If you’ve read “Planning Your Thru-Hike of the John Muir Trail”, you know that I recommend hiking later in the season. As I put it in the book:
“The window of opportunity to hike the trail is chronologically bounded on both sides in white, and the white is snow. The high mountain passes are the problem, and since many of them are over 11,000 feet, it’s not unusual to find substantial accumulations well into July. If the snows have been particularly heavy the winter before, the passes can be difficult even in early August. (The year 2011 was just such a year.)
“When the snow begins to melt you’re faced with a couple of different problems: lots of swollen streams, with deep, rapidly flowing water, and an abundance of mosquitoes.
“Unless you are an experienced hiker in these conditions, I strongly recommend against starting your hike early in the summer.
“There is a weather nirvana, however, where the streams flow gently and the mosquitoes are conveniently dead (murdered in their sleep, during nights of near freezing weather). That place is: September.”
The same cold weather that eliminates those buzzing pests also requires a warmer sleeping bag, particularly if you are a cold sleeper, like I am. Either a down-filled or a synthetic-filled sleeping bag, appropriately rated (for me, that means getting a bag with a rating about 15 degrees lower than I expect to encounter), will keep you warm. So what are the differences?
The differences are these: price, water-resistance, weight and bulk.
Price: down bags are a tad pricey, no doubt about it. You can find them under $100, but a good one that will pack small and keep you warm at Guitar Lake in September will be closer to $200. Want the very best? Marmot has a zero-degree bag that weighs less than three pounds for only $500!
Water-resistance: you would think that a sleeping bag stuffed with fine feathers plucked from the skin of waterfowl would be just what you want in a damp environment. Not true! Down sleeping bags lose almost all of their insulating capabilities when wet, and they take a very long time (and the right conditions) to dry. If you are caught in the rain, far from a bail-out point, and your only way to keep warm is with a wet, down sleeping bag, you are in trouble. I hope you can start a fire in the rain, because hypothermia is not too far away.
During the day, you can keep a down bag dry pretty easily—just put it in a waterproof bag. At night, make sure your tent is properly pitched in order to keep water away from the down.
Synthetic bags won’t keep you comfortably warm if they’re wet, either, but they will keep you alive.
Weight and bulk: besides keeping you comfy while you sleep, the real advantage of down is that it is light, and can be stuffed into impossibly small bags. The down weighs little, and its compressibility is nothing less than amazing. The synthetics are getting better, but still can’t compete on this point alone.
What did I do? I took a down bag (carried in a waterproof bag) and I slept in a tent that was a proven rain-shedder. That strategy worked well, for me. If you are going to try to save a bunch of weight by taking a less weather-resistant tent, or if you intend to sleep under a simple tarp, I wouldn’t run the risk of using down; spend some of that weight you saved on shelter and use it for a synthetic sleeping bag.
Good hiking, Ray
UPDATE: Can you have your cake and eat it, too? Perhaps you can with water-resistant down!