Having bought a not inexpensive bivvybag – a Snugpak Special Forces in case you’re wondering – and endured within it an unpleasantly damp night pelted by heavy Welsh rain and slopping around in my own condensation, I was nonetheless determined to persevere. Returning to Ronald Turnbull’s Book of the Bivvy, I ruefully contemplated his basic law of bivvying – you’ll either be ‘Wet and Warm, or Cold and Dry’. It doesn’t sound great, does it?
Still, the lure of the bivvybag for me endures. It potentially means I can fit a complete three season sleepout into a daysack. Not only that, I can in theory doss down in any old crook and nanny; no more anxious searches for a flat and big enough pitch with darkness closing in, no more fiddling with pegs. No more staying dry.
After at least several seconds of deep contemplation it occurred to me that the secret of a happy bivvy is that ideally it shouldn’t actually rain. Just call me Einstein. So when a casual glance at the weather forecast indicated an entire day of heavy downpours, I set out again. No, wait – it also predicted a completely dry night, followed by a sunny morning. Perfect, I could test my re-proofed shell jacket then bivvy out as a bonus.
Into my Haglöfs L.I.M. Lite 25 litre daypack (£22.50 on Gumtree) I can easily fit a three season synthetic sleeping bag, the bivvy, my absurdly luxurious Exped Synmat Winterlite mat and a promising-looking Regatta synthetic insulated jacket I’ve just bought for £20 on eBay (I’m so over down, I’m tired of being cold as well as wet). All that fits into the Exped Schnozzle pump bag which doubles as a pack liner. Off I trot from my own back doorstep, geared up to sleep out in frost, I reckon, with that little lot, and at a total pack weight of less than five kilos, including buns.
After another typical day of Oldie Outdoors adventures (three miles of shingle, hours of lashing rain, freezing squalls off the sea, an excessive lunch of chips and ice cream then annoying tendonitis after accidentally walking 53 km) I found myself bivvied down for the night in a confidential location.
A slight issue with the Norfolk Coast Path is that informal camping is not encouraged and in flat country it’s hard to hide. I tucked myself into a nook at the top of a high dune, both for the view and for the breeze which I was hoping would help with the condensation issue.
The night was cool, dry and starry but there was a heavy dew, so I did have to arrange the bivvy fabric over my face in order to get to sleep. Hence I fully expected to wake in a sack full of water once again. To my surprise, at dawn the foot end of my sleeping bag was very slightly damp but otherwise there was no condensation at all.
Here then are my two top bivvy tips so far, with a big hat tip to RT.
Firstly, to stay dry, you need a cool, dry night and a nice breeze wafting over your bag. In Wales my night out was warm and wet and I’d made the beginner’s error of sleeping out of the wind. Secondly, don’t breathe inside your bag. If you have to cover your face, make a breathing tunnel. I may look into making some kind of small tarp to cover my head. I’ve read elsewhere that it’s even possible to adapt an umbrella, just to keep dew and rain off your face.
Both these tips arise from the basic laws of breathability. For a waterproof fabric to ‘breathe’ there must be a moisture differential across it, the inside wetter than the outside. You also want a temperature differential – inside warmer than out – plus moving air externally to draw away vapour. If all three of these conditions apply, your membrane will breathe and you’ll stay dry. On a warm night, in pouring rain and with no breeze, your bivvybag will fill with condensation: get used to it.
Why then would we endure bivvying, waking up in an obscure sand dune in the middle of nowhere at five a.m. when all sane people are in beds, in proper houses? This is why….