feeling warm and had taken my hat off and zipped my windproof open. I was only wearing a thin baselayer, windproof, leggings, gloves and bladder sack. The wind was blasting across the moor.

I also remember being determined to keep going, to get home. And the feeling of cold, grey, damp, immobile lifelessness, like a dead fish, that persisted for a surprisingly long time, even after I'd got back into our warm house and stumbled into the shower.

I'd bitten off more than I could chew and misjudged the balance between fitness, distance, conditions and clothing. But the interesting thing is that there was no shivering warning of impending hypothermia. Just a straight switch from vigorous activity to brain not working properly.

Click here for more on hypothermia.

Swiss Air Rescue and the Swiss Alpine Club

Blizzard Survival Bags are now an integral part of the rescue kits on board their Eurocopter EC145s.

Trail Review Blizzard Jackets

Trail reviewed various synthetic jackets in the February 2008 issue, including the Blizzard Jacket as a rank outsider. They praised it as an excellent lightweight survival jacket but it clearly isn't the same type of garment as the others tested.

The magazine included insulation tests at Leeds university which were interesting:-

1. Blizzard Jacket (reflexcell), £25, 250g, 4.8Togs, warmth:weight 19.2
2. Mountain Equipment Aplamayo (primaloft), £140, 535g, 2.7Togs, warmth:weight 5.0
3. Rab Neutrino Endurance (down), £200, 648g, 7.4Togs, warmth:weight 11.4

Contrary to some of the other information available about the Blizzard Reflexcell technology these tests show that the warmth to weight ratio doesn't quite double the performance of one of the best down jackets on the market, though it came close. However, this is like trying to compare chalk, cheese and chips!

(This post is copied from "Reviews")

Blizzard Tog Values

Blizzard Reflexcell offers about 8 Togs of insulation (as tested by Leeds University). It is particularly effective for emergency use because it loses very little performance when wet and is completely waterproof. Click here for more on the reduction of insulation in the wet and here for more information on Tog values.

Please click the graph to enlarge.

Outdoors Magic Blizzard Review

This link takes you to the Outdoors Magic review of the Blizzard Bag.

You can find posts on my experiences of using Blizzard kit here. (Please scroll down to find posts relating to OMM)