I was on a caving trip this weekend, but we camped outside the cave during the nights, and it was raining all weekend, thats three nights of rain. I brought all synthetic insulations on this trip and now have a greater appreciation for their ability to keep you warm when wet. It was about 35 degrees each night+-. and I wore under armor cold gear top, polyester tights, polyester compression shorts(underwear),a fleece beenie, fleece socks, and a cocoon jacket. inside my 50 degree mont bell clo-up sheet, and I was warm enough. I also had a fleece vest, but did not wear it while sleeping, but did in adition to my under armor, fleece hat, and nylon pants in the 50 degree cave
any way, I was thinking when I got back, I would rather have synthetics all the time, and I was confused as to how they are so heavy. So I went to thru-hiker.com and checked out what they had to make a sleeping bag. I guessed that for an arc bag, you would need less than 5 yards of fabric. thats only about 5 oz with .9oz fabric but I added an ounce for webbing, draw cord and toggles, that means only about a 6 oz shell for a bag without baffles. and for insulation you only need about 2 yards. and I found some 1 inch thick climasheild HL for only 2.7oz a yard, I rounded to 3 oz a yard X 2 thats six ounces for insulation. thats a 12oz(probably less) synthetic 40-45 degree arc bag.
I guessed on this temp rating of 40-45 for a 1 inch loft
why is this not made by a big company?
or even warmer bag with 2 layers of climasheild HL thats 1.5-2 inches of loft
so you need 4 yards instead of 2 and the 6 oz shell
2.7 X 4= 10.8
10.8 + 6= 16.8
thats a 30-35 degree synthetic bag for a pound
Ray jardine says 2 layers of .9" synthetic is rated 28 degrees
am I missing something here?
sounds good to me.