No, I haven’t been in Scotland.
But it felt like it.
Carol Crooker, Aubrin Heinrichs, and I just spent three days in the Specimen Creek drainage in Yellowstone National Park. We spent last night at Sedge Lake.
When we left, the weather was forecast for lows near 10 degrees – perfect winter conditions. Instead, we awoke this morning to temperatures that were exactly 32 degrees in my Epic tent and overnight snowfall of nearly a foot of heavy crud.
After two nights of this, it became clear that any gear – whether down or synthetic – is going to fail. It’s just a matter of when, and time zero starts at the trailhead.
Just for kicks, we weighed our bags and measured their loft when we got back into town tonight.
Carol was using a Valandre Shocking Blue, which lost almost 20% of its loft for a weight gain of water of around 10%. I was using an Arc X, which only weighs a pound dry, gained 25% of its weight in water (interestingly, about the same weight gain as the Shocking Blue – 4 oz or so), but with far less down to buffer the effect, lost an amazing 80% of its loft.
Neither bag was particularly “flat” this morning – we speculate that the primary mechanism by which so much loft is lost is during packing – stuffing a bag with moisture on its shell into a stuff sack, causing that moisture to migrate into the insulation.
In these conditions, synthetic will delay failure, but not necessarily prevent it. My synthetic jacket, a MontBell Thermawrap Parka, which I wore in camp and on the trail at rest while it was snowing/slushing, gained about 25% of its weight as well, but lost less than 10% of its loft.
And so, if you’re heading out into winter crap, which is about the only term that describes “temperatures near freezing with sustained heavy snow and rain and no opportunity to dry gear”, follow these rules:
1. Down won’t work. Don’t even try to make it work. No waterproof-breathable fabric bivy sack or tent will help. No super breathable system (think: tarp, no bivy) will help. At these temperatures, the dew point will be inside the bag and any moisture in your shelter (bivy, tent, tarp, snow cave, it doesn’t matter) will condense on the outer fabric. You’ll pack your wet bag into a stuff sack in the morning and enjoy the beginning of an absolutely awful night when you unpack it that evening.
2. Synthetics won’t work either. But they at least will allow you to spend an extra night or two.
My pick for shelter and sleep systems:
If you like a double wall tent, use one with NO mesh in the inner tent, so condensation can readily pass through its fabric. Or, a single wall tent made of eVENT. Gore-Tex and Epic tents fail miserably at temperatures near freezing when the humidity is high. Tarps should offer protection from blowing snow. Pyramid-type shelters are popular but vent moisture poorly. Standard tarps let in a lot of spindrift. If using the latter, you best have a bivy of some sort – I recommend eVENT. Pair any of these options with a synthetic sleeping bag with synthetic fill parka and pants, and even in the worst of conditions (sustained), you should be able to buy yourself enough warmth for a 5 or 6 day trek.