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push 3 season bag and pad into light 4 season
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Jun 11, 2011 at 8:41 am #1275266
my 4 season gear:
– Isomat Exped Downmat 7, 957g
– Sleeping bag Mammut Tyin Winter -15C, 2778gmy 3 season gear:
– Sleeping bag All Black 0C, 680g (windproof down bag)
– Isomat Thermarest Prolite, 575gI find having extra winter gear disturbing, bulky and heavy…
I plan to push the 0C bag with insulation layers on my body, possibly a bivy too. I should get as low as -10C I think…
What about the pad? How can I push this without adding too much weight/bulk? cell foam pad? which one?Jun 22, 2011 at 10:52 am #1752103no suggestions/experiences to share here?
I plan to push my 0C (freeezing temp) with an insulation layer (top/pants)…
on the pad I plan adding a closed cell foam pad (how much R-value do I need to end up with)?This should do it, right?
Jun 22, 2011 at 12:21 pm #1752142You should be able to get close to -10C if you aim for R-5 and a mid-filled down jacket and pants (montbell alpine line jacket, down inner pants). The best way is to look at the fill weights of all your gear and comparable sleeping bags and use that to work as a rough guideline. You can add 5 degrees for a margin of safety.
For example, for my sleeping system, my quilt has 9oz of fill, the flash jacket has 3oz of fill, the down pants have 2oz of fill. This is 14oz of fill. The Katabatic Sawatch is conservatively rated at 15 degrees has 15oz of fill (minus balaclava).
Since it's conservatively rated, I figure I can ignore the 1oz difference, especially paired with the extra fabric layers from using a sleep system. I use a bivy in cold or wet weather, so I also ignore the lack of a balaclava with the Swatch. I figure I'll be fine for any forecasts of 20 degrees or higher (15 degrees without the 5 degree margin of safety), as I've managed to push an aggressively-rated 20 degree bag to 18 degrees with an aggressively-rated R-4 pad (more like R-3 or R-3.5).
This all is so personal, you really need to experiment to know what you can handle. But it is possible, with the right gear and body physiology to push a 0C bag to -10C. You'll want to aim for an ~R-5 pad. I use different CCF pads with my NeoAir, max'ing out at R-4.5 combined.
A full belly goes a long way also.
Jun 25, 2011 at 1:48 pm #1753259thanks for sharing this Brian… good to know R5 is about what I'm looking at for the pad & thanks for the tip with comparing the fills for the clothing/bag… cheers,
Jun 25, 2011 at 3:27 pm #1753275I'm pretty new to winter backpacking, but my understanding – and observation – is that at sub-freezing temperatures you need a lot more pad insulation if you're on a bare surface than if you're on snow.
Jun 25, 2011 at 6:43 pm #1753333My REI bag is rated 20 F (-7 C) so it's probably really 25 (-4) and I have slept very comfortably in it at -2 F (-19) wearing my puffy clothing (Fugu jacket & Cocoon pants) and extra socks (I get cold feet) with my NeoAir sandwiched between 2 generic blue 1/2 inch (12 mm) CCF pads.
You might look into Oware's new winter torso pad. Pretty good price for an R2 though don't know what int'l shipping would be.
Jun 26, 2011 at 7:08 am #1753418I spent a couple nights out at -10f in a 15f bag last winter. I was using all the usual tricks: Bivy dry insulation, prolite+ and foam pad. The only thing I can add is the use of foam sit pads to cover cold spots in your bottom insulation. In my case as a side sleeper, under my hips and shoulders. It made the difference between sleep and no sleep for me. Mine are cut to fit in the bottom of a milk crate to act as a bottom, lid, seat pad on crate, sit pad, knee pad and "spot insulation. I know a milk crate is'nt SUL, but it intigrates into my pulk based winter "system" at this point.
Jun 26, 2011 at 7:33 pm #1753568my first question is how does your bag feel at freezing? as we all sleep a little differently (warm to cold) you need to know where you fit in that scheme and also how accurate your bag rating is for you.
it's certainly not out of the question to gain 10 degrees (maybe even more) w/ insulating clothing, if you add a bivy you can figure adding a few more degrees
as others have mentioned, insuring an adequate r rated pad is critical- just as easy to freeze from underneath
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