by Alteknacker » Fri Apr 12, 2019 11:42 pm
My tuppence worth...
1. I agree completely with mrssanta and Holly that the R value of the mattress is the most important thing, even more so in the case of a down sleeping bag (because the down squashes flat when you lie on it and provides very little insulation). The highest R value I'm aware you can get is 5.7 (Exped). I've used my Exped in the depths of winter, and been fine with a 3/4 season bag sleeping on icy ground in temperatures well below zero, and only wearing pyjamas.
2. If you want light and tiny, it really has to be down. And it is possible to keep it dry, if you're careful. I recently bought a new goose down bag from a Chinese supplier on the internet - 800 cuin, and 380gm non-hydrophobic down. The reason was that I wanted as light a bag as possible for multi-day trips. It weighs 720gm and packs into a minute 6 litres!!! The comfort temperature rating is 3 degrees, and the comfort limit is -2 degrees. It cost £90. When it arrived I saw that the zip baffle didn't really cover the zip effectively when the bag is in use, so I had to sew in velcro strip to ensure proper cover.
I made this product choice after extensive comparison of what was available.
I tested it on the recent WH weekend meet in Applecross, when the night temperatures were pretty close to zero, and I was perfectly warm.
By comparison:-
- my other 3/4 season down bag weighs 1.5kg, and has a packed volume of 19 litres! Comfort temp is -2, comfort limit temp is -9 degrees.
- the Vango Ultralite 300 weighs 1.35 kg, has a packed volume of 12 litres, and claims a comfort temp of -1 degrees (of which I'd be quite sceptical!!).
- the Snugpak Softie 3 weighs 900gm, claims a packed volume of 3 litres!!!!, and a comfort temp of 5 degrees. For the weight and claimed volume I would want testimony from someone who'd used it that it really is good for 5 degrees - this seems very unlikely to me. And I simply don't believe the claimed packed volume.
Finally, I have the results of my research on a spreadsheet, which I'm happy to share with you. Just send me a PM if you're interested.
On the subject of bivvy bags, I bought a Karrimor bag just before Christmas, tried it out in the garden on a very frosty night and was warm and dry. On the strength of this I plan to use it this year, late spring. It weighs a bit over 200gm, which light weight was a primary factor in choosing it. I know the Hunka is the "gold standard", but I felt that the 200gm weight of the Karrimor, if it worked, was very attractive. Hence buying and testing it.
Good luck whatever route you go, and enjoy the wild!!!
AK