When I heard that Therm-a-Rest’s new Hyperion 20 sleeping bag was rated for 20 degrees Fahrenheit-even at an impossibly light weight of 1lb. 4oz.-I needed to know if it could actually handle all that cold.
The bag uses a number of tech advances to achieve the warmth at such a low weight. The bag incorporates what Therm-a-Rest calls “Box Bafffled Construction.” What that means is within the bag certain areas prone to cold spots, like at the seams of the bag, have mesh box baffles to separate chunks of down from one another. This maximizes the loft of the down to get greater thermal efficiency out of what is packed in.
Of course, the down they use is equally as high tech. Wet down isn’t as effective as dry down, so bag uses 900-fill Nikiwax Hydrophobic down. It absorbs 90 percent less water than standard down, it maintains its loft (think warmth) 60 times longer than standard down, and if it does get wet, it dries three times faster than standard down.
But Therm-a-Rest wanted to get the most out of both of these innovations, so they thought carefully of just where they put them. To lower weight, they gave you down where you need it, and pulled it from where you don’t. That means the down is distributed unevenly with 70 percent on the sides and top, and just 30 percent on the back. As an extra feature, the bag is ready with SynergyLink connectors so you can snap the bag to a compatible Therm-a-rest mattress for greatest efficiency. But that isn’t necessary to get serious warmth out of this bag.
That’s all nice, but those are the stats. I needed to see what this bag was capable of, and in the depths of winter in Vermont, that could mean a lot of things. But the idea of sleeping in my 22-degree backyard, next to my truck and trash cans, wasn’t thrilling. Watching The Great Outdoors on my porch, though? That I could do.
I unpacked the bag, walked out to my porch couch with my laptop and a bowl of popcorn, and got settled in. The Hyperion comes as a mummy bag, but I opted to just pull it up to my shoulders and wear a beanie for the greatest movie watching-and popcorn eating-experience.
With the hydrophobic down, I didn’t mind too much as the foot box of the bag settled into a pile of snow on my porch, I didn’t notice the cold of it anyway. As the somewhat predictable slapstick antics of John Candy and Dan Akroyd developed, I had to pull my torso out of the bag only 20 minutes in. I was getting too warm.
As I found the comfortable position, with the bag pulled about halfway up my chest, I had the weird experience of forgetting I was outside. My front was warm and toasty, I felt dry, the different zones of insulation kept me warn (I never noticed that there was less insulation on the back of the bag), and I could have stayed out there for much longer than the film's runtime.
While The Great Outdoors is mostly mediocre, the bag fared much better. For the weight, the warmth is unreal, but the bag offers so much more. The hydrophobic down and packability alone make this a bag that’s ready for adventures far past the front porch.
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